77f5221233
The main motivation for this is that threaded compilation can fall
over if we were to allocate IR inside constant_expression_value()
when calling it on a builtin. This is because builtins are shared
across the whole OpenGL context.
f81ede4699 worked around the problem by cloning the entire
builtin before constant_expression_value() could be called on
it. However cloning the whole function each time we referenced
it lead to a significant reduction in the GLSL IR compiler
performance. This change along with the following patch
helps fix that performance regression.
Other advantages are that we reduce the number of calls to
ralloc_parent(), and for loop unrolling we free constants after
they are used rather than leaving them hanging around.
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
128 lines
3.7 KiB
C++
128 lines
3.7 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 opt_if_simplification.cpp
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*
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* Moves constant branches of if statements out to the surrounding
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* instruction stream, and inverts if conditionals to avoid empty
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* "then" blocks.
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*/
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#include "ir.h"
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namespace {
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class ir_if_simplification_visitor : public ir_hierarchical_visitor {
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public:
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ir_if_simplification_visitor()
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{
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this->made_progress = false;
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}
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ir_visitor_status visit_leave(ir_if *);
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ir_visitor_status visit_enter(ir_assignment *);
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bool made_progress;
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};
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} /* unnamed namespace */
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/* We only care about the top level "if" instructions, so don't
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* descend into expressions.
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*/
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ir_visitor_status
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ir_if_simplification_visitor::visit_enter(ir_assignment *ir)
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{
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(void) ir;
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return visit_continue_with_parent;
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}
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bool
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do_if_simplification(exec_list *instructions)
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{
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ir_if_simplification_visitor v;
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v.run(instructions);
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return v.made_progress;
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}
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ir_visitor_status
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ir_if_simplification_visitor::visit_leave(ir_if *ir)
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{
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/* If the if statement has nothing on either side, remove it. */
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if (ir->then_instructions.is_empty() &&
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ir->else_instructions.is_empty()) {
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ir->remove();
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this->made_progress = true;
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return visit_continue;
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}
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/* FINISHME: Ideally there would be a way to note that the condition results
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* FINISHME: in a constant before processing both of the other subtrees.
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* FINISHME: This can probably be done with some flags, but it would take
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* FINISHME: some work to get right.
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*/
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ir_constant *condition_constant =
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ir->condition->constant_expression_value(ralloc_parent(ir));
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if (condition_constant) {
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/* Move the contents of the one branch of the conditional
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* that matters out.
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*/
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if (condition_constant->value.b[0]) {
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ir->insert_before(&ir->then_instructions);
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} else {
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ir->insert_before(&ir->else_instructions);
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}
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ir->remove();
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this->made_progress = true;
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return visit_continue;
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}
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/* Turn:
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*
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* if (cond) {
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* } else {
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* do_work();
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* }
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*
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* into :
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*
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* if (!cond)
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* do_work();
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*
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* which avoids control flow for "else" (which is usually more
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* expensive than normal operations), and the "not" can usually be
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* folded into the generation of "cond" anyway.
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*/
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if (ir->then_instructions.is_empty()) {
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ir->condition = new(ralloc_parent(ir->condition))
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ir_expression(ir_unop_logic_not, ir->condition);
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ir->else_instructions.move_nodes_to(&ir->then_instructions);
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this->made_progress = true;
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}
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return visit_continue;
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}
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