Revision: 15529
Author: [email protected]
Date: Sat Jul 6 23:00:15 2013
Log: Turn dead code elimination into a proper HPhase.
[email protected]
Review URL: https://codereview.chromium.org/18791002
http://code.google.com/p/v8/source/detail?r=15529
Added:
/branches/bleeding_edge/src/hydrogen-dce.cc
/branches/bleeding_edge/src/hydrogen-dce.h
Modified:
/branches/bleeding_edge/src/hydrogen.cc
/branches/bleeding_edge/src/hydrogen.h
/branches/bleeding_edge/tools/gyp/v8.gyp
=======================================
--- /dev/null
+++ /branches/bleeding_edge/src/hydrogen-dce.cc Sat Jul 6 23:00:15 2013
@@ -0,0 +1,125 @@
+// Copyright 2013 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+// * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+// * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following
+// disclaimer in the documentation and/or other materials provided
+// with the distribution.
+// * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived
+// from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include "hydrogen-dce.h"
+#include "v8.h"
+
+namespace v8 {
+namespace internal {
+
+bool HDeadCodeEliminationPhase::MarkLive(HValue* ref, HValue* instr) {
+ if (instr->CheckFlag(HValue::kIsLive)) return false;
+ instr->SetFlag(HValue::kIsLive);
+
+ if (FLAG_trace_dead_code_elimination) {
+ HeapStringAllocator allocator;
+ StringStream stream(&allocator);
+ if (ref != NULL) {
+ ref->PrintTo(&stream);
+ } else {
+ stream.Add("root ");
+ }
+ stream.Add(" -> ");
+ instr->PrintTo(&stream);
+ PrintF("[MarkLive %s]\n", *stream.ToCString());
+ }
+
+ return true;
+}
+
+
+void HDeadCodeEliminationPhase::MarkLiveInstructions() {
+ ZoneList<HValue*> worklist(graph()->blocks()->length(), zone());
+
+ // Mark initial root instructions for dead code elimination.
+ for (int i = 0; i < graph()->blocks()->length(); ++i) {
+ HBasicBlock* block = graph()->blocks()->at(i);
+ for (HInstructionIterator it(block); !it.Done(); it.Advance()) {
+ HInstruction* instr = it.Current();
+ if (instr->CannotBeEliminated() && MarkLive(NULL, instr)) {
+ worklist.Add(instr, zone());
+ }
+ }
+ for (int j = 0; j < block->phis()->length(); j++) {
+ HPhi* phi = block->phis()->at(j);
+ if (phi->CannotBeEliminated() && MarkLive(NULL, phi)) {
+ worklist.Add(phi, zone());
+ }
+ }
+ }
+
+ // Transitively mark all inputs of live instructions live.
+ while (!worklist.is_empty()) {
+ HValue* instr = worklist.RemoveLast();
+ for (int i = 0; i < instr->OperandCount(); ++i) {
+ if (MarkLive(instr, instr->OperandAt(i))) {
+ worklist.Add(instr->OperandAt(i), zone());
+ }
+ }
+ }
+}
+
+
+void HDeadCodeEliminationPhase::RemoveDeadInstructions() {
+ ZoneList<HPhi*> worklist(graph()->blocks()->length(), zone());
+
+ // Remove any instruction not marked kIsLive.
+ for (int i = 0; i < graph()->blocks()->length(); ++i) {
+ HBasicBlock* block = graph()->blocks()->at(i);
+ for (HInstructionIterator it(block); !it.Done(); it.Advance()) {
+ HInstruction* instr = it.Current();
+ if (!instr->CheckFlag(HValue::kIsLive)) {
+ // Instruction has not been marked live; assume it is dead and
remove.
+ // TODO(titzer): we don't remove constants because some special
ones
+ // might be used by later phases and are assumed to be in the graph
+ if (!instr->IsConstant()) instr->DeleteAndReplaceWith(NULL);
+ } else {
+ // Clear the liveness flag to leave the graph clean for the next
DCE.
+ instr->ClearFlag(HValue::kIsLive);
+ }
+ }
+ // Collect phis that are dead and remove them in the next pass.
+ for (int j = 0; j < block->phis()->length(); j++) {
+ HPhi* phi = block->phis()->at(j);
+ if (!phi->CheckFlag(HValue::kIsLive)) {
+ worklist.Add(phi, zone());
+ } else {
+ phi->ClearFlag(HValue::kIsLive);
+ }
+ }
+ }
+
+ // Process phis separately to avoid simultaneously mutating the phi list.
+ while (!worklist.is_empty()) {
+ HPhi* phi = worklist.RemoveLast();
+ HBasicBlock* block = phi->block();
+ phi->DeleteAndReplaceWith(NULL);
+ block->RecordDeletedPhi(phi->merged_index());
+ }
+}
+
+} } // namespace v8::internal
=======================================
--- /dev/null
+++ /branches/bleeding_edge/src/hydrogen-dce.h Sat Jul 6 23:00:15 2013
@@ -0,0 +1,56 @@
+// Copyright 2013 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+// * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+// * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following
+// disclaimer in the documentation and/or other materials provided
+// with the distribution.
+// * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived
+// from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#ifndef V8_HYDROGEN_DCE_H_
+#define V8_HYDROGEN_DCE_H_
+
+#include "hydrogen.h"
+
+namespace v8 {
+namespace internal {
+
+
+class HDeadCodeEliminationPhase : public HPhase {
+ public:
+ explicit HDeadCodeEliminationPhase(HGraph* graph)
+ : HPhase("H_Dead code elimination", graph) { }
+
+ void Run() {
+ MarkLiveInstructions();
+ RemoveDeadInstructions();
+ }
+
+ private:
+ bool MarkLive(HValue* ref, HValue* instr);
+ void MarkLiveInstructions();
+ void RemoveDeadInstructions();
+};
+
+
+} } // namespace v8::internal
+
+#endif // V8_HYDROGEN_DCE_H_
=======================================
--- /branches/bleeding_edge/src/hydrogen.cc Fri Jul 5 03:40:14 2013
+++ /branches/bleeding_edge/src/hydrogen.cc Sat Jul 6 23:00:15 2013
@@ -33,6 +33,7 @@
#include "codegen.h"
#include "full-codegen.h"
#include "hashmap.h"
+#include "hydrogen-dce.h"
#include "hydrogen-environment-liveness.h"
#include "hydrogen-escape-analysis.h"
#include "hydrogen-infer-representation.h"
@@ -3464,9 +3465,7 @@
}
// Remove dead code and phis
- if (FLAG_dead_code_elimination) {
- DeadCodeElimination("H_Eliminate early dead code");
- }
+ if (FLAG_dead_code_elimination) Run<HDeadCodeEliminationPhase>();
CollectPhis();
if (has_osr()) osr()->FinishOsrValues();
@@ -3507,9 +3506,7 @@
EliminateRedundantBoundsChecks();
}
if (FLAG_array_index_dehoisting) DehoistSimpleArrayIndexComputations();
- if (FLAG_dead_code_elimination) {
- DeadCodeElimination("H_Eliminate late dead code");
- }
+ if (FLAG_dead_code_elimination) Run<HDeadCodeEliminationPhase>();
RestoreActualValues();
@@ -3988,99 +3985,6 @@
}
}
}
-
-
-void HGraph::DeadCodeElimination(const char* phase_name) {
- HPhase phase(phase_name, this);
- MarkLiveInstructions();
- RemoveDeadInstructions();
-}
-
-
-void HGraph::MarkLiveInstructions() {
- ZoneList<HValue*> worklist(blocks_.length(), zone());
-
- // Mark initial root instructions for dead code elimination.
- for (int i = 0; i < blocks()->length(); ++i) {
- HBasicBlock* block = blocks()->at(i);
- for (HInstructionIterator it(block); !it.Done(); it.Advance()) {
- HInstruction* instr = it.Current();
- if (instr->CannotBeEliminated()) MarkLive(NULL, instr, &worklist);
- }
- for (int j = 0; j < block->phis()->length(); j++) {
- HPhi* phi = block->phis()->at(j);
- if (phi->CannotBeEliminated()) MarkLive(NULL, phi, &worklist);
- }
- }
-
- // Transitively mark all inputs of live instructions live.
- while (!worklist.is_empty()) {
- HValue* instr = worklist.RemoveLast();
- for (int i = 0; i < instr->OperandCount(); ++i) {
- MarkLive(instr, instr->OperandAt(i), &worklist);
- }
- }
-}
-
-
-void HGraph::MarkLive(HValue* ref, HValue* instr, ZoneList<HValue*>*
worklist) {
- if (!instr->CheckFlag(HValue::kIsLive)) {
- instr->SetFlag(HValue::kIsLive);
- worklist->Add(instr, zone());
-
- if (FLAG_trace_dead_code_elimination) {
- HeapStringAllocator allocator;
- StringStream stream(&allocator);
- if (ref != NULL) {
- ref->PrintTo(&stream);
- } else {
- stream.Add("root ");
- }
- stream.Add(" -> ");
- instr->PrintTo(&stream);
- PrintF("[MarkLive %s]\n", *stream.ToCString());
- }
- }
-}
-
-
-void HGraph::RemoveDeadInstructions() {
- ZoneList<HPhi*> dead_phis(blocks_.length(), zone());
-
- // Remove any instruction not marked kIsLive.
- for (int i = 0; i < blocks()->length(); ++i) {
- HBasicBlock* block = blocks()->at(i);
- for (HInstructionIterator it(block); !it.Done(); it.Advance()) {
- HInstruction* instr = it.Current();
- if (!instr->CheckFlag(HValue::kIsLive)) {
- // Instruction has not been marked live; assume it is dead and
remove.
- // TODO(titzer): we don't remove constants because some special
ones
- // might be used by later phases and are assumed to be in the graph
- if (!instr->IsConstant()) instr->DeleteAndReplaceWith(NULL);
- } else {
- // Clear the liveness flag to leave the graph clean for the next
DCE.
- instr->ClearFlag(HValue::kIsLive);
- }
- }
- // Collect phis that are dead and remove them in the next pass.
- for (int j = 0; j < block->phis()->length(); j++) {
- HPhi* phi = block->phis()->at(j);
- if (!phi->CheckFlag(HValue::kIsLive)) {
- dead_phis.Add(phi, zone());
- } else {
- phi->ClearFlag(HValue::kIsLive);
- }
- }
- }
-
- // Process phis separately to avoid simultaneously mutating the phi list.
- while (!dead_phis.is_empty()) {
- HPhi* phi = dead_phis.RemoveLast();
- HBasicBlock* block = phi->block();
- phi->DeleteAndReplaceWith(NULL);
- block->RecordDeletedPhi(phi->merged_index());
- }
-}
void HGraph::RestoreActualValues() {
=======================================
--- /branches/bleeding_edge/src/hydrogen.h Fri Jul 5 03:40:14 2013
+++ /branches/bleeding_edge/src/hydrogen.h Sat Jul 6 23:00:15 2013
@@ -306,7 +306,6 @@
void EliminateRedundantBoundsChecks();
void DehoistSimpleArrayIndexComputations();
void RestoreActualValues();
- void DeadCodeElimination(const char *phase_name);
void PropagateDeoptimizingMark();
void AnalyzeAndPruneEnvironmentLiveness();
@@ -451,9 +450,6 @@
phase.Run();
}
- void MarkLive(HValue* ref, HValue* instr, ZoneList<HValue*>* worklist);
- void MarkLiveInstructions();
- void RemoveDeadInstructions();
void MarkAsDeoptimizingRecursively(HBasicBlock* block);
void NullifyUnreachableInstructions();
void InsertTypeConversions(HInstruction* instr);
=======================================
--- /branches/bleeding_edge/tools/gyp/v8.gyp Thu Jul 4 12:25:16 2013
+++ /branches/bleeding_edge/tools/gyp/v8.gyp Sat Jul 6 23:00:15 2013
@@ -335,6 +335,8 @@
'../../src/heap-snapshot-generator.h',
'../../src/heap.cc',
'../../src/heap.h',
+ '../../src/hydrogen-dce.cc',
+ '../../src/hydrogen-dce.h',
'../../src/hydrogen-environment-liveness.cc',
'../../src/hydrogen-environment-liveness.h',
'../../src/hydrogen-escape-analysis.cc',
--
--
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