1 // Copyright 2015 the V8 project authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #include "src/compiler/graph-trimmer.h" 6 7 #include "src/compiler/graph.h" 8 9 namespace v8 { 10 namespace internal { 11 namespace compiler { 12 13 GraphTrimmer::GraphTrimmer(Zone* zone, Graph* graph) 14 : graph_(graph), is_live_(graph, 2), live_(zone) { 15 live_.reserve(graph->NodeCount()); 16 } 17 18 19 GraphTrimmer::~GraphTrimmer() {} 20 21 22 void GraphTrimmer::TrimGraph() { 23 // Mark end node as live. 24 MarkAsLive(graph()->end()); 25 // Compute transitive closure of live nodes. 26 for (size_t i = 0; i < live_.size(); ++i) { 27 Node* const live = live_[i]; 28 for (Node* const input : live->inputs()) MarkAsLive(input); 29 } 30 // Remove dead->live edges. 31 for (Node* const live : live_) { 32 DCHECK(IsLive(live)); 33 for (Edge edge : live->use_edges()) { 34 Node* const user = edge.from(); 35 if (!IsLive(user)) { 36 if (FLAG_trace_turbo_trimming) { 37 OFStream os(stdout); 38 os << "DeadLink: " << *user << "(" << edge.index() << ") -> " << *live 39 << std::endl; 40 } 41 edge.UpdateTo(nullptr); 42 } 43 } 44 } 45 } 46 47 } // namespace compiler 48 } // namespace internal 49 } // namespace v8 50
