From b7148380ccb881e8107f8b0c2596eca628ff69df Mon Sep 17 00:00:00 2001
From: "bmeurer@chromium.org"
 <bmeurer@chromium.org@ce2b1a6d-e550-0410-aec6-3dcde31c8c00>
Date: Fri, 2 May 2014 05:59:07 +0000
Subject: [PATCH] Drop obsolete HCheckMaps::HandleSideEffectsDominator().

In HCheckMaps::HandleSideEffectsDominator() we try to remove
redundant HCheckMaps instructions that are dominated by an
HStoreNamedField instruction with a transition. This is just
a special case of the check elimination and therefore obsolete
(it also gives some nice speedup since GVN just got cheaper).

R=svenpanne@chromium.org

Review URL: https://codereview.chromium.org/261003002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@21108 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
---
 src/hydrogen-instructions.cc | 19 -------------------
 src/hydrogen-instructions.h  |  5 +----
 2 files changed, 1 insertion(+), 23 deletions(-)

diff --git a/src/hydrogen-instructions.cc b/src/hydrogen-instructions.cc
index 9e29ff7..59b43b6 100644
--- a/src/hydrogen-instructions.cc
+++ b/src/hydrogen-instructions.cc
@@ -1669,25 +1669,6 @@ void HCheckInstanceType::GetCheckMaskAndTag(uint8_t* mask, uint8_t* tag) {
 }
 
 
-bool HCheckMaps::HandleSideEffectDominator(GVNFlag side_effect,
-                                           HValue* dominator) {
-  ASSERT(side_effect == kMaps);
-  // TODO(mstarzinger): For now we specialize on HStoreNamedField, but once
-  // type information is rich enough we should generalize this to any HType
-  // for which the map is known.
-  if (HasNoUses() && dominator->IsStoreNamedField()) {
-    HStoreNamedField* store = HStoreNamedField::cast(dominator);
-    if (!store->has_transition() || store->object() != value()) return false;
-    HConstant* transition = HConstant::cast(store->transition());
-    if (map_set_.Contains(Unique<Map>::cast(transition->GetUnique()))) {
-      DeleteAndReplaceWith(NULL);
-      return true;
-    }
-  }
-  return false;
-}
-
-
 void HCheckMaps::PrintDataTo(StringStream* stream) {
   value()->PrintNameTo(stream);
   stream->Add(" [%p", *map_set_.at(0).handle());
diff --git a/src/hydrogen-instructions.h b/src/hydrogen-instructions.h
index 98b6fa2..c69a941 100644
--- a/src/hydrogen-instructions.h
+++ b/src/hydrogen-instructions.h
@@ -161,7 +161,6 @@ class LChunkBuilder;
   V(WrapReceiver)
 
 #define GVN_TRACKED_FLAG_LIST(V)               \
-  V(Maps)                                      \
   V(NewSpacePromotion)
 
 #define GVN_UNTRACKED_FLAG_LIST(V)             \
@@ -177,6 +176,7 @@ class LChunkBuilder;
   V(ElementsPointer)                           \
   V(GlobalVars)                                \
   V(InobjectFields)                            \
+  V(Maps)                                      \
   V(OsrEntries)                                \
   V(ExternalMemory)                            \
   V(StringChars)                               \
@@ -2762,8 +2762,6 @@ class HCheckMaps V8_FINAL : public HTemplateInstruction<2> {
   virtual Representation RequiredInputRepresentation(int index) V8_OVERRIDE {
     return Representation::Tagged();
   }
-  virtual bool HandleSideEffectDominator(GVNFlag side_effect,
-                                         HValue* dominator) V8_OVERRIDE;
   virtual void PrintDataTo(StringStream* stream) V8_OVERRIDE;
 
   HValue* value() { return OperandAt(0); }
@@ -2813,7 +2811,6 @@ class HCheckMaps V8_FINAL : public HTemplateInstruction<2> {
     SetOperandAt(1, typecheck != NULL ? typecheck : value);
     set_representation(Representation::Tagged());
     SetFlag(kUseGVN);
-    SetFlag(kTrackSideEffectDominators);
   }
 
   bool omit_;
-- 
2.7.4