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// Copyright 2014 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "src/compiler/select-lowering.h"
#include "src/compiler/common-operator.h"
#include "src/compiler/diamond.h"
#include "src/compiler/generic-node-inl.h"
#include "src/compiler/graph.h"
namespace v8 {
namespace internal {
namespace compiler {
SelectLowering::SelectLowering(Graph* graph, CommonOperatorBuilder* common)
: common_(common),
graph_(graph),
merges_(Merges::key_compare(), Merges::allocator_type(graph->zone())) {}
SelectLowering::~SelectLowering() {}
Reduction SelectLowering::Reduce(Node* node) {
if (node->opcode() != IrOpcode::kSelect) return NoChange();
SelectParameters const p = SelectParametersOf(node->op());
Node* const cond = node->InputAt(0);
// Check if we already have a diamond for this condition.
auto i = merges_.find(cond);
if (i == merges_.end()) {
// Create a new diamond for this condition and remember its merge node.
Diamond d(graph(), common(), cond, p.hint());
i = merges_.insert(std::make_pair(cond, d.merge)).first;
}
DCHECK_EQ(cond, i->first);
// Create a Phi hanging off the previously determined merge.
node->set_op(common()->Phi(p.type(), 2));
node->ReplaceInput(0, node->InputAt(1));
node->ReplaceInput(1, node->InputAt(2));
node->ReplaceInput(2, i->second);
return Changed(node);
}
} // namespace compiler
} // namespace internal
} // namespace v8
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