From e1fb12a4b9e1d0685a1a1b060f2887f79b3c297f Mon Sep 17 00:00:00 2001 From: Claire Wolf Date: Wed, 15 Apr 2020 20:36:40 +0200 Subject: [PATCH] Add LookaheadRewriter for proper bitselwrite support Signed-off-by: Claire Wolf --- frontends/ast/ast.cc | 5 ++ frontends/ast/ast.h | 4 ++ frontends/ast/genrtlil.cc | 131 +++++++++++++++++++++++++++++++++++++- frontends/ast/simplify.cc | 8 ++- 4 files changed, 144 insertions(+), 4 deletions(-) diff --git a/frontends/ast/ast.cc b/frontends/ast/ast.cc index 2b6002548..4cf329f75 100644 --- a/frontends/ast/ast.cc +++ b/frontends/ast/ast.cc @@ -218,6 +218,7 @@ AstNode::AstNode(AstNodeType type, AstNode *child1, AstNode *child2, AstNode *ch realvalue = 0; id2ast = NULL; basic_prep = false; + lookahead = false; if (child1) children.push_back(child1); @@ -310,6 +311,10 @@ void AstNode::dumpAst(FILE *f, std::string indent) const fprintf(f, " reg"); if (is_signed) fprintf(f, " signed"); + if (basic_prep) + fprintf(f, " basic_prep"); + if (lookahead) + fprintf(f, " lookahead"); if (port_id > 0) fprintf(f, " port=%d", port_id); if (range_valid || range_left != -1 || range_right != 0) diff --git a/frontends/ast/ast.h b/frontends/ast/ast.h index 3dd40238f..3f6329112 100644 --- a/frontends/ast/ast.h +++ b/frontends/ast/ast.h @@ -202,6 +202,9 @@ namespace AST // this is used by simplify to detect if basic analysis has been performed already on the node bool basic_prep; + // this is used for ID references in RHS expressions that should use the "new" value for non-blocking assignments + bool lookahead; + // this is the original sourcecode location that resulted in this AST node // it is automatically set by the constructor using AST::current_filename and // the AST::get_line_num() callback function. @@ -352,6 +355,7 @@ namespace AST_INTERNAL extern AST::AstNode *current_always, *current_top_block, *current_block, *current_block_child; extern AST::AstModule *current_module; extern bool current_always_clocked; + struct LookaheadRewriter; struct ProcessGenerator; } diff --git a/frontends/ast/genrtlil.cc b/frontends/ast/genrtlil.cc index ab368fdb0..ff3f5b84c 100644 --- a/frontends/ast/genrtlil.cc +++ b/frontends/ast/genrtlil.cc @@ -157,6 +157,126 @@ static RTLIL::SigSpec mux2rtlil(AstNode *that, const RTLIL::SigSpec &cond, const return wire; } +// helper class for rewriting simple lookahead references in AST always blocks +struct AST_INTERNAL::LookaheadRewriter +{ + dict> lookaheadids; + + void collect_lookaheadids(AstNode *node) + { + if (node->lookahead) { + log_assert(node->type == AST_IDENTIFIER); + if (!lookaheadids.count(node->str)) { + AstNode *wire = new AstNode(AST_WIRE); + for (auto c : node->id2ast->children) + wire->children.push_back(c->clone()); + wire->str = stringf("$lookahead%s$%d", node->str.c_str(), autoidx++); + wire->attributes["\\nosync"] = AstNode::mkconst_int(1, false); + wire->is_logic = true; + while (wire->simplify(true, false, false, 1, -1, false, false)) { } + current_ast_mod->children.push_back(wire); + lookaheadids[node->str] = make_pair(node->id2ast, wire); + wire->genRTLIL(); + } + } + + for (auto child : node->children) + collect_lookaheadids(child); + } + + bool has_lookaheadids(AstNode *node) + { + if (node->type == AST_IDENTIFIER && lookaheadids.count(node->str) != 0) + return true; + + for (auto child : node->children) + if (has_lookaheadids(child)) + return true; + + return false; + } + + bool has_nonlookaheadids(AstNode *node) + { + if (node->type == AST_IDENTIFIER && lookaheadids.count(node->str) == 0) + return true; + + for (auto child : node->children) + if (has_nonlookaheadids(child)) + return true; + + return false; + } + + void rewrite_lookaheadids(AstNode *node, bool lhs = false) + { + if (node->type == AST_ASSIGN_LE) + { + if (has_lookaheadids(node->children[0])) + { + if (has_nonlookaheadids(node->children[0])) + log_error("incompatible mix of lookahead and non-lookahead IDs in LHS expression.\n"); + + rewrite_lookaheadids(node->children[0], true); + node->type = AST_ASSIGN_EQ; + } + + rewrite_lookaheadids(node->children[1], lhs); + return; + } + + if (node->type == AST_IDENTIFIER && (node->lookahead || lhs)) { + AstNode *newwire = lookaheadids.at(node->str).second; + node->str = newwire->str; + node->id2ast = newwire; + lhs = false; + } + + for (auto child : node->children) + rewrite_lookaheadids(child, lhs); + } + + LookaheadRewriter(AstNode *top) + { + // top->dumpAst(NULL, "REWRITE-BEFORE> "); + // top->dumpVlog(NULL, "REWRITE-BEFORE> "); + + AstNode *block = nullptr; + + for (auto c : top->children) + if (c->type == AST_BLOCK) { + log_assert(block == nullptr); + block = c; + } + log_assert(block != nullptr); + + collect_lookaheadids(block); + rewrite_lookaheadids(block); + + for (auto it : lookaheadids) + { + AstNode *ref_orig = new AstNode(AST_IDENTIFIER); + ref_orig->str = it.second.first->str; + ref_orig->id2ast = it.second.first; + ref_orig->was_checked = true; + + AstNode *ref_temp = new AstNode(AST_IDENTIFIER); + ref_temp->str = it.second.second->str; + ref_temp->id2ast = it.second.second; + ref_temp->was_checked = true; + + AstNode *init_assign = new AstNode(AST_ASSIGN_EQ, ref_temp->clone(), ref_orig->clone()); + AstNode *final_assign = new AstNode(AST_ASSIGN_LE, ref_orig, ref_temp); + + block->children.insert(block->children.begin(), init_assign); + block->children.push_back(final_assign); + } + + // top->dumpAst(NULL, "REWRITE-AFTER> "); + // top->dumpVlog(NULL, "REWRITE-AFTER> "); + } +}; + // helper class for converting AST always nodes to RTLIL processes struct AST_INTERNAL::ProcessGenerator { @@ -191,6 +311,9 @@ struct AST_INTERNAL::ProcessGenerator ProcessGenerator(AstNode *always, RTLIL::SigSpec initSyncSignalsArg = RTLIL::SigSpec()) : always(always), initSyncSignals(initSyncSignalsArg) { + // rewrite lookahead references + LookaheadRewriter la_rewriter(always); + // generate process and simple root case proc = new RTLIL::Process; proc->attributes[ID::src] = stringf("%s:%d.%d-%d.%d", always->filename.c_str(), always->location.first_line, always->location.first_column, always->location.last_line, always->location.last_column); @@ -338,7 +461,7 @@ struct AST_INTERNAL::ProcessGenerator return chunks; } - // recursively traverse the AST an collect all assigned signals + // recursively traverse the AST and collect all assigned signals void collect_lvalues(RTLIL::SigSpec ®, AstNode *ast, bool type_eq, bool type_le, bool run_sort_and_unify = true) { switch (ast->type) @@ -1010,7 +1133,9 @@ RTLIL::SigSpec AstNode::genRTLIL(int width_hint, bool sign_hint) int add_undef_bits_msb = 0; int add_undef_bits_lsb = 0; - if (id2ast && id2ast->type == AST_AUTOWIRE && current_module->wires_.count(str) == 0) { + log_assert(id2ast != nullptr); + + if (id2ast->type == AST_AUTOWIRE && current_module->wires_.count(str) == 0) { RTLIL::Wire *wire = current_module->addWire(str); wire->attributes[ID::src] = stringf("%s:%d.%d-%d.%d", filename.c_str(), location.first_line, location.first_column, location.last_line, location.last_column); wire->name = str; @@ -1025,7 +1150,7 @@ RTLIL::SigSpec AstNode::genRTLIL(int width_hint, bool sign_hint) chunk = RTLIL::Const(id2ast->children[0]->bits); goto use_const_chunk; } - else if (id2ast && (id2ast->type == AST_WIRE || id2ast->type == AST_AUTOWIRE || id2ast->type == AST_MEMORY) && current_module->wires_.count(str) != 0) { + else if ((id2ast->type == AST_WIRE || id2ast->type == AST_AUTOWIRE || id2ast->type == AST_MEMORY) && current_module->wires_.count(str) != 0) { RTLIL::Wire *current_wire = current_module->wire(str); if (current_wire->get_bool_attribute(ID::is_interface)) is_interface = true; diff --git a/frontends/ast/simplify.cc b/frontends/ast/simplify.cc index e181af140..18ad6926f 100644 --- a/frontends/ast/simplify.cc +++ b/frontends/ast/simplify.cc @@ -1797,19 +1797,25 @@ bool AstNode::simplify(bool const_fold, bool at_zero, bool in_lvalue, int stage, 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; newNode->children.push_back(new AstNode(AST_ASSIGN_EQ, ref_mask->clone(), new AstNode(AST_SHIFT_LEFT, mkconst_bits(std::vector(result_width, State::S1), false), shamt->clone()))); newNode->children.push_back(new AstNode(AST_ASSIGN_EQ, ref_data->clone(), new AstNode(AST_SHIFT_LEFT, new AstNode(AST_BIT_AND, mkconst_bits(std::vector(result_width, State::S1), false), children[1]->clone()), shamt))); - newNode->children.push_back(new AstNode(type, lvalue, new AstNode(AST_BIT_OR, new AstNode(AST_BIT_AND, lvalue->clone(), new AstNode(AST_BIT_NOT, ref_mask)), ref_data))); + newNode->children.push_back(new AstNode(type, lvalue, new AstNode(AST_BIT_OR, new AstNode(AST_BIT_AND, old_data, new AstNode(AST_BIT_NOT, ref_mask)), ref_data))); } goto apply_newNode; -- 2.30.2