Turn merge removable simulates into a proper HPhase.

R=dslomov@chromium.org

Review URL: https://codereview.chromium.org/18258004

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15609 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/hydrogen-removable-simulates.cc

+// 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-removable-simulates.h"
+
+namespace v8 {
+namespace internal {
+
+void HMergeRemovableSimulatesPhase::Run() {
+  ZoneList<HSimulate*> mergelist(2, zone());
+  for (int i = 0; i < graph()->blocks()->length(); ++i) {
+    HBasicBlock* block = graph()->blocks()->at(i);
+    // Make sure the merge list is empty at the start of a block.
+    ASSERT(mergelist.is_empty());
+    // Nasty heuristic: Never remove the first simulate in a block. This
+    // just so happens to have a beneficial effect on register allocation.
+    bool first = true;
+    for (HInstructionIterator it(block); !it.Done(); it.Advance()) {
+      HInstruction* current = it.Current();
+      if (current->IsLeaveInlined()) {
+        // Never fold simulates from inlined environments into simulates
+        // in the outer environment.
+        // (Before each HEnterInlined, there is a non-foldable HSimulate
+        // anyway, so we get the barrier in the other direction for free.)
+        // Simply remove all accumulated simulates without merging.  This
+        // is safe because simulates after instructions with side effects
+        // are never added to the merge list.
+        while (!mergelist.is_empty()) {
+          mergelist.RemoveLast()->DeleteAndReplaceWith(NULL);
+        }
+        continue;
+      }
+      if (current->IsReturn()) {
+        // Drop mergeable simulates in the list. This is safe because
+        // simulates after instructions with side effects are never added
+        // to the merge list.
+        while (!mergelist.is_empty()) {
+          mergelist.RemoveLast()->DeleteAndReplaceWith(NULL);
+        }
+        continue;
+      }
+      // Skip the non-simulates and the first simulate.
+      if (!current->IsSimulate()) continue;
+      if (first) {
+        first = false;
+        continue;
+      }
+      HSimulate* current_simulate = HSimulate::cast(current);
+      if ((current_simulate->previous()->HasObservableSideEffects() &&
+           !current_simulate->next()->IsSimulate()) ||
+          !current_simulate->is_candidate_for_removal()) {
+        // This simulate is not suitable for folding.
+        // Fold the ones accumulated so far.
+        current_simulate->MergeWith(&mergelist);
+        continue;
+      } else {
+        // Accumulate this simulate for folding later on.
+        mergelist.Add(current_simulate, zone());
+      }
+    }
+
+    if (!mergelist.is_empty()) {
+      // Merge the accumulated simulates at the end of the block.
+      HSimulate* last = mergelist.RemoveLast();
+      last->MergeWith(&mergelist);
+    }
+  }
+}
+
+} }  // namespace v8::internal

src/hydrogen-removable-simulates.h

+// 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_REMOVABLE_SIMULATES_H_
+#define V8_HYDROGEN_REMOVABLE_SIMULATES_H_
+
+#include "hydrogen.h"
+
+namespace v8 {
+namespace internal {
+
+
+class HMergeRemovableSimulatesPhase : public HPhase {
+ public:
+  explicit HMergeRemovableSimulatesPhase(HGraph* graph)
+      : HPhase("H_Merge removable simulates", graph) { }
+
+  void Run();
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(HMergeRemovableSimulatesPhase);
+};
+
+
+} }  // namespace v8::internal
+
+#endif  // V8_HYDROGEN_REMOVABLE_SIMULATES_H_

src/hydrogen.cc

@@ -44,6 +44,7 @@
 #include "hydrogen-osr.h"
 #include "hydrogen-range-analysis.h"
 #include "hydrogen-redundant-phi.h"
+#include "hydrogen-removable-simulates.h"
 #include "hydrogen-representation-changes.h"
 #include "hydrogen-sce.h"
 #include "hydrogen-uint32-analysis.h"
@@ -2572,69 +2573,6 @@ void HGraph::CollectPhis() {
 }
 
 
-void HGraph::MergeRemovableSimulates() {
-  HPhase phase("H_Merge removable simulates", this);
-  ZoneList<HSimulate*> mergelist(2, zone());
-  for (int i = 0; i < blocks()->length(); ++i) {
-    HBasicBlock* block = blocks()->at(i);
-    // Make sure the merge list is empty at the start of a block.
-    ASSERT(mergelist.is_empty());
-    // Nasty heuristic: Never remove the first simulate in a block. This
-    // just so happens to have a beneficial effect on register allocation.
-    bool first = true;
-    for (HInstructionIterator it(block); !it.Done(); it.Advance()) {
-      HInstruction* current = it.Current();
-      if (current->IsLeaveInlined()) {
-        // Never fold simulates from inlined environments into simulates
-        // in the outer environment.
-        // (Before each HEnterInlined, there is a non-foldable HSimulate
-        // anyway, so we get the barrier in the other direction for free.)
-        // Simply remove all accumulated simulates without merging.  This
-        // is safe because simulates after instructions with side effects
-        // are never added to the merge list.
-        while (!mergelist.is_empty()) {
-          mergelist.RemoveLast()->DeleteAndReplaceWith(NULL);
-        }
-        continue;
-      }
-      if (current->IsReturn()) {
-        // Drop mergeable simulates in the list. This is safe because
-        // simulates after instructions with side effects are never added
-        // to the merge list.
-        while (!mergelist.is_empty()) {
-          mergelist.RemoveLast()->DeleteAndReplaceWith(NULL);
-        }
-        continue;
-      }
-      // Skip the non-simulates and the first simulate.
-      if (!current->IsSimulate()) continue;
-      if (first) {
-        first = false;
-        continue;
-      }
-      HSimulate* current_simulate = HSimulate::cast(current);
-      if ((current_simulate->previous()->HasObservableSideEffects() &&
-           !current_simulate->next()->IsSimulate()) ||
-          !current_simulate->is_candidate_for_removal()) {
-        // This simulate is not suitable for folding.
-        // Fold the ones accumulated so far.
-        current_simulate->MergeWith(&mergelist);
-        continue;
-      } else {
-        // Accumulate this simulate for folding later on.
-        mergelist.Add(current_simulate, zone());
-      }
-    }
-
-    if (!mergelist.is_empty()) {
-      // Merge the accumulated simulates at the end of the block.
-      HSimulate* last = mergelist.RemoveLast();
-      last->MergeWith(&mergelist);
-    }
-  }
-}
-
-
 void HGraph::RecursivelyMarkPhiDeoptimizeOnUndefined(HPhi* phi) {
   if (!phi->CheckFlag(HValue::kAllowUndefinedAsNaN)) return;
   phi->ClearFlag(HValue::kAllowUndefinedAsNaN);
@@ -3137,7 +3075,7 @@ bool HGraph::Optimize(SmartArrayPointer<char>* bailout_reason) {
   // Remove HSimulate instructions that have turned out not to be needed
   // after all by folding them into the following HSimulate.
   // This must happen after inferring representations.
-  MergeRemovableSimulates();
+  Run<HMergeRemovableSimulatesPhase>();
 
   MarkDeoptimizeOnUndefined();
   Run<HRepresentationChangesPhase>();

src/hydrogen.h

@@ -292,7 +292,6 @@ class HGraph: public ZoneObject {
 
   void FinalizeUniqueValueIds();
   void InsertTypeConversions();
-  void MergeRemovableSimulates();
   void MarkDeoptimizeOnUndefined();
   bool ProcessArgumentsObject();
   void Canonicalize();

tools/gyp/v8.gyp

@@ -359,6 +359,8 @@
         '../../src/hydrogen-range-analysis.h',
         '../../src/hydrogen-redundant-phi.cc',
         '../../src/hydrogen-redundant-phi.h',
+        '../../src/hydrogen-removable-simulates.cc',
+        '../../src/hydrogen-removable-simulates.h',
         '../../src/hydrogen-representation-changes.cc',
         '../../src/hydrogen-representation-changes.h',
         '../../src/hydrogen-sce.cc',