Make max size and max length of strings consistent.

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 1773 matching lines @@
     BuildCreateAllocationMemento(
         object, object_size, allocation_mode.current_site());
   }
 
   return object;
 }
 
 
 HValue* HGraphBuilder::BuildAddStringLengths(HValue* left_length,
                                              HValue* right_length) {
-  // Compute the combined string length. If the result is larger than the max
-  // supported string length, we bailout to the runtime. This is done implicitly
-  // when converting the result back to a smi in case the max string length
-  // equals the max smi value. Otherwise, for platforms with 32-bit smis, we do
+  // Compute the combined string length and check against max string length.
   HValue* length = AddUncasted<HAdd>(left_length, right_length);
-  STATIC_ASSERT(String::kMaxLength <= Smi::kMaxValue);
-  if (String::kMaxLength != Smi::kMaxValue) {
-    IfBuilder if_nooverflow(this);
-    if_nooverflow.If<HCompareNumericAndBranch>(
-        length, Add<HConstant>(String::kMaxLength), Token::LTE);
-    if_nooverflow.Then();
-    if_nooverflow.ElseDeopt("String length exceeds limit");
-  }
+  IfBuilder if_nooverflow(this);
+  if_nooverflow.If<HCompareNumericAndBranch>(
+      length, Add<HConstant>(String::kMaxLength), Token::LTE);

[Benedikt Meurer, 2014/03/20 07:41:59]

Maybe we should use an HBoundsCheck here instead?

+  if_nooverflow.Then();
+  if_nooverflow.ElseDeopt("String length exceeds limit");
   return length;
 }
 
 
 HValue* HGraphBuilder::BuildCreateConsString(
     HValue* length,
     HValue* left,
     HValue* right,
     HAllocationMode allocation_mode) {
   // Determine the string instance types.
@@ skipping 9493 matching lines @@
   if (ShouldProduceTraceOutput()) {
     isolate()->GetHTracer()->TraceHydrogen(name(), graph_);
   }
 
 #ifdef DEBUG
   graph_->Verify(false);  // No full verify.
 #endif
 }
 
 } }  // namespace v8::internal