// Copyright 2015 the V8 project authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#include "src/compiler/graph-trimmer.h"
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#include "src/compiler/graph.h"
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namespace v8 {
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namespace internal {
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namespace compiler {
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GraphTrimmer::GraphTrimmer(Zone* zone, Graph* graph)
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: graph_(graph), is_live_(graph, 2), live_(zone) {
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live_.reserve(graph->NodeCount());
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}
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GraphTrimmer::~GraphTrimmer() {}
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void GraphTrimmer::TrimGraph() {
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// Mark end node as live.
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MarkAsLive(graph()->end());
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// Compute transitive closure of live nodes.
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for (size_t i = 0; i < live_.size(); ++i) {
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Node* const live = live_[i];
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for (Node* const input : live->inputs()) MarkAsLive(input);
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}
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// Remove dead->live edges.
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for (Node* const live : live_) {
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DCHECK(IsLive(live));
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for (Edge edge : live->use_edges()) {
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Node* const user = edge.from();
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if (!IsLive(user)) {
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if (FLAG_trace_turbo_trimming) {
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StdoutStream{} << "DeadLink: " << *user << "(" << edge.index()
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<< ") -> " << *live << std::endl;
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}
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edge.UpdateTo(nullptr);
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}
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}
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}
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}
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} // namespace compiler
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} // namespace internal
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} // namespace v8
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