Turn redundant phi elimination into proper HPhase.

R=dslomov@chromium.org

Review URL: https://codereview.chromium.org/18549004

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15533 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/hydrogen-redundant-phi.cc

@@ -0,0 +1,76 @@
+// 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-redundant-phi.h"
+
+namespace v8 {
+namespace internal {
+
+void HRedundantPhiEliminationPhase::Run() {
+  // We do a simple fixed point iteration without any work list, because
+  // machine-generated JavaScript can lead to a very dense Hydrogen graph with
+  // an enormous work list and will consequently result in OOM. Experiments
+  // showed that this simple algorithm is good enough, and even e.g. tracking
+  // the set or range of blocks to consider is not a real improvement.
+  bool need_another_iteration;
+  const ZoneList<HBasicBlock*>* blocks(graph()->blocks());
+  ZoneList<HPhi*> redundant_phis(blocks->length(), zone());
+  do {
+    need_another_iteration = false;
+    for (int i = 0; i < blocks->length(); ++i) {
+      HBasicBlock* block = blocks->at(i);
+      for (int j = 0; j < block->phis()->length(); j++) {
+        HPhi* phi = block->phis()->at(j);
+        HValue* replacement = phi->GetRedundantReplacement();
+        if (replacement != NULL) {
+          // Remember phi to avoid concurrent modification of the block's phis.
+          redundant_phis.Add(phi, zone());
+          for (HUseIterator it(phi->uses()); !it.Done(); it.Advance()) {
+            HValue* value = it.value();
+            value->SetOperandAt(it.index(), replacement);
+            need_another_iteration |= value->IsPhi();
+          }
+        }
+      }
+      for (int i = 0; i < redundant_phis.length(); i++) {
+        block->RemovePhi(redundant_phis[i]);
+      }
+      redundant_phis.Clear();
+    }
+  } while (need_another_iteration);
+
+#if DEBUG
+  // Make sure that we *really* removed all redundant phis.
+  for (int i = 0; i < blocks->length(); ++i) {
+    for (int j = 0; j < blocks->at(i)->phis()->length(); j++) {
+      ASSERT(blocks->at(i)->phis()->at(j)->GetRedundantReplacement() == NULL);
+    }
+  }
+#endif
+}
+
+} }  // namespace v8::internal

src/hydrogen-redundant-phi.h

@@ -0,0 +1,53 @@
+// 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_REDUNDANT_PHI_H_
+#define V8_HYDROGEN_REDUNDANT_PHI_H_
+
+#include "hydrogen.h"
+
+namespace v8 {
+namespace internal {
+
+
+// Replace all phis consisting of a single non-loop operand plus any number of
+// loop operands by that single non-loop operand.
+class HRedundantPhiEliminationPhase : public HPhase {
+ public:
+  explicit HRedundantPhiEliminationPhase(HGraph* graph)
+      : HPhase("H_Redundant phi elimination", graph) { }
+
+  void Run();
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(HRedundantPhiEliminationPhase);
+};
+
+
+} }  // namespace v8::internal
+
+#endif  // V8_HYDROGEN_REDUNDANT_PHI_H_

src/hydrogen.cc

@@ -40,6 +40,7 @@
 #include "hydrogen-gvn.h"
 #include "hydrogen-osr.h"
 #include "hydrogen-range-analysis.h"
+#include "hydrogen-redundant-phi.h"
 #include "hydrogen-sce.h"
 #include "hydrogen-uint32-analysis.h"
 #include "lithium-allocator.h"
@@ -2523,53 +2524,6 @@ void HGraph::NullifyUnreachableInstructions() {
 }
 
 
-// Replace all phis consisting of a single non-loop operand plus any number of
-// loop operands by that single non-loop operand.
-void HGraph::EliminateRedundantPhis() {
-  HPhase phase("H_Redundant phi elimination", this);
-
-  // We do a simple fixed point iteration without any work list, because
-  // machine-generated JavaScript can lead to a very dense Hydrogen graph with
-  // an enormous work list and will consequently result in OOM. Experiments
-  // showed that this simple algorithm is good enough, and even e.g. tracking
-  // the set or range of blocks to consider is not a real improvement.
-  bool need_another_iteration;
-  ZoneList<HPhi*> redundant_phis(blocks_.length(), zone());
-  do {
-    need_another_iteration = false;
-    for (int i = 0; i < blocks_.length(); ++i) {
-      HBasicBlock* block = blocks_[i];
-      for (int j = 0; j < block->phis()->length(); j++) {
-        HPhi* phi = block->phis()->at(j);
-        HValue* replacement = phi->GetRedundantReplacement();
-        if (replacement != NULL) {
-          // Remember phi to avoid concurrent modification of the block's phis.
-          redundant_phis.Add(phi, zone());
-          for (HUseIterator it(phi->uses()); !it.Done(); it.Advance()) {
-            HValue* value = it.value();
-            value->SetOperandAt(it.index(), replacement);
-            need_another_iteration |= value->IsPhi();
-          }
-        }
-      }
-      for (int i = 0; i < redundant_phis.length(); i++) {
-        block->RemovePhi(redundant_phis[i]);
-      }
-      redundant_phis.Clear();
-    }
-  } while (need_another_iteration);
-
-#if DEBUG
-  // Make sure that we *really* removed all redundant phis.
-  for (int i = 0; i < blocks_.length(); ++i) {
-    for (int j = 0; j < blocks_[i]->phis()->length(); j++) {
-      ASSERT(blocks_[i]->phis()->at(j)->GetRedundantReplacement() == NULL);
-    }
-  }
-#endif
-}
-
-
 bool HGraph::CheckArgumentsPhiUses() {
   int block_count = blocks_.length();
   for (int i = 0; i < block_count; ++i) {
@@ -3417,7 +3371,7 @@ bool HGraph::Optimize(SmartArrayPointer<char>* bailout_reason) {
         "Unsupported phi use of const variable"));
     return false;
   }
-  EliminateRedundantPhis();
+  Run<HRedundantPhiEliminationPhase>();
   if (!CheckArgumentsPhiUses()) {
     *bailout_reason = SmartArrayPointer<char>(StrDup(
         "Unsupported phi use of arguments"));

src/hydrogen.h

@@ -298,7 +298,6 @@ class HGraph: public ZoneObject {
   void MarkDeoptimizeOnUndefined();
   void ComputeMinusZeroChecks();
   bool ProcessArgumentsObject();
-  void EliminateRedundantPhis();
   void Canonicalize();
   void OrderBlocks();
   void AssignDominators();

tools/gyp/v8.gyp

@@ -351,6 +351,8 @@
         '../../src/hydrogen-infer-representation.h',
         '../../src/hydrogen-range-analysis.cc',
         '../../src/hydrogen-range-analysis.h',
+        '../../src/hydrogen-redundant-phi.cc',
+        '../../src/hydrogen-redundant-phi.h',
         '../../src/hydrogen-sce.cc',
         '../../src/hydrogen-sce.h',
         '../../src/hydrogen-uint32-analysis.cc',