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/*
* 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_flatten_nested_if_blocks.cpp
*
* Flattens nested if blocks such as:
*
* if (x) {
* if (y) {
* ...
* }
* }
*
* into a single if block with a combined condition:
*
* if (x && y) {
* ...
* }
*/
#include "ir.h"
#include "ir_builder.h"
using namespace ir_builder;
namespace {
class nested_if_flattener : public ir_hierarchical_visitor {
public:
nested_if_flattener()
{
progress = false;
}
ir_visitor_status visit_leave(ir_if *);
ir_visitor_status visit_enter(ir_assignment *);
bool progress;
};
} /* unnamed namespace */
/* We only care about the top level "if" instructions, so don't
* descend into expressions.
*/
ir_visitor_status
nested_if_flattener::visit_enter(ir_assignment *ir)
{
(void) ir;
return visit_continue_with_parent;
}
bool
opt_flatten_nested_if_blocks(exec_list *instructions)
{
nested_if_flattener v;
v.run(instructions);
return v.progress;
}
ir_visitor_status
nested_if_flattener::visit_leave(ir_if *ir)
{
/* Only handle a single ir_if within the then clause of an ir_if. No extra
* instructions, no else clauses, nothing.
*/
if (ir->then_instructions.is_empty() || !ir->else_instructions.is_empty())
return visit_continue;
ir_if *inner = ((ir_instruction *) ir->then_instructions.get_head_raw())->as_if();
if (!inner || !inner->next->is_tail_sentinel() ||
!inner->else_instructions.is_empty())
return visit_continue;
ir->condition = logic_and(ir->condition, inner->condition);
inner->then_instructions.move_nodes_to(&ir->then_instructions);
progress = true;
return visit_continue;
}
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