Skip dead blocks/instructions in store elimination.

src/hydrogen-store-elimination.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "hydrogen-store-elimination.h"
 #include "hydrogen-instructions.h"
 
 namespace v8 {
 namespace internal {
 
@@ skipping 12 matching lines @@
   flags.Add(kDoubleFields);
   flags.Add(kElementsPointer);
   flags.Add(kInobjectFields);
   flags.Add(kExternalMemory);
   flags.Add(kStringChars);
   flags.Add(kTypedArrayElements);
 
   for (int i = 0; i < graph()->blocks()->length(); i++) {
     unobserved_.Rewind(0);
     HBasicBlock* block = graph()->blocks()->at(i);
+    if (!block->IsReachable()) continue;
     for (HInstructionIterator it(block); !it.Done(); it.Advance()) {
       HInstruction* instr = it.Current();
+      if (instr->CheckFlag(HValue::kIsDead)) continue;
 
       // TODO(titzer): eliminate unobserved HStoreKeyed instructions too.
       switch (instr->opcode()) {
         case HValue::kStoreNamedField:
           // Remove any unobserved stores overwritten by this store.
           ProcessStore(HStoreNamedField::cast(instr));
           break;
         case HValue::kLoadNamedField:
           // Observe any unobserved stores on this object + field.
           ProcessLoad(HLoadNamedField::cast(instr));
@@ skipping 45 matching lines @@
       i++;
     }
   }
 }
 
 
 void HStoreEliminationPhase::ProcessInstr(HInstruction* instr,
     GVNFlagSet flags) {
   if (unobserved_.length() == 0) return;  // Nothing to do.
   if (instr->CanDeoptimize()) {
-    TRACE(("-- Observed stores at I%d (might deoptimize)\n", instr->id()));
+    TRACE(("-- Observed stores at I%d (%s might deoptimize)\n",
+           instr->id(), instr->Mnemonic()));
     unobserved_.Rewind(0);
     return;
   }
   if (instr->CheckChangesFlag(kNewSpacePromotion)) {
-    TRACE(("-- Observed stores at I%d (might GC)\n", instr->id()));
+    TRACE(("-- Observed stores at I%d (%s might GC)\n",
+           instr->id(), instr->Mnemonic()));
     unobserved_.Rewind(0);
     return;
   }
   if (instr->DependsOnFlags().ContainsAnyOf(flags)) {
-    TRACE(("-- Observed stores at I%d (GVN flags)\n", instr->id()));
+    TRACE(("-- Observed stores at I%d (GVN flags of %s)\n",
+           instr->id(), instr->Mnemonic()));
     unobserved_.Rewind(0);
     return;
   }
 }
 
 } }  // namespace v8::internal