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// Copyright 2015 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/graph-trimmer.h"
#include "src/compiler/graph.h"
namespace v8 {
namespace internal {
namespace compiler {
GraphTrimmer::GraphTrimmer(Zone* zone, Graph* graph)
: graph_(graph), is_live_(graph, 2), live_(zone) {
live_.reserve(graph->NodeCount());
}
GraphTrimmer::~GraphTrimmer() {}
void GraphTrimmer::TrimGraph() {
// Mark end node as live.
MarkAsLive(graph()->end());
// Compute transitive closure of live nodes.
for (size_t i = 0; i < live_.size(); ++i) {
Node* const live = live_[i];
for (Node* const input : live->inputs()) MarkAsLive(input);
}
// Remove dead->live edges.
for (Node* const live : live_) {
DCHECK(IsLive(live));
for (Edge edge : live->use_edges()) {
Node* const user = edge.from();
if (!IsLive(user)) {
if (FLAG_trace_turbo_trimming) {
OFStream os(stdout);
os << "DeadLink: " << *user << "(" << edge.index() << ") -> " << *live
<< std::endl;
}
edge.UpdateTo(nullptr);
}
}
}
}
} // namespace compiler
} // namespace internal
} // namespace v8
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