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// Copyright 2016 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/backend/bitcast-elider.h"
#include "src/compiler/graph.h"
namespace v8 {
namespace internal {
namespace compiler {
namespace {
bool IsBitcast(Node* node) {
// We can only elide kBitcastTaggedToWordForTagAndSmiBits and
// kBitcastWordToTaggedSigned because others might affect GC / safepoint
// tables.
return node->opcode() == IrOpcode::kBitcastTaggedToWordForTagAndSmiBits ||
node->opcode() == IrOpcode::kBitcastWordToTaggedSigned;
}
} // namespace
void BitcastElider::Enqueue(Node* node) {
if (seen_.Get(node)) return;
seen_.Set(node, true);
to_visit_.push(node);
}
void BitcastElider::VisitNode(Node* node) {
for (int i = 0; i < node->InputCount(); i++) {
Node* input = node->InputAt(i);
bool should_replace_input = false;
while (IsBitcast(input)) {
input = input->InputAt(0);
should_replace_input = true;
}
if (should_replace_input) {
node->ReplaceInput(i, input);
}
Enqueue(input);
}
}
void BitcastElider::ProcessGraph() {
Enqueue(graph_->end());
while (!to_visit_.empty()) {
Node* node = to_visit_.front();
to_visit_.pop();
VisitNode(node);
}
}
BitcastElider::BitcastElider(Zone* zone, Graph* graph)
: graph_(graph), to_visit_(zone), seen_(graph, 2) {}
void BitcastElider::Reduce() { ProcessGraph(); }
} // namespace compiler
} // namespace internal
} // namespace v8
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