Ensure constant truncation is only done when it is safe.

src/hydrogen-instructions.cc

 // Copyright 2012 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
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 //       disclaimer in the documentation and/or other materials provided
@@ skipping 2557 matching lines @@
   if (has_int32_value_) {
     res = new(zone) HConstant(int32_value_,
                               Representation::Integer32(),
                               is_not_in_new_space_,
                               handle_);
   } else if (has_double_value_) {
     res = new(zone) HConstant(DoubleToInt32(double_value_),
                               Representation::Integer32(),
                               is_not_in_new_space_,
                               handle_);
-  } else {
-    ASSERT(!HasNumberValue());
-    Maybe<HConstant*> number = CopyToTruncatedNumber(zone);
-    if (number.has_value) return number.value->CopyToTruncatedInt32(zone);
   }
   return Maybe<HConstant*>(res != NULL, res);
 }
 
 
-Maybe<HConstant*> HConstant::CopyToTruncatedNumber(Zone* zone) {
+Maybe<HConstant*> HConstant::CopyToTruncatedNumberAndAdd(
+    Zone* zone, HGraphBuilder* builder) {

[Michael Starzinger, 2013/09/17 12:10:13]

I don't like passing around the HGraphBuilder into HInstructions. I see that
this would give static guarantees that no-one introduces call to this method
outside the graph builder, but it destroys decoupling please revert this part of
the change and just keep the fix in HConstant::CopyToTruncatedInt32.

   HConstant* res = NULL;
   Handle<Object> handle = this->handle(zone->isolate());
   if (handle->IsBoolean()) {
-    res = handle->BooleanValue() ?
-      new(zone) HConstant(1) : new(zone) HConstant(0);
+    res = handle->BooleanValue()
+      ? builder->graph()->GetConstant1()
+      : builder->graph()->GetConstant0();
   } else if (handle->IsUndefined()) {
-    res = new(zone) HConstant(OS::nan_value());
+    res = builder->Add<HConstant>(OS::nan_value());
   } else if (handle->IsNull()) {
-    res = new(zone) HConstant(0);
+    res = builder->graph()->GetConstant0();
   }
   return Maybe<HConstant*>(res != NULL, res);
 }
 
 
 void HConstant::PrintDataTo(StringStream* stream) {
   if (has_int32_value_) {
     stream->Add("%d ", int32_value_);
   } else if (has_double_value_) {
     stream->Add("%f ", FmtElm(double_value_));
@@ skipping 1633 matching lines @@
       break;
     case kExternalMemory:
       stream->Add("[external-memory]");
       break;
   }
 
   stream->Add("@%d", offset());
 }
 
 } }  // namespace v8::internal