Fix handling of constant global variable assignments.

src/hydrogen.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
@@ skipping 5891 matching lines @@
 void HOptimizedGraphBuilder::HandleGlobalVariableAssignment(
     Variable* var,
     HValue* value,
     BailoutId ast_id) {
   LookupResult lookup(isolate());
   GlobalPropertyAccess type = LookupGlobalProperty(var, &lookup, STORE);
   if (type == kUseCell) {
     Handle<GlobalObject> global(current_info()->global_object());
     Handle<PropertyCell> cell(global->GetPropertyCell(&lookup));
     if (cell->type()->IsConstant()) {
-      IfBuilder builder(this);
-      HValue* constant = Add<HConstant>(cell->type()->AsConstant());
-      if (cell->type()->AsConstant()->IsNumber()) {
-        builder.If<HCompareNumericAndBranch>(value, constant, Token::EQ);
+      Handle<Object> constant = cell->type()->AsConstant();
+      if (value->IsConstant()) {
+        HConstant* c_value = HConstant::cast(value);
+        if (!constant.is_identical_to(c_value->handle(isolate()))) {
+          Add<HDeoptimize>("Constant global variable assignment",
+                           Deoptimizer::EAGER);
+        }
       } else {
-        builder.If<HCompareObjectEqAndBranch>(value, constant);
+        HValue* c_constant = Add<HConstant>(constant);
+        IfBuilder builder(this);
+        if (constant->IsNumber()) {
+          builder.If<HCompareNumericAndBranch>(value, c_constant, Token::EQ);
+        } else {
+          builder.If<HCompareObjectEqAndBranch>(value, c_constant);
+        }
+        builder.Then();
+        builder.Else();
+        Add<HDeoptimize>("Constant global variable assignment",
+                         Deoptimizer::EAGER);
+        builder.End();
       }
-      builder.Then();
-      builder.Else();
-      Add<HDeoptimize>("Constant global variable assignment",
-                       Deoptimizer::EAGER);
-      builder.End();
     }
     HInstruction* instr =
         Add<HStoreGlobalCell>(value, cell, lookup.GetPropertyDetails());
     if (instr->HasObservableSideEffects()) {
       Add<HSimulate>(ast_id, REMOVABLE_SIMULATE);
     }
   } else {
     HValue* global_object = Add<HLoadNamedField>(
         context(), static_cast<HValue*>(NULL),
         HObjectAccess::ForContextSlot(Context::GLOBAL_OBJECT_INDEX));
@@ skipping 5355 matching lines @@
   if (ShouldProduceTraceOutput()) {
     isolate()->GetHTracer()->TraceHydrogen(name(), graph_);
   }
 
 #ifdef DEBUG
   graph_->Verify(false);  // No full verify.
 #endif
 }
 
 } }  // namespace v8::internal