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/*
* Copyright © 2014 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_conditional_discard.cpp
*
* Replace
*
* if (cond) discard;
*
* with
*
* (discard <condition>)
*/
#include "compiler/glsl_types.h"
#include "ir.h"
namespace {
class opt_conditional_discard_visitor : public ir_hierarchical_visitor {
public:
opt_conditional_discard_visitor()
{
progress = false;
}
ir_visitor_status visit_leave(ir_if *);
bool progress;
};
} /* anonymous namespace */
bool
opt_conditional_discard(exec_list *instructions)
{
opt_conditional_discard_visitor v;
v.run(instructions);
return v.progress;
}
ir_visitor_status
opt_conditional_discard_visitor::visit_leave(ir_if *ir)
{
/* Look for "if (...) discard" with no else clause or extra statements. */
if (ir->then_instructions.is_empty() ||
!ir->then_instructions.get_head_raw()->next->is_tail_sentinel() ||
!((ir_instruction *) ir->then_instructions.get_head_raw())->as_discard() ||
!ir->else_instructions.is_empty())
return visit_continue;
/* Move the condition and replace the ir_if with the ir_discard. */
ir_discard *discard = (ir_discard *) ir->then_instructions.get_head_raw();
if (!discard->condition)
discard->condition = ir->condition;
else {
void *ctx = ralloc_parent(ir);
discard->condition = new(ctx) ir_expression(ir_binop_logic_and,
ir->condition,
discard->condition);
}
ir->replace_with(discard);
progress = true;
return visit_continue;
}