166 lines
4.5 KiB
C++
166 lines
4.5 KiB
C++
/*
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* Copyright © 2010 Intel Corporation
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice (including the next
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* paragraph) shall be included in all copies or substantial portions of the
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* Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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* DEALINGS IN THE SOFTWARE.
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*/
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/**
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* \file ir_constant_variable.cpp
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*
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* Marks variables assigned a single constant value over the course
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* of the program as constant.
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*
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* The goal here is to trigger further constant folding and then dead
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* code elimination. This is common with vector/matrix constructors
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* and calls to builtin functions.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include "ir.h"
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#include "ir_print_visitor.h"
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#include "ir_visitor.h"
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#include "ir_optimization.h"
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#include "glsl_types.h"
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#include "linux_list.h"
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struct assignment_entry {
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struct list link;
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int assignment_count;
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ir_variable *var;
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ir_constant *constval;
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};
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class ir_constant_variable_visitor : public ir_hierarchical_visitor {
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public:
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ir_constant_variable_visitor()
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{
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list_init(&list);
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}
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virtual ir_visitor_status visit_enter(ir_assignment *);
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struct list list;
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};
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static struct assignment_entry *
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get_assignment_entry(ir_variable *var, struct list *list)
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{
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struct assignment_entry *entry;
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list_foreach_entry(entry, struct assignment_entry, list, link) {
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if (entry->var == var)
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return entry;
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}
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entry = (struct assignment_entry *)calloc(1, sizeof(*entry));
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entry->var = var;
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list_add(&entry->link, list);
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return entry;
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}
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ir_visitor_status
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ir_constant_variable_visitor::visit_enter(ir_assignment *ir)
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{
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ir_constant *constval;
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struct assignment_entry *entry;
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entry = get_assignment_entry(ir->lhs->variable_referenced(), &this->list);
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assert(entry);
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entry->assignment_count++;
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/* If it's already constant, don't do the work. */
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if (entry->var->constant_value)
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return visit_continue;
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/* OK, now find if we actually have all the right conditions for
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* this to be a constant value assigned to the var.
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*/
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if (ir->condition) {
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constval = ir->condition->constant_expression_value();
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if (!constval || !constval->value.b[0])
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return visit_continue;
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}
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ir_variable *var = ir->lhs->whole_variable_referenced();
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if (!var)
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return visit_continue;
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constval = ir->rhs->constant_expression_value();
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if (!constval)
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return visit_continue;
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/* Mark this entry as having a constant assignment (if the
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* assignment count doesn't go >1). do_constant_variable will fix
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* up the variable with the constant value later.
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*/
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entry->constval = constval;
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return visit_continue;
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}
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/**
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* Does a copy propagation pass on the code present in the instruction stream.
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*/
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bool
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do_constant_variable(exec_list *instructions)
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{
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bool progress = false;
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ir_constant_variable_visitor v;
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v.run(instructions);
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while (!list_is_empty(&v.list)) {
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struct assignment_entry *entry;
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entry = list_entry(v.list.next, struct assignment_entry, link);
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if (entry->assignment_count == 1 && entry->constval) {
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entry->var->constant_value = entry->constval;
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progress = true;
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}
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list_del(&entry->link);
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free(entry);
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}
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return progress;
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}
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bool
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do_constant_variable_unlinked(exec_list *instructions)
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{
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bool progress = false;
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foreach_iter(exec_list_iterator, iter, *instructions) {
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ir_instruction *ir = (ir_instruction *)iter.get();
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ir_function *f = ir->as_function();
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if (f) {
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foreach_iter(exec_list_iterator, sigiter, *f) {
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ir_function_signature *sig =
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(ir_function_signature *) sigiter.get();
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if (do_constant_variable(&sig->body))
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progress = true;
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}
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}
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}
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return progress;
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}
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