--- /dev/null
+/*
+ * Copyright © 2013 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+/**
+ * \file opt_cse.cpp
+ *
+ * constant subexpression elimination at the GLSL IR level.
+ *
+ * Compare to brw_fs_cse.cpp for a more complete CSE implementation. This one
+ * is generic and handles texture operations, but it's rather simple currently
+ * and doesn't support modification of variables in the available expressions
+ * list, so it can't do variables other than uniforms or shader inputs.
+ */
+
+#include "ir.h"
+#include "ir_visitor.h"
+#include "ir_rvalue_visitor.h"
+#include "ir_basic_block.h"
+#include "ir_optimization.h"
+#include "ir_builder.h"
+#include "glsl_types.h"
+
+using namespace ir_builder;
+
+static bool debug = false;
+
+namespace {
+
+/**
+ * This is the record of an available expression for common subexpression
+ * elimination.
+ */
+class ae_entry : public exec_node
+{
+public:
+ ae_entry(ir_instruction *base_ir, ir_rvalue **val)
+ : val(val), base_ir(base_ir)
+ {
+ assert(val);
+ assert(*val);
+ assert(base_ir);
+
+ var = NULL;
+ }
+
+ /**
+ * The pointer to the expression that we might be able to reuse
+ *
+ * Note the double pointer -- this is the place in the base_ir expression
+ * tree that we would rewrite to move the expression out to a new variable
+ * assignment.
+ */
+ ir_rvalue **val;
+
+ /**
+ * Root instruction in the basic block where the expression appeared.
+ *
+ * This is used so that we can insert the new variable declaration into the
+ * instruction stream (since *val is just somewhere in base_ir's expression
+ * tree).
+ */
+ ir_instruction *base_ir;
+
+ /**
+ * The variable that the expression has been stored in, if it's been CSEd
+ * once already.
+ */
+ ir_variable *var;
+};
+
+class cse_visitor : public ir_rvalue_visitor {
+public:
+ cse_visitor(exec_list *validate_instructions)
+ : validate_instructions(validate_instructions)
+ {
+ progress = false;
+ mem_ctx = ralloc_context(NULL);
+ this->ae = new(mem_ctx) exec_list;
+ }
+ ~cse_visitor()
+ {
+ ralloc_free(mem_ctx);
+ }
+
+ virtual ir_visitor_status visit_enter(ir_function_signature *ir);
+ virtual ir_visitor_status visit_enter(ir_loop *ir);
+ virtual ir_visitor_status visit_enter(ir_if *ir);
+ virtual ir_visitor_status visit_enter(ir_call *ir);
+ virtual void handle_rvalue(ir_rvalue **rvalue);
+
+ bool progress;
+
+private:
+ void *mem_ctx;
+
+ ir_rvalue *try_cse(ir_rvalue *rvalue);
+ void add_to_ae(ir_rvalue **rvalue);
+
+ /** List of ae_entry: The available expressions to reuse */
+ exec_list *ae;
+
+ /**
+ * The whole shader, so that we can validate_ir_tree in debug mode.
+ *
+ * This proved quite useful when trying to get the tree manipulation
+ * right.
+ */
+ exec_list *validate_instructions;
+};
+
+/**
+ * Visitor to walk an expression tree to check that all variables referenced
+ * are constants.
+ */
+class is_cse_candidate_visitor : public ir_hierarchical_visitor
+{
+public:
+
+ is_cse_candidate_visitor()
+ : ok(true)
+ {
+ }
+
+ virtual ir_visitor_status visit(ir_dereference_variable *ir);
+
+ bool ok;
+};
+
+
+class contains_rvalue_visitor : public ir_rvalue_visitor
+{
+public:
+
+ contains_rvalue_visitor(ir_rvalue *val)
+ : val(val)
+ {
+ found = false;
+ }
+
+ virtual void handle_rvalue(ir_rvalue **rvalue);
+
+ bool found;
+
+private:
+ ir_rvalue *val;
+};
+
+} /* unnamed namespace */
+
+static void
+dump_ae(exec_list *ae)
+{
+ int i = 0;
+
+ printf("CSE: AE contents:\n");
+ foreach_list(node, ae) {
+ ae_entry *entry = (ae_entry *)node;
+
+ printf("CSE: AE %2d (%p): ", i, entry);
+ (*entry->val)->print();
+ printf("\n");
+
+ if (entry->var)
+ printf("CSE: in var %p:\n", entry->var);
+
+ i++;
+ }
+}
+
+ir_visitor_status
+is_cse_candidate_visitor::visit(ir_dereference_variable *ir)
+{
+ /* Currently, since we don't handle kills of the ae based on variables
+ * getting assigned, we can only handle constant variables.
+ */
+ if (ir->var->read_only) {
+ return visit_continue;
+ } else {
+ ok = false;
+ return visit_stop;
+ }
+}
+
+void
+contains_rvalue_visitor::handle_rvalue(ir_rvalue **rvalue)
+{
+ if (*rvalue == val)
+ found = true;
+}
+
+static bool
+contains_rvalue(ir_rvalue *haystack, ir_rvalue *needle)
+{
+ contains_rvalue_visitor v(needle);
+ haystack->accept(&v);
+ return v.found;
+}
+
+static bool
+is_cse_candidate(ir_rvalue *ir)
+{
+ /* Our temporary variable assignment generation isn't ready to handle
+ * anything bigger than a vector.
+ */
+ if (!ir->type->is_vector() && !ir->type->is_scalar())
+ return false;
+
+ /* Only handle expressions and textures currently. We may want to extend
+ * to variable-index array dereferences at some point.
+ */
+ switch (ir->ir_type) {
+ case ir_type_expression:
+ case ir_type_texture:
+ break;
+ default:
+ return false;
+ }
+
+ is_cse_candidate_visitor v;
+
+ ir->accept(&v);
+
+ return v.ok;
+}
+
+static bool
+equals(ir_rvalue *a, ir_rvalue *b);
+
+static bool
+equals(ir_constant *a, ir_constant *b)
+{
+ if (!a || !b)
+ return false;
+
+ if (a->type != b->type)
+ return false;
+
+ for (unsigned i = 0; i < a->type->components(); i++) {
+ if (a->value.u[i] != b->value.u[i])
+ return false;
+ }
+
+ return true;
+}
+
+static bool
+equals(ir_dereference_variable *a, ir_dereference_variable *b)
+{
+ if (!a || !b)
+ return false;
+
+ return a->var == b->var;
+}
+
+static bool
+equals(ir_dereference_array *a, ir_dereference_array *b)
+{
+ if (!a || !b)
+ return false;
+
+ if (!equals(a->array, b->array))
+ return false;
+
+ if (!equals(a->array_index, b->array_index))
+ return false;
+
+ return true;
+}
+
+static bool
+equals(ir_swizzle *a, ir_swizzle *b)
+{
+ if (!a || !b)
+ return false;
+
+ if (a->type != b->type)
+ return false;
+
+ if (a->mask.x != b->mask.x ||
+ a->mask.y != b->mask.y ||
+ a->mask.z != b->mask.z ||
+ a->mask.w != b->mask.w) {
+ return false;
+ }
+
+ return equals(a->val, b->val);
+}
+
+static bool
+equals(ir_texture *a, ir_texture *b)
+{
+ if (!a || !b)
+ return false;
+
+ if (a->type != b->type)
+ return false;
+
+ if (a->op != b->op)
+ return false;
+
+ if (!equals(a->coordinate, b->coordinate))
+ return false;
+
+ if (!equals(a->projector, b->projector))
+ return false;
+
+ if (!equals(a->shadow_comparitor, b->shadow_comparitor))
+ return false;
+
+ if (!equals(a->offset, b->offset))
+ return false;
+
+ if (!equals(a->sampler, b->sampler))
+ return false;
+
+ switch (a->op) {
+ case ir_tex:
+ case ir_lod:
+ case ir_query_levels:
+ break;
+ case ir_txb:
+ if (!equals(a->lod_info.bias, b->lod_info.bias))
+ return false;
+ break;
+ case ir_txl:
+ case ir_txf:
+ case ir_txs:
+ if (!equals(a->lod_info.lod, b->lod_info.lod))
+ return false;
+ break;
+ case ir_txd:
+ if (!equals(a->lod_info.grad.dPdx, b->lod_info.grad.dPdx) ||
+ !equals(a->lod_info.grad.dPdy, b->lod_info.grad.dPdy))
+ return false;
+ case ir_txf_ms:
+ if (!equals(a->lod_info.sample_index, b->lod_info.sample_index))
+ return false;
+ break;
+ case ir_tg4:
+ if (!equals(a->lod_info.component, b->lod_info.component))
+ return false;
+ default:
+ assert(!"Unrecognized texture op");
+ }
+
+ return true;
+}
+
+static bool
+equals(ir_expression *a, ir_expression *b)
+{
+ if (!a || !b)
+ return false;
+
+ if (a->type != b->type)
+ return false;
+
+ if (a->operation != b->operation)
+ return false;
+
+ for (unsigned i = 0; i < a->get_num_operands(); i++) {
+ if (!equals(a->operands[i], b->operands[i]))
+ return false;
+ }
+
+ return true;
+}
+
+static bool
+equals(ir_rvalue *a, ir_rvalue *b)
+{
+ if (!a || !b)
+ return !a && !b;
+
+ if (a->type != b->type)
+ return false;
+
+ switch (a->ir_type) {
+ case ir_type_texture:
+ return equals(a->as_texture(), b->as_texture());
+
+ case ir_type_constant:
+ return equals(a->as_constant(), b->as_constant());
+
+ case ir_type_expression:
+ return equals(a->as_expression(), b->as_expression());
+
+ case ir_type_dereference_variable:
+ return equals(a->as_dereference_variable(), b->as_dereference_variable());
+
+ case ir_type_dereference_array:
+ return equals(a->as_dereference_array(), b->as_dereference_array());
+
+ case ir_type_swizzle:
+ return equals(a->as_swizzle(), b->as_swizzle());
+
+ default:
+ return false;
+ }
+}
+
+/**
+ * Tries to find and return a reference to a previous computation of a given
+ * expression.
+ *
+ * Walk the list of available expressions checking if any of them match the
+ * rvalue, and if so, move the previous copy of the expression to a temporary
+ * and return a reference of the temporary.
+ */
+ir_rvalue *
+cse_visitor::try_cse(ir_rvalue *rvalue)
+{
+ foreach_list(node, ae) {
+ ae_entry *entry = (ae_entry *)node;
+
+ if (debug) {
+ printf("Comparing to AE %p: ", entry);
+ (*entry->val)->print();
+ printf("\n");
+ }
+
+ if (!equals(rvalue, *entry->val))
+ continue;
+
+ if (debug) {
+ printf("CSE: Replacing: ");
+ (*entry->val)->print();
+ printf("\n");
+ printf("CSE: with: ");
+ rvalue->print();
+ printf("\n");
+ }
+
+ if (!entry->var) {
+ ir_instruction *base_ir = entry->base_ir;
+
+ ir_variable *var = new(rvalue) ir_variable(rvalue->type,
+ "cse",
+ ir_var_auto);
+
+ /* Write the previous expression result into a new variable. */
+ base_ir->insert_before(var);
+ ir_assignment *assignment = assign(var, *entry->val);
+ base_ir->insert_before(assignment);
+
+ /* Replace the expression in the original tree with a deref of the
+ * variable, but keep tracking the expression for further reuse.
+ */
+ *entry->val = new(rvalue) ir_dereference_variable(var);
+ entry->val = &assignment->rhs;
+
+ entry->var = var;
+
+ /* Update the base_irs in the AE list. We have to be sure that
+ * they're correct -- expressions from our base_ir that weren't moved
+ * need to stay in this base_ir (so that later consumption of them
+ * puts new variables between our new variable and our base_ir), but
+ * expressions from our base_ir that we *did* move need base_ir
+ * updated so that any further elimination from inside gets its new
+ * assignments put before our new assignment.
+ */
+ foreach_list(fixup_node, ae) {
+ ae_entry *fixup_entry = (ae_entry *)fixup_node;
+ if (contains_rvalue(assignment->rhs, *fixup_entry->val))
+ fixup_entry->base_ir = assignment;
+ }
+
+ if (debug)
+ dump_ae(ae);
+ }
+
+ /* Replace the expression in our current tree with the variable. */
+ return new(rvalue) ir_dereference_variable(entry->var);
+ }
+
+ return NULL;
+}
+
+/** Add the rvalue to the list of available expressions for CSE. */
+void
+cse_visitor::add_to_ae(ir_rvalue **rvalue)
+{
+ if (debug) {
+ printf("CSE: Add to AE: ");
+ (*rvalue)->print();
+ printf("\n");
+ }
+
+ ae->push_tail(new(mem_ctx) ae_entry(base_ir, rvalue));
+
+ if (debug)
+ dump_ae(ae);
+}
+
+void
+cse_visitor::handle_rvalue(ir_rvalue **rvalue)
+{
+ if (!*rvalue)
+ return;
+
+ if (debug) {
+ printf("CSE: handle_rvalue ");
+ (*rvalue)->print();
+ printf("\n");
+ }
+
+ if (!is_cse_candidate(*rvalue))
+ return;
+
+ ir_rvalue *new_rvalue = try_cse(*rvalue);
+ if (new_rvalue) {
+ *rvalue = new_rvalue;
+ progress = true;
+
+ if (debug)
+ validate_ir_tree(validate_instructions);
+ } else {
+ add_to_ae(rvalue);
+ }
+}
+
+ir_visitor_status
+cse_visitor::visit_enter(ir_if *ir)
+{
+ handle_rvalue(&ir->condition);
+
+ ae->make_empty();
+ visit_list_elements(this, &ir->then_instructions);
+
+ ae->make_empty();
+ visit_list_elements(this, &ir->else_instructions);
+
+ ae->make_empty();
+ return visit_continue_with_parent;
+}
+
+ir_visitor_status
+cse_visitor::visit_enter(ir_function_signature *ir)
+{
+ ae->make_empty();
+ visit_list_elements(this, &ir->body);
+
+ ae->make_empty();
+ return visit_continue_with_parent;
+}
+
+ir_visitor_status
+cse_visitor::visit_enter(ir_loop *ir)
+{
+ ae->make_empty();
+ visit_list_elements(this, &ir->body_instructions);
+
+ ae->make_empty();
+ return visit_continue_with_parent;
+}
+
+ir_visitor_status
+cse_visitor::visit_enter(ir_call *ir)
+{
+ /* Because call is an exec_list of ir_rvalues, handle_rvalue gets passed a
+ * pointer to the (ir_rvalue *) on the stack. Since we save those pointers
+ * in the AE list, we can't let handle_rvalue get called.
+ */
+ return visit_continue_with_parent;
+}
+
+/**
+ * Does a (uniform-value) constant subexpression elimination pass on the code
+ * present in the instruction stream.
+ */
+bool
+do_cse(exec_list *instructions)
+{
+ cse_visitor v(instructions);
+
+ visit_list_elements(&v, instructions);
+
+ return v.progress;
+}
projects / mesa.git / commitdiff