verilog: fix multiple AST_PREFIX scope resolution issues

[yosys.git] / frontends / ast / simplify.cc

/*
 *  yosys -- Yosys Open SYnthesis Suite
 *
 *  Copyright (C) 2012  Claire Xenia Wolf <claire@yosyshq.com>
 *
 *  Permission to use, copy, modify, and/or distribute this software for any
 *  purpose with or without fee is hereby granted, provided that the above
 *  copyright notice and this permission notice appear in all copies.
 *
 *  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 *  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 *  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 *  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 *  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 *  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 *  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 *  ---
 *
 *  This is the AST frontend library.
 *
 *  The AST frontend library is not a frontend on it's own but provides a
 *  generic abstract syntax tree (AST) abstraction for HDL code and can be
 *  used by HDL frontends. See "ast.h" for an overview of the API and the
 *  Verilog frontend for an usage example.
 *
 */

#include "kernel/log.h"
#include "libs/sha1/sha1.h"
#include "frontends/verilog/verilog_frontend.h"
#include "ast.h"

#include <sstream>
#include <stdarg.h>
#include <stdlib.h>
#include <math.h>

YOSYS_NAMESPACE_BEGIN

using namespace AST;
using namespace AST_INTERNAL;

// Process a format string and arguments for $display, $write, $sprintf, etc

std::string AstNode::process_format_str(const std::string &sformat, int next_arg, int stage, int width_hint, bool sign_hint) {
        // Other arguments are placeholders. Process the string as we go through it
        std::string sout;
        for (size_t i = 0; i < sformat.length(); i++)
        {
                // format specifier
                if (sformat[i] == '%')
                {
                        // If there's no next character, that's a problem
                        if (i+1 >= sformat.length())
                                log_file_error(filename, location.first_line, "System task `%s' called with `%%' at end of string.\n", str.c_str());

                        char cformat = sformat[++i];

                        // %% is special, does not need a matching argument
                        if (cformat == '%')
                        {
                                sout += '%';
                                continue;
                        }

                        bool got_len = false;
                        bool got_zlen = false;
                        int len_value = 0;

                        while ('0' <= cformat && cformat <= '9')
                        {
                                if (!got_len && cformat == '0')
                                        got_zlen = true;

                                got_len = true;
                                len_value = 10*len_value + (cformat - '0');

                                cformat = sformat[++i];
                        }

                        // Simplify the argument
                        AstNode *node_arg = nullptr;

                        // Everything from here on depends on the format specifier
                        switch (cformat)
                        {
                                case 's':
                                case 'S':
                                case 'd':
                                case 'D':
                                        if (got_len && len_value != 0)
                                                goto unsupported_format;
                                        YS_FALLTHROUGH
                                case 'x':
                                case 'X':
                                        if (next_arg >= GetSize(children))
                                                log_file_error(filename, location.first_line, "Missing argument for %%%c format specifier in system task `%s'.\n",
                                                                cformat, str.c_str());

                                        node_arg = children[next_arg++];
                                        while (node_arg->simplify(true, false, false, stage, width_hint, sign_hint, false)) { }
                                        if (node_arg->type != AST_CONSTANT)
                                                log_file_error(filename, location.first_line, "Failed to evaluate system task `%s' with non-constant argument.\n", str.c_str());
                                        break;

                                case 'm':
                                case 'M':
                                        if (got_len)
                                                goto unsupported_format;
                                        break;

                                case 'l':
                                case 'L':
                                        if (got_len)
                                                goto unsupported_format;
                                        break;

                                default:
                                unsupported_format:
                                        log_file_error(filename, location.first_line, "System task `%s' called with invalid/unsupported format specifier.\n", str.c_str());
                                        break;
                        }

                        switch (cformat)
                        {
                                case 's':
                                case 'S':
                                        sout += node_arg->bitsAsConst().decode_string();
                                        break;

                                case 'd':
                                case 'D':
                                        sout += stringf("%d", node_arg->bitsAsConst().as_int());
                                        break;

                                case 'x':
                                case 'X':
                                        {
                                                Const val = node_arg->bitsAsConst();

                                                while (GetSize(val) % 4 != 0)
                                                        val.bits.push_back(State::S0);

                                                int len = GetSize(val) / 4;
                                                for (int i = len; i < len_value; i++)
                                                        sout += got_zlen ? '0' : ' ';

                                                for (int i = len-1; i >= 0; i--) {
                                                        Const digit = val.extract(4*i, 4);
                                                        if (digit.is_fully_def())
                                                                sout += stringf(cformat == 'x' ? "%x" : "%X", digit.as_int());
                                                        else
                                                                sout += cformat == 'x' ? "x" : "X";
                                                }
                                        }
                                        break;

                                case 'm':
                                case 'M':
                                        sout += log_id(current_module->name);
                                        break;

                                case 'l':
                                case 'L':
                                        sout += log_id(current_module->name);
                                        break;

                                default:
                                        log_abort();
                        }
                }

                // not a format specifier
                else
                        sout += sformat[i];
        }
        return sout;
}


void AstNode::annotateTypedEnums(AstNode *template_node)
{
        //check if enum
        if (template_node->attributes.count(ID::enum_type)) {
                //get reference to enum node:
                std::string enum_type = template_node->attributes[ID::enum_type]->str.c_str();
                //                      log("enum_type=%s (count=%lu)\n", enum_type.c_str(), current_scope.count(enum_type));
                //                      log("current scope:\n");
                //                      for (auto &it : current_scope)
                //                              log("  %s\n", it.first.c_str());
                log_assert(current_scope.count(enum_type) == 1);
                AstNode *enum_node = current_scope.at(enum_type);
                log_assert(enum_node->type == AST_ENUM);
                while (enum_node->simplify(true, false, false, 1, -1, false, true)) { }
                //get width from 1st enum item:
                log_assert(enum_node->children.size() >= 1);
                AstNode *enum_item0 = enum_node->children[0];
                log_assert(enum_item0->type == AST_ENUM_ITEM);
                int width;
                if (!enum_item0->range_valid)
                        width = 1;
                else if (enum_item0->range_swapped)
                        width = enum_item0->range_right - enum_item0->range_left + 1;
                else
                        width = enum_item0->range_left - enum_item0->range_right + 1;
                log_assert(width > 0);
                //add declared enum items:
                for (auto enum_item : enum_node->children){
                        log_assert(enum_item->type == AST_ENUM_ITEM);
                        //get is_signed
                        bool is_signed;
                        if (enum_item->children.size() == 1){
                                is_signed = false;
                        } else if (enum_item->children.size() == 2){
                                log_assert(enum_item->children[1]->type == AST_RANGE);
                                is_signed = enum_item->children[1]->is_signed;
                        } else {
                                log_error("enum_item children size==%lu, expected 1 or 2 for %s (%s)\n",
                                                  enum_item->children.size(),
                                                  enum_item->str.c_str(), enum_node->str.c_str()
                                );
                        }
                        //start building attribute string
                        std::string enum_item_str = "\\enum_value_";
                        //get enum item value
                        if(enum_item->children[0]->type != AST_CONSTANT){
                                log_error("expected const, got %s for %s (%s)\n",
                                                  type2str(enum_item->children[0]->type).c_str(),
                                                  enum_item->str.c_str(), enum_node->str.c_str()
                                                );
                        }
                        RTLIL::Const val = enum_item->children[0]->bitsAsConst(width, is_signed);
                        enum_item_str.append(val.as_string());
                        //set attribute for available val to enum item name mappings
                        attributes[enum_item_str.c_str()] = mkconst_str(enum_item->str);
                }
        }
}

static bool name_has_dot(const std::string &name, std::string &struct_name)
{
        // check if plausible struct member name \sss.mmm
        std::string::size_type pos;
        if (name.substr(0, 1) == "\\" && (pos = name.find('.', 0)) != std::string::npos) {
                struct_name = name.substr(0, pos);
                return true;
        }
        return false;
}

static AstNode *make_range(int left, int right, bool is_signed = false)
{
        // generate a pre-validated range node for a fixed signal range.
        auto range = new AstNode(AST_RANGE);
        range->range_left = left;
        range->range_right = right;
        range->range_valid = true;
        range->children.push_back(AstNode::mkconst_int(left, true));
        range->children.push_back(AstNode::mkconst_int(right, true));
        range->is_signed = is_signed;
        return range;
}

static int range_width(AstNode *node, AstNode *rnode)
{
        log_assert(rnode->type==AST_RANGE);
        if (!rnode->range_valid) {
                log_file_error(node->filename, node->location.first_line, "Size must be constant in packed struct/union member %s\n", node->str.c_str());

        }
        // note: range swapping has already been checked for
        return rnode->range_left - rnode->range_right + 1;
}

[[noreturn]] static void struct_array_packing_error(AstNode *node)
{
        log_file_error(node->filename, node->location.first_line, "Unpacked array in packed struct/union member %s\n", node->str.c_str());
}

static void save_struct_array_width(AstNode *node, int width)
{
        // stash the stride for the array
        node->multirange_dimensions.push_back(width);

}

static int get_struct_array_width(AstNode *node)
{
        // the stride for the array, 1 if not an array
        return (node->multirange_dimensions.empty() ? 1 : node->multirange_dimensions.back());

}

static int size_packed_struct(AstNode *snode, int base_offset)
{
        // Struct members will be laid out in the structure contiguously from left to right.
        // Union members all have zero offset from the start of the union.
        // Determine total packed size and assign offsets.  Store these in the member node.
        bool is_union = (snode->type == AST_UNION);
        int offset = 0;
        int packed_width = -1;
        // examine members from last to first
        for (auto it = snode->children.rbegin(); it != snode->children.rend(); ++it) {
                auto node = *it;
                int width;
                if (node->type == AST_STRUCT || node->type == AST_UNION) {
                        // embedded struct or union
                        width = size_packed_struct(node, base_offset + offset);
                }
                else {
                        log_assert(node->type == AST_STRUCT_ITEM);
                        if (node->children.size() > 0 && node->children[0]->type == AST_RANGE) {
                                // member width e.g. bit [7:0] a
                                width = range_width(node, node->children[0]);
                                if (node->children.size() == 2) {
                                        if (node->children[1]->type == AST_RANGE) {
                                                // unpacked array e.g. bit [63:0] a [0:3]
                                                auto rnode = node->children[1];
                                                int array_count = range_width(node, rnode);
                                                if (array_count == 1) {
                                                        // C-type array size e.g. bit [63:0] a [4]
                                                        array_count = rnode->range_left;
                                                }
                                                save_struct_array_width(node, width);
                                                width *= array_count;
                                        }
                                        else {
                                                // array element must be single bit for a packed array
                                                struct_array_packing_error(node);
                                        }
                                }
                                // range nodes are now redundant
                                for (AstNode *child : node->children)
                                        delete child;
                                node->children.clear();
                        }
                        else if (node->children.size() == 1 && node->children[0]->type == AST_MULTIRANGE) {
                                // packed 2D array, e.g. bit [3:0][63:0] a
                                auto rnode = node->children[0];
                                if (rnode->children.size() != 2) {
                                        // packed arrays can only be 2D
                                        struct_array_packing_error(node);
                                }
                                int array_count = range_width(node, rnode->children[0]);
                                width = range_width(node, rnode->children[1]);
                                save_struct_array_width(node, width);
                                width *= array_count;
                                // range nodes are now redundant
                                for (AstNode *child : node->children)
                                        delete child;
                                node->children.clear();
                        }
                        else if (node->range_left < 0) {
                                // 1 bit signal: bit, logic or reg
                                width = 1;
                        }
                        else {
                                // already resolved and compacted
                                width = node->range_left - node->range_right + 1;
                        }
                        if (is_union) {
                                node->range_right = base_offset;
                                node->range_left = base_offset + width - 1;
                        }
                        else {
                                node->range_right = base_offset + offset;
                                node->range_left = base_offset + offset + width - 1;
                        }
                        node->range_valid = true;
                }
                if (is_union) {
                        // check that all members have the same size
                        if (packed_width == -1) {
                                // first member
                                packed_width = width;
                        }
                        else {
                                if (packed_width != width) {

                                        log_file_error(node->filename, node->location.first_line, "member %s of a packed union has %d bits, expecting %d\n", node->str.c_str(), width, packed_width);
                                }
                        }
                }
                else {
                        offset += width;
                }
        }
        return (is_union ? packed_width : offset);
}

[[noreturn]] static void struct_op_error(AstNode *node)
{
        log_file_error(node->filename, node->location.first_line, "Unsupported operation for struct/union member %s\n", node->str.c_str()+1);
}

static AstNode *node_int(int ival)
{
        return AstNode::mkconst_int(ival, true);
}

static AstNode *multiply_by_const(AstNode *expr_node, int stride)
{
        return new AstNode(AST_MUL, expr_node, node_int(stride));
}

static AstNode *offset_indexed_range(int offset, int stride, AstNode *left_expr, AstNode *right_expr)
{
        // adjust the range expressions to add an offset into the struct
        // and maybe index using an array stride
        auto left  = left_expr->clone();
        auto right = right_expr->clone();
        if (stride > 1) {
                // newleft = (left + 1) * stride - 1
                left  = new AstNode(AST_SUB, multiply_by_const(new AstNode(AST_ADD, left, node_int(1)), stride), node_int(1));
                // newright = right * stride
                right = multiply_by_const(right, stride);
        }
        // add the offset
        if (offset) {
                left  = new AstNode(AST_ADD, node_int(offset), left);
                right = new AstNode(AST_ADD, node_int(offset), right);
        }
        return new AstNode(AST_RANGE, left, right);
}

static AstNode *make_struct_index_range(AstNode *node, AstNode *rnode, int stride, int offset)
{
        // generate a range node to perform either bit or array indexing
        if (rnode->children.size() == 1) {
                // index e.g. s.a[i]
                return offset_indexed_range(offset, stride, rnode->children[0], rnode->children[0]);
        }
        else if (rnode->children.size() == 2) {
                // slice e.g. s.a[i:j]
                return offset_indexed_range(offset, stride, rnode->children[0], rnode->children[1]);
        }
        else {
                struct_op_error(node);
        }
}

static AstNode *slice_range(AstNode *rnode, AstNode *snode)
{
        // apply the bit slice indicated by snode to the range rnode
        log_assert(rnode->type==AST_RANGE);
        auto left  = rnode->children[0];
        auto right = rnode->children[1];
        log_assert(snode->type==AST_RANGE);
        auto slice_left  = snode->children[0];
        auto slice_right = snode->children[1];
        auto width = new AstNode(AST_SUB, slice_left->clone(), slice_right->clone());
        right = new AstNode(AST_ADD, right->clone(), slice_right->clone());
        left  = new AstNode(AST_ADD, right->clone(), width);
        return new AstNode(AST_RANGE, left, right);
}


AstNode *AST::make_struct_member_range(AstNode *node, AstNode *member_node)
{
        // Work out the range in the packed array that corresponds to a struct member
        // taking into account any range operations applicable to the current node
        // such as array indexing or slicing
        int range_left = member_node->range_left;
        int range_right = member_node->range_right;
        if (node->children.empty()) {
                // no range operations apply, return the whole width
                return make_range(range_left, range_right);
        }
        int stride = get_struct_array_width(member_node);
        if (node->children.size() == 1 && node->children[0]->type == AST_RANGE) {
                // bit or array indexing e.g. s.a[2] or s.a[1:0]
                return make_struct_index_range(node, node->children[0], stride, range_right);
        }
        else if (node->children.size() == 1 && node->children[0]->type == AST_MULTIRANGE) {
                // multirange, i.e. bit slice after array index, e.g. s.a[i][p:q]
                log_assert(stride > 1);
                auto mrnode = node->children[0];
                auto element_range = make_struct_index_range(node, mrnode->children[0], stride, range_right);
                // then apply bit slice range
                auto range = slice_range(element_range, mrnode->children[1]);
                delete element_range;
                return range;
        }
        else {
                struct_op_error(node);
        }
}

static void add_members_to_scope(AstNode *snode, std::string name)
{
        // add all the members in a struct or union to local scope
        // in case later referenced in assignments
        log_assert(snode->type==AST_STRUCT || snode->type==AST_UNION);
        for (auto *node : snode->children) {
                if (node->type != AST_STRUCT_ITEM) {
                        // embedded struct or union
                        add_members_to_scope(node, name + "." + node->str);
                }
                else {
                        auto member_name = name + "." + node->str;
                        current_scope[member_name] = node;
                }
        }
}

static int get_max_offset(AstNode *node)
{
        // get the width from the MS member in the struct
        // as members are laid out from left to right in the packed wire
        log_assert(node->type==AST_STRUCT || node->type==AST_UNION);
        while (node->type != AST_STRUCT_ITEM) {
                node = node->children[0];
        }
        return node->range_left;
}

static AstNode *make_packed_struct(AstNode *template_node, std::string &name)
{
        // create a wire for the packed struct
        auto wnode = new AstNode(AST_WIRE);
        wnode->str = name;
        wnode->is_logic = true;
        wnode->range_valid = true;
        wnode->is_signed = template_node->is_signed;
        int offset = get_max_offset(template_node);
        auto range = make_range(offset, 0);
        wnode->children.push_back(range);
        // make sure this node is the one in scope for this name
        current_scope[name] = wnode;
        // add all the struct members to scope under the wire's name
        add_members_to_scope(template_node, name);
        return wnode;
}

// check if a node or its children contains an assignment to the given variable
static bool node_contains_assignment_to(const AstNode* node, const AstNode* var)
{
        if (node->type == AST_ASSIGN_EQ || node->type == AST_ASSIGN_LE) {
                // current node is iteslf an assignment
                log_assert(node->children.size() >= 2);
                const AstNode* lhs = node->children[0];
                if (lhs->type == AST_IDENTIFIER && lhs->str == var->str)
                        return false;
        }
        for (const AstNode* child : node->children) {
                // if this child shadows the given variable
                if (child != var && child->str == var->str && child->type == AST_WIRE)
                        break; // skip the remainder of this block/scope
                // depth-first short circuit
                if (!node_contains_assignment_to(child, var))
                        return false;
        }
        return true;
}

static std::string prefix_id(const std::string &prefix, const std::string &str)
{
        log_assert(!prefix.empty() && (prefix.front() == '$' || prefix.front() == '\\'));
        log_assert(!str.empty() && (str.front() == '$' || str.front() == '\\'));
        log_assert(prefix.back() == '.');
        if (str.front() == '\\')
                return prefix + str.substr(1);
        return prefix + str;
}

// convert the AST into a simpler AST that has all parameters substituted by their
// values, unrolled for-loops, expanded generate blocks, etc. when this function
// is done with an AST it can be converted into RTLIL using genRTLIL().
//
// this function also does all name resolving and sets the id2ast member of all
// nodes that link to a different node using names and lexical scoping.
bool AstNode::simplify(bool const_fold, bool at_zero, bool in_lvalue, int stage, int width_hint, bool sign_hint, bool in_param)
{
        static int recursion_counter = 0;
        static bool deep_recursion_warning = false;

        if (recursion_counter++ == 1000 && deep_recursion_warning) {
                log_warning("Deep recursion in AST simplifier.\nDoes this design contain overly long or deeply nested expressions, or excessive recursion?\n");
                deep_recursion_warning = false;
        }

        static bool unevaluated_tern_branch = false;

        AstNode *newNode = NULL;
        bool did_something = false;

#if 0
        log("-------------\n");
        log("AST simplify[%d] depth %d at %s:%d on %s %p:\n", stage, recursion_counter, filename.c_str(), location.first_line, type2str(type).c_str(), this);
        log("const_fold=%d, at_zero=%d, in_lvalue=%d, stage=%d, width_hint=%d, sign_hint=%d, in_param=%d\n",
                        int(const_fold), int(at_zero), int(in_lvalue), int(stage), int(width_hint), int(sign_hint), int(in_param));
        // dumpAst(NULL, "> ");
#endif

        if (stage == 0)
        {
                log_assert(type == AST_MODULE || type == AST_INTERFACE);

                deep_recursion_warning = true;
                while (simplify(const_fold, at_zero, in_lvalue, 1, width_hint, sign_hint, in_param)) { }

                if (!flag_nomem2reg && !get_bool_attribute(ID::nomem2reg))
                {
                        dict<AstNode*, pool<std::string>> mem2reg_places;
                        dict<AstNode*, uint32_t> mem2reg_candidates, dummy_proc_flags;
                        uint32_t flags = flag_mem2reg ? AstNode::MEM2REG_FL_ALL : 0;
                        mem2reg_as_needed_pass1(mem2reg_places, mem2reg_candidates, dummy_proc_flags, flags);

                        pool<AstNode*> mem2reg_set;
                        for (auto &it : mem2reg_candidates)
                        {
                                AstNode *mem = it.first;
                                uint32_t memflags = it.second;
                                bool this_nomeminit = flag_nomeminit;
                                log_assert((memflags & ~0x00ffff00) == 0);

                                if (mem->get_bool_attribute(ID::nomem2reg))
                                        continue;

                                if (mem->get_bool_attribute(ID::nomeminit) || get_bool_attribute(ID::nomeminit))
                                        this_nomeminit = true;

                                if (memflags & AstNode::MEM2REG_FL_FORCED)
                                        goto silent_activate;

                                if (memflags & AstNode::MEM2REG_FL_EQ2)
                                        goto verbose_activate;

                                if (memflags & AstNode::MEM2REG_FL_SET_ASYNC)
                                        goto verbose_activate;

                                if ((memflags & AstNode::MEM2REG_FL_SET_INIT) && (memflags & AstNode::MEM2REG_FL_SET_ELSE) && this_nomeminit)
                                        goto verbose_activate;

                                if (memflags & AstNode::MEM2REG_FL_CMPLX_LHS)
                                        goto verbose_activate;

                                if ((memflags & AstNode::MEM2REG_FL_CONST_LHS) && !(memflags & AstNode::MEM2REG_FL_VAR_LHS))
                                        goto verbose_activate;

                                // log("Note: Not replacing memory %s with list of registers (flags=0x%08lx).\n", mem->str.c_str(), long(memflags));
                                continue;

                        verbose_activate:
                                if (mem2reg_set.count(mem) == 0) {
                                        std::string message = stringf("Replacing memory %s with list of registers.", mem->str.c_str());
                                        bool first_element = true;
                                        for (auto &place : mem2reg_places[it.first]) {
                                                message += stringf("%s%s", first_element ? " See " : ", ", place.c_str());
                                                first_element = false;
                                        }
                                        log_warning("%s\n", message.c_str());
                                }

                        silent_activate:
                                // log("Note: Replacing memory %s with list of registers (flags=0x%08lx).\n", mem->str.c_str(), long(memflags));
                                mem2reg_set.insert(mem);
                        }

                        for (auto node : mem2reg_set)
                        {
                                int mem_width, mem_size, addr_bits;
                                node->meminfo(mem_width, mem_size, addr_bits);

                                int data_range_left = node->children[0]->range_left;
                                int data_range_right = node->children[0]->range_right;

                                if (node->children[0]->range_swapped)
                                        std::swap(data_range_left, data_range_right);

                                for (int i = 0; i < mem_size; i++) {
                                        AstNode *reg = new AstNode(AST_WIRE, new AstNode(AST_RANGE,
                                                        mkconst_int(data_range_left, true), mkconst_int(data_range_right, true)));
                                        reg->str = stringf("%s[%d]", node->str.c_str(), i);
                                        reg->is_reg = true;
                                        reg->is_signed = node->is_signed;
                                        for (auto &it : node->attributes)
                                                if (it.first != ID::mem2reg)
                                                        reg->attributes.emplace(it.first, it.second->clone());
                                        reg->filename = node->filename;
                                        reg->location = node->location;
                                        children.push_back(reg);
                                        while (reg->simplify(true, false, false, 1, -1, false, false)) { }
                                }
                        }

                        AstNode *async_block = NULL;
                        while (mem2reg_as_needed_pass2(mem2reg_set, this, NULL, async_block)) { }

                        vector<AstNode*> delnodes;
                        mem2reg_remove(mem2reg_set, delnodes);

                        for (auto node : delnodes)
                                delete node;
                }

                while (simplify(const_fold, at_zero, in_lvalue, 2, width_hint, sign_hint, in_param)) { }
                recursion_counter--;
                return false;
        }

        current_filename = filename;

        // we do not look inside a task or function
        // (but as soon as a task or function is instantiated we process the generated AST as usual)
        if (type == AST_FUNCTION || type == AST_TASK) {
                recursion_counter--;
                return false;
        }

        // deactivate all calls to non-synthesis system tasks
        // note that $display, $finish, and $stop are used for synthesis-time DRC so they're not in this list
        if ((type == AST_FCALL || type == AST_TCALL) && (str == "$strobe" || str == "$monitor" || str == "$time" ||
                        str == "$dumpfile" || str == "$dumpvars" || str == "$dumpon" || str == "$dumpoff" || str == "$dumpall")) {
                log_file_warning(filename, location.first_line, "Ignoring call to system %s %s.\n", type == AST_FCALL ? "function" : "task", str.c_str());
                delete_children();
                str = std::string();
        }

        if ((type == AST_TCALL) && (str == "$display" || str == "$write") && (!current_always || current_always->type != AST_INITIAL)) {
                log_file_warning(filename, location.first_line, "System task `%s' outside initial block is unsupported.\n", str.c_str());
                delete_children();
                str = std::string();
        }

        // print messages if this a call to $display() or $write()
        // This code implements only a small subset of Verilog-2005 $display() format specifiers,
        // but should be good enough for most uses
        if ((type == AST_TCALL) && ((str == "$display") || (str == "$write")))
        {
                int nargs = GetSize(children);
                if (nargs < 1)
                        log_file_error(filename, location.first_line, "System task `%s' got %d arguments, expected >= 1.\n",
                                        str.c_str(), int(children.size()));

                // First argument is the format string
                AstNode *node_string = children[0];
                while (node_string->simplify(true, false, false, stage, width_hint, sign_hint, false)) { }
                if (node_string->type != AST_CONSTANT)
                        log_file_error(filename, location.first_line, "Failed to evaluate system task `%s' with non-constant 1st argument.\n", str.c_str());
                std::string sformat = node_string->bitsAsConst().decode_string();
                std::string sout = process_format_str(sformat, 1, stage, width_hint, sign_hint);
                // Finally, print the message (only include a \n for $display, not for $write)
                log("%s", sout.c_str());
                if (str == "$display")
                        log("\n");
                delete_children();
                str = std::string();
        }

        // activate const folding if this is anything that must be evaluated statically (ranges, parameters, attributes, etc.)
        if (type == AST_WIRE || type == AST_PARAMETER || type == AST_LOCALPARAM || type == AST_ENUM_ITEM || type == AST_DEFPARAM || type == AST_PARASET || type == AST_RANGE || type == AST_PREFIX || type == AST_TYPEDEF)
                const_fold = true;
        if (type == AST_IDENTIFIER && current_scope.count(str) > 0 && (current_scope[str]->type == AST_PARAMETER || current_scope[str]->type == AST_LOCALPARAM || current_scope[str]->type == AST_ENUM_ITEM))
                const_fold = true;

        // in certain cases a function must be evaluated constant. this is what in_param controls.
        if (type == AST_PARAMETER || type == AST_LOCALPARAM || type == AST_DEFPARAM || type == AST_PARASET || type == AST_PREFIX)
                in_param = true;

        std::map<std::string, AstNode*> backup_scope;

        // create name resolution entries for all objects with names
        // also merge multiple declarations for the same wire (e.g. "output foobar; reg foobar;")
        if (type == AST_MODULE) {
                current_scope.clear();
                std::set<std::string> existing;
                int counter = 0;
                label_genblks(existing, counter);
                std::map<std::string, AstNode*> this_wire_scope;
                for (size_t i = 0; i < children.size(); i++) {
                        AstNode *node = children[i];

                        if (node->type == AST_WIRE) {
                                if (node->children.size() == 1 && node->children[0]->type == AST_RANGE) {
                                        for (auto c : node->children[0]->children) {
                                                if (!c->is_simple_const_expr()) {
                                                        if (attributes.count(ID::dynports))
                                                                delete attributes.at(ID::dynports);
                                                        attributes[ID::dynports] = AstNode::mkconst_int(1, true);
                                                }
                                        }
                                }
                                if (this_wire_scope.count(node->str) > 0) {
                                        AstNode *first_node = this_wire_scope[node->str];
                                        if (first_node->is_input && node->is_reg)
                                                goto wires_are_incompatible;
                                        if (!node->is_input && !node->is_output && node->is_reg && node->children.size() == 0)
                                                goto wires_are_compatible;
                                        if (first_node->children.size() == 0 && node->children.size() == 1 && node->children[0]->type == AST_RANGE) {
                                                AstNode *r = node->children[0];
                                                if (r->range_valid && r->range_left == 0 && r->range_right == 0) {
                                                        delete r;
                                                        node->children.pop_back();
                                                }
                                        }
                                        if (first_node->children.size() != node->children.size())
                                                goto wires_are_incompatible;
                                        for (size_t j = 0; j < node->children.size(); j++) {
                                                AstNode *n1 = first_node->children[j], *n2 = node->children[j];
                                                if (n1->type == AST_RANGE && n2->type == AST_RANGE && n1->range_valid && n2->range_valid) {
                                                        if (n1->range_left != n2->range_left)
                                                                goto wires_are_incompatible;
                                                        if (n1->range_right != n2->range_right)
                                                                goto wires_are_incompatible;
                                                } else if (*n1 != *n2)
                                                        goto wires_are_incompatible;
                                        }
                                        if (first_node->range_left != node->range_left)
                                                goto wires_are_incompatible;
                                        if (first_node->range_right != node->range_right)
                                                goto wires_are_incompatible;
                                        if (first_node->port_id == 0 && (node->is_input || node->is_output))
                                                goto wires_are_incompatible;
                                wires_are_compatible:
                                        if (node->is_input)
                                                first_node->is_input = true;
                                        if (node->is_output)
                                                first_node->is_output = true;
                                        if (node->is_reg)
                                                first_node->is_reg = true;
                                        if (node->is_logic)
                                                first_node->is_logic = true;
                                        if (node->is_signed)
                                                first_node->is_signed = true;
                                        for (auto &it : node->attributes) {
                                                if (first_node->attributes.count(it.first) > 0)
                                                        delete first_node->attributes[it.first];
                                                first_node->attributes[it.first] = it.second->clone();
                                        }
                                        children.erase(children.begin()+(i--));
                                        did_something = true;
                                        delete node;
                                        continue;
                                wires_are_incompatible:
                                        if (stage > 1)
                                                log_file_error(filename, location.first_line, "Incompatible re-declaration of wire %s.\n", node->str.c_str());
                                        continue;
                                }
                                this_wire_scope[node->str] = node;
                        }
                        // these nodes appear at the top level in a module and can define names
                        if (node->type == AST_PARAMETER || node->type == AST_LOCALPARAM || node->type == AST_WIRE || node->type == AST_AUTOWIRE || node->type == AST_GENVAR ||
                                        node->type == AST_MEMORY || node->type == AST_FUNCTION || node->type == AST_TASK || node->type == AST_DPI_FUNCTION || node->type == AST_CELL ||
                                        node->type == AST_TYPEDEF) {
                                backup_scope[node->str] = current_scope[node->str];
                                current_scope[node->str] = node;
                        }
                        if (node->type == AST_ENUM) {
                                current_scope[node->str] = node;
                                for (auto enode : node->children) {
                                        log_assert(enode->type==AST_ENUM_ITEM);
                                        if (current_scope.count(enode->str) == 0)
                                                current_scope[enode->str] = enode;
                                        else
                                                log_file_error(filename, location.first_line, "enum item %s already exists\n", enode->str.c_str());
                                }
                        }
                }
                for (size_t i = 0; i < children.size(); i++) {
                        AstNode *node = children[i];
                        if (node->type == AST_PARAMETER || node->type == AST_LOCALPARAM || node->type == AST_WIRE || node->type == AST_AUTOWIRE || node->type == AST_MEMORY || node->type == AST_TYPEDEF)
                                while (node->simplify(true, false, false, 1, -1, false, node->type == AST_PARAMETER || node->type == AST_LOCALPARAM))
                                        did_something = true;
                        if (node->type == AST_ENUM) {
                                for (auto enode : node->children){
                                        log_assert(enode->type==AST_ENUM_ITEM);
                                        while (node->simplify(true, false, false, 1, -1, false, in_param))
                                                did_something = true;
                                }
                        }
                }
        }

        // create name resolution entries for all objects with names
        if (type == AST_PACKAGE) {
                //add names to package scope
                for (size_t i = 0; i < children.size(); i++) {
                        AstNode *node = children[i];
                        // these nodes appear at the top level in a package and can define names
                        if (node->type == AST_PARAMETER || node->type == AST_LOCALPARAM || node->type == AST_TYPEDEF || node->type == AST_FUNCTION || node->type == AST_TASK) {
                                current_scope[node->str] = node;
                        }
                        if (node->type == AST_ENUM) {
                                current_scope[node->str] = node;
                                for (auto enode : node->children) {
                                        log_assert(enode->type==AST_ENUM_ITEM);
                                        if (current_scope.count(enode->str) == 0)
                                                current_scope[enode->str] = enode;
                                        else
                                                log_file_error(filename, location.first_line, "enum item %s already exists in package\n", enode->str.c_str());
                                }
                        }
                }
        }


        auto backup_current_block = current_block;
        auto backup_current_block_child = current_block_child;
        auto backup_current_top_block = current_top_block;
        auto backup_current_always = current_always;
        auto backup_current_always_clocked = current_always_clocked;

        if (type == AST_ALWAYS || type == AST_INITIAL)
        {
                if (current_always != nullptr)
                        log_file_error(filename, location.first_line, "Invalid nesting of always blocks and/or initializations.\n");

                current_always = this;
                current_always_clocked = false;

                if (type == AST_ALWAYS)
                        for (auto child : children) {
                                if (child->type == AST_POSEDGE || child->type == AST_NEGEDGE)
                                        current_always_clocked = true;
                                if (child->type == AST_EDGE && GetSize(child->children) == 1 &&
                                                child->children[0]->type == AST_IDENTIFIER && child->children[0]->str == "\\$global_clock")
                                        current_always_clocked = true;
                        }
        }

        if (type == AST_ARGUMENT)
        {
                if (children.size() == 1 && children[0]->type == AST_CONSTANT)
                {
                        // HACK: For port bindings using unbased unsized literals, mark them
                        // signed so they sign-extend. The hierarchy will still incorrectly
                        // generate a warning complaining about resizing the expression.
                        // This also doesn't handle the complex of something like a ternary
                        // expression bound to a port, where the actual size of the port is
                        // needed to resolve the expression correctly.
                        AstNode *arg = children[0];
                        if (arg->is_unsized)
                                arg->is_signed = true;
                }
        }

        int backup_width_hint = width_hint;
        bool backup_sign_hint = sign_hint;

        bool detect_width_simple = false;
        bool child_0_is_self_determined = false;
        bool child_1_is_self_determined = false;
        bool child_2_is_self_determined = false;
        bool children_are_self_determined = false;
        bool reset_width_after_children = false;

        switch (type)
        {
        case AST_ASSIGN_EQ:
        case AST_ASSIGN_LE:
        case AST_ASSIGN:
                while (!children[0]->basic_prep && children[0]->simplify(false, false, true, stage, -1, false, in_param) == true)
                        did_something = true;
                while (!children[1]->basic_prep && children[1]->simplify(false, false, false, stage, -1, false, in_param) == true)
                        did_something = true;
                children[0]->detectSignWidth(backup_width_hint, backup_sign_hint);
                children[1]->detectSignWidth(width_hint, sign_hint);
                width_hint = max(width_hint, backup_width_hint);
                child_0_is_self_determined = true;
                // test only once, before optimizations and memory mappings but after assignment LHS was mapped to an identifier
                if (children[0]->id2ast && !children[0]->was_checked) {
                        if ((type == AST_ASSIGN_LE || type == AST_ASSIGN_EQ) && children[0]->id2ast->is_logic)
                                children[0]->id2ast->is_reg = true; // if logic type is used in a block asignment
                        if ((type == AST_ASSIGN_LE || type == AST_ASSIGN_EQ) && !children[0]->id2ast->is_reg)
                                log_warning("wire '%s' is assigned in a block at %s.\n", children[0]->str.c_str(), loc_string().c_str());
                        if (type == AST_ASSIGN && children[0]->id2ast->is_reg) {
                                bool is_rand_reg = false;
                                if (children[1]->type == AST_FCALL) {
                                        if (children[1]->str == "\\$anyconst")
                                                is_rand_reg = true;
                                        if (children[1]->str == "\\$anyseq")
                                                is_rand_reg = true;
                                        if (children[1]->str == "\\$allconst")
                                                is_rand_reg = true;
                                        if (children[1]->str == "\\$allseq")
                                                is_rand_reg = true;
                                }
                                if (!is_rand_reg)
                                        log_warning("reg '%s' is assigned in a continuous assignment at %s.\n", children[0]->str.c_str(), loc_string().c_str());
                        }
                        children[0]->was_checked = true;
                }
                break;

        case AST_STRUCT:
        case AST_UNION:
                if (!basic_prep) {
                        for (auto *node : children) {
                                // resolve any ranges
                                while (!node->basic_prep && node->simplify(true, false, false, stage, -1, false, false)) {
                                        did_something = true;
                                }
                        }
                        // determine member offsets and widths
                        size_packed_struct(this, 0);

                        // instance rather than just a type in a typedef or outer struct?
                        if (!str.empty() && str[0] == '\\') {
                                // instance so add a wire for the packed structure
                                auto wnode = make_packed_struct(this, str);
                                log_assert(current_ast_mod);
                                current_ast_mod->children.push_back(wnode);
                        }
                        basic_prep = true;
                }
                break;

        case AST_STRUCT_ITEM:
                break;

        case AST_ENUM:
                //log("\nENUM %s: %d child %d\n", str.c_str(), basic_prep, children[0]->basic_prep);
                if (!basic_prep) {
                        for (auto item_node : children) {
                                while (!item_node->basic_prep && item_node->simplify(false, false, false, stage, -1, false, in_param))
                                        did_something = true;
                        }
                        // allocate values (called more than once)
                        allocateDefaultEnumValues();
                }
                break;

        case AST_PARAMETER:
        case AST_LOCALPARAM:
                while (!children[0]->basic_prep && children[0]->simplify(false, false, false, stage, -1, false, true) == true)
                        did_something = true;
                children[0]->detectSignWidth(width_hint, sign_hint);
                if (children.size() > 1 && children[1]->type == AST_RANGE) {
                        while (!children[1]->basic_prep && children[1]->simplify(false, false, false, stage, -1, false, true) == true)
                                did_something = true;
                        if (!children[1]->range_valid)
                                log_file_error(filename, location.first_line, "Non-constant width range on parameter decl.\n");
                        width_hint = max(width_hint, children[1]->range_left - children[1]->range_right + 1);
                }
                break;
        case AST_ENUM_ITEM:
                while (!children[0]->basic_prep && children[0]->simplify(false, false, false, stage, -1, false, in_param))
                        did_something = true;
                children[0]->detectSignWidth(width_hint, sign_hint);
                if (children.size() > 1 && children[1]->type == AST_RANGE) {
                        while (!children[1]->basic_prep && children[1]->simplify(false, false, false, stage, -1, false, in_param))
                                did_something = true;
                        if (!children[1]->range_valid)
                                log_file_error(filename, location.first_line, "Non-constant width range on enum item decl.\n");
                        width_hint = max(width_hint, children[1]->range_left - children[1]->range_right + 1);
                }
                break;

        case AST_TO_BITS:
        case AST_TO_SIGNED:
        case AST_TO_UNSIGNED:
        case AST_SELFSZ:
        case AST_CAST_SIZE:
        case AST_CONCAT:
        case AST_REPLICATE:
        case AST_REDUCE_AND:
        case AST_REDUCE_OR:
        case AST_REDUCE_XOR:
        case AST_REDUCE_XNOR:
        case AST_REDUCE_BOOL:
                detect_width_simple = true;
                children_are_self_determined = true;
                break;

        case AST_NEG:
        case AST_BIT_NOT:
        case AST_POS:
        case AST_BIT_AND:
        case AST_BIT_OR:
        case AST_BIT_XOR:
        case AST_BIT_XNOR:
        case AST_ADD:
        case AST_SUB:
        case AST_MUL:
        case AST_DIV:
        case AST_MOD:
                detect_width_simple = true;
                break;

        case AST_SHIFT_LEFT:
        case AST_SHIFT_RIGHT:
        case AST_SHIFT_SLEFT:
        case AST_SHIFT_SRIGHT:
        case AST_POW:
                detect_width_simple = true;
                child_1_is_self_determined = true;
                break;

        case AST_LT:
        case AST_LE:
        case AST_EQ:
        case AST_NE:
        case AST_EQX:
        case AST_NEX:
        case AST_GE:
        case AST_GT:
                width_hint = -1;
                sign_hint = true;
                for (auto child : children) {
                        while (!child->basic_prep && child->simplify(false, false, in_lvalue, stage, -1, false, in_param) == true)
                                did_something = true;
                        child->detectSignWidthWorker(width_hint, sign_hint);
                }
                reset_width_after_children = true;
                break;

        case AST_LOGIC_AND:
        case AST_LOGIC_OR:
        case AST_LOGIC_NOT:
                detect_width_simple = true;
                children_are_self_determined = true;
                break;

        case AST_TERNARY:
                child_0_is_self_determined = true;
                break;

        case AST_MEMRD:
                detect_width_simple = true;
                children_are_self_determined = true;
                break;

        case AST_FCALL:
        case AST_TCALL:
                children_are_self_determined = true;
                break;

        default:
                width_hint = -1;
                sign_hint = false;
        }

        if (detect_width_simple && width_hint < 0) {
                if (type == AST_REPLICATE)
                        while (children[0]->simplify(true, false, in_lvalue, stage, -1, false, true) == true)
                                did_something = true;
                for (auto child : children)
                        while (!child->basic_prep && child->simplify(false, false, in_lvalue, stage, -1, false, in_param) == true)
                                did_something = true;
                detectSignWidth(width_hint, sign_hint);
        }

        if (type == AST_FCALL && str == "\\$past")
                detectSignWidth(width_hint, sign_hint);

        if (type == AST_TERNARY) {
                if (width_hint < 0) {
                        while (!children[0]->basic_prep && children[0]->simplify(true, false, in_lvalue, stage, -1, false, in_param))
                                did_something = true;

                        bool backup_unevaluated_tern_branch = unevaluated_tern_branch;
                        AstNode *chosen = get_tern_choice().first;

                        unevaluated_tern_branch = backup_unevaluated_tern_branch || chosen == children[2];
                        while (!children[1]->basic_prep && children[1]->simplify(false, false, in_lvalue, stage, -1, false, in_param))
                                did_something = true;

                        unevaluated_tern_branch = backup_unevaluated_tern_branch || chosen == children[1];
                        while (!children[2]->basic_prep && children[2]->simplify(false, false, in_lvalue, stage, -1, false, in_param))
                                did_something = true;

                        unevaluated_tern_branch = backup_unevaluated_tern_branch;
                        detectSignWidth(width_hint, sign_hint);
                }
                int width_hint_left, width_hint_right;
                bool sign_hint_left, sign_hint_right;
                bool found_real_left, found_real_right;
                children[1]->detectSignWidth(width_hint_left, sign_hint_left, &found_real_left);
                children[2]->detectSignWidth(width_hint_right, sign_hint_right, &found_real_right);
                if (found_real_left || found_real_right) {
                        child_1_is_self_determined = true;
                        child_2_is_self_determined = true;
                }
        }

        if (type == AST_CONDX && children.size() > 0 && children.at(0)->type == AST_CONSTANT) {
                for (auto &bit : children.at(0)->bits)
                        if (bit == State::Sz || bit == State::Sx)
                                bit = State::Sa;
        }

        if (type == AST_CONDZ && children.size() > 0 && children.at(0)->type == AST_CONSTANT) {
                for (auto &bit : children.at(0)->bits)
                        if (bit == State::Sz)
                                bit = State::Sa;
        }

        if (const_fold && type == AST_CASE)
        {
                int width_hint;
                bool sign_hint;
                detectSignWidth(width_hint, sign_hint);
                while (children[0]->simplify(const_fold, at_zero, in_lvalue, stage, width_hint, sign_hint, in_param)) { }
                if (children[0]->type == AST_CONSTANT && children[0]->bits_only_01()) {
                        RTLIL::Const case_expr = children[0]->bitsAsConst(width_hint, sign_hint);
                        std::vector<AstNode*> new_children;
                        new_children.push_back(children[0]);
                        for (int i = 1; i < GetSize(children); i++) {
                                AstNode *child = children[i];
                                log_assert(child->type == AST_COND || child->type == AST_CONDX || child->type == AST_CONDZ);
                                for (auto v : child->children) {
                                        if (v->type == AST_DEFAULT)
                                                goto keep_const_cond;
                                        if (v->type == AST_BLOCK)
                                                continue;
                                        while (v->simplify(const_fold, at_zero, in_lvalue, stage, width_hint, sign_hint, in_param)) { }
                                        if (v->type == AST_CONSTANT && v->bits_only_01()) {
                                                RTLIL::Const case_item_expr = v->bitsAsConst(width_hint, sign_hint);
                                                RTLIL::Const match = const_eq(case_expr, case_item_expr, sign_hint, sign_hint, 1);
                                                log_assert(match.bits.size() == 1);
                                                if (match.bits.front() == RTLIL::State::S1) {
                                                        while (i+1 < GetSize(children))
                                                                delete children[++i];
                                                        goto keep_const_cond;
                                                }
                                                continue;
                                        }
                                        goto keep_const_cond;
                                }
                                if (0)
                        keep_const_cond:
                                        new_children.push_back(child);
                                else
                                        delete child;
                        }
                        new_children.swap(children);
                }
        }

        dict<std::string, pool<int>> backup_memwr_visible;
        dict<std::string, pool<int>> final_memwr_visible;

        if (type == AST_CASE && stage == 2) {
                backup_memwr_visible = current_memwr_visible;
                final_memwr_visible = current_memwr_visible;
        }

        // simplify all children first
        // (iterate by index as e.g. auto wires can add new children in the process)
        for (size_t i = 0; i < children.size(); i++) {
                bool did_something_here = true;
                bool backup_flag_autowire = flag_autowire;
                bool backup_unevaluated_tern_branch = unevaluated_tern_branch;
                if ((type == AST_GENFOR || type == AST_FOR) && i >= 3)
                        break;
                if ((type == AST_GENIF || type == AST_GENCASE) && i >= 1)
                        break;
                if (type == AST_GENBLOCK)
                        break;
                if (type == AST_BLOCK && !str.empty())
                        break;
                if (type == AST_PREFIX && i >= 1)
                        break;
                if (type == AST_DEFPARAM && i == 0)
                        flag_autowire = true;
                if (type == AST_TERNARY && i > 0 && !unevaluated_tern_branch) {
                        AstNode *chosen = get_tern_choice().first;
                        unevaluated_tern_branch = chosen && chosen != children[i];
                }
                while (did_something_here && i < children.size()) {
                        bool const_fold_here = const_fold, in_lvalue_here = in_lvalue;
                        int width_hint_here = width_hint;
                        bool sign_hint_here = sign_hint;
                        bool in_param_here = in_param;
                        if (i == 0 && (type == AST_REPLICATE || type == AST_WIRE))
                                const_fold_here = true, in_param_here = true;
                        if (i == 0 && (type == AST_GENIF || type == AST_GENCASE))
                                in_param_here = true;
                        if (i == 1 && (type == AST_FOR || type == AST_GENFOR))
                                in_param_here = true;
                        if (type == AST_PARAMETER || type == AST_LOCALPARAM)
                                const_fold_here = true;
                        if (i == 0 && (type == AST_ASSIGN || type == AST_ASSIGN_EQ || type == AST_ASSIGN_LE))
                                in_lvalue_here = true;
                        if (type == AST_BLOCK) {
                                current_block = this;
                                current_block_child = children[i];
                        }
                        if ((type == AST_ALWAYS || type == AST_INITIAL) && children[i]->type == AST_BLOCK)
                                current_top_block = children[i];
                        if (i == 0 && child_0_is_self_determined)
                                width_hint_here = -1, sign_hint_here = false;
                        if (i == 1 && child_1_is_self_determined)
                                width_hint_here = -1, sign_hint_here = false;
                        if (i == 2 && child_2_is_self_determined)
                                width_hint_here = -1, sign_hint_here = false;
                        if (children_are_self_determined)
                                width_hint_here = -1, sign_hint_here = false;
                        did_something_here = children[i]->simplify(const_fold_here, at_zero, in_lvalue_here, stage, width_hint_here, sign_hint_here, in_param_here);
                        if (did_something_here)
                                did_something = true;
                }
                if (stage == 2 && children[i]->type == AST_INITIAL && current_ast_mod != this) {
                        current_ast_mod->children.push_back(children[i]);
                        children.erase(children.begin() + (i--));
                        did_something = true;
                }
                flag_autowire = backup_flag_autowire;
                unevaluated_tern_branch = backup_unevaluated_tern_branch;
                if (stage == 2 && type == AST_CASE) {
                        for (auto &x : current_memwr_visible) {
                                for (int y : x.second)
                                        final_memwr_visible[x.first].insert(y);
                        }
                        current_memwr_visible = backup_memwr_visible;
                }
        }
        for (auto &attr : attributes) {
                while (attr.second->simplify(true, false, false, stage, -1, false, true))
                        did_something = true;
        }
        if (type == AST_CASE && stage == 2) {
                current_memwr_visible = final_memwr_visible;
        }
        if (type == AST_ALWAYS && stage == 2) {
                current_memwr_visible.clear();
                current_memwr_count.clear();
        }

        if (reset_width_after_children) {
                width_hint = backup_width_hint;
                sign_hint = backup_sign_hint;
                if (width_hint < 0)
                        detectSignWidth(width_hint, sign_hint);
        }

        current_block = backup_current_block;
        current_block_child = backup_current_block_child;
        current_top_block = backup_current_top_block;
        current_always = backup_current_always;
        current_always_clocked = backup_current_always_clocked;

        for (auto it = backup_scope.begin(); it != backup_scope.end(); it++) {
                if (it->second == NULL)
                        current_scope.erase(it->first);
                else
                        current_scope[it->first] = it->second;
        }

        current_filename = filename;

        if (type == AST_MODULE)
                current_scope.clear();

        // convert defparam nodes to cell parameters
        if (type == AST_DEFPARAM && !children.empty())
        {
                if (children[0]->type != AST_IDENTIFIER)
                        log_file_error(filename, location.first_line, "Module name in defparam contains non-constant expressions!\n");

                string modname, paramname = children[0]->str;

                size_t pos = paramname.rfind('.');

                while (pos != 0 && pos != std::string::npos)
                {
                        modname = paramname.substr(0, pos);

                        if (current_scope.count(modname))
                                break;

                        pos = paramname.rfind('.', pos - 1);
                }

                if (pos == std::string::npos)
                        log_file_error(filename, location.first_line, "Can't find object for defparam `%s`!\n", RTLIL::unescape_id(paramname).c_str());

                paramname = "\\" + paramname.substr(pos+1);

                if (current_scope.at(modname)->type != AST_CELL)
                        log_file_error(filename, location.first_line, "Defparam argument `%s . %s` does not match a cell!\n",
                                        RTLIL::unescape_id(modname).c_str(), RTLIL::unescape_id(paramname).c_str());

                AstNode *paraset = new AstNode(AST_PARASET, children[1]->clone(), GetSize(children) > 2 ? children[2]->clone() : NULL);
                paraset->str = paramname;

                AstNode *cell = current_scope.at(modname);
                cell->children.insert(cell->children.begin() + 1, paraset);
                delete_children();
        }

        // resolve typedefs
        if (type == AST_TYPEDEF) {
                log_assert(children.size() == 1);
                auto type_node = children[0];
                log_assert(type_node->type == AST_WIRE || type_node->type == AST_MEMORY || type_node->type == AST_STRUCT || type_node->type == AST_UNION);
                while (type_node->simplify(const_fold, at_zero, in_lvalue, stage, width_hint, sign_hint, in_param)) {
                        did_something = true;
                }
                log_assert(!type_node->is_custom_type);
        }

        // resolve types of wires
        if (type == AST_WIRE || type == AST_MEMORY) {
                if (is_custom_type) {
                        log_assert(children.size() >= 1);
                        log_assert(children[0]->type == AST_WIRETYPE);
                        auto type_name = children[0]->str;
                        if (!current_scope.count(type_name)) {
                                log_file_error(filename, location.first_line, "Unknown identifier `%s' used as type name\n", type_name.c_str());
                        }
                        AstNode *resolved_type_node = current_scope.at(type_name);
                        if (resolved_type_node->type != AST_TYPEDEF)
                                log_file_error(filename, location.first_line, "`%s' does not name a type\n", type_name.c_str());
                        log_assert(resolved_type_node->children.size() == 1);
                        AstNode *template_node = resolved_type_node->children[0];

                        // Ensure typedef itself is fully simplified
                        while (template_node->simplify(const_fold, at_zero, in_lvalue, stage, width_hint, sign_hint, in_param)) {};

                        if (template_node->type == AST_STRUCT || template_node->type == AST_UNION) {
                                // replace with wire representing the packed structure
                                newNode = make_packed_struct(template_node, str);
                                // add original input/output attribute to resolved wire
                                newNode->is_input = this->is_input;
                                newNode->is_output = this->is_output;
                                current_scope[str] = this;
                                goto apply_newNode;
                        }

                        // Remove type reference
                        delete children[0];
                        children.erase(children.begin());

                        if (type == AST_WIRE)
                                type = template_node->type;
                        is_reg = template_node->is_reg;
                        is_logic = template_node->is_logic;
                        is_signed = template_node->is_signed;
                        is_string = template_node->is_string;
                        is_custom_type = template_node->is_custom_type;

                        range_valid = template_node->range_valid;
                        range_swapped = template_node->range_swapped;
                        range_left = template_node->range_left;
                        range_right = template_node->range_right;

                        attributes[ID::wiretype] = mkconst_str(resolved_type_node->str);

                        // if an enum then add attributes to support simulator tracing
                        annotateTypedEnums(template_node);

                        // Insert clones children from template at beginning
                        for (int i  = 0; i < GetSize(template_node->children); i++)
                                children.insert(children.begin() + i, template_node->children[i]->clone());

                        if (type == AST_MEMORY && GetSize(children) == 1) {
                                // Single-bit memories must have [0:0] range
                                AstNode *rng = make_range(0, 0);
                                children.insert(children.begin(), rng);
                        }
                        did_something = true;
                }
                log_assert(!is_custom_type);
        }

        // resolve types of parameters
        if (type == AST_LOCALPARAM || type == AST_PARAMETER) {
                if (is_custom_type) {
                        log_assert(children.size() == 2);
                        log_assert(children[1]->type == AST_WIRETYPE);
                        if (!current_scope.count(children[1]->str))
                                log_file_error(filename, location.first_line, "Unknown identifier `%s' used as type name\n", children[1]->str.c_str());
                        AstNode *resolved_type_node = current_scope.at(children[1]->str);
                        if (resolved_type_node->type != AST_TYPEDEF)
                                log_file_error(filename, location.first_line, "`%s' does not name a type\n", children[1]->str.c_str());
                        log_assert(resolved_type_node->children.size() == 1);
                        AstNode *template_node = resolved_type_node->children[0];
                        delete children[1];
                        children.pop_back();

                        // Ensure typedef itself is fully simplified
                        while(template_node->simplify(const_fold, at_zero, in_lvalue, stage, width_hint, sign_hint, in_param)) {};

                        if (template_node->type == AST_MEMORY)
                                log_file_error(filename, location.first_line, "unpacked array type `%s' cannot be used for a parameter\n", children[1]->str.c_str());
                        is_signed = template_node->is_signed;
                        is_string = template_node->is_string;
                        is_custom_type = template_node->is_custom_type;

                        range_valid = template_node->range_valid;
                        range_swapped = template_node->range_swapped;
                        range_left = template_node->range_left;
                        range_right = template_node->range_right;
                        attributes[ID::wiretype] = mkconst_str(resolved_type_node->str);
                        for (auto template_child : template_node->children)
                                children.push_back(template_child->clone());
                        did_something = true;
                }
                log_assert(!is_custom_type);
        }

        // resolve constant prefixes
        if (type == AST_PREFIX) {
                if (children[0]->type != AST_CONSTANT) {
                        // dumpAst(NULL, ">   ");
                        log_file_error(filename, location.first_line, "Index in generate block prefix syntax is not constant!\n");
                }
                if (children[1]->type == AST_PREFIX)
                        children[1]->simplify(const_fold, at_zero, in_lvalue, stage, width_hint, sign_hint, in_param);
                log_assert(children[1]->type == AST_IDENTIFIER);
                newNode = children[1]->clone();
                const char *second_part = children[1]->str.c_str();
                if (second_part[0] == '\\')
                        second_part++;
                newNode->str = stringf("%s[%d].%s", str.c_str(), children[0]->integer, second_part);
                goto apply_newNode;
        }

        // evaluate TO_BITS nodes
        if (type == AST_TO_BITS) {
                if (children[0]->type != AST_CONSTANT)
                        log_file_error(filename, location.first_line, "Left operand of to_bits expression is not constant!\n");
                if (children[1]->type != AST_CONSTANT)
                        log_file_error(filename, location.first_line, "Right operand of to_bits expression is not constant!\n");
                RTLIL::Const new_value = children[1]->bitsAsConst(children[0]->bitsAsConst().as_int(), children[1]->is_signed);
                newNode = mkconst_bits(new_value.bits, children[1]->is_signed);
                goto apply_newNode;
        }

        // annotate constant ranges
        if (type == AST_RANGE) {
                bool old_range_valid = range_valid;
                range_valid = false;
                range_swapped = false;
                range_left = -1;
                range_right = 0;
                log_assert(children.size() >= 1);
                if (children[0]->type == AST_CONSTANT) {
                        range_valid = true;
                        range_left = children[0]->integer;
                        if (children.size() == 1)
                                range_right = range_left;
                }
                if (children.size() >= 2) {
                        if (children[1]->type == AST_CONSTANT)
                                range_right = children[1]->integer;
                        else
                                range_valid = false;
                }
                if (old_range_valid != range_valid)
                        did_something = true;
                if (range_valid && range_right > range_left) {
                        int tmp = range_right;
                        range_right = range_left;
                        range_left = tmp;
                        range_swapped = true;
                }
        }

        // annotate wires with their ranges
        if (type == AST_WIRE) {
                if (children.size() > 0) {
                        if (children[0]->range_valid) {
                                if (!range_valid)
                                        did_something = true;
                                range_valid = true;
                                range_swapped = children[0]->range_swapped;
                                range_left = children[0]->range_left;
                                range_right = children[0]->range_right;
                                bool force_upto = false, force_downto = false;
                                if (attributes.count(ID::force_upto)) {
                                        AstNode *val = attributes[ID::force_upto];
                                        if (val->type != AST_CONSTANT)
                                                log_file_error(filename, location.first_line, "Attribute `force_upto' with non-constant value!\n");
                                        force_upto = val->asAttrConst().as_bool();
                                }
                                if (attributes.count(ID::force_downto)) {
                                        AstNode *val = attributes[ID::force_downto];
                                        if (val->type != AST_CONSTANT)
                                                log_file_error(filename, location.first_line, "Attribute `force_downto' with non-constant value!\n");
                                        force_downto = val->asAttrConst().as_bool();
                                }
                                if (force_upto && force_downto)
                                        log_file_error(filename, location.first_line, "Attributes `force_downto' and `force_upto' cannot be both set!\n");
                                if ((force_upto && !range_swapped) || (force_downto && range_swapped)) {
                                        std::swap(range_left, range_right);
                                        range_swapped = force_upto;
                                }
                        }
                } else {
                        if (!range_valid)
                                did_something = true;
                        range_valid = true;
                        range_swapped = false;
                        range_left = 0;
                        range_right = 0;
                }
        }

        // resolve multiranges on memory decl
        if (type == AST_MEMORY && children.size() > 1 && children[1]->type == AST_MULTIRANGE)
        {
                int total_size = 1;
                multirange_dimensions.clear();
                multirange_swapped.clear();
                for (auto range : children[1]->children) {
                        if (!range->range_valid)
                                log_file_error(filename, location.first_line, "Non-constant range on memory decl.\n");
                        multirange_dimensions.push_back(min(range->range_left, range->range_right));
                        multirange_dimensions.push_back(max(range->range_left, range->range_right) - min(range->range_left, range->range_right) + 1);
                        multirange_swapped.push_back(range->range_swapped);
                        total_size *= multirange_dimensions.back();
                }
                delete children[1];
                children[1] = new AstNode(AST_RANGE, AstNode::mkconst_int(0, true), AstNode::mkconst_int(total_size-1, true));
                did_something = true;
        }

        // resolve multiranges on memory access
        if (type == AST_IDENTIFIER && id2ast && id2ast->type == AST_MEMORY && children.size() > 0 && children[0]->type == AST_MULTIRANGE)
        {
                AstNode *index_expr = nullptr;

                integer = children[0]->children.size(); // save original number of dimensions for $size() etc.
                for (int i = 0; 2*i < GetSize(id2ast->multirange_dimensions); i++)
                {
                        if (GetSize(children[0]->children) <= i)
                                log_file_error(filename, location.first_line, "Insufficient number of array indices for %s.\n", log_id(str));

                        AstNode *new_index_expr = children[0]->children[i]->children.at(0)->clone();

                        if (id2ast->multirange_dimensions[2*i])
                                new_index_expr = new AstNode(AST_SUB, new_index_expr, AstNode::mkconst_int(id2ast->multirange_dimensions[2*i], true));

                        if (i == 0)
                                index_expr = new_index_expr;
                        else
                                index_expr = new AstNode(AST_ADD, new AstNode(AST_MUL, index_expr, AstNode::mkconst_int(id2ast->multirange_dimensions[2*i+1], true)), new_index_expr);
                }

                for (int i = GetSize(id2ast->multirange_dimensions)/2; i < GetSize(children[0]->children); i++)
                        children.push_back(children[0]->children[i]->clone());

                delete children[0];
                if (index_expr == nullptr)
                        children.erase(children.begin());
                else
                        children[0] = new AstNode(AST_RANGE, index_expr);

                did_something = true;
        }

        // trim/extend parameters
        if (type == AST_PARAMETER || type == AST_LOCALPARAM || type == AST_ENUM_ITEM) {
                if (children.size() > 1 && children[1]->type == AST_RANGE) {
                        if (!children[1]->range_valid)
                                log_file_error(filename, location.first_line, "Non-constant width range on parameter decl.\n");
                        int width = std::abs(children[1]->range_left - children[1]->range_right) + 1;
                        if (children[0]->type == AST_REALVALUE) {
                                RTLIL::Const constvalue = children[0]->realAsConst(width);
                                log_file_warning(filename, location.first_line, "converting real value %e to binary %s.\n",
                                                children[0]->realvalue, log_signal(constvalue));
                                delete children[0];
                                children[0] = mkconst_bits(constvalue.bits, sign_hint);
                                did_something = true;
                        }
                        if (children[0]->type == AST_CONSTANT) {
                                if (width != int(children[0]->bits.size())) {
                                        RTLIL::SigSpec sig(children[0]->bits);
                                        sig.extend_u0(width, children[0]->is_signed);
                                        AstNode *old_child_0 = children[0];
                                        children[0] = mkconst_bits(sig.as_const().bits, is_signed);
                                        delete old_child_0;
                                }
                                children[0]->is_signed = is_signed;
                        }
                        range_valid = true;
                        range_swapped = children[1]->range_swapped;
                        range_left = children[1]->range_left;
                        range_right = children[1]->range_right;
                } else
                if (children.size() > 1 && children[1]->type == AST_REALVALUE && children[0]->type == AST_CONSTANT) {
                        double as_realvalue = children[0]->asReal(sign_hint);
                        delete children[0];
                        children[0] = new AstNode(AST_REALVALUE);
                        children[0]->realvalue = as_realvalue;
                        did_something = true;
                }
        }

        if (type == AST_IDENTIFIER && !basic_prep) {
                // check if a plausible struct member sss.mmmm
                std::string sname;
                if (name_has_dot(str, sname)) {
                        if (current_scope.count(str) > 0) {
                                auto item_node = current_scope[str];
                                if (item_node->type == AST_STRUCT_ITEM) {
                                        // structure member, rewrite this node to reference the packed struct wire
                                        auto range = make_struct_member_range(this, item_node);
                                        newNode = new AstNode(AST_IDENTIFIER, range);
                                        newNode->str = sname;
                                        newNode->basic_prep = true;
                                        if (item_node->is_signed)
                                                newNode = new AstNode(AST_TO_SIGNED, newNode);
                                        goto apply_newNode;
                                }
                        }
                }
        }
        // annotate identifiers using scope resolution and create auto-wires as needed
        if (type == AST_IDENTIFIER) {
                if (current_scope.count(str) == 0) {
                        AstNode *current_scope_ast = (current_ast_mod == nullptr) ? current_ast : current_ast_mod;
                        str = try_pop_module_prefix();
                        for (auto node : current_scope_ast->children) {
                                //log("looking at mod scope child %s\n", type2str(node->type).c_str());
                                switch (node->type) {
                                case AST_PARAMETER:
                                case AST_LOCALPARAM:
                                case AST_WIRE:
                                case AST_AUTOWIRE:
                                case AST_GENVAR:
                                case AST_MEMORY:
                                case AST_FUNCTION:
                                case AST_TASK:
                                case AST_DPI_FUNCTION:
                                        //log("found child %s, %s\n", type2str(node->type).c_str(), node->str.c_str());
                                        if (str == node->str) {
                                                //log("add %s, type %s to scope\n", str.c_str(), type2str(node->type).c_str());
                                                current_scope[node->str] = node;
                                        }
                                        break;
                                case AST_ENUM:
                                        current_scope[node->str] = node;
                                        for (auto enum_node : node->children) {
                                                log_assert(enum_node->type==AST_ENUM_ITEM);
                                                if (str == enum_node->str) {
                                                        //log("\nadding enum item %s to scope\n", str.c_str());
                                                        current_scope[str] = enum_node;
                                                }
                                        }
                                        break;
                                default:
                                        break;
                                }
                        }
                }
                if (current_scope.count(str) == 0) {
                        if (current_ast_mod == nullptr) {
                                log_file_error(filename, location.first_line, "Identifier `%s' is implicitly declared outside of a module.\n", str.c_str());
                        } else if (flag_autowire || str == "\\$global_clock") {
                                AstNode *auto_wire = new AstNode(AST_AUTOWIRE);
                                auto_wire->str = str;
                                current_ast_mod->children.push_back(auto_wire);
                                current_scope[str] = auto_wire;
                                did_something = true;
                        } else {
                                log_file_error(filename, location.first_line, "Identifier `%s' is implicitly declared and `default_nettype is set to none.\n", str.c_str());
                        }
                }
                if (id2ast != current_scope[str]) {
                        id2ast = current_scope[str];
                        did_something = true;
                }
        }

        // split memory access with bit select to individual statements
        if (type == AST_IDENTIFIER && children.size() == 2 && children[0]->type == AST_RANGE && children[1]->type == AST_RANGE && !in_lvalue && stage == 2)
        {
                if (id2ast == NULL || id2ast->type != AST_MEMORY || children[0]->children.size() != 1)
                        log_file_error(filename, location.first_line, "Invalid bit-select on memory access!\n");

                int mem_width, mem_size, addr_bits;
                id2ast->meminfo(mem_width, mem_size, addr_bits);

                int data_range_left = id2ast->children[0]->range_left;
                int data_range_right = id2ast->children[0]->range_right;

                if (id2ast->children[0]->range_swapped)
                        std::swap(data_range_left, data_range_right);

                std::stringstream sstr;
                sstr << "$mem2bits$" << str << "$" << filename << ":" << location.first_line << "$" << (autoidx++);
                std::string wire_id = sstr.str();

                AstNode *wire = new AstNode(AST_WIRE, new AstNode(AST_RANGE, mkconst_int(data_range_left, true), mkconst_int(data_range_right, true)));
                wire->str = wire_id;
                if (current_block)
                        wire->attributes[ID::nosync] = AstNode::mkconst_int(1, false);
                current_ast_mod->children.push_back(wire);
                while (wire->simplify(true, false, false, 1, -1, false, false)) { }

                AstNode *data = clone();
                delete data->children[1];
                data->children.pop_back();

                AstNode *assign = new AstNode(AST_ASSIGN_EQ, new AstNode(AST_IDENTIFIER), data);
                assign->children[0]->str = wire_id;
                assign->children[0]->was_checked = true;

                if (current_block)
                {
                        size_t assign_idx = 0;
                        while (assign_idx < current_block->children.size() && current_block->children[assign_idx] != current_block_child)
                                assign_idx++;
                        log_assert(assign_idx < current_block->children.size());
                        current_block->children.insert(current_block->children.begin()+assign_idx, assign);
                        wire->is_reg = true;
                }
                else
                {
                        AstNode *proc = new AstNode(AST_ALWAYS, new AstNode(AST_BLOCK));
                        proc->children[0]->children.push_back(assign);
                        current_ast_mod->children.push_back(proc);
                }

                newNode = new AstNode(AST_IDENTIFIER, children[1]->clone());
                newNode->str = wire_id;
                newNode->integer = integer; // save original number of dimensions for $size() etc.
                newNode->id2ast = wire;
                goto apply_newNode;
        }

        if (type == AST_WHILE)
                log_file_error(filename, location.first_line, "While loops are only allowed in constant functions!\n");

        if (type == AST_REPEAT)
        {
                AstNode *count = children[0];
                AstNode *body = children[1];

                // eval count expression
                while (count->simplify(true, false, false, stage, 32, true, false)) { }

                if (count->type != AST_CONSTANT)
                        log_file_error(filename, location.first_line, "Repeat loops outside must have constant repeat counts!\n");

                // convert to a block with the body repeated n times
                type = AST_BLOCK;
                children.clear();
                for (int i = 0; i < count->bitsAsConst().as_int(); i++)
                        children.insert(children.begin(), body->clone());

                delete count;
                delete body;
                did_something = true;
        }

        // unroll for loops and generate-for blocks
        if ((type == AST_GENFOR || type == AST_FOR) && children.size() != 0)
        {
                AstNode *init_ast = children[0];
                AstNode *while_ast = children[1];
                AstNode *next_ast = children[2];
                AstNode *body_ast = children[3];

                while (body_ast->type == AST_GENBLOCK && body_ast->str.empty() &&
                                body_ast->children.size() == 1 && body_ast->children.at(0)->type == AST_GENBLOCK)
                        body_ast = body_ast->children.at(0);

                const char* loop_type_str = "procedural";
                const char* var_type_str = "register";
                AstNodeType var_type = AST_WIRE;
                if (type == AST_GENFOR) {
                        loop_type_str = "generate";
                        var_type_str = "genvar";
                        var_type = AST_GENVAR;
                }

                if (init_ast->type != AST_ASSIGN_EQ)
                        log_file_error(filename, location.first_line, "Unsupported 1st expression of %s for-loop!\n", loop_type_str);
                if (next_ast->type != AST_ASSIGN_EQ)
                        log_file_error(filename, location.first_line, "Unsupported 3rd expression of %s for-loop!\n", loop_type_str);

                if (init_ast->children[0]->id2ast == NULL || init_ast->children[0]->id2ast->type != var_type)
                        log_file_error(filename, location.first_line, "Left hand side of 1st expression of %s for-loop is not a %s!\n", loop_type_str, var_type_str);
                if (next_ast->children[0]->id2ast == NULL || next_ast->children[0]->id2ast->type != var_type)
                        log_file_error(filename, location.first_line, "Left hand side of 3rd expression of %s for-loop is not a %s!\n", loop_type_str, var_type_str);

                if (init_ast->children[0]->id2ast != next_ast->children[0]->id2ast)
                        log_file_error(filename, location.first_line, "Incompatible left-hand sides in 1st and 3rd expression of %s for-loop!\n", loop_type_str);

                // eval 1st expression
                AstNode *varbuf = init_ast->children[1]->clone();
                {
                        int expr_width_hint = -1;
                        bool expr_sign_hint = true;
                        varbuf->detectSignWidth(expr_width_hint, expr_sign_hint);
                        while (varbuf->simplify(true, false, false, stage, 32, true, false)) { }
                }

                if (varbuf->type != AST_CONSTANT)
                        log_file_error(filename, location.first_line, "Right hand side of 1st expression of %s for-loop is not constant!\n", loop_type_str);

                auto resolved = current_scope.at(init_ast->children[0]->str);
                if (resolved->range_valid) {
                        int const_size = varbuf->range_left - varbuf->range_right;
                        int resolved_size = resolved->range_left - resolved->range_right;
                        if (const_size < resolved_size) {
                                for (int i = const_size; i < resolved_size; i++)
                                        varbuf->bits.push_back(resolved->is_signed ? varbuf->bits.back() : State::S0);
                                varbuf->range_left = resolved->range_left;
                                varbuf->range_right = resolved->range_right;
                                varbuf->range_swapped = resolved->range_swapped;
                                varbuf->range_valid = resolved->range_valid;
                        }
                }

                varbuf = new AstNode(AST_LOCALPARAM, varbuf);
                varbuf->str = init_ast->children[0]->str;

                AstNode *backup_scope_varbuf = current_scope[varbuf->str];
                current_scope[varbuf->str] = varbuf;

                size_t current_block_idx = 0;
                if (type == AST_FOR) {
                        while (current_block_idx < current_block->children.size() &&
                                        current_block->children[current_block_idx] != current_block_child)
                                current_block_idx++;
                }

                while (1)
                {
                        // eval 2nd expression
                        AstNode *buf = while_ast->clone();
                        {
                                int expr_width_hint = -1;
                                bool expr_sign_hint = true;
                                buf->detectSignWidth(expr_width_hint, expr_sign_hint);
                                while (buf->simplify(true, false, false, stage, expr_width_hint, expr_sign_hint, false)) { }
                        }

                        if (buf->type != AST_CONSTANT)
                                log_file_error(filename, location.first_line, "2nd expression of %s for-loop is not constant!\n", loop_type_str);

                        if (buf->integer == 0) {
                                delete buf;
                                break;
                        }
                        delete buf;

                        // expand body
                        int index = varbuf->children[0]->integer;
                        log_assert(body_ast->type == AST_GENBLOCK || body_ast->type == AST_BLOCK);
                        log_assert(!body_ast->str.empty());
                        buf = body_ast->clone();

                        std::stringstream sstr;
                        sstr << buf->str << "[" << index << "].";
                        std::string prefix = sstr.str();

                        // create a scoped localparam for the current value of the loop variable
                        AstNode *local_index = varbuf->clone();
                        size_t pos = local_index->str.rfind('.');
                        if (pos != std::string::npos) // remove outer prefix
                                local_index->str = "\\" + local_index->str.substr(pos + 1);
                        local_index->str = prefix_id(prefix, local_index->str);
                        current_scope[local_index->str] = local_index;
                        current_ast_mod->children.push_back(local_index);

                        buf->expand_genblock(prefix);

                        if (type == AST_GENFOR) {
                                for (size_t i = 0; i < buf->children.size(); i++) {
                                        buf->children[i]->simplify(const_fold, false, false, stage, -1, false, false);
                                        current_ast_mod->children.push_back(buf->children[i]);
                                }
                        } else {
                                for (size_t i = 0; i < buf->children.size(); i++)
                                        current_block->children.insert(current_block->children.begin() + current_block_idx++, buf->children[i]);
                        }
                        buf->children.clear();
                        delete buf;

                        // eval 3rd expression
                        buf = next_ast->children[1]->clone();
                        {
                                int expr_width_hint = -1;
                                bool expr_sign_hint = true;
                                buf->detectSignWidth(expr_width_hint, expr_sign_hint);
                                while (buf->simplify(true, false, false, stage, expr_width_hint, expr_sign_hint, true)) { }
                        }

                        if (buf->type != AST_CONSTANT)
                                log_file_error(filename, location.first_line, "Right hand side of 3rd expression of %s for-loop is not constant (%s)!\n", loop_type_str, type2str(buf->type).c_str());

                        delete varbuf->children[0];
                        varbuf->children[0] = buf;
                }

                if (type == AST_FOR) {
                        AstNode *buf = next_ast->clone();
                        delete buf->children[1];
                        buf->children[1] = varbuf->children[0]->clone();
                        current_block->children.insert(current_block->children.begin() + current_block_idx++, buf);
                }

                current_scope[varbuf->str] = backup_scope_varbuf;
                delete varbuf;
                delete_children();
                did_something = true;
        }

        // check for local objects in unnamed block
        if (type == AST_BLOCK && str.empty())
        {
                for (size_t i = 0; i < children.size(); i++)
                        if (children[i]->type == AST_WIRE || children[i]->type == AST_MEMORY || children[i]->type == AST_PARAMETER || children[i]->type == AST_LOCALPARAM || children[i]->type == AST_TYPEDEF)
                        {
                                log_assert(!VERILOG_FRONTEND::sv_mode);
                                log_file_error(children[i]->filename, children[i]->location.first_line, "Local declaration in unnamed block is only supported in SystemVerilog mode!\n");
                        }
        }

        // transform block with name
        if (type == AST_BLOCK && !str.empty())
        {
                expand_genblock(str + ".");

                std::vector<AstNode*> new_children;
                for (size_t i = 0; i < children.size(); i++)
                        if (children[i]->type == AST_WIRE || children[i]->type == AST_MEMORY || children[i]->type == AST_PARAMETER || children[i]->type == AST_LOCALPARAM || children[i]->type == AST_TYPEDEF) {
                                children[i]->simplify(false, false, false, stage, -1, false, false);
                                current_ast_mod->children.push_back(children[i]);
                                current_scope[children[i]->str] = children[i];
                        } else
                                new_children.push_back(children[i]);

                children.swap(new_children);
                did_something = true;
                str.clear();
        }

        // simplify unconditional generate block
        if (type == AST_GENBLOCK && children.size() != 0)
        {
                if (!str.empty()) {
                        expand_genblock(str + ".");
                }

                for (size_t i = 0; i < children.size(); i++) {
                        children[i]->simplify(const_fold, false, false, stage, -1, false, false);
                        current_ast_mod->children.push_back(children[i]);
                }

                children.clear();
                did_something = true;
        }

        // simplify generate-if blocks
        if (type == AST_GENIF && children.size() != 0)
        {
                AstNode *buf = children[0]->clone();
                while (buf->simplify(true, false, false, stage, width_hint, sign_hint, false)) { }
                if (buf->type != AST_CONSTANT) {
                        // for (auto f : log_files)
                        //      dumpAst(f, "verilog-ast> ");
                        log_file_error(filename, location.first_line, "Condition for generate if is not constant!\n");
                }
                if (buf->asBool() != 0) {
                        delete buf;
                        buf = children[1]->clone();
                } else {
                        delete buf;
                        buf = children.size() > 2 ? children[2]->clone() : NULL;
                }

                if (buf)
                {
                        if (buf->type != AST_GENBLOCK)
                                buf = new AstNode(AST_GENBLOCK, buf);

                        if (!buf->str.empty()) {
                                buf->expand_genblock(buf->str + ".");
                        }

                        for (size_t i = 0; i < buf->children.size(); i++) {
                                buf->children[i]->simplify(const_fold, false, false, stage, -1, false, false);
                                current_ast_mod->children.push_back(buf->children[i]);
                        }

                        buf->children.clear();
                        delete buf;
                }

                delete_children();
                did_something = true;
        }

        // simplify generate-case blocks
        if (type == AST_GENCASE && children.size() != 0)
        {
                AstNode *buf = children[0]->clone();
                while (buf->simplify(true, false, false, stage, width_hint, sign_hint, false)) { }
                if (buf->type != AST_CONSTANT) {
                        // for (auto f : log_files)
                        //      dumpAst(f, "verilog-ast> ");
                        log_file_error(filename, location.first_line, "Condition for generate case is not constant!\n");
                }

                bool ref_signed = buf->is_signed;
                RTLIL::Const ref_value = buf->bitsAsConst();
                delete buf;

                AstNode *selected_case = NULL;
                for (size_t i = 1; i < children.size(); i++)
                {
                        log_assert(children.at(i)->type == AST_COND || children.at(i)->type == AST_CONDX || children.at(i)->type == AST_CONDZ);

                        AstNode *this_genblock = NULL;
                        for (auto child : children.at(i)->children) {
                                log_assert(this_genblock == NULL);
                                if (child->type == AST_GENBLOCK)
                                        this_genblock = child;
                        }

                        for (auto child : children.at(i)->children)
                        {
                                if (child->type == AST_DEFAULT) {
                                        if (selected_case == NULL)
                                                selected_case = this_genblock;
                                        continue;
                                }
                                if (child->type == AST_GENBLOCK)
                                        continue;

                                buf = child->clone();
                                while (buf->simplify(true, false, false, stage, width_hint, sign_hint, true)) { }
                                if (buf->type != AST_CONSTANT) {
                                        // for (auto f : log_files)
                                        //      dumpAst(f, "verilog-ast> ");
                                        log_file_error(filename, location.first_line, "Expression in generate case is not constant!\n");
                                }

                                bool is_selected = RTLIL::const_eq(ref_value, buf->bitsAsConst(), ref_signed && buf->is_signed, ref_signed && buf->is_signed, 1).as_bool();
                                delete buf;

                                if (is_selected) {
                                        selected_case = this_genblock;
                                        i = children.size();
                                        break;
                                }
                        }
                }

                if (selected_case != NULL)
                {
                        log_assert(selected_case->type == AST_GENBLOCK);
                        buf = selected_case->clone();

                        if (!buf->str.empty()) {
                                buf->expand_genblock(buf->str + ".");
                        }

                        for (size_t i = 0; i < buf->children.size(); i++) {
                                buf->children[i]->simplify(const_fold, false, false, stage, -1, false, false);
                                current_ast_mod->children.push_back(buf->children[i]);
                        }

                        buf->children.clear();
                        delete buf;
                }

                delete_children();
                did_something = true;
        }

        // unroll cell arrays
        if (type == AST_CELLARRAY)
        {
                if (!children.at(0)->range_valid)
                        log_file_error(filename, location.first_line, "Non-constant array range on cell array.\n");

                newNode = new AstNode(AST_GENBLOCK);
                int num = max(children.at(0)->range_left, children.at(0)->range_right) - min(children.at(0)->range_left, children.at(0)->range_right) + 1;

                for (int i = 0; i < num; i++) {
                        int idx = children.at(0)->range_left > children.at(0)->range_right ? children.at(0)->range_right + i : children.at(0)->range_right - i;
                        AstNode *new_cell = children.at(1)->clone();
                        newNode->children.push_back(new_cell);
                        new_cell->str += stringf("[%d]", idx);
                        if (new_cell->type == AST_PRIMITIVE) {
                                log_file_error(filename, location.first_line, "Cell arrays of primitives are currently not supported.\n");
                        } else {
                                log_assert(new_cell->children.at(0)->type == AST_CELLTYPE);
                                new_cell->children.at(0)->str = stringf("$array:%d:%d:%s", i, num, new_cell->children.at(0)->str.c_str());
                        }
                }

                goto apply_newNode;
        }

        // replace primitives with assignments
        if (type == AST_PRIMITIVE)
        {
                if (children.size() < 2)
                        log_file_error(filename, location.first_line, "Insufficient number of arguments for primitive `%s'!\n", str.c_str());

                std::vector<AstNode*> children_list;
                for (auto child : children) {
                        log_assert(child->type == AST_ARGUMENT);
                        log_assert(child->children.size() == 1);
                        children_list.push_back(child->children[0]);
                        child->children.clear();
                        delete child;
                }
                children.clear();

                if (str == "bufif0" || str == "bufif1" || str == "notif0" || str == "notif1")
                {
                        if (children_list.size() != 3)
                                log_file_error(filename, location.first_line, "Invalid number of arguments for primitive `%s'!\n", str.c_str());

                        std::vector<RTLIL::State> z_const(1, RTLIL::State::Sz);

                        AstNode *mux_input = children_list.at(1);
                        if (str == "notif0" || str == "notif1") {
                                mux_input = new AstNode(AST_BIT_NOT, mux_input);
                        }
                        AstNode *node = new AstNode(AST_TERNARY, children_list.at(2));
                        if (str == "bufif0") {
                                node->children.push_back(AstNode::mkconst_bits(z_const, false));
                                node->children.push_back(mux_input);
                        } else {
                                node->children.push_back(mux_input);
                                node->children.push_back(AstNode::mkconst_bits(z_const, false));
                        }

                        str.clear();
                        type = AST_ASSIGN;
                        children.push_back(children_list.at(0));
                        children.back()->was_checked = true;
                        children.push_back(node);
                        did_something = true;
                }
                else if (str == "buf" || str == "not")
                {
                        AstNode *input = children_list.back();
                        if (str == "not")
                                input = new AstNode(AST_BIT_NOT, input);

                        newNode = new AstNode(AST_GENBLOCK);
                        for (auto it = children_list.begin(); it != std::prev(children_list.end()); it++) {
                                newNode->children.push_back(new AstNode(AST_ASSIGN, *it, input->clone()));
                                newNode->children.back()->was_checked = true;
                        }
                        delete input;

                        did_something = true;
                }
                else
                {
                        AstNodeType op_type = AST_NONE;
                        bool invert_results = false;

                        if (str == "and")
                                op_type = AST_BIT_AND;
                        if (str == "nand")
                                op_type = AST_BIT_AND, invert_results = true;
                        if (str == "or")
                                op_type = AST_BIT_OR;
                        if (str == "nor")
                                op_type = AST_BIT_OR, invert_results = true;
                        if (str == "xor")
                                op_type = AST_BIT_XOR;
                        if (str == "xnor")
                                op_type = AST_BIT_XOR, invert_results = true;
                        log_assert(op_type != AST_NONE);

                        AstNode *node = children_list[1];
                        if (op_type != AST_POS)
                                for (size_t i = 2; i < children_list.size(); i++) {
                                        node = new AstNode(op_type, node, children_list[i]);
                                        node->location = location;
                                }
                        if (invert_results)
                                node = new AstNode(AST_BIT_NOT, node);

                        str.clear();
                        type = AST_ASSIGN;
                        children.push_back(children_list[0]);
                        children.back()->was_checked = true;
                        children.push_back(node);
                        did_something = true;
                }
        }

        // replace dynamic ranges in left-hand side expressions (e.g. "foo[bar] <= 1'b1;") with
        // either a big case block that selects the correct single-bit assignment, or mask and
        // shift operations.
        if (type == AST_ASSIGN_EQ || type == AST_ASSIGN_LE)
        {
                if (children[0]->type != AST_IDENTIFIER || children[0]->children.size() == 0)
                        goto skip_dynamic_range_lvalue_expansion;
                if (children[0]->children[0]->range_valid || did_something)
                        goto skip_dynamic_range_lvalue_expansion;
                if (children[0]->id2ast == NULL || children[0]->id2ast->type != AST_WIRE)
                        goto skip_dynamic_range_lvalue_expansion;
                if (!children[0]->id2ast->range_valid)
                        goto skip_dynamic_range_lvalue_expansion;

                int source_width = children[0]->id2ast->range_left - children[0]->id2ast->range_right + 1;
                int result_width = 1;

                AstNode *shift_expr = NULL;
                AstNode *range = children[0]->children[0];

                if (range->children.size() == 1) {
                        shift_expr = range->children[0]->clone();
                } else {
                        shift_expr = range->children[1]->clone();
                        AstNode *left_at_zero_ast = range->children[0]->clone();
                        AstNode *right_at_zero_ast = range->children[1]->clone();
                        while (left_at_zero_ast->simplify(true, true, false, stage, -1, false, false)) { }
                        while (right_at_zero_ast->simplify(true, true, false, stage, -1, false, false)) { }
                        if (left_at_zero_ast->type != AST_CONSTANT || right_at_zero_ast->type != AST_CONSTANT)
                                log_file_error(filename, location.first_line, "Unsupported expression on dynamic range select on signal `%s'!\n", str.c_str());
                        result_width = abs(int(left_at_zero_ast->integer - right_at_zero_ast->integer)) + 1;
                        delete left_at_zero_ast;
                        delete right_at_zero_ast;
                }

                bool use_case_method = false;

                if (children[0]->id2ast->attributes.count(ID::nowrshmsk)) {
                        AstNode *node = children[0]->id2ast->attributes.at(ID::nowrshmsk);
                        while (node->simplify(true, false, false, stage, -1, false, false)) { }
                        if (node->type != AST_CONSTANT)
                                log_file_error(filename, location.first_line, "Non-constant value for `nowrshmsk' attribute on `%s'!\n", children[0]->id2ast->str.c_str());
                        if (node->asAttrConst().as_bool())
                                use_case_method = true;
                }

                if (!use_case_method && current_always->detect_latch(children[0]->str))
                        use_case_method = true;

                if (use_case_method)
                {
                        // big case block

                        did_something = true;
                        newNode = new AstNode(AST_CASE, shift_expr);
                        for (int i = 0; i < source_width; i++) {
                                int start_bit = children[0]->id2ast->range_right + i;
                                int end_bit = std::min(start_bit+result_width,source_width) - 1;
                                AstNode *cond = new AstNode(AST_COND, mkconst_int(start_bit, true));
                                AstNode *lvalue = children[0]->clone();
                                lvalue->delete_children();
                                lvalue->children.push_back(new AstNode(AST_RANGE,
                                                mkconst_int(end_bit, true), mkconst_int(start_bit, true)));
                                cond->children.push_back(new AstNode(AST_BLOCK, new AstNode(type, lvalue, children[1]->clone())));
                                newNode->children.push_back(cond);
                        }
                }
                else
                {
                        // mask and shift operations, disabled for now

                        AstNode *wire_mask = new AstNode(AST_WIRE, new AstNode(AST_RANGE, mkconst_int(source_width-1, true), mkconst_int(0, true)));
                        wire_mask->str = stringf("$bitselwrite$mask$%s:%d$%d", filename.c_str(), location.first_line, autoidx++);
                        wire_mask->attributes[ID::nosync] = AstNode::mkconst_int(1, false);
                        wire_mask->is_logic = true;
                        while (wire_mask->simplify(true, false, false, 1, -1, false, false)) { }
                        current_ast_mod->children.push_back(wire_mask);

                        AstNode *wire_data = new AstNode(AST_WIRE, new AstNode(AST_RANGE, mkconst_int(source_width-1, true), mkconst_int(0, true)));
                        wire_data->str = stringf("$bitselwrite$data$%s:%d$%d", filename.c_str(), location.first_line, autoidx++);
                        wire_data->attributes[ID::nosync] = AstNode::mkconst_int(1, false);
                        wire_data->is_logic = true;
                        while (wire_data->simplify(true, false, false, 1, -1, false, false)) { }
                        current_ast_mod->children.push_back(wire_data);

                        did_something = true;
                        newNode = new AstNode(AST_BLOCK);

                        AstNode *lvalue = children[0]->clone();
                        lvalue->delete_children();

                        AstNode *ref_mask = new AstNode(AST_IDENTIFIER);
                        ref_mask->str = wire_mask->str;
                        ref_mask->id2ast = wire_mask;
                        ref_mask->was_checked = true;

                        AstNode *ref_data = new AstNode(AST_IDENTIFIER);
                        ref_data->str = wire_data->str;
                        ref_data->id2ast = wire_data;
                        ref_data->was_checked = true;

                        AstNode *old_data = lvalue->clone();
                        if (type == AST_ASSIGN_LE)
                                old_data->lookahead = true;

                        AstNode *shamt = shift_expr;

                        int shamt_width_hint = 0;
                        bool shamt_sign_hint = true;
                        shamt->detectSignWidth(shamt_width_hint, shamt_sign_hint);

                        int start_bit = children[0]->id2ast->range_right;
                        bool use_shift = shamt_sign_hint;

                        if (start_bit != 0) {
                                shamt = new AstNode(AST_SUB, shamt, mkconst_int(start_bit, true));
                                use_shift = true;
                        }

                        AstNode *t;

                        t = mkconst_bits(std::vector<RTLIL::State>(result_width, State::S1), false);
                        if (use_shift)
                                t = new AstNode(AST_SHIFT, t, new AstNode(AST_NEG, shamt->clone()));
                        else
                                t = new AstNode(AST_SHIFT_LEFT, t, shamt->clone());
                        t = new AstNode(AST_ASSIGN_EQ, ref_mask->clone(), t);
                        newNode->children.push_back(t);

                        t = new AstNode(AST_BIT_AND, mkconst_bits(std::vector<RTLIL::State>(result_width, State::S1), false), children[1]->clone());
                        if (use_shift)
                                t = new AstNode(AST_SHIFT, t, new AstNode(AST_NEG, shamt));
                        else
                                t = new AstNode(AST_SHIFT_LEFT, t, shamt);
                        t = new AstNode(AST_ASSIGN_EQ, ref_data->clone(), t);
                        newNode->children.push_back(t);

                        t = new AstNode(AST_BIT_AND, old_data, new AstNode(AST_BIT_NOT, ref_mask));
                        t = new AstNode(AST_BIT_OR, t, ref_data);
                        t = new AstNode(type, lvalue, t);
                        newNode->children.push_back(t);
                }

                goto apply_newNode;
        }
skip_dynamic_range_lvalue_expansion:;

        if (stage > 1 && (type == AST_ASSERT || type == AST_ASSUME || type == AST_LIVE || type == AST_FAIR || type == AST_COVER) && current_block != NULL)
        {
                std::stringstream sstr;
                sstr << "$formal$" << filename << ":" << location.first_line << "$" << (autoidx++);
                std::string id_check = sstr.str() + "_CHECK", id_en = sstr.str() + "_EN";

                AstNode *wire_check = new AstNode(AST_WIRE);
                wire_check->str = id_check;
                wire_check->was_checked = true;
                current_ast_mod->children.push_back(wire_check);
                current_scope[wire_check->str] = wire_check;
                while (wire_check->simplify(true, false, false, 1, -1, false, false)) { }

                AstNode *wire_en = new AstNode(AST_WIRE);
                wire_en->str = id_en;
                wire_en->was_checked = true;
                current_ast_mod->children.push_back(wire_en);
                if (current_always_clocked) {
                        current_ast_mod->children.push_back(new AstNode(AST_INITIAL, new AstNode(AST_BLOCK, new AstNode(AST_ASSIGN_LE, new AstNode(AST_IDENTIFIER), AstNode::mkconst_int(0, false, 1)))));
                        current_ast_mod->children.back()->children[0]->children[0]->children[0]->str = id_en;
                        current_ast_mod->children.back()->children[0]->children[0]->children[0]->was_checked = true;
                }
                current_scope[wire_en->str] = wire_en;
                while (wire_en->simplify(true, false, false, 1, -1, false, false)) { }

                AstNode *check_defval;
                if (type == AST_LIVE || type == AST_FAIR) {
                        check_defval = new AstNode(AST_REDUCE_BOOL, children[0]->clone());
                } else {
                        std::vector<RTLIL::State> x_bit;
                        x_bit.push_back(RTLIL::State::Sx);
                        check_defval = mkconst_bits(x_bit, false);
                }

                AstNode *assign_check = new AstNode(AST_ASSIGN_LE, new AstNode(AST_IDENTIFIER), check_defval);
                assign_check->children[0]->str = id_check;
                assign_check->children[0]->was_checked = true;

                AstNode *assign_en = new AstNode(AST_ASSIGN_LE, new AstNode(AST_IDENTIFIER), mkconst_int(0, false, 1));
                assign_en->children[0]->str = id_en;
                assign_en->children[0]->was_checked = true;

                AstNode *default_signals = new AstNode(AST_BLOCK);
                default_signals->children.push_back(assign_check);
                default_signals->children.push_back(assign_en);
                current_top_block->children.insert(current_top_block->children.begin(), default_signals);

                if (type == AST_LIVE || type == AST_FAIR) {
                        assign_check = nullptr;
                } else {
                        assign_check = new AstNode(AST_ASSIGN_LE, new AstNode(AST_IDENTIFIER), new AstNode(AST_REDUCE_BOOL, children[0]->clone()));
                        assign_check->children[0]->str = id_check;
                        assign_check->children[0]->was_checked = true;
                }

                if (current_always == nullptr || current_always->type != AST_INITIAL) {
                        assign_en = new AstNode(AST_ASSIGN_LE, new AstNode(AST_IDENTIFIER), mkconst_int(1, false, 1));
                } else {
                        assign_en = new AstNode(AST_ASSIGN_LE, new AstNode(AST_IDENTIFIER), new AstNode(AST_FCALL));
                        assign_en->children[1]->str = "\\$initstate";
                }
                assign_en->children[0]->str = id_en;
                assign_en->children[0]->was_checked = true;

                newNode = new AstNode(AST_BLOCK);
                if (assign_check != nullptr)
                        newNode->children.push_back(assign_check);
                newNode->children.push_back(assign_en);

                AstNode *assertnode = new AstNode(type);
                assertnode->location = location;
                assertnode->str = str;
                assertnode->children.push_back(new AstNode(AST_IDENTIFIER));
                assertnode->children.push_back(new AstNode(AST_IDENTIFIER));
                assertnode->children[0]->str = id_check;
                assertnode->children[1]->str = id_en;
                assertnode->attributes.swap(attributes);
                current_ast_mod->children.push_back(assertnode);

                goto apply_newNode;
        }

        if (stage > 1 && (type == AST_ASSERT || type == AST_ASSUME || type == AST_LIVE || type == AST_FAIR || type == AST_COVER) && children.size() == 1)
        {
                children.push_back(mkconst_int(1, false, 1));
                did_something = true;
        }

        // found right-hand side identifier for memory -> replace with memory read port
        if (stage > 1 && type == AST_IDENTIFIER && id2ast != NULL && id2ast->type == AST_MEMORY && !in_lvalue &&
                        children.size() == 1 && children[0]->type == AST_RANGE && children[0]->children.size() == 1) {
                newNode = new AstNode(AST_MEMRD, children[0]->children[0]->clone());
                newNode->str = str;
                newNode->id2ast = id2ast;
                goto apply_newNode;
        }

        // assignment with nontrivial member in left-hand concat expression -> split assignment
        if ((type == AST_ASSIGN_EQ || type == AST_ASSIGN_LE) && children[0]->type == AST_CONCAT && width_hint > 0)
        {
                bool found_nontrivial_member = false;

                for (auto child : children[0]->children) {
                        if (child->type == AST_IDENTIFIER && child->id2ast != NULL && child->id2ast->type == AST_MEMORY)
                                found_nontrivial_member = true;
                }

                if (found_nontrivial_member)
                {
                        newNode = new AstNode(AST_BLOCK);

                        AstNode *wire_tmp = new AstNode(AST_WIRE, new AstNode(AST_RANGE, mkconst_int(width_hint-1, true), mkconst_int(0, true)));
                        wire_tmp->str = stringf("$splitcmplxassign$%s:%d$%d", filename.c_str(), location.first_line, autoidx++);
                        current_ast_mod->children.push_back(wire_tmp);
                        current_scope[wire_tmp->str] = wire_tmp;
                        wire_tmp->attributes[ID::nosync] = AstNode::mkconst_int(1, false);
                        while (wire_tmp->simplify(true, false, false, 1, -1, false, false)) { }
                        wire_tmp->is_logic = true;

                        AstNode *wire_tmp_id = new AstNode(AST_IDENTIFIER);
                        wire_tmp_id->str = wire_tmp->str;

                        newNode->children.push_back(new AstNode(AST_ASSIGN_EQ, wire_tmp_id, children[1]->clone()));
                        newNode->children.back()->was_checked = true;

                        int cursor = 0;
                        for (auto child : children[0]->children)
                        {
                                int child_width_hint = -1;
                                bool child_sign_hint = true;
                                child->detectSignWidth(child_width_hint, child_sign_hint);

                                AstNode *rhs = wire_tmp_id->clone();
                                rhs->children.push_back(new AstNode(AST_RANGE, AstNode::mkconst_int(cursor+child_width_hint-1, true), AstNode::mkconst_int(cursor, true)));
                                newNode->children.push_back(new AstNode(type, child->clone(), rhs));

                                cursor += child_width_hint;
                        }

                        goto apply_newNode;
                }
        }

        // assignment with memory in left-hand side expression -> replace with memory write port
        if (stage > 1 && (type == AST_ASSIGN_EQ || type == AST_ASSIGN_LE) && children[0]->type == AST_IDENTIFIER &&
                        children[0]->id2ast && children[0]->id2ast->type == AST_MEMORY && children[0]->id2ast->children.size() >= 2 &&
                        children[0]->id2ast->children[0]->range_valid && children[0]->id2ast->children[1]->range_valid &&
                        (children[0]->children.size() == 1 || children[0]->children.size() == 2) && children[0]->children[0]->type == AST_RANGE)
        {
                std::stringstream sstr;
                sstr << "$memwr$" << children[0]->str << "$" << filename << ":" << location.first_line << "$" << (autoidx++);
                std::string id_addr = sstr.str() + "_ADDR", id_data = sstr.str() + "_DATA", id_en = sstr.str() + "_EN";

                int mem_width, mem_size, addr_bits;
                bool mem_signed = children[0]->id2ast->is_signed;
                children[0]->id2ast->meminfo(mem_width, mem_size, addr_bits);

                newNode = new AstNode(AST_BLOCK);
                AstNode *defNode = new AstNode(AST_BLOCK);

                int data_range_left = children[0]->id2ast->children[0]->range_left;
                int data_range_right = children[0]->id2ast->children[0]->range_right;
                int mem_data_range_offset = std::min(data_range_left, data_range_right);

                int addr_width_hint = -1;
                bool addr_sign_hint = true;
                children[0]->children[0]->children[0]->detectSignWidthWorker(addr_width_hint, addr_sign_hint);
                addr_bits = std::max(addr_bits, addr_width_hint);

                std::vector<RTLIL::State> x_bits_addr, x_bits_data, set_bits_en;
                for (int i = 0; i < addr_bits; i++)
                        x_bits_addr.push_back(RTLIL::State::Sx);
                for (int i = 0; i < mem_width; i++)
                        x_bits_data.push_back(RTLIL::State::Sx);
                for (int i = 0; i < mem_width; i++)
                        set_bits_en.push_back(RTLIL::State::S1);

                AstNode *node_addr = nullptr;
                if (children[0]->children[0]->children[0]->isConst()) {
                        node_addr = children[0]->children[0]->children[0]->clone();
                } else {
                        AstNode *wire_addr = new AstNode(AST_WIRE, new AstNode(AST_RANGE, mkconst_int(addr_bits-1, true), mkconst_int(0, true)));
                        wire_addr->str = id_addr;
                        wire_addr->was_checked = true;
                        current_ast_mod->children.push_back(wire_addr);
                        current_scope[wire_addr->str] = wire_addr;
                        while (wire_addr->simplify(true, false, false, 1, -1, false, false)) { }

                        AstNode *assign_addr = new AstNode(AST_ASSIGN_EQ, new AstNode(AST_IDENTIFIER), mkconst_bits(x_bits_addr, false));
                        assign_addr->children[0]->str = id_addr;
                        assign_addr->children[0]->was_checked = true;
                        defNode->children.push_back(assign_addr);

                        assign_addr = new AstNode(AST_ASSIGN_EQ, new AstNode(AST_IDENTIFIER), children[0]->children[0]->children[0]->clone());
                        assign_addr->children[0]->str = id_addr;
                        assign_addr->children[0]->was_checked = true;
                        newNode->children.push_back(assign_addr);

                        node_addr = new AstNode(AST_IDENTIFIER);
                        node_addr->str = id_addr;
                }

                AstNode *node_data = nullptr;
                if (children[0]->children.size() == 1 && children[1]->isConst()) {
                        node_data = children[1]->clone();
                } else {
                        AstNode *wire_data = new AstNode(AST_WIRE, new AstNode(AST_RANGE, mkconst_int(mem_width-1, true), mkconst_int(0, true)));
                        wire_data->str = id_data;
                        wire_data->was_checked = true;
                        wire_data->is_signed = mem_signed;
                        current_ast_mod->children.push_back(wire_data);
                        current_scope[wire_data->str] = wire_data;
                        while (wire_data->simplify(true, false, false, 1, -1, false, false)) { }

                        AstNode *assign_data = new AstNode(AST_ASSIGN_EQ, new AstNode(AST_IDENTIFIER), mkconst_bits(x_bits_data, false));
                        assign_data->children[0]->str = id_data;
                        assign_data->children[0]->was_checked = true;
                        defNode->children.push_back(assign_data);

                        node_data = new AstNode(AST_IDENTIFIER);
                        node_data->str = id_data;
                }

                AstNode *wire_en = new AstNode(AST_WIRE, new AstNode(AST_RANGE, mkconst_int(mem_width-1, true), mkconst_int(0, true)));
                wire_en->str = id_en;
                wire_en->was_checked = true;
                current_ast_mod->children.push_back(wire_en);
                current_scope[wire_en->str] = wire_en;
                while (wire_en->simplify(true, false, false, 1, -1, false, false)) { }

                AstNode *assign_en_first = new AstNode(AST_ASSIGN_EQ, new AstNode(AST_IDENTIFIER), mkconst_int(0, false, mem_width));
                assign_en_first->children[0]->str = id_en;
                assign_en_first->children[0]->was_checked = true;
                defNode->children.push_back(assign_en_first);

                AstNode *node_en = new AstNode(AST_IDENTIFIER);
                node_en->str = id_en;

                if (!defNode->children.empty())
                        current_top_block->children.insert(current_top_block->children.begin(), defNode);
                else
                        delete defNode;

                AstNode *assign_data = nullptr;
                AstNode *assign_en = nullptr;
                if (children[0]->children.size() == 2)
                {
                        if (children[0]->children[1]->range_valid)
                        {
                                int offset = children[0]->children[1]->range_right;
                                int width = children[0]->children[1]->range_left - offset + 1;
                                offset -= mem_data_range_offset;

                                std::vector<RTLIL::State> padding_x(offset, RTLIL::State::Sx);

                                assign_data = new AstNode(AST_ASSIGN_EQ, new AstNode(AST_IDENTIFIER),
                                                new AstNode(AST_CONCAT, mkconst_bits(padding_x, false), children[1]->clone()));
                                assign_data->children[0]->str = id_data;
                                assign_data->children[0]->was_checked = true;

                                for (int i = 0; i < mem_width; i++)
                                        set_bits_en[i] = offset <= i && i < offset+width ? RTLIL::State::S1 : RTLIL::State::S0;
                                assign_en = new AstNode(AST_ASSIGN_EQ, new AstNode(AST_IDENTIFIER), mkconst_bits(set_bits_en, false));
                                assign_en->children[0]->str = id_en;
                                assign_en->children[0]->was_checked = true;
                        }
                        else
                        {
                                AstNode *the_range = children[0]->children[1];
                                AstNode *left_at_zero_ast = the_range->children[0]->clone();
                                AstNode *right_at_zero_ast = the_range->children.size() >= 2 ? the_range->children[1]->clone() : left_at_zero_ast->clone();
                                AstNode *offset_ast = right_at_zero_ast->clone();

                                if (mem_data_range_offset)
                                        offset_ast = new AstNode(AST_SUB, offset_ast, mkconst_int(mem_data_range_offset, true));

                                while (left_at_zero_ast->simplify(true, true, false, 1, -1, false, false)) { }
                                while (right_at_zero_ast->simplify(true, true, false, 1, -1, false, false)) { }
                                if (left_at_zero_ast->type != AST_CONSTANT || right_at_zero_ast->type != AST_CONSTANT)
                                        log_file_error(filename, location.first_line, "Unsupported expression on dynamic range select on signal `%s'!\n", str.c_str());
                                int width = abs(int(left_at_zero_ast->integer - right_at_zero_ast->integer)) + 1;

                                assign_data = new AstNode(AST_ASSIGN_EQ, new AstNode(AST_IDENTIFIER),
                                                new AstNode(AST_SHIFT_LEFT, children[1]->clone(), offset_ast->clone()));
                                assign_data->children[0]->str = id_data;
                                assign_data->children[0]->was_checked = true;

                                for (int i = 0; i < mem_width; i++)
                                        set_bits_en[i] = i < width ? RTLIL::State::S1 : RTLIL::State::S0;
                                assign_en = new AstNode(AST_ASSIGN_EQ, new AstNode(AST_IDENTIFIER),
                                                new AstNode(AST_SHIFT_LEFT, mkconst_bits(set_bits_en, false), offset_ast->clone()));
                                assign_en->children[0]->str = id_en;
                                assign_en->children[0]->was_checked = true;

                                delete left_at_zero_ast;
                                delete right_at_zero_ast;
                                delete offset_ast;
                        }
                }
                else
                {
                        if (!(children[0]->children.size() == 1 && children[1]->isConst())) {
                                assign_data = new AstNode(AST_ASSIGN_EQ, new AstNode(AST_IDENTIFIER), children[1]->clone());
                                assign_data->children[0]->str = id_data;
                                assign_data->children[0]->was_checked = true;
                        }

                        assign_en = new AstNode(AST_ASSIGN_EQ, new AstNode(AST_IDENTIFIER), mkconst_bits(set_bits_en, false));
                        assign_en->children[0]->str = id_en;
                        assign_en->children[0]->was_checked = true;
                }
                if (assign_data)
                        newNode->children.push_back(assign_data);
                if (assign_en)
                        newNode->children.push_back(assign_en);

                AstNode *wrnode;
                if (current_always->type == AST_INITIAL)
                        wrnode = new AstNode(AST_MEMINIT, node_addr, node_data, node_en, mkconst_int(1, false));
                else
                        wrnode = new AstNode(AST_MEMWR, node_addr, node_data, node_en);
                wrnode->str = children[0]->str;
                wrnode->id2ast = children[0]->id2ast;
                wrnode->location = location;
                if (wrnode->type == AST_MEMWR) {
                        int portid = current_memwr_count[wrnode->str]++;
                        wrnode->children.push_back(mkconst_int(portid, false));
                        std::vector<RTLIL::State> priority_mask;
                        for (int i = 0; i < portid; i++) {
                                bool has_prio = current_memwr_visible[wrnode->str].count(i);
                                priority_mask.push_back(State(has_prio));
                        }
                        wrnode->children.push_back(mkconst_bits(priority_mask, false));
                        current_memwr_visible[wrnode->str].insert(portid);
                        current_always->children.push_back(wrnode);
                } else {
                        current_ast_mod->children.push_back(wrnode);
                }

                if (newNode->children.empty()) {
                        delete newNode;
                        newNode = new AstNode();
                }
                goto apply_newNode;
        }

        // replace function and task calls with the code from the function or task
        if ((type == AST_FCALL || type == AST_TCALL) && !str.empty())
        {
                if (type == AST_FCALL)
                {
                        if (str == "\\$initstate")
                        {
                                int myidx = autoidx++;

                                AstNode *wire = new AstNode(AST_WIRE);
                                wire->str = stringf("$initstate$%d_wire", myidx);
                                current_ast_mod->children.push_back(wire);
                                while (wire->simplify(true, false, false, 1, -1, false, false)) { }

                                AstNode *cell = new AstNode(AST_CELL, new AstNode(AST_CELLTYPE), new AstNode(AST_ARGUMENT, new AstNode(AST_IDENTIFIER)));
                                cell->str = stringf("$initstate$%d", myidx);
                                cell->children[0]->str = "$initstate";
                                cell->children[1]->str = "\\Y";
                                cell->children[1]->children[0]->str = wire->str;
                                cell->children[1]->children[0]->id2ast = wire;
                                current_ast_mod->children.push_back(cell);
                                while (cell->simplify(true, false, false, 1, -1, false, false)) { }

                                newNode = new AstNode(AST_IDENTIFIER);
                                newNode->str = wire->str;
                                newNode->id2ast = wire;
                                goto apply_newNode;
                        }

                        if (str == "\\$past")
                        {
                                if (width_hint < 0)
                                        goto replace_fcall_later;

                                int num_steps = 1;

                                if (GetSize(children) != 1 && GetSize(children) != 2)
                                        log_file_error(filename, location.first_line, "System function %s got %d arguments, expected 1 or 2.\n",
                                                        RTLIL::unescape_id(str).c_str(), int(children.size()));

                                if (!current_always_clocked)
                                        log_file_error(filename, location.first_line, "System function %s is only allowed in clocked blocks.\n",
                                                        RTLIL::unescape_id(str).c_str());

                                if (GetSize(children) == 2)
                                {
                                        AstNode *buf = children[1]->clone();
                                        while (buf->simplify(true, false, false, stage, -1, false, false)) { }
                                        if (buf->type != AST_CONSTANT)
                                                log_file_error(filename, location.first_line, "Failed to evaluate system function `%s' with non-constant value.\n", str.c_str());

                                        num_steps = buf->asInt(true);
                                        delete buf;
                                }

                                AstNode *block = nullptr;

                                for (auto child : current_always->children)
                                        if (child->type == AST_BLOCK)
                                                block = child;

                                log_assert(block != nullptr);

                                if (num_steps == 0) {
                                        newNode = children[0]->clone();
                                        goto apply_newNode;
                                }

                                int myidx = autoidx++;
                                AstNode *outreg = nullptr;

                                for (int i = 0; i < num_steps; i++)
                                {
                                        AstNode *reg = new AstNode(AST_WIRE, new AstNode(AST_RANGE,
                                                        mkconst_int(width_hint-1, true), mkconst_int(0, true)));

                                        reg->str = stringf("$past$%s:%d$%d$%d", filename.c_str(), location.first_line, myidx, i);
                                        reg->is_reg = true;

                                        current_ast_mod->children.push_back(reg);

                                        while (reg->simplify(true, false, false, 1, -1, false, false)) { }

                                        AstNode *regid = new AstNode(AST_IDENTIFIER);
                                        regid->str = reg->str;
                                        regid->id2ast = reg;
                                        regid->was_checked = true;

                                        AstNode *rhs = nullptr;

                                        if (outreg == nullptr) {
                                                rhs = children.at(0)->clone();
                                        } else {
                                                rhs = new AstNode(AST_IDENTIFIER);
                                                rhs->str = outreg->str;
                                                rhs->id2ast = outreg;
                                        }

                                        block->children.push_back(new AstNode(AST_ASSIGN_LE, regid, rhs));
                                        outreg = reg;
                                }

                                newNode = new AstNode(AST_IDENTIFIER);
                                newNode->str = outreg->str;
                                newNode->id2ast = outreg;
                                goto apply_newNode;
                        }

                        if (str == "\\$stable" || str == "\\$rose" || str == "\\$fell" || str == "\\$changed")
                        {
                                if (GetSize(children) != 1)
                                        log_file_error(filename, location.first_line, "System function %s got %d arguments, expected 1.\n",
                                                        RTLIL::unescape_id(str).c_str(), int(children.size()));

                                if (!current_always_clocked)
                                        log_file_error(filename, location.first_line, "System function %s is only allowed in clocked blocks.\n",
                                                        RTLIL::unescape_id(str).c_str());

                                AstNode *present = children.at(0)->clone();
                                AstNode *past = clone();
                                past->str = "\\$past";

                                if (str == "\\$stable")
                                        newNode = new AstNode(AST_EQ, past, present);

                                else if (str == "\\$changed")
                                        newNode = new AstNode(AST_NE, past, present);

                                else if (str == "\\$rose")
                                        newNode = new AstNode(AST_LOGIC_AND,
                                                        new AstNode(AST_LOGIC_NOT, new AstNode(AST_BIT_AND, past, mkconst_int(1,false))),
                                                        new AstNode(AST_BIT_AND, present, mkconst_int(1,false)));

                                else if (str == "\\$fell")
                                        newNode = new AstNode(AST_LOGIC_AND,
                                                        new AstNode(AST_BIT_AND, past, mkconst_int(1,false)),
                                                        new AstNode(AST_LOGIC_NOT, new AstNode(AST_BIT_AND, present, mkconst_int(1,false))));

                                else
                                        log_abort();

                                goto apply_newNode;
                        }

                        // $anyconst and $anyseq are mapped in AstNode::genRTLIL()
                        if (str == "\\$anyconst" || str == "\\$anyseq" || str == "\\$allconst" || str == "\\$allseq") {
                                recursion_counter--;
                                return false;
                        }

                        if (str == "\\$clog2")
                        {
                                if (children.size() != 1)
                                        log_file_error(filename, location.first_line, "System function %s got %d arguments, expected 1.\n",
                                                        RTLIL::unescape_id(str).c_str(), int(children.size()));

                                AstNode *buf = children[0]->clone();
                                while (buf->simplify(true, false, false, stage, width_hint, sign_hint, false)) { }
                                if (buf->type != AST_CONSTANT)
                                        log_file_error(filename, location.first_line, "Failed to evaluate system function `%s' with non-constant value.\n", str.c_str());

                                RTLIL::Const arg_value = buf->bitsAsConst();
                                if (arg_value.as_bool())
                                        arg_value = const_sub(arg_value, 1, false, false, GetSize(arg_value));
                                delete buf;

                                uint32_t result = 0;
                                for (size_t i = 0; i < arg_value.bits.size(); i++)
                                        if (arg_value.bits.at(i) == RTLIL::State::S1)
                                                result = i + 1;

                                newNode = mkconst_int(result, true);
                                goto apply_newNode;
                        }

                        if (str == "\\$size" || str == "\\$bits" || str == "\\$high" || str == "\\$low" || str == "\\$left" || str == "\\$right")
                        {
                                int dim = 1;
                                if (str == "\\$bits") {
                                        if (children.size() != 1)
                                                log_file_error(filename, location.first_line, "System function %s got %d arguments, expected 1.\n",
                                                                RTLIL::unescape_id(str).c_str(), int(children.size()));
                                } else {
                                        if (children.size() != 1 && children.size() != 2)
                                                log_file_error(filename, location.first_line, "System function %s got %d arguments, expected 1 or 2.\n",
                                                        RTLIL::unescape_id(str).c_str(), int(children.size()));
                                        if (children.size() == 2) {
                                                AstNode *buf = children[1]->clone();
                                                // Evaluate constant expression
                                                while (buf->simplify(true, false, false, stage, width_hint, sign_hint, false)) { }
                                                dim = buf->asInt(false);
                                                delete buf;
                                        }
                                }
                                AstNode *buf = children[0]->clone();
                                int mem_depth = 1;
                                int result, high = 0, low = 0, left = 0, right = 0, width = 1; // defaults for a simple wire
                                AstNode *id_ast = NULL;

                                // Is this needed?
                                //while (buf->simplify(true, false, false, stage, width_hint, sign_hint, false)) { }
                                buf->detectSignWidth(width_hint, sign_hint);

                                if (buf->type == AST_IDENTIFIER) {
                                        id_ast = buf->id2ast;
                                        if (id_ast == NULL && current_scope.count(buf->str))
                                                id_ast = current_scope.at(buf->str);
                                        if (!id_ast)
                                                log_file_error(filename, location.first_line, "Failed to resolve identifier %s for width detection!\n", buf->str.c_str());
                                        // a slice of our identifier means we advance to the next dimension, e.g. $size(a[3])
                                        if (buf->children.size() > 0) {
                                                // something is hanging below this identifier
                                                if (buf->children[0]->type == AST_RANGE && buf->integer == 0)
                                                        // if integer == 0, this node was originally created as AST_RANGE so it's dimension is 1
                                                        dim++;
                                                // more than one range, e.g. $size(a[3][2])
                                                else // created an AST_MULTIRANGE, converted to AST_RANGE, but original dimension saved in 'integer' field
                                                        dim += buf->integer; // increment by multirange size
                                        }
                                        // We have 4 cases:
                                        // wire x;                ==> AST_WIRE, no AST_RANGE children
                                        // wire [1:0]x;           ==> AST_WIRE, AST_RANGE children
                                        // wire [1:0]x[1:0];      ==> AST_MEMORY, two AST_RANGE children (1st for packed, 2nd for unpacked)
                                        // wire [1:0]x[1:0][1:0]; ==> AST_MEMORY, one AST_RANGE child (0) for packed, then AST_MULTIRANGE child (1) for unpacked
                                        // (updated: actually by the time we are here, AST_MULTIRANGE is converted into one big AST_RANGE)
                                        // case 0 handled by default
                                        if ((id_ast->type == AST_WIRE || id_ast->type == AST_MEMORY) && id_ast->children.size() > 0) {
                                                // handle packed array left/right for case 1, and cases 2/3 when requesting the last dimension (packed side)
                                                AstNode *wire_range = id_ast->children[0];
                                                left = wire_range->children[0]->integer;
                                                right = wire_range->children[1]->integer;
                                                high = max(left, right);
                                                low  = min(left, right);
                                        }
                                        if (id_ast->type == AST_MEMORY) {
                                                // We got here only if the argument is a memory
                                                // Otherwise $size() and $bits() return the expression width
                                                AstNode *mem_range = id_ast->children[1];
                                                if (str == "\\$bits") {
                                                        if (mem_range->type == AST_RANGE) {
                                                                if (!mem_range->range_valid)
                                                                        log_file_error(filename, location.first_line, "Failed to detect width of memory access `%s'!\n", buf->str.c_str());
                                                                mem_depth = mem_range->range_left - mem_range->range_right + 1;
                                                        } else
                                                                log_file_error(filename, location.first_line, "Unknown memory depth AST type in `%s'!\n", buf->str.c_str());
                                                } else {
                                                        // $size(), $left(), $right(), $high(), $low()
                                                        int dims = 1;
                                                        if (mem_range->type == AST_RANGE) {
                                                                if (id_ast->multirange_dimensions.empty()) {
                                                                        if (!mem_range->range_valid)
                                                                                log_file_error(filename, location.first_line, "Failed to detect width of memory access `%s'!\n", buf->str.c_str());
                                                                        if (dim == 1) {
                                                                                left  = mem_range->range_right;
                                                                                right = mem_range->range_left;
                                                                                high = max(left, right);
                                                                                low  = min(left, right);
                                                                        }
                                                                } else {
                                                                        dims = GetSize(id_ast->multirange_dimensions)/2;
                                                                        if (dim <= dims) {
                                                                                width_hint = id_ast->multirange_dimensions[2*dim-1];
                                                                                high = id_ast->multirange_dimensions[2*dim-2] + id_ast->multirange_dimensions[2*dim-1] - 1;
                                                                                low  = id_ast->multirange_dimensions[2*dim-2];
                                                                                if (id_ast->multirange_swapped[dim-1]) {
                                                                                        left = low;
                                                                                        right = high;
                                                                                } else {
                                                                                        right = low;
                                                                                        left = high;
                                                                                }
                                                                        } else if ((dim > dims+1) || (dim < 0))
                                                                                log_file_error(filename, location.first_line, "Dimension %d out of range in `%s', as it only has dimensions 1..%d!\n", dim, buf->str.c_str(), dims+1);
                                                                }
                                                        } else {
                                                                log_file_error(filename, location.first_line, "Unknown memory depth AST type in `%s'!\n", buf->str.c_str());
                                                        }
                                                }
                                        }
                                        width = high - low + 1;
                                } else {
                                        width = width_hint;
                                }
                                delete buf;
                                if (str == "\\$high")
                                        result = high;
                                else if (str == "\\$low")
                                        result = low;
                                else if (str == "\\$left")
                                        result = left;
                                else if (str == "\\$right")
                                        result = right;
                                else if (str == "\\$size")
                                        result = width;
                                else {
                                        result = width * mem_depth;
                                }
                                newNode = mkconst_int(result, false);
                                goto apply_newNode;
                        }

                        if (str == "\\$ln" || str == "\\$log10" || str == "\\$exp" || str == "\\$sqrt" || str == "\\$pow" ||
                                        str == "\\$floor" || str == "\\$ceil" || str == "\\$sin" || str == "\\$cos" || str == "\\$tan" ||
                                        str == "\\$asin" || str == "\\$acos" || str == "\\$atan" || str == "\\$atan2" || str == "\\$hypot" ||
                                        str == "\\$sinh" || str == "\\$cosh" || str == "\\$tanh" || str == "\\$asinh" || str == "\\$acosh" || str == "\\$atanh" ||
                                        str == "\\$rtoi" || str == "\\$itor")
                        {
                                bool func_with_two_arguments = str == "\\$pow" || str == "\\$atan2" || str == "\\$hypot";
                                double x = 0, y = 0;

                                if (func_with_two_arguments) {
                                        if (children.size() != 2)
                                                log_file_error(filename, location.first_line, "System function %s got %d arguments, expected 2.\n",
                                                                RTLIL::unescape_id(str).c_str(), int(children.size()));
                                } else {
                                        if (children.size() != 1)
                                                log_file_error(filename, location.first_line, "System function %s got %d arguments, expected 1.\n",
                                                                RTLIL::unescape_id(str).c_str(), int(children.size()));
                                }

                                if (children.size() >= 1) {
                                        while (children[0]->simplify(true, false, false, stage, width_hint, sign_hint, false)) { }
                                        if (!children[0]->isConst())
                                                log_file_error(filename, location.first_line, "Failed to evaluate system function `%s' with non-constant argument.\n",
                                                                RTLIL::unescape_id(str).c_str());
                                        int child_width_hint = width_hint;
                                        bool child_sign_hint = sign_hint;
                                        children[0]->detectSignWidth(child_width_hint, child_sign_hint);
                                        x = children[0]->asReal(child_sign_hint);
                                }

                                if (children.size() >= 2) {
                                        while (children[1]->simplify(true, false, false, stage, width_hint, sign_hint, false)) { }
                                        if (!children[1]->isConst())
                                                log_file_error(filename, location.first_line, "Failed to evaluate system function `%s' with non-constant argument.\n",
                                                                RTLIL::unescape_id(str).c_str());
                                        int child_width_hint = width_hint;
                                        bool child_sign_hint = sign_hint;
                                        children[1]->detectSignWidth(child_width_hint, child_sign_hint);
                                        y = children[1]->asReal(child_sign_hint);
                                }

                                if (str == "\\$rtoi") {
                                        newNode = AstNode::mkconst_int(x, true);
                                } else {
                                        newNode = new AstNode(AST_REALVALUE);
                                        if (str == "\\$ln")         newNode->realvalue = ::log(x);
                                        else if (str == "\\$log10") newNode->realvalue = ::log10(x);
                                        else if (str == "\\$exp")   newNode->realvalue = ::exp(x);
                                        else if (str == "\\$sqrt")  newNode->realvalue = ::sqrt(x);
                                        else if (str == "\\$pow")   newNode->realvalue = ::pow(x, y);
                                        else if (str == "\\$floor") newNode->realvalue = ::floor(x);
                                        else if (str == "\\$ceil")  newNode->realvalue = ::ceil(x);
                                        else if (str == "\\$sin")   newNode->realvalue = ::sin(x);
                                        else if (str == "\\$cos")   newNode->realvalue = ::cos(x);
                                        else if (str == "\\$tan")   newNode->realvalue = ::tan(x);
                                        else if (str == "\\$asin")  newNode->realvalue = ::asin(x);
                                        else if (str == "\\$acos")  newNode->realvalue = ::acos(x);
                                        else if (str == "\\$atan")  newNode->realvalue = ::atan(x);
                                        else if (str == "\\$atan2") newNode->realvalue = ::atan2(x, y);
                                        else if (str == "\\$hypot") newNode->realvalue = ::hypot(x, y);
                                        else if (str == "\\$sinh")  newNode->realvalue = ::sinh(x);
                                        else if (str == "\\$cosh")  newNode->realvalue = ::cosh(x);
                                        else if (str == "\\$tanh")  newNode->realvalue = ::tanh(x);
                                        else if (str == "\\$asinh") newNode->realvalue = ::asinh(x);
                                        else if (str == "\\$acosh") newNode->realvalue = ::acosh(x);
                                        else if (str == "\\$atanh") newNode->realvalue = ::atanh(x);
                                        else if (str == "\\$itor")  newNode->realvalue = x;
                                        else log_abort();
                                }
                                goto apply_newNode;
                        }

                        if (str == "\\$sformatf") {
                                AstNode *node_string = children[0];
                                while (node_string->simplify(true, false, false, stage, width_hint, sign_hint, false)) { }
                                if (node_string->type != AST_CONSTANT)
                                        log_file_error(filename, location.first_line, "Failed to evaluate system function `%s' with non-constant 1st argument.\n", str.c_str());
                                std::string sformat = node_string->bitsAsConst().decode_string();
                                std::string sout = process_format_str(sformat, 1, stage, width_hint, sign_hint);
                                newNode = AstNode::mkconst_str(sout);
                                goto apply_newNode;
                        }

                        if (str == "\\$countbits") {
                                if (children.size() < 2)
                                        log_file_error(filename, location.first_line, "System function %s got %d arguments, expected at least 2.\n",
                                                        RTLIL::unescape_id(str).c_str(), int(children.size()));

                                std::vector<RTLIL::State> control_bits;

                                // Determine which bits to count
                                for (size_t i = 1; i < children.size(); i++) {
                                        AstNode *node = children[i];
                                        while (node->simplify(true, false, false, stage, -1, false, false)) { }
                                        if (node->type != AST_CONSTANT)
                                                log_file_error(filename, location.first_line, "Failed to evaluate system function `%s' with non-constant control bit argument.\n", str.c_str());
                                        if (node->bits.size() != 1)
                                                log_file_error(filename, location.first_line, "Failed to evaluate system function `%s' with control bit width != 1.\n", str.c_str());
                                        control_bits.push_back(node->bits[0]);
                                }

                                // Detect width of exp (first argument of $countbits)
                                int  exp_width = -1;
                                bool exp_sign  = false;
                                AstNode *exp = children[0];
                                exp->detectSignWidth(exp_width, exp_sign, NULL);

                                newNode = mkconst_int(0, false);

                                for (int i = 0; i < exp_width; i++) {
                                        // Generate nodes for:  exp << i >> ($size(exp) - 1)
                                        //                          ^^   ^^
                                        AstNode *lsh_node = new AstNode(AST_SHIFT_LEFT, exp->clone(), mkconst_int(i, false));
                                        AstNode *rsh_node = new AstNode(AST_SHIFT_RIGHT, lsh_node, mkconst_int(exp_width - 1, false));

                                        AstNode *or_node = nullptr;

                                        for (RTLIL::State control_bit : control_bits) {
                                                // Generate node for:  (exp << i >> ($size(exp) - 1)) === control_bit
                                                //                                                    ^^^
                                                AstNode *eq_node = new AstNode(AST_EQX, rsh_node->clone(), mkconst_bits({control_bit}, false));

                                                // Or the result for each checked bit value
                                                if (or_node)
                                                        or_node = new AstNode(AST_LOGIC_OR, or_node, eq_node);
                                                else
                                                        or_node = eq_node;
                                        }

                                        // We should have at least one element in control_bits,
                                        // because we checked for the number of arguments above
                                        log_assert(or_node != nullptr);

                                        delete rsh_node;

                                        // Generate node for adding with result of previous bit
                                        newNode = new AstNode(AST_ADD, newNode, or_node);
                                }

                                goto apply_newNode;
                        }

                        if (str == "\\$countones" || str == "\\$isunknown" || str == "\\$onehot" || str == "\\$onehot0") {
                                if (children.size() != 1)
                                        log_file_error(filename, location.first_line, "System function %s got %d arguments, expected 1.\n",
                                                        RTLIL::unescape_id(str).c_str(), int(children.size()));

                                AstNode *countbits = clone();
                                countbits->str = "\\$countbits";

                                if (str == "\\$countones") {
                                        countbits->children.push_back(mkconst_bits({RTLIL::State::S1}, false));
                                        newNode = countbits;
                                } else if (str == "\\$isunknown") {
                                        countbits->children.push_back(mkconst_bits({RTLIL::Sx}, false));
                                        countbits->children.push_back(mkconst_bits({RTLIL::Sz}, false));
                                        newNode = new AstNode(AST_GT, countbits, mkconst_int(0, false));
                                } else if (str == "\\$onehot") {
                                        countbits->children.push_back(mkconst_bits({RTLIL::State::S1}, false));
                                        newNode = new AstNode(AST_EQ, countbits, mkconst_int(1, false));
                                } else if (str == "\\$onehot0") {
                                        countbits->children.push_back(mkconst_bits({RTLIL::State::S1}, false));
                                        newNode = new AstNode(AST_LE, countbits, mkconst_int(1, false));
                                } else {
                                        log_abort();
                                }

                                goto apply_newNode;
                        }

                        if (current_scope.count(str) != 0 && current_scope[str]->type == AST_DPI_FUNCTION)
                        {
                                AstNode *dpi_decl = current_scope[str];

                                std::string rtype, fname;
                                std::vector<std::string> argtypes;
                                std::vector<AstNode*> args;

                                rtype = RTLIL::unescape_id(dpi_decl->children.at(0)->str);
                                fname = RTLIL::unescape_id(dpi_decl->children.at(1)->str);

                                for (int i = 2; i < GetSize(dpi_decl->children); i++)
                                {
                                        if (i-2 >= GetSize(children))
                                                log_file_error(filename, location.first_line, "Insufficient number of arguments in DPI function call.\n");

                                        argtypes.push_back(RTLIL::unescape_id(dpi_decl->children.at(i)->str));
                                        args.push_back(children.at(i-2)->clone());
                                        while (args.back()->simplify(true, false, false, stage, -1, false, true)) { }

                                        if (args.back()->type != AST_CONSTANT && args.back()->type != AST_REALVALUE)
                                                log_file_error(filename, location.first_line, "Failed to evaluate DPI function with non-constant argument.\n");
                                }

                                newNode = dpi_call(rtype, fname, argtypes, args);

                                for (auto arg : args)
                                        delete arg;

                                goto apply_newNode;
                        }

                        if (current_scope.count(str) == 0 || current_scope[str]->type != AST_FUNCTION)
                                log_file_error(filename, location.first_line, "Can't resolve function name `%s'.\n", str.c_str());
                }

                if (type == AST_TCALL)
                {
                        if (str == "$finish" || str == "$stop")
                        {
                                if (!current_always || current_always->type != AST_INITIAL)
                                        log_file_error(filename, location.first_line, "System task `%s' outside initial block is unsupported.\n", str.c_str());

                                log_file_error(filename, location.first_line, "System task `%s' executed.\n", str.c_str());
                        }

                        if (str == "\\$readmemh" || str == "\\$readmemb")
                        {
                                if (GetSize(children) < 2 || GetSize(children) > 4)
                                        log_file_error(filename, location.first_line, "System function %s got %d arguments, expected 2-4.\n",
                                                        RTLIL::unescape_id(str).c_str(), int(children.size()));

                                AstNode *node_filename = children[0]->clone();
                                while (node_filename->simplify(true, false, false, stage, width_hint, sign_hint, false)) { }
                                if (node_filename->type != AST_CONSTANT)
                                        log_file_error(filename, location.first_line, "Failed to evaluate system function `%s' with non-constant 1st argument.\n", str.c_str());

                                AstNode *node_memory = children[1]->clone();
                                while (node_memory->simplify(true, false, false, stage, width_hint, sign_hint, false)) { }
                                if (node_memory->type != AST_IDENTIFIER || node_memory->id2ast == nullptr || node_memory->id2ast->type != AST_MEMORY)
                                        log_file_error(filename, location.first_line, "Failed to evaluate system function `%s' with non-memory 2nd argument.\n", str.c_str());

                                int start_addr = -1, finish_addr = -1;

                                if (GetSize(children) > 2) {
                                        AstNode *node_addr = children[2]->clone();
                                        while (node_addr->simplify(true, false, false, stage, width_hint, sign_hint, false)) { }
                                        if (node_addr->type != AST_CONSTANT)
                                                log_file_error(filename, location.first_line, "Failed to evaluate system function `%s' with non-constant 3rd argument.\n", str.c_str());
                                        start_addr = int(node_addr->asInt(false));
                                }

                                if (GetSize(children) > 3) {
                                        AstNode *node_addr = children[3]->clone();
                                        while (node_addr->simplify(true, false, false, stage, width_hint, sign_hint, false)) { }
                                        if (node_addr->type != AST_CONSTANT)
                                                log_file_error(filename, location.first_line, "Failed to evaluate system function `%s' with non-constant 4th argument.\n", str.c_str());
                                        finish_addr = int(node_addr->asInt(false));
                                }

                                bool unconditional_init = false;
                                if (current_always->type == AST_INITIAL) {
                                        pool<AstNode*> queue;
                                        log_assert(current_always->children[0]->type == AST_BLOCK);
                                        queue.insert(current_always->children[0]);
                                        while (!unconditional_init && !queue.empty()) {
                                                pool<AstNode*> next_queue;
                                                for (auto n : queue)
                                                for (auto c : n->children) {
                                                        if (c == this)
                                                                unconditional_init = true;
                                                        next_queue.insert(c);
                                                }
                                                next_queue.swap(queue);
                                        }
                                }

                                newNode = readmem(str == "\\$readmemh", node_filename->bitsAsConst().decode_string(), node_memory->id2ast, start_addr, finish_addr, unconditional_init);
                                delete node_filename;
                                delete node_memory;
                                goto apply_newNode;
                        }

                        if (current_scope.count(str) == 0 || current_scope[str]->type != AST_TASK)
                                log_file_error(filename, location.first_line, "Can't resolve task name `%s'.\n", str.c_str());
                }


                std::stringstream sstr;
                sstr << str << "$func$" << filename << ":" << location.first_line << "$" << (autoidx++) << '.';
                std::string prefix = sstr.str();

                AstNode *decl = current_scope[str];
                if (unevaluated_tern_branch && decl->is_recursive_function())
                        goto replace_fcall_later;
                decl = decl->clone();
                decl->replace_result_wire_name_in_function(str, "$result"); // enables recursion
                decl->expand_genblock(prefix);

                if (decl->type == AST_FUNCTION && !decl->attributes.count(ID::via_celltype))
                {
                        bool require_const_eval = decl->has_const_only_constructs();
                        bool all_args_const = true;
                        for (auto child : children) {
                                while (child->simplify(true, false, false, 1, -1, false, true)) { }
                                if (child->type != AST_CONSTANT && child->type != AST_REALVALUE)
                                        all_args_const = false;
                        }

                        if (all_args_const) {
                                AstNode *func_workspace = decl->clone();
                                func_workspace->str = prefix_id(prefix, "$result");
                                newNode = func_workspace->eval_const_function(this, in_param || require_const_eval);
                                delete func_workspace;
                                if (newNode) {
                                        delete decl;
                                        goto apply_newNode;
                                }
                        }

                        if (in_param)
                                log_file_error(filename, location.first_line, "Non-constant function call in constant expression.\n");
                        if (require_const_eval)
                                log_file_error(filename, location.first_line, "Function %s can only be called with constant arguments.\n", str.c_str());
                }

                size_t arg_count = 0;
                dict<std::string, AstNode*> wire_cache;
                vector<AstNode*> new_stmts;
                vector<AstNode*> output_assignments;

                if (current_block == NULL)
                {
                        log_assert(type == AST_FCALL);

                        AstNode *wire = NULL;
                        std::string res_name = prefix_id(prefix, "$result");
                        for (auto child : decl->children)
                                if (child->type == AST_WIRE && child->str == res_name)
                                        wire = child->clone();
                        log_assert(wire != NULL);

                        wire->port_id = 0;
                        wire->is_input = false;
                        wire->is_output = false;

                        current_scope[wire->str] = wire;
                        current_ast_mod->children.push_back(wire);
                        while (wire->simplify(true, false, false, 1, -1, false, false)) { }

                        AstNode *lvalue = new AstNode(AST_IDENTIFIER);
                        lvalue->str = wire->str;

                        AstNode *always = new AstNode(AST_ALWAYS, new AstNode(AST_BLOCK,
                                        new AstNode(AST_ASSIGN_EQ, lvalue, clone())));
                        always->children[0]->children[0]->was_checked = true;

                        current_ast_mod->children.push_back(always);

                        goto replace_fcall_with_id;
                }

                if (decl->attributes.count(ID::via_celltype))
                {
                        std::string celltype = decl->attributes.at(ID::via_celltype)->asAttrConst().decode_string();
                        std::string outport = str;

                        if (celltype.find(' ') != std::string::npos) {
                                int pos = celltype.find(' ');
                                outport = RTLIL::escape_id(celltype.substr(pos+1));
                                celltype = RTLIL::escape_id(celltype.substr(0, pos));
                        } else
                                celltype = RTLIL::escape_id(celltype);

                        AstNode *cell = new AstNode(AST_CELL, new AstNode(AST_CELLTYPE));
                        cell->str = prefix.substr(0, GetSize(prefix)-1);
                        cell->children[0]->str = celltype;

                        for (auto attr : decl->attributes)
                                if (attr.first.str().rfind("\\via_celltype_defparam_", 0) == 0)
                                {
                                        AstNode *cell_arg = new AstNode(AST_PARASET, attr.second->clone());
                                        cell_arg->str = RTLIL::escape_id(attr.first.substr(strlen("\\via_celltype_defparam_")));
                                        cell->children.push_back(cell_arg);
                                }

                        for (auto child : decl->children)
                                if (child->type == AST_WIRE && (child->is_input || child->is_output || (type == AST_FCALL && child->str == str)))
                                {
                                        AstNode *wire = child->clone();
                                        wire->port_id = 0;
                                        wire->is_input = false;
                                        wire->is_output = false;
                                        current_ast_mod->children.push_back(wire);
                                        while (wire->simplify(true, false, false, 1, -1, false, false)) { }

                                        AstNode *wire_id = new AstNode(AST_IDENTIFIER);
                                        wire_id->str = wire->str;

                                        if ((child->is_input || child->is_output) && arg_count < children.size())
                                        {
                                                AstNode *arg = children[arg_count++]->clone();
                                                AstNode *assign = child->is_input ?
                                                                new AstNode(AST_ASSIGN_EQ, wire_id->clone(), arg) :
                                                                new AstNode(AST_ASSIGN_EQ, arg, wire_id->clone());
                                                assign->children[0]->was_checked = true;

                                                for (auto it = current_block->children.begin(); it != current_block->children.end(); it++) {
                                                        if (*it != current_block_child)
                                                                continue;
                                                        current_block->children.insert(it, assign);
                                                        break;
                                                }
                                        }

                                        AstNode *cell_arg = new AstNode(AST_ARGUMENT, wire_id);
                                        cell_arg->str = child->str == str ? outport : child->str;
                                        cell->children.push_back(cell_arg);
                                }

                        current_ast_mod->children.push_back(cell);
                        goto replace_fcall_with_id;
                }

                for (auto child : decl->children)
                        if (child->type == AST_WIRE || child->type == AST_MEMORY || child->type == AST_PARAMETER || child->type == AST_LOCALPARAM || child->type == AST_ENUM_ITEM)
                        {
                                AstNode *wire = nullptr;

                                if (wire_cache.count(child->str))
                                {
                                        wire = wire_cache.at(child->str);
                                        bool contains_value = wire->type == AST_LOCALPARAM;
                                        if (wire->children.size() == contains_value) {
                                                for (auto c : child->children)
                                                        wire->children.push_back(c->clone());
                                        } else if (!child->children.empty()) {
                                                while (child->simplify(true, false, false, stage, -1, false, false)) { }
                                                if (GetSize(child->children) == GetSize(wire->children) - contains_value) {
                                                        for (int i = 0; i < GetSize(child->children); i++)
                                                                if (*child->children.at(i) != *wire->children.at(i + contains_value))
                                                                        goto tcall_incompatible_wires;
                                                } else {
                                        tcall_incompatible_wires:
                                                        log_file_error(filename, location.first_line, "Incompatible re-declaration of wire %s.\n", child->str.c_str());
                                                }
                                        }
                                }
                                else
                                {
                                        wire = child->clone();
                                        wire->port_id = 0;
                                        wire->is_input = false;
                                        wire->is_output = false;
                                        wire->is_reg = true;
                                        wire->attributes[ID::nosync] = AstNode::mkconst_int(1, false);
                                        if (child->type == AST_ENUM_ITEM)
                                                wire->attributes[ID::enum_base_type] = child->attributes[ID::enum_base_type];

                                        wire_cache[child->str] = wire;

                                        current_scope[wire->str] = wire;
                                        current_ast_mod->children.push_back(wire);
                                }

                                while (wire->simplify(true, false, false, 1, -1, false, false)) { }

                                if ((child->is_input || child->is_output) && arg_count < children.size())
                                {
                                        AstNode *arg = children[arg_count++]->clone();
                                        // convert purely constant arguments into localparams
                                        if (child->is_input && child->type == AST_WIRE && arg->type == AST_CONSTANT && node_contains_assignment_to(decl, child)) {
                                                wire->type = AST_LOCALPARAM;
                                                if (wire->attributes.count(ID::nosync))
                                                        delete wire->attributes.at(ID::nosync);
                                                wire->attributes.erase(ID::nosync);
                                                wire->children.insert(wire->children.begin(), arg->clone());
                                                // args without a range implicitly have width 1
                                                if (wire->children.back()->type != AST_RANGE) {
                                                        // check if this wire is redeclared with an explicit size
                                                        bool uses_explicit_size = false;
                                                        for (const AstNode *other_child : decl->children)
                                                                if (other_child->type == AST_WIRE && child->str == other_child->str
                                                                                && !other_child->children.empty()
                                                                                && other_child->children.back()->type == AST_RANGE) {
                                                                        uses_explicit_size = true;
                                                                        break;
                                                                }
                                                        if (!uses_explicit_size) {
                                                                AstNode* range = new AstNode();
                                                                range->type = AST_RANGE;
                                                                wire->children.push_back(range);
                                                                range->children.push_back(mkconst_int(0, true));
                                                                range->children.push_back(mkconst_int(0, true));
                                                        }
                                                }
                                                // updates the sizing
                                                while (wire->simplify(true, false, false, 1, -1, false, false)) { }
                                                delete arg;
                                                continue;
                                        }
                                        AstNode *wire_id = new AstNode(AST_IDENTIFIER);
                                        wire_id->str = wire->str;
                                        AstNode *assign = child->is_input ?
                                                        new AstNode(AST_ASSIGN_EQ, wire_id, arg) :
                                                        new AstNode(AST_ASSIGN_EQ, arg, wire_id);
                                        assign->children[0]->was_checked = true;
                                        if (child->is_input)
                                                new_stmts.push_back(assign);
                                        else
                                                output_assignments.push_back(assign);
                                }
                        }

                for (auto child : decl->children)
                        if (child->type != AST_WIRE && child->type != AST_MEMORY && child->type != AST_PARAMETER && child->type != AST_LOCALPARAM)
                                new_stmts.push_back(child->clone());

                new_stmts.insert(new_stmts.end(), output_assignments.begin(), output_assignments.end());

                for (auto it = current_block->children.begin(); ; it++) {
                        log_assert(it != current_block->children.end());
                        if (*it == current_block_child) {
                                current_block->children.insert(it, new_stmts.begin(), new_stmts.end());
                                break;
                        }
                }

        replace_fcall_with_id:
                delete decl;
                if (type == AST_FCALL) {
                        delete_children();
                        type = AST_IDENTIFIER;
                        str = prefix_id(prefix, "$result");
                }
                if (type == AST_TCALL)
                        str = "";
                did_something = true;
        }

replace_fcall_later:;

        // perform const folding when activated
        if (const_fold)
        {
                bool string_op;
                std::vector<RTLIL::State> tmp_bits;
                RTLIL::Const (*const_func)(const RTLIL::Const&, const RTLIL::Const&, bool, bool, int);
                RTLIL::Const dummy_arg;

                switch (type)
                {
                case AST_IDENTIFIER:
                        if (current_scope.count(str) > 0 && (current_scope[str]->type == AST_PARAMETER || current_scope[str]->type == AST_LOCALPARAM || current_scope[str]->type == AST_ENUM_ITEM)) {
                                if (current_scope[str]->children[0]->type == AST_CONSTANT) {
                                        if (children.size() != 0 && children[0]->type == AST_RANGE && children[0]->range_valid) {
                                                std::vector<RTLIL::State> data;
                                                bool param_upto = current_scope[str]->range_valid && current_scope[str]->range_swapped;
                                                int param_offset = current_scope[str]->range_valid ? current_scope[str]->range_right : 0;
                                                int param_width = current_scope[str]->range_valid ? current_scope[str]->range_left - current_scope[str]->range_right + 1 :
                                                                GetSize(current_scope[str]->children[0]->bits);
                                                int tmp_range_left = children[0]->range_left, tmp_range_right = children[0]->range_right;
                                                if (param_upto) {
                                                        tmp_range_left = (param_width + 2*param_offset) - children[0]->range_right - 1;
                                                        tmp_range_right = (param_width + 2*param_offset) - children[0]->range_left - 1;
                                                }
                                                for (int i = tmp_range_right; i <= tmp_range_left; i++) {
                                                        int index = i - param_offset;
                                                        if (0 <= index && index < param_width)
                                                                data.push_back(current_scope[str]->children[0]->bits[index]);
                                                        else
                                                                data.push_back(RTLIL::State::Sx);
                                                }
                                                newNode = mkconst_bits(data, false);
                                        } else
                                        if (children.size() == 0)
                                                newNode = current_scope[str]->children[0]->clone();
                                } else
                                if (current_scope[str]->children[0]->isConst())
                                        newNode = current_scope[str]->children[0]->clone();
                        }
                        else if (at_zero && current_scope.count(str) > 0) {
                                AstNode *node = current_scope[str];
                                if (node->type == AST_WIRE || node->type == AST_AUTOWIRE || node->type == AST_MEMORY)
                                        newNode = mkconst_int(0, sign_hint, width_hint);
                        }
                        break;
                case AST_MEMRD:
                        if (at_zero) {
                                newNode = mkconst_int(0, sign_hint, width_hint);
                        }
                        break;
                case AST_BIT_NOT:
                        if (children[0]->type == AST_CONSTANT) {
                                RTLIL::Const y = RTLIL::const_not(children[0]->bitsAsConst(width_hint, sign_hint), dummy_arg, sign_hint, false, width_hint);
                                newNode = mkconst_bits(y.bits, sign_hint);
                        }
                        break;
                case AST_TO_SIGNED:
                case AST_TO_UNSIGNED:
                        if (children[0]->type == AST_CONSTANT) {
                                RTLIL::Const y = children[0]->bitsAsConst(width_hint, sign_hint);
                                newNode = mkconst_bits(y.bits, type == AST_TO_SIGNED);
                        }
                        break;
                if (0) { case AST_BIT_AND:  const_func = RTLIL::const_and;  }
                if (0) { case AST_BIT_OR:   const_func = RTLIL::const_or;   }
                if (0) { case AST_BIT_XOR:  const_func = RTLIL::const_xor;  }
                if (0) { case AST_BIT_XNOR: const_func = RTLIL::const_xnor; }
                        if (children[0]->type == AST_CONSTANT && children[1]->type == AST_CONSTANT) {
                                RTLIL::Const y = const_func(children[0]->bitsAsConst(width_hint, sign_hint),
                                                children[1]->bitsAsConst(width_hint, sign_hint), sign_hint, sign_hint, width_hint);
                                newNode = mkconst_bits(y.bits, sign_hint);
                        }
                        break;
                if (0) { case AST_REDUCE_AND:  const_func = RTLIL::const_reduce_and;  }
                if (0) { case AST_REDUCE_OR:   const_func = RTLIL::const_reduce_or;   }
                if (0) { case AST_REDUCE_XOR:  const_func = RTLIL::const_reduce_xor;  }
                if (0) { case AST_REDUCE_XNOR: const_func = RTLIL::const_reduce_xnor; }
                if (0) { case AST_REDUCE_BOOL: const_func = RTLIL::const_reduce_bool; }
                        if (children[0]->type == AST_CONSTANT) {
                                RTLIL::Const y = const_func(RTLIL::Const(children[0]->bits), dummy_arg, false, false, -1);
                                newNode = mkconst_bits(y.bits, false);
                        }
                        break;
                case AST_LOGIC_NOT:
                        if (children[0]->type == AST_CONSTANT) {
                                RTLIL::Const y = RTLIL::const_logic_not(RTLIL::Const(children[0]->bits), dummy_arg, children[0]->is_signed, false, -1);
                                newNode = mkconst_bits(y.bits, false);
                        } else
                        if (children[0]->isConst()) {
                                newNode = mkconst_int(children[0]->asReal(sign_hint) == 0, false, 1);
                        }
                        break;
                if (0) { case AST_LOGIC_AND: const_func = RTLIL::const_logic_and; }
                if (0) { case AST_LOGIC_OR:  const_func = RTLIL::const_logic_or;  }
                        if (children[0]->type == AST_CONSTANT && children[1]->type == AST_CONSTANT) {
                                RTLIL::Const y = const_func(RTLIL::Const(children[0]->bits), RTLIL::Const(children[1]->bits),
                                                children[0]->is_signed, children[1]->is_signed, -1);
                                newNode = mkconst_bits(y.bits, false);
                        } else
                        if (children[0]->isConst() && children[1]->isConst()) {
                                if (type == AST_LOGIC_AND)
                                        newNode = mkconst_int((children[0]->asReal(sign_hint) != 0) && (children[1]->asReal(sign_hint) != 0), false, 1);
                                else
                                        newNode = mkconst_int((children[0]->asReal(sign_hint) != 0) || (children[1]->asReal(sign_hint) != 0), false, 1);
                        }
                        break;
                if (0) { case AST_SHIFT_LEFT:   const_func = RTLIL::const_shl;  }
                if (0) { case AST_SHIFT_RIGHT:  const_func = RTLIL::const_shr;  }
                if (0) { case AST_SHIFT_SLEFT:  const_func = RTLIL::const_sshl; }
                if (0) { case AST_SHIFT_SRIGHT: const_func = RTLIL::const_sshr; }
                if (0) { case AST_POW:          const_func = RTLIL::const_pow; }
                        if (children[0]->type == AST_CONSTANT && children[1]->type == AST_CONSTANT) {
                                RTLIL::Const y = const_func(children[0]->bitsAsConst(width_hint, sign_hint),
                                                RTLIL::Const(children[1]->bits), sign_hint, type == AST_POW ? children[1]->is_signed : false, width_hint);
                                newNode = mkconst_bits(y.bits, sign_hint);
                        } else
                        if (type == AST_POW && children[0]->isConst() && children[1]->isConst()) {
                                newNode = new AstNode(AST_REALVALUE);
                                newNode->realvalue = pow(children[0]->asReal(sign_hint), children[1]->asReal(sign_hint));
                        }
                        break;
                if (0) { case AST_LT:  const_func = RTLIL::const_lt; }
                if (0) { case AST_LE:  const_func = RTLIL::const_le; }
                if (0) { case AST_EQ:  const_func = RTLIL::const_eq; }
                if (0) { case AST_NE:  const_func = RTLIL::const_ne; }
                if (0) { case AST_EQX: const_func = RTLIL::const_eqx; }
                if (0) { case AST_NEX: const_func = RTLIL::const_nex; }
                if (0) { case AST_GE:  const_func = RTLIL::const_ge; }
                if (0) { case AST_GT:  const_func = RTLIL::const_gt; }
                        if (children[0]->type == AST_CONSTANT && children[1]->type == AST_CONSTANT) {
                                int cmp_width = max(children[0]->bits.size(), children[1]->bits.size());
                                bool cmp_signed = children[0]->is_signed && children[1]->is_signed;
                                RTLIL::Const y = const_func(children[0]->bitsAsConst(cmp_width, cmp_signed),
                                                children[1]->bitsAsConst(cmp_width, cmp_signed), cmp_signed, cmp_signed, 1);
                                newNode = mkconst_bits(y.bits, false);
                        } else
                        if (children[0]->isConst() && children[1]->isConst()) {
                                bool cmp_signed = (children[0]->type == AST_REALVALUE || children[0]->is_signed) && (children[1]->type == AST_REALVALUE || children[1]->is_signed);
                                switch (type) {
                                case AST_LT:  newNode = mkconst_int(children[0]->asReal(cmp_signed) <  children[1]->asReal(cmp_signed), false, 1); break;
                                case AST_LE:  newNode = mkconst_int(children[0]->asReal(cmp_signed) <= children[1]->asReal(cmp_signed), false, 1); break;
                                case AST_EQ:  newNode = mkconst_int(children[0]->asReal(cmp_signed) == children[1]->asReal(cmp_signed), false, 1); break;
                                case AST_NE:  newNode = mkconst_int(children[0]->asReal(cmp_signed) != children[1]->asReal(cmp_signed), false, 1); break;
                                case AST_EQX: newNode = mkconst_int(children[0]->asReal(cmp_signed) == children[1]->asReal(cmp_signed), false, 1); break;
                                case AST_NEX: newNode = mkconst_int(children[0]->asReal(cmp_signed) != children[1]->asReal(cmp_signed), false, 1); break;
                                case AST_GE:  newNode = mkconst_int(children[0]->asReal(cmp_signed) >= children[1]->asReal(cmp_signed), false, 1); break;
                                case AST_GT:  newNode = mkconst_int(children[0]->asReal(cmp_signed) >  children[1]->asReal(cmp_signed), false, 1); break;
                                default: log_abort();
                                }
                        }
                        break;
                if (0) { case AST_ADD: const_func = RTLIL::const_add; }
                if (0) { case AST_SUB: const_func = RTLIL::const_sub; }
                if (0) { case AST_MUL: const_func = RTLIL::const_mul; }
                if (0) { case AST_DIV: const_func = RTLIL::const_div; }
                if (0) { case AST_MOD: const_func = RTLIL::const_mod; }
                        if (children[0]->type == AST_CONSTANT && children[1]->type == AST_CONSTANT) {
                                RTLIL::Const y = const_func(children[0]->bitsAsConst(width_hint, sign_hint),
                                                children[1]->bitsAsConst(width_hint, sign_hint), sign_hint, sign_hint, width_hint);
                                newNode = mkconst_bits(y.bits, sign_hint);
                        } else
                        if (children[0]->isConst() && children[1]->isConst()) {
                                newNode = new AstNode(AST_REALVALUE);
                                switch (type) {
                                case AST_ADD: newNode->realvalue = children[0]->asReal(sign_hint) + children[1]->asReal(sign_hint); break;
                                case AST_SUB: newNode->realvalue = children[0]->asReal(sign_hint) - children[1]->asReal(sign_hint); break;
                                case AST_MUL: newNode->realvalue = children[0]->asReal(sign_hint) * children[1]->asReal(sign_hint); break;
                                case AST_DIV: newNode->realvalue = children[0]->asReal(sign_hint) / children[1]->asReal(sign_hint); break;
                                case AST_MOD: newNode->realvalue = fmod(children[0]->asReal(sign_hint), children[1]->asReal(sign_hint)); break;
                                default: log_abort();
                                }
                        }
                        break;
                if (0) { case AST_SELFSZ: const_func = RTLIL::const_pos; }
                if (0) { case AST_POS: const_func = RTLIL::const_pos; }
                if (0) { case AST_NEG: const_func = RTLIL::const_neg; }
                        if (children[0]->type == AST_CONSTANT) {
                                RTLIL::Const y = const_func(children[0]->bitsAsConst(width_hint, sign_hint), dummy_arg, sign_hint, false, width_hint);
                                newNode = mkconst_bits(y.bits, sign_hint);
                        } else
                        if (children[0]->isConst()) {
                                newNode = new AstNode(AST_REALVALUE);
                                if (type == AST_NEG)
                                        newNode->realvalue = -children[0]->asReal(sign_hint);
                                else
                                        newNode->realvalue = +children[0]->asReal(sign_hint);
                        }
                        break;
                case AST_TERNARY:
                        if (children[0]->isConst())
                        {
                                auto pair = get_tern_choice();
                                AstNode *choice = pair.first;
                                AstNode *not_choice = pair.second;

                                if (choice != NULL) {
                                        if (choice->type == AST_CONSTANT) {
                                                int other_width_hint = width_hint;
                                                bool other_sign_hint = sign_hint, other_real = false;
                                                not_choice->detectSignWidth(other_width_hint, other_sign_hint, &other_real);
                                                if (other_real) {
                                                        newNode = new AstNode(AST_REALVALUE);
                                                        choice->detectSignWidth(width_hint, sign_hint);
                                                        newNode->realvalue = choice->asReal(sign_hint);
                                                } else {
                                                        RTLIL::Const y = choice->bitsAsConst(width_hint, sign_hint);
                                                        if (choice->is_string && y.bits.size() % 8 == 0 && sign_hint == false)
                                                                newNode = mkconst_str(y.bits);
                                                        else
                                                                newNode = mkconst_bits(y.bits, sign_hint);
                                                }
                                        } else
                                        if (choice->isConst()) {
                                                newNode = choice->clone();
                                        }
                                } else if (children[1]->type == AST_CONSTANT && children[2]->type == AST_CONSTANT) {
                                        RTLIL::Const a = children[1]->bitsAsConst(width_hint, sign_hint);
                                        RTLIL::Const b = children[2]->bitsAsConst(width_hint, sign_hint);
                                        log_assert(a.bits.size() == b.bits.size());
                                        for (size_t i = 0; i < a.bits.size(); i++)
                                                if (a.bits[i] != b.bits[i])
                                                        a.bits[i] = RTLIL::State::Sx;
                                        newNode = mkconst_bits(a.bits, sign_hint);
                                } else if (children[1]->isConst() && children[2]->isConst()) {
                                        newNode = new AstNode(AST_REALVALUE);
                                        if (children[1]->asReal(sign_hint) == children[2]->asReal(sign_hint))
                                                newNode->realvalue = children[1]->asReal(sign_hint);
                                        else
                                                // IEEE Std 1800-2012 Sec. 11.4.11 states that the entry in Table 7-1 for
                                                // the data type in question should be returned if the ?: is ambiguous. The
                                                // value in Table 7-1 for the 'real' type is 0.0.
                                                newNode->realvalue = 0.0;
                                }
                        }
                        break;
                case AST_CAST_SIZE:
                        if (children.at(0)->type == AST_CONSTANT && children.at(1)->type == AST_CONSTANT) {
                                int width = children[0]->bitsAsConst().as_int();
                                RTLIL::Const val;
                                if (children[1]->is_unsized)
                                        val = children[1]->bitsAsUnsizedConst(width);
                                else
                                        val = children[1]->bitsAsConst(width);
                                newNode = mkconst_bits(val.bits, children[1]->is_signed);
                        }
                        break;
                case AST_CONCAT:
                        string_op = !children.empty();
                        for (auto it = children.begin(); it != children.end(); it++) {
                                if ((*it)->type != AST_CONSTANT)
                                        goto not_const;
                                if (!(*it)->is_string)
                                        string_op = false;
                                tmp_bits.insert(tmp_bits.end(), (*it)->bits.begin(), (*it)->bits.end());
                        }
                        newNode = string_op ? mkconst_str(tmp_bits) : mkconst_bits(tmp_bits, false);
                        break;
                case AST_REPLICATE:
                        if (children.at(0)->type != AST_CONSTANT || children.at(1)->type != AST_CONSTANT)
                                goto not_const;
                        for (int i = 0; i < children[0]->bitsAsConst().as_int(); i++)
                                tmp_bits.insert(tmp_bits.end(), children.at(1)->bits.begin(), children.at(1)->bits.end());
                        newNode = children.at(1)->is_string ? mkconst_str(tmp_bits) : mkconst_bits(tmp_bits, false);
                        break;
                default:
                not_const:
                        break;
                }
        }

        // if any of the above set 'newNode' -> use 'newNode' as template to update 'this'
        if (newNode) {
apply_newNode:
                // fprintf(stderr, "----\n");
                // dumpAst(stderr, "- ");
                // newNode->dumpAst(stderr, "+ ");
                log_assert(newNode != NULL);
                newNode->filename = filename;
                newNode->location = location;
                newNode->cloneInto(this);
                delete newNode;
                did_something = true;
        }

        if (!did_something)
                basic_prep = true;

        recursion_counter--;
        return did_something;
}

void AstNode::replace_result_wire_name_in_function(const std::string &from, const std::string &to)
{
        for (AstNode *child : children)
                child->replace_result_wire_name_in_function(from, to);
        if (str == from && type != AST_FCALL && type != AST_TCALL)
                str = to;
}

// replace a readmem[bh] TCALL ast node with a block of memory assignments
AstNode *AstNode::readmem(bool is_readmemh, std::string mem_filename, AstNode *memory, int start_addr, int finish_addr, bool unconditional_init)
{
        int mem_width, mem_size, addr_bits;
        memory->meminfo(mem_width, mem_size, addr_bits);

        AstNode *block = new AstNode(AST_BLOCK);

        AstNode *meminit = nullptr;
        int next_meminit_cursor=0;
        vector<State> meminit_bits;
        vector<State> en_bits;
        int meminit_size=0;

        for (int i = 0; i < mem_width; i++)
                en_bits.push_back(State::S1);

        std::ifstream f;
        f.open(mem_filename.c_str());
        if (f.fail()) {
#ifdef _WIN32
                char slash = '\\';
#else
                char slash = '/';
#endif
                std::string path = filename.substr(0, filename.find_last_of(slash)+1);
                f.open(path + mem_filename.c_str());
                yosys_input_files.insert(path + mem_filename);
        } else {
                yosys_input_files.insert(mem_filename);
        }
        if (f.fail() || GetSize(mem_filename) == 0)
                log_file_error(filename, location.first_line, "Can not open file `%s` for %s.\n", mem_filename.c_str(), str.c_str());

        log_assert(GetSize(memory->children) == 2 && memory->children[1]->type == AST_RANGE && memory->children[1]->range_valid);
        int range_left =  memory->children[1]->range_left, range_right =  memory->children[1]->range_right;
        int range_min = min(range_left, range_right), range_max = max(range_left, range_right);

        if (start_addr < 0)
                start_addr = range_min;

        if (finish_addr < 0)
                finish_addr = range_max + 1;

        bool in_comment = false;
        int increment = start_addr <= finish_addr ? +1 : -1;
        int cursor = start_addr;

        while (!f.eof())
        {
                std::string line, token;
                std::getline(f, line);

                for (int i = 0; i < GetSize(line); i++) {
                        if (in_comment && line.compare(i, 2, "*/") == 0) {
                                line[i] = ' ';
                                line[i+1] = ' ';
                                in_comment = false;
                                continue;
                        }
                        if (!in_comment && line.compare(i, 2, "/*") == 0)
                                in_comment = true;
                        if (in_comment)
                                line[i] = ' ';
                }

                while (1)
                {
                        token = next_token(line, " \t\r\n");
                        if (token.empty() || token.compare(0, 2, "//") == 0)
                                break;

                        if (token[0] == '@') {
                                token = token.substr(1);
                                const char *nptr = token.c_str();
                                char *endptr;
                                cursor = strtol(nptr, &endptr, 16);
                                if (!*nptr || *endptr)
                                        log_file_error(filename, location.first_line, "Can not parse address `%s` for %s.\n", nptr, str.c_str());
                                continue;
                        }

                        AstNode *value = VERILOG_FRONTEND::const2ast(stringf("%d'%c", mem_width, is_readmemh ? 'h' : 'b') + token);

                        if (unconditional_init)
                        {
                                if (meminit == nullptr || cursor != next_meminit_cursor)
                                {
                                        if (meminit != nullptr) {
                                                meminit->children[1] = AstNode::mkconst_bits(meminit_bits, false);
                                                meminit->children[3] = AstNode::mkconst_int(meminit_size, false);
                                        }

                                        meminit = new AstNode(AST_MEMINIT);
                                        meminit->children.push_back(AstNode::mkconst_int(cursor, false));
                                        meminit->children.push_back(nullptr);
                                        meminit->children.push_back(AstNode::mkconst_bits(en_bits, false));
                                        meminit->children.push_back(nullptr);
                                        meminit->str = memory->str;
                                        meminit->id2ast = memory;
                                        meminit_bits.clear();
                                        meminit_size = 0;

                                        current_ast_mod->children.push_back(meminit);
                                        next_meminit_cursor = cursor;
                                }

                                meminit_size++;
                                next_meminit_cursor++;
                                meminit_bits.insert(meminit_bits.end(), value->bits.begin(), value->bits.end());
                                delete value;
                        }
                        else
                        {
                                block->children.push_back(new AstNode(AST_ASSIGN_EQ, new AstNode(AST_IDENTIFIER, new AstNode(AST_RANGE, AstNode::mkconst_int(cursor, false))), value));
                                block->children.back()->children[0]->str = memory->str;
                                block->children.back()->children[0]->id2ast = memory;
                                block->children.back()->children[0]->was_checked = true;
                        }

                        cursor += increment;
                        if ((cursor == finish_addr+increment) || (increment > 0 && cursor > range_max) || (increment < 0 && cursor < range_min))
                                break;
                }

                if ((cursor == finish_addr+increment) || (increment > 0 && cursor > range_max) || (increment < 0 && cursor < range_min))
                        break;
        }

        if (meminit != nullptr) {
                meminit->children[1] = AstNode::mkconst_bits(meminit_bits, false);
                meminit->children[3] = AstNode::mkconst_int(meminit_size, false);
        }

        return block;
}

// annotate the names of all wires and other named objects in a named generate
// or procedural block; nested blocks are themselves annotated such that the
// prefix is carried forward, but resolution of their children is deferred
void AstNode::expand_genblock(const std::string &prefix)
{
        if (type == AST_IDENTIFIER || type == AST_FCALL || type == AST_TCALL || type == AST_WIRETYPE || type == AST_PREFIX) {
                log_assert(!str.empty());

                // search starting in the innermost scope and then stepping outward
                for (size_t ppos = prefix.size() - 1; ppos; --ppos) {
                        if (prefix.at(ppos) != '.') continue;

                        std::string new_prefix = prefix.substr(0, ppos + 1);
                        auto attempt_resolve = [&new_prefix](const std::string &ident) -> std::string {
                                std::string new_name = prefix_id(new_prefix, ident);
                                if (current_scope.count(new_name))
                                        return new_name;
                                return {};
                        };

                        // attempt to resolve the full identifier
                        std::string resolved = attempt_resolve(str);
                        if (!resolved.empty()) {
                                str = resolved;
                                break;
                        }

                        // attempt to resolve hierarchical prefixes within the identifier,
                        // as the prefix could refer to a local scope which exists but
                        // hasn't yet been elaborated
                        for (size_t spos = str.size() - 1; spos; --spos) {
                                if (str.at(spos) != '.') continue;
                                resolved = attempt_resolve(str.substr(0, spos));
                                if (!resolved.empty()) {
                                        str = resolved + str.substr(spos);
                                        ppos = 1; // break outer loop
                                        break;
                                }
                        }

                }
        }

        auto prefix_node = [&prefix](AstNode* child) {
                if (child->str.empty()) return;
                std::string new_name = prefix_id(prefix, child->str);
                if (child->type == AST_FUNCTION)
                        child->replace_result_wire_name_in_function(child->str, new_name);
                else
                        child->str = new_name;
                current_scope[new_name] = child;
        };

        for (size_t i = 0; i < children.size(); i++) {
                AstNode *child = children[i];

                switch (child->type) {
                case AST_WIRE:
                case AST_MEMORY:
                case AST_PARAMETER:
                case AST_LOCALPARAM:
                case AST_FUNCTION:
                case AST_TASK:
                case AST_CELL:
                case AST_TYPEDEF:
                case AST_ENUM_ITEM:
                case AST_GENVAR:
                        prefix_node(child);
                        break;

                case AST_BLOCK:
                case AST_GENBLOCK:
                        if (!child->str.empty())
                                prefix_node(child);
                        break;

                case AST_ENUM:
                        current_scope[child->str] = child;
                        for (auto enode : child->children){
                                log_assert(enode->type == AST_ENUM_ITEM);
                                prefix_node(enode);
                        }
                        break;

                default:
                        break;
                }
        }

        for (size_t i = 0; i < children.size(); i++) {
                AstNode *child = children[i];
                // AST_PREFIX member names should not be prefixed; we recurse into them
                // as normal to ensure indices and ranges are properly resolved, and
                // then restore the previous string
                if (type == AST_PREFIX && i == 1) {
                        std::string backup_scope_name = child->str;
                        child->expand_genblock(prefix);
                        child->str = backup_scope_name;
                        continue;
                }
                // functions/tasks may reference wires, constants, etc. in this scope
                if (child->type == AST_FUNCTION || child->type == AST_TASK)
                        continue;
                // named blocks pick up the current prefix and will expanded later
                if ((child->type == AST_GENBLOCK || child->type == AST_BLOCK) && !child->str.empty())
                        continue;

                child->expand_genblock(prefix);
        }
}

// add implicit AST_GENBLOCK names according to IEEE 1364-2005 Section 12.4.3 or
// IEEE 1800-2017 Section 27.6
void AstNode::label_genblks(std::set<std::string>& existing, int &counter)
{
        switch (type) {
        case AST_GENIF:
        case AST_GENFOR:
        case AST_GENCASE:
                // seeing a proper generate control flow construct increments the
                // counter once
                ++counter;
                for (AstNode *child : children)
                        child->label_genblks(existing, counter);
                break;

        case AST_GENBLOCK: {
                // if this block is unlabeled, generate its corresponding unique name
                for (int padding = 0; str.empty(); ++padding) {
                        std::string candidate = "\\genblk";
                        for (int i = 0; i < padding; ++i)
                                candidate += '0';
                        candidate += std::to_string(counter);
                        if (!existing.count(candidate))
                                str = candidate;
                }
                // within a genblk, the counter starts fresh
                std::set<std::string> existing_local = existing;
                int counter_local = 0;
                for (AstNode *child : children)
                        child->label_genblks(existing_local, counter_local);
                break;
        }

        default:
                // track names which could conflict with implicit genblk names
                if (str.rfind("\\genblk", 0) == 0)
                        existing.insert(str);
                for (AstNode *child : children)
                        child->label_genblks(existing, counter);
                break;
        }
}

// helper function for mem2reg_as_needed_pass1
static void mark_memories_assign_lhs_complex(dict<AstNode*, pool<std::string>> &mem2reg_places,
                dict<AstNode*, uint32_t> &mem2reg_candidates, AstNode *that)
{
        for (auto &child : that->children)
                mark_memories_assign_lhs_complex(mem2reg_places, mem2reg_candidates, child);

        if (that->type == AST_IDENTIFIER && that->id2ast && that->id2ast->type == AST_MEMORY) {
                AstNode *mem = that->id2ast;
                if (!(mem2reg_candidates[mem] & AstNode::MEM2REG_FL_CMPLX_LHS))
                        mem2reg_places[mem].insert(stringf("%s:%d", that->filename.c_str(), that->location.first_line));
                mem2reg_candidates[mem] |= AstNode::MEM2REG_FL_CMPLX_LHS;
        }
}

// find memories that should be replaced by registers
void AstNode::mem2reg_as_needed_pass1(dict<AstNode*, pool<std::string>> &mem2reg_places,
                dict<AstNode*, uint32_t> &mem2reg_candidates, dict<AstNode*, uint32_t> &proc_flags, uint32_t &flags)
{
        uint32_t children_flags = 0;
        int lhs_children_counter = 0;

        if (type == AST_TYPEDEF)
                return; // don't touch content of typedefs

        if (type == AST_ASSIGN || type == AST_ASSIGN_LE || type == AST_ASSIGN_EQ)
        {
                // mark all memories that are used in a complex expression on the left side of an assignment
                for (auto &lhs_child : children[0]->children)
                        mark_memories_assign_lhs_complex(mem2reg_places, mem2reg_candidates, lhs_child);

                if (children[0]->type == AST_IDENTIFIER && children[0]->id2ast && children[0]->id2ast->type == AST_MEMORY)
                {
                        AstNode *mem = children[0]->id2ast;

                        // activate mem2reg if this is assigned in an async proc
                        if (flags & AstNode::MEM2REG_FL_ASYNC) {
                                if (!(mem2reg_candidates[mem] & AstNode::MEM2REG_FL_SET_ASYNC))
                                        mem2reg_places[mem].insert(stringf("%s:%d", filename.c_str(), location.first_line));
                                mem2reg_candidates[mem] |= AstNode::MEM2REG_FL_SET_ASYNC;
                        }

                        // remember if this is assigned blocking (=)
                        if (type == AST_ASSIGN_EQ) {
                                if (!(proc_flags[mem] & AstNode::MEM2REG_FL_EQ1))
                                        mem2reg_places[mem].insert(stringf("%s:%d", filename.c_str(), location.first_line));
                                proc_flags[mem] |= AstNode::MEM2REG_FL_EQ1;
                        }

                        // for proper (non-init) writes: remember if this is a constant index or not
                        if ((flags & MEM2REG_FL_INIT) == 0) {
                                if (children[0]->children.size() && children[0]->children[0]->type == AST_RANGE && children[0]->children[0]->children.size()) {
                                        if (children[0]->children[0]->children[0]->type == AST_CONSTANT)
                                                mem2reg_candidates[mem] |= AstNode::MEM2REG_FL_CONST_LHS;
                                        else
                                                mem2reg_candidates[mem] |= AstNode::MEM2REG_FL_VAR_LHS;
                                }
                        }

                        // remember where this is
                        if (flags & MEM2REG_FL_INIT) {
                                if (!(mem2reg_candidates[mem] & AstNode::MEM2REG_FL_SET_INIT))
                                        mem2reg_places[mem].insert(stringf("%s:%d", filename.c_str(), location.first_line));
                                mem2reg_candidates[mem] |= AstNode::MEM2REG_FL_SET_INIT;
                        } else {
                                if (!(mem2reg_candidates[mem] & AstNode::MEM2REG_FL_SET_ELSE))
                                        mem2reg_places[mem].insert(stringf("%s:%d", filename.c_str(), location.first_line));
                                mem2reg_candidates[mem] |= AstNode::MEM2REG_FL_SET_ELSE;
                        }
                }

                lhs_children_counter = 1;
        }

        if (type == AST_IDENTIFIER && id2ast && id2ast->type == AST_MEMORY)
        {
                AstNode *mem = id2ast;

                // flag if used after blocking assignment (in same proc)
                if ((proc_flags[mem] & AstNode::MEM2REG_FL_EQ1) && !(mem2reg_candidates[mem] & AstNode::MEM2REG_FL_EQ2)) {
                        mem2reg_places[mem].insert(stringf("%s:%d", filename.c_str(), location.first_line));
                        mem2reg_candidates[mem] |= AstNode::MEM2REG_FL_EQ2;
                }
        }

        // also activate if requested, either by using mem2reg attribute or by declaring array as 'wire' instead of 'reg' or 'logic'
        if (type == AST_MEMORY && (get_bool_attribute(ID::mem2reg) || (flags & AstNode::MEM2REG_FL_ALL) || !(is_reg || is_logic)))
                mem2reg_candidates[this] |= AstNode::MEM2REG_FL_FORCED;

        if (type == AST_MODULE && get_bool_attribute(ID::mem2reg))
                children_flags |= AstNode::MEM2REG_FL_ALL;

        dict<AstNode*, uint32_t> *proc_flags_p = NULL;

        if (type == AST_ALWAYS) {
                int count_edge_events = 0;
                for (auto child : children)
                        if (child->type == AST_POSEDGE || child->type == AST_NEGEDGE)
                                count_edge_events++;
                if (count_edge_events != 1)
                        children_flags |= AstNode::MEM2REG_FL_ASYNC;
                proc_flags_p = new dict<AstNode*, uint32_t>;
        }

        if (type == AST_INITIAL) {
                children_flags |= AstNode::MEM2REG_FL_INIT;
                proc_flags_p = new dict<AstNode*, uint32_t>;
        }

        uint32_t backup_flags = flags;
        flags |= children_flags;
        log_assert((flags & ~0x000000ff) == 0);

        for (auto child : children)
        {
                if (lhs_children_counter > 0) {
                        lhs_children_counter--;
                        if (child->children.size() && child->children[0]->type == AST_RANGE && child->children[0]->children.size()) {
                                for (auto c : child->children[0]->children) {
                                        if (proc_flags_p)
                                                c->mem2reg_as_needed_pass1(mem2reg_places, mem2reg_candidates, *proc_flags_p, flags);
                                        else
                                                c->mem2reg_as_needed_pass1(mem2reg_places, mem2reg_candidates, proc_flags, flags);
                                }
                        }
                } else
                if (proc_flags_p)
                        child->mem2reg_as_needed_pass1(mem2reg_places, mem2reg_candidates, *proc_flags_p, flags);
                else
                        child->mem2reg_as_needed_pass1(mem2reg_places, mem2reg_candidates, proc_flags, flags);
        }

        flags &= ~children_flags | backup_flags;

        if (proc_flags_p) {
#ifndef NDEBUG
                for (auto it : *proc_flags_p)
                        log_assert((it.second & ~0xff000000) == 0);
#endif
                delete proc_flags_p;
        }
}

bool AstNode::mem2reg_check(pool<AstNode*> &mem2reg_set)
{
        if (type != AST_IDENTIFIER || !id2ast || !mem2reg_set.count(id2ast))
                return false;

        if (children.empty() || children[0]->type != AST_RANGE || GetSize(children[0]->children) != 1)
                log_file_error(filename, location.first_line, "Invalid array access.\n");

        return true;
}

void AstNode::mem2reg_remove(pool<AstNode*> &mem2reg_set, vector<AstNode*> &delnodes)
{
        log_assert(mem2reg_set.count(this) == 0);

        if (mem2reg_set.count(id2ast))
                id2ast = nullptr;

        for (size_t i = 0; i < children.size(); i++) {
                if (mem2reg_set.count(children[i]) > 0) {
                        delnodes.push_back(children[i]);
                        children.erase(children.begin() + (i--));
                } else {
                        children[i]->mem2reg_remove(mem2reg_set, delnodes);
                }
        }
}

// actually replace memories with registers
bool AstNode::mem2reg_as_needed_pass2(pool<AstNode*> &mem2reg_set, AstNode *mod, AstNode *block, AstNode *&async_block)
{
        bool did_something = false;

        if (type == AST_BLOCK)
                block = this;

        if (type == AST_FUNCTION || type == AST_TASK)
                return false;

        if (type == AST_TYPEDEF)
                return false;

        if (type == AST_MEMINIT && id2ast && mem2reg_set.count(id2ast))
        {
                log_assert(children[0]->type == AST_CONSTANT);
                log_assert(children[1]->type == AST_CONSTANT);
                log_assert(children[2]->type == AST_CONSTANT);
                log_assert(children[3]->type == AST_CONSTANT);

                int cursor = children[0]->asInt(false);
                Const data = children[1]->bitsAsConst();
                Const en = children[2]->bitsAsConst();
                int length = children[3]->asInt(false);

                if (length != 0)
                {
                        AstNode *block = new AstNode(AST_INITIAL, new AstNode(AST_BLOCK));
                        mod->children.push_back(block);
                        block = block->children[0];

                        int wordsz = GetSize(data) / length;

                        for (int i = 0; i < length; i++) {
                                int pos = 0;
                                while (pos < wordsz) {
                                        if (en[pos] != State::S1) {
                                                pos++;
                                        } else {
                                                int epos = pos + 1;
                                                while (epos < wordsz && en[epos] == State::S1)
                                                        epos++;
                                                int clen = epos - pos;
                                                AstNode *range = new AstNode(AST_RANGE, AstNode::mkconst_int(cursor+i, false));
                                                if (pos != 0 || epos != wordsz) {
                                                        int left;
                                                        int right;
                                                        AstNode *mrange = id2ast->children[0];
                                                        if (mrange->range_left < mrange->range_right) {
                                                                right = mrange->range_right - pos;
                                                                left = mrange->range_right - epos + 1;
                                                        } else {
                                                                right = mrange->range_right + pos;
                                                                left = mrange->range_right + epos - 1;
                                                        }
                                                        range = new AstNode(AST_MULTIRANGE, range, new AstNode(AST_RANGE, AstNode::mkconst_int(left, true), AstNode::mkconst_int(right, true)));
                                                }
                                                AstNode *target = new AstNode(AST_IDENTIFIER, range);
                                                target->str = str;
                                                target->id2ast = id2ast;
                                                target->was_checked = true;
                                                block->children.push_back(new AstNode(AST_ASSIGN_EQ, target, mkconst_bits(data.extract(i*wordsz + pos, clen).bits, false)));
                                                pos = epos;
                                        }
                                }
                        }
                }

                AstNode *newNode = new AstNode(AST_NONE);
                newNode->cloneInto(this);
                delete newNode;

                did_something = true;
        }

        if (type == AST_ASSIGN && block == NULL && children[0]->mem2reg_check(mem2reg_set))
        {
                if (async_block == NULL) {
                        async_block = new AstNode(AST_ALWAYS, new AstNode(AST_BLOCK));
                        mod->children.push_back(async_block);
                }

                AstNode *newNode = clone();
                newNode->type = AST_ASSIGN_EQ;
                newNode->children[0]->was_checked = true;
                async_block->children[0]->children.push_back(newNode);

                newNode = new AstNode(AST_NONE);
                newNode->cloneInto(this);
                delete newNode;

                did_something = true;
        }

        if ((type == AST_ASSIGN_LE || type == AST_ASSIGN_EQ) && children[0]->mem2reg_check(mem2reg_set) &&
                        children[0]->children[0]->children[0]->type != AST_CONSTANT)
        {
                std::stringstream sstr;
                sstr << "$mem2reg_wr$" << children[0]->str << "$" << filename << ":" << location.first_line << "$" << (autoidx++);
                std::string id_addr = sstr.str() + "_ADDR", id_data = sstr.str() + "_DATA";

                int mem_width, mem_size, addr_bits;
                bool mem_signed = children[0]->id2ast->is_signed;
                children[0]->id2ast->meminfo(mem_width, mem_size, addr_bits);

                AstNode *wire_addr = new AstNode(AST_WIRE, new AstNode(AST_RANGE, mkconst_int(addr_bits-1, true), mkconst_int(0, true)));
                wire_addr->str = id_addr;
                wire_addr->is_reg = true;
                wire_addr->was_checked = true;
                wire_addr->attributes[ID::nosync] = AstNode::mkconst_int(1, false);
                mod->children.push_back(wire_addr);
                while (wire_addr->simplify(true, false, false, 1, -1, false, false)) { }

                AstNode *wire_data = new AstNode(AST_WIRE, new AstNode(AST_RANGE, mkconst_int(mem_width-1, true), mkconst_int(0, true)));
                wire_data->str = id_data;
                wire_data->is_reg = true;
                wire_data->was_checked = true;
                wire_data->is_signed = mem_signed;
                wire_data->attributes[ID::nosync] = AstNode::mkconst_int(1, false);
                mod->children.push_back(wire_data);
                while (wire_data->simplify(true, false, false, 1, -1, false, false)) { }

                log_assert(block != NULL);
                size_t assign_idx = 0;
                while (assign_idx < block->children.size() && block->children[assign_idx] != this)
                        assign_idx++;
                log_assert(assign_idx < block->children.size());

                AstNode *assign_addr = new AstNode(AST_ASSIGN_EQ, new AstNode(AST_IDENTIFIER), children[0]->children[0]->children[0]->clone());
                assign_addr->children[0]->str = id_addr;
                assign_addr->children[0]->was_checked = true;
                block->children.insert(block->children.begin()+assign_idx+1, assign_addr);

                AstNode *case_node = new AstNode(AST_CASE, new AstNode(AST_IDENTIFIER));
                case_node->children[0]->str = id_addr;
                for (int i = 0; i < mem_size; i++) {
                        if (children[0]->children[0]->children[0]->type == AST_CONSTANT && int(children[0]->children[0]->children[0]->integer) != i)
                                continue;
                        AstNode *cond_node = new AstNode(AST_COND, AstNode::mkconst_int(i, false, addr_bits), new AstNode(AST_BLOCK));
                        AstNode *assign_reg = new AstNode(type, new AstNode(AST_IDENTIFIER), new AstNode(AST_IDENTIFIER));
                        if (children[0]->children.size() == 2)
                                assign_reg->children[0]->children.push_back(children[0]->children[1]->clone());
                        assign_reg->children[0]->str = stringf("%s[%d]", children[0]->str.c_str(), i);
                        assign_reg->children[1]->str = id_data;
                        cond_node->children[1]->children.push_back(assign_reg);
                        case_node->children.push_back(cond_node);
                }
                block->children.insert(block->children.begin()+assign_idx+2, case_node);

                children[0]->delete_children();
                children[0]->range_valid = false;
                children[0]->id2ast = NULL;
                children[0]->str = id_data;
                type = AST_ASSIGN_EQ;
                children[0]->was_checked = true;

                did_something = true;
        }

        if (mem2reg_check(mem2reg_set))
        {
                AstNode *bit_part_sel = NULL;
                if (children.size() == 2)
                        bit_part_sel = children[1]->clone();

                if (children[0]->children[0]->type == AST_CONSTANT)
                {
                        int id = children[0]->children[0]->integer;
                        int left = id2ast->children[1]->children[0]->integer;
                        int right = id2ast->children[1]->children[1]->integer;
                        bool valid_const_access =
                                (left <= id && id <= right) ||
                                (right <= id && id <= left);
                        if (valid_const_access)
                        {
                                str = stringf("%s[%d]", str.c_str(), id);
                                delete_children();
                                range_valid = false;
                                id2ast = NULL;
                        }
                        else
                        {
                                int width;
                                if (bit_part_sel)
                                {
                                        bit_part_sel->dumpAst(nullptr, "? ");
                                        if (bit_part_sel->children.size() == 1)
                                                width = 0;
                                        else
                                                width = bit_part_sel->children[0]->integer -
                                                        bit_part_sel->children[1]->integer;
                                        delete bit_part_sel;
                                        bit_part_sel = nullptr;
                                }
                                else
                                {
                                        width = id2ast->children[0]->children[0]->integer -
                                                id2ast->children[0]->children[1]->integer;
                                }
                                width = abs(width) + 1;

                                delete_children();

                                std::vector<RTLIL::State> x_bits;
                                for (int i = 0; i < width; i++)
                                        x_bits.push_back(RTLIL::State::Sx);
                                AstNode *constant = AstNode::mkconst_bits(x_bits, false);
                                constant->cloneInto(this);
                                delete constant;
                        }
                }
                else
                {
                        std::stringstream sstr;
                        sstr << "$mem2reg_rd$" << str << "$" << filename << ":" << location.first_line << "$" << (autoidx++);
                        std::string id_addr = sstr.str() + "_ADDR", id_data = sstr.str() + "_DATA";

                        int mem_width, mem_size, addr_bits;
                        bool mem_signed = id2ast->is_signed;
                        id2ast->meminfo(mem_width, mem_size, addr_bits);

                        AstNode *wire_addr = new AstNode(AST_WIRE, new AstNode(AST_RANGE, mkconst_int(addr_bits-1, true), mkconst_int(0, true)));
                        wire_addr->str = id_addr;
                        wire_addr->is_reg = true;
                        wire_addr->was_checked = true;
                        if (block)
                                wire_addr->attributes[ID::nosync] = AstNode::mkconst_int(1, false);
                        mod->children.push_back(wire_addr);
                        while (wire_addr->simplify(true, false, false, 1, -1, false, false)) { }

                        AstNode *wire_data = new AstNode(AST_WIRE, new AstNode(AST_RANGE, mkconst_int(mem_width-1, true), mkconst_int(0, true)));
                        wire_data->str = id_data;
                        wire_data->is_reg = true;
                        wire_data->was_checked = true;
                        wire_data->is_signed = mem_signed;
                        if (block)
                                wire_data->attributes[ID::nosync] = AstNode::mkconst_int(1, false);
                        mod->children.push_back(wire_data);
                        while (wire_data->simplify(true, false, false, 1, -1, false, false)) { }

                        AstNode *assign_addr = new AstNode(block ? AST_ASSIGN_EQ : AST_ASSIGN, new AstNode(AST_IDENTIFIER), children[0]->children[0]->clone());
                        assign_addr->children[0]->str = id_addr;
                        assign_addr->children[0]->was_checked = true;

                        AstNode *case_node = new AstNode(AST_CASE, new AstNode(AST_IDENTIFIER));
                        case_node->children[0]->str = id_addr;

                        for (int i = 0; i < mem_size; i++) {
                                if (children[0]->children[0]->type == AST_CONSTANT && int(children[0]->children[0]->integer) != i)
                                        continue;
                                AstNode *cond_node = new AstNode(AST_COND, AstNode::mkconst_int(i, false, addr_bits), new AstNode(AST_BLOCK));
                                AstNode *assign_reg = new AstNode(AST_ASSIGN_EQ, new AstNode(AST_IDENTIFIER), new AstNode(AST_IDENTIFIER));
                                assign_reg->children[0]->str = id_data;
                                assign_reg->children[0]->was_checked = true;
                                assign_reg->children[1]->str = stringf("%s[%d]", str.c_str(), i);
                                cond_node->children[1]->children.push_back(assign_reg);
                                case_node->children.push_back(cond_node);
                        }

                        std::vector<RTLIL::State> x_bits;
                        for (int i = 0; i < mem_width; i++)
                                x_bits.push_back(RTLIL::State::Sx);

                        AstNode *cond_node = new AstNode(AST_COND, new AstNode(AST_DEFAULT), new AstNode(AST_BLOCK));
                        AstNode *assign_reg = new AstNode(AST_ASSIGN_EQ, new AstNode(AST_IDENTIFIER), AstNode::mkconst_bits(x_bits, false));
                        assign_reg->children[0]->str = id_data;
                        assign_reg->children[0]->was_checked = true;
                        cond_node->children[1]->children.push_back(assign_reg);
                        case_node->children.push_back(cond_node);

                        if (block)
                        {
                                size_t assign_idx = 0;
                                while (assign_idx < block->children.size() && !block->children[assign_idx]->contains(this))
                                        assign_idx++;
                                log_assert(assign_idx < block->children.size());
                                block->children.insert(block->children.begin()+assign_idx, case_node);
                                block->children.insert(block->children.begin()+assign_idx, assign_addr);
                        }
                        else
                        {
                                AstNode *proc = new AstNode(AST_ALWAYS, new AstNode(AST_BLOCK));
                                proc->children[0]->children.push_back(case_node);
                                mod->children.push_back(proc);
                                mod->children.push_back(assign_addr);
                        }

                        delete_children();
                        range_valid = false;
                        id2ast = NULL;
                        str = id_data;
                }

                if (bit_part_sel)
                        children.push_back(bit_part_sel);

                did_something = true;
        }

        log_assert(id2ast == NULL || mem2reg_set.count(id2ast) == 0);

        auto children_list = children;
        for (size_t i = 0; i < children_list.size(); i++)
                if (children_list[i]->mem2reg_as_needed_pass2(mem2reg_set, mod, block, async_block))
                        did_something = true;

        return did_something;
}

// calculate memory dimensions
void AstNode::meminfo(int &mem_width, int &mem_size, int &addr_bits)
{
        log_assert(type == AST_MEMORY);

        mem_width = children[0]->range_left - children[0]->range_right + 1;
        mem_size = children[1]->range_left - children[1]->range_right;

        if (mem_size < 0)
                mem_size *= -1;
        mem_size += min(children[1]->range_left, children[1]->range_right) + 1;

        addr_bits = 1;
        while ((1 << addr_bits) < mem_size)
                addr_bits++;
}

bool AstNode::detect_latch(const std::string &var)
{
        switch (type)
        {
        case AST_ALWAYS:
                for (auto &c : children)
                {
                        switch (c->type)
                        {
                        case AST_POSEDGE:
                        case AST_NEGEDGE:
                                return false;
                        case AST_EDGE:
                                break;
                        case AST_BLOCK:
                                if (!c->detect_latch(var))
                                        return false;
                                break;
                        default:
                                log_abort();
                        }
                }
                return true;
        case AST_BLOCK:
                for (auto &c : children)
                        if (!c->detect_latch(var))
                                return false;
                return true;
        case AST_CASE:
                {
                        bool r = true;
                        for (auto &c : children) {
                                if (c->type == AST_COND) {
                                        if (c->children.at(1)->detect_latch(var))
                                                return true;
                                        r = false;
                                }
                                if (c->type == AST_DEFAULT) {
                                        if (c->children.at(0)->detect_latch(var))
                                                return true;
                                        r = false;
                                }
                        }
                        return r;
                }
        case AST_ASSIGN_EQ:
        case AST_ASSIGN_LE:
                if (children.at(0)->type == AST_IDENTIFIER &&
                                children.at(0)->children.empty() && children.at(0)->str == var)
                        return false;
                return true;
        default:
                return true;
        }
}

bool AstNode::has_const_only_constructs()
{
        if (type == AST_WHILE || type == AST_REPEAT)
                return true;
        for (auto child : children)
                if (child->has_const_only_constructs())
                        return true;
        return false;
}

bool AstNode::is_simple_const_expr()
{
        if (type == AST_IDENTIFIER)
                return false;
        for (auto child : children)
                if (!child->is_simple_const_expr())
                        return false;
        return true;
}

// helper function for AstNode::eval_const_function()
bool AstNode::replace_variables(std::map<std::string, AstNode::varinfo_t> &variables, AstNode *fcall, bool must_succeed)
{
        if (type == AST_IDENTIFIER && variables.count(str)) {
                int offset = variables.at(str).offset, width = variables.at(str).val.bits.size();
                if (!children.empty()) {
                        if (children.size() != 1 || children.at(0)->type != AST_RANGE) {
                                if (!must_succeed)
                                        return false;
                                log_file_error(filename, location.first_line, "Memory access in constant function is not supported\n%s: ...called from here.\n",
                                                fcall->loc_string().c_str());
                        }
                        if (!children.at(0)->replace_variables(variables, fcall, must_succeed))
                                return false;
                        while (simplify(true, false, false, 1, -1, false, true)) { }
                        if (!children.at(0)->range_valid) {
                                if (!must_succeed)
                                        return false;
                                log_file_error(filename, location.first_line, "Non-constant range\n%s: ... called from here.\n",
                                                fcall->loc_string().c_str());
                        }
                        offset = min(children.at(0)->range_left, children.at(0)->range_right);
                        width = min(std::abs(children.at(0)->range_left - children.at(0)->range_right) + 1, width);
                }
                offset -= variables.at(str).offset;
                std::vector<RTLIL::State> &var_bits = variables.at(str).val.bits;
                std::vector<RTLIL::State> new_bits(var_bits.begin() + offset, var_bits.begin() + offset + width);
                AstNode *newNode = mkconst_bits(new_bits, variables.at(str).is_signed);
                newNode->cloneInto(this);
                delete newNode;
                return true;
        }

        for (auto &child : children)
                if (!child->replace_variables(variables, fcall, must_succeed))
                        return false;
        return true;
}

// attempt to statically evaluate a functions with all-const arguments
AstNode *AstNode::eval_const_function(AstNode *fcall, bool must_succeed)
{
        std::map<std::string, AstNode*> backup_scope = current_scope;
        std::map<std::string, AstNode::varinfo_t> variables;
        std::vector<AstNode*> to_delete;
        AstNode *block = new AstNode(AST_BLOCK);
        AstNode *result = nullptr;

        size_t argidx = 0;
        for (auto child : children)
        {
                block->children.push_back(child->clone());
        }

        while (!block->children.empty())
        {
                AstNode *stmt = block->children.front();

#if 0
                log("-----------------------------------\n");
                for (auto &it : variables)
                        log("%20s %40s\n", it.first.c_str(), log_signal(it.second.val));
                stmt->dumpAst(NULL, "stmt> ");
#endif

                if (stmt->type == AST_WIRE)
                {
                        while (stmt->simplify(true, false, false, 1, -1, false, true)) { }
                        if (!stmt->range_valid) {
                                if (!must_succeed)
                                        goto finished;
                                log_file_error(stmt->filename, stmt->location.first_line, "Can't determine size of variable %s\n%s: ... called from here.\n",
                                                stmt->str.c_str(), fcall->loc_string().c_str());
                        }
                        AstNode::varinfo_t &variable = variables[stmt->str];
                        int width = abs(stmt->range_left - stmt->range_right) + 1;
                        // if this variable has already been declared as an input, check the
                        // sizes match if it already had an explicit size
                        if (variable.arg && variable.explicitly_sized && variable.val.size() != width) {
                                log_file_error(filename, location.first_line, "Incompatible re-declaration of constant function wire %s.\n", stmt->str.c_str());
                        }
                        variable.val = RTLIL::Const(RTLIL::State::Sx, width);
                        variable.offset = min(stmt->range_left, stmt->range_right);
                        variable.is_signed = stmt->is_signed;
                        variable.explicitly_sized = stmt->children.size() &&
                                stmt->children.back()->type == AST_RANGE;
                        // identify the argument corresponding to this wire, if applicable
                        if (stmt->is_input && argidx < fcall->children.size()) {
                                variable.arg = fcall->children.at(argidx++);
                        }
                        // load the constant arg's value into this variable
                        if (variable.arg) {
                                if (variable.arg->type == AST_CONSTANT) {
                                        variable.val = variable.arg->bitsAsConst(width);
                                } else {
                                        log_assert(variable.arg->type == AST_REALVALUE);
                                        variable.val = variable.arg->realAsConst(width);
                                }
                        }
                        current_scope[stmt->str] = stmt;

                        block->children.erase(block->children.begin());
                        to_delete.push_back(stmt);
                        continue;
                }

                log_assert(variables.count(str) != 0);

                if (stmt->type == AST_LOCALPARAM)
                {
                        while (stmt->simplify(true, false, false, 1, -1, false, true)) { }

                        current_scope[stmt->str] = stmt;

                        block->children.erase(block->children.begin());
                        to_delete.push_back(stmt);
                        continue;
                }

                if (stmt->type == AST_ASSIGN_EQ)
                {
                        if (stmt->children.at(0)->type == AST_IDENTIFIER && stmt->children.at(0)->children.size() != 0 &&
                                        stmt->children.at(0)->children.at(0)->type == AST_RANGE)
                                if (!stmt->children.at(0)->children.at(0)->replace_variables(variables, fcall, must_succeed))
                                        goto finished;
                        if (!stmt->children.at(1)->replace_variables(variables, fcall, must_succeed))
                                goto finished;
                        while (stmt->simplify(true, false, false, 1, -1, false, true)) { }

                        if (stmt->type != AST_ASSIGN_EQ)
                                continue;

                        if (stmt->children.at(1)->type != AST_CONSTANT) {
                                if (!must_succeed)
                                        goto finished;
                                log_file_error(stmt->filename, stmt->location.first_line, "Non-constant expression in constant function\n%s: ... called from here. X\n",
                                                fcall->loc_string().c_str());
                        }

                        if (stmt->children.at(0)->type != AST_IDENTIFIER) {
                                if (!must_succeed)
                                        goto finished;
                                log_file_error(stmt->filename, stmt->location.first_line, "Unsupported composite left hand side in constant function\n%s: ... called from here.\n",
                                                fcall->loc_string().c_str());
                        }

                        if (!variables.count(stmt->children.at(0)->str)) {
                                if (!must_succeed)
                                        goto finished;
                                log_file_error(stmt->filename, stmt->location.first_line, "Assignment to non-local variable in constant function\n%s: ... called from here.\n",
                                                fcall->loc_string().c_str());
                        }

                        if (stmt->children.at(0)->children.empty()) {
                                variables[stmt->children.at(0)->str].val = stmt->children.at(1)->bitsAsConst(variables[stmt->children.at(0)->str].val.bits.size());
                        } else {
                                AstNode *range = stmt->children.at(0)->children.at(0);
                                if (!range->range_valid) {
                                        if (!must_succeed)
                                                goto finished;
                                        log_file_error(range->filename, range->location.first_line, "Non-constant range\n%s: ... called from here.\n",
                                                        fcall->loc_string().c_str());
                                }
                                int offset = min(range->range_left, range->range_right);
                                int width = std::abs(range->range_left - range->range_right) + 1;
                                varinfo_t &v = variables[stmt->children.at(0)->str];
                                RTLIL::Const r = stmt->children.at(1)->bitsAsConst(v.val.bits.size());
                                for (int i = 0; i < width; i++)
                                        v.val.bits.at(i+offset-v.offset) = r.bits.at(i);
                        }

                        delete block->children.front();
                        block->children.erase(block->children.begin());
                        continue;
                }

                if (stmt->type == AST_FOR)
                {
                        block->children.insert(block->children.begin(), stmt->children.at(0));
                        stmt->children.at(3)->children.push_back(stmt->children.at(2));
                        stmt->children.erase(stmt->children.begin() + 2);
                        stmt->children.erase(stmt->children.begin());
                        stmt->type = AST_WHILE;
                        continue;
                }

                if (stmt->type == AST_WHILE)
                {
                        AstNode *cond = stmt->children.at(0)->clone();
                        if (!cond->replace_variables(variables, fcall, must_succeed))
                                goto finished;
                        while (cond->simplify(true, false, false, 1, -1, false, true)) { }

                        if (cond->type != AST_CONSTANT) {
                                if (!must_succeed)
                                        goto finished;
                                log_file_error(stmt->filename, stmt->location.first_line, "Non-constant expression in constant function\n%s: ... called from here.\n",
                                                fcall->loc_string().c_str());
                        }

                        if (cond->asBool()) {
                                block->children.insert(block->children.begin(), stmt->children.at(1)->clone());
                        } else {
                                delete block->children.front();
                                block->children.erase(block->children.begin());
                        }

                        delete cond;
                        continue;
                }

                if (stmt->type == AST_REPEAT)
                {
                        AstNode *num = stmt->children.at(0)->clone();
                        if (!num->replace_variables(variables, fcall, must_succeed))
                                goto finished;
                        while (num->simplify(true, false, false, 1, -1, false, true)) { }

                        if (num->type != AST_CONSTANT) {
                                if (!must_succeed)
                                        goto finished;
                                log_file_error(stmt->filename, stmt->location.first_line, "Non-constant expression in constant function\n%s: ... called from here.\n",
                                                fcall->loc_string().c_str());
                        }

                        block->children.erase(block->children.begin());
                        for (int i = 0; i < num->bitsAsConst().as_int(); i++)
                                block->children.insert(block->children.begin(), stmt->children.at(1)->clone());

                        delete stmt;
                        delete num;
                        continue;
                }

                if (stmt->type == AST_CASE)
                {
                        AstNode *expr = stmt->children.at(0)->clone();
                        if (!expr->replace_variables(variables, fcall, must_succeed))
                                goto finished;
                        while (expr->simplify(true, false, false, 1, -1, false, true)) { }

                        AstNode *sel_case = NULL;
                        for (size_t i = 1; i < stmt->children.size(); i++)
                        {
                                bool found_match = false;
                                log_assert(stmt->children.at(i)->type == AST_COND || stmt->children.at(i)->type == AST_CONDX || stmt->children.at(i)->type == AST_CONDZ);

                                if (stmt->children.at(i)->children.front()->type == AST_DEFAULT) {
                                        sel_case = stmt->children.at(i)->children.back();
                                        continue;
                                }

                                for (size_t j = 0; j+1 < stmt->children.at(i)->children.size() && !found_match; j++)
                                {
                                        AstNode *cond = stmt->children.at(i)->children.at(j)->clone();
                                        if (!cond->replace_variables(variables, fcall, must_succeed))
                                                goto finished;

                                        cond = new AstNode(AST_EQ, expr->clone(), cond);
                                        while (cond->simplify(true, false, false, 1, -1, false, true)) { }

                                        if (cond->type != AST_CONSTANT) {
                                                if (!must_succeed)
                                                        goto finished;
                                                log_file_error(stmt->filename, stmt->location.first_line, "Non-constant expression in constant function\n%s: ... called from here.\n",
                                                                fcall->loc_string().c_str());
                                        }

                                        found_match = cond->asBool();
                                        delete cond;
                                }

                                if (found_match) {
                                        sel_case = stmt->children.at(i)->children.back();
                                        break;
                                }
                        }

                        block->children.erase(block->children.begin());
                        if (sel_case)
                                block->children.insert(block->children.begin(), sel_case->clone());
                        delete stmt;
                        delete expr;
                        continue;
                }

                if (stmt->type == AST_BLOCK)
                {
                        if (!stmt->str.empty())
                                stmt->expand_genblock(stmt->str + ".");

                        block->children.erase(block->children.begin());
                        block->children.insert(block->children.begin(), stmt->children.begin(), stmt->children.end());
                        stmt->children.clear();
                        delete stmt;
                        continue;
                }

                if (!must_succeed)
                        goto finished;
                log_file_error(stmt->filename, stmt->location.first_line, "Unsupported language construct in constant function\n%s: ... called from here.\n",
                                fcall->loc_string().c_str());
                log_abort();
        }

        result = AstNode::mkconst_bits(variables.at(str).val.bits, variables.at(str).is_signed);

finished:
        delete block;
        current_scope = backup_scope;

        for (auto it : to_delete) {
                delete it;
        }
        to_delete.clear();

        return result;
}

void AstNode::allocateDefaultEnumValues()
{
        log_assert(type==AST_ENUM);
        log_assert(children.size() > 0);
        if (children.front()->attributes.count(ID::enum_base_type))
                return; // already elaborated
        int last_enum_int = -1;
        for (auto node : children) {
                log_assert(node->type==AST_ENUM_ITEM);
                node->attributes[ID::enum_base_type] = mkconst_str(str);
                for (size_t i = 0; i < node->children.size(); i++) {
                        switch (node->children[i]->type) {
                        case AST_NONE:
                                // replace with auto-incremented constant
                                delete node->children[i];
                                node->children[i] = AstNode::mkconst_int(++last_enum_int, true);
                                break;
                        case AST_CONSTANT:
                                // explicit constant (or folded expression)
                                // TODO: can't extend 'x or 'z item
                                last_enum_int = node->children[i]->integer;
                                break;
                        default:
                                // ignore ranges
                                break;
                        }
                        // TODO: range check
                }
        }
}

bool AstNode::is_recursive_function() const
{
        std::set<const AstNode *> visited;
        std::function<bool(const AstNode *node)> visit = [&](const AstNode *node) {
                if (visited.count(node))
                        return node == this;
                visited.insert(node);
                if (node->type == AST_FCALL) {
                        auto it = current_scope.find(node->str);
                        if (it != current_scope.end() && visit(it->second))
                                return true;
                }
                for (const AstNode *child : node->children) {
                        if (visit(child))
                                return true;
                }
                return false;
        };

        log_assert(type == AST_FUNCTION);
        return visit(this);
}

std::pair<AstNode*, AstNode*> AstNode::get_tern_choice()
{
        if (!children[0]->isConst())
                return {};

        bool found_sure_true = false;
        bool found_maybe_true = false;

        if (children[0]->type == AST_CONSTANT)
                for (auto &bit : children[0]->bits) {
                        if (bit == RTLIL::State::S1)
                                found_sure_true = true;
                        if (bit > RTLIL::State::S1)
                                found_maybe_true = true;
                }
        else
                found_sure_true = children[0]->asReal(true) != 0;

        AstNode *choice = nullptr, *not_choice = nullptr;
        if (found_sure_true)
                choice = children[1], not_choice = children[2];
        else if (!found_maybe_true)
                choice = children[2], not_choice = children[1];

        return {choice, not_choice};
}

std::string AstNode::try_pop_module_prefix() const
{
        AstNode *current_scope_ast = (current_ast_mod == nullptr) ? current_ast : current_ast_mod;
        size_t pos = str.find('.', 1);
        if (str[0] == '\\' && pos != std::string::npos) {
                std::string new_str = "\\" + str.substr(pos + 1);
                if (current_scope.count(new_str)) {
                        std::string prefix = str.substr(0, pos);
                        auto it = current_scope_ast->attributes.find(ID::hdlname);
                        if ((it != current_scope_ast->attributes.end() && it->second->str == prefix)
                                        || prefix == current_scope_ast->str)
                                return new_str;
                }
        }
        return str;
}

YOSYS_NAMESPACE_END