Merge up to bleeding_edge r7201 to isolates branch.

src/ia32/code-stubs-ia32.cc

Index: src/ia32/code-stubs-ia32.cc
diff --git a/src/ia32/code-stubs-ia32.cc b/src/ia32/code-stubs-ia32.cc
index 830f714225db850b95185a69d9f96f0782ed04da..b9f9126844efea1b0b9f51001ff68d0d2a7a60b4 100644
--- a/src/ia32/code-stubs-ia32.cc
+++ b/src/ia32/code-stubs-ia32.cc
@@ -5527,8 +5527,8 @@ void StringAddStub::Generate(MacroAssembler* masm) {
   STATIC_ASSERT(Smi::kMaxValue == String::kMaxLength);
   // Handle exceptionally long strings in the runtime system.
   __ j(overflow, &string_add_runtime);
-  // Use the runtime system when adding two one character strings, as it
-  // contains optimizations for this specific case using the symbol table.
+  // Use the symbol table when adding two one character strings, as it
+  // helps later optimizations to return a symbol here.
   __ cmp(Operand(ebx), Immediate(Smi::FromInt(2)));
   __ j(not_equal, &longer_than_two);
 
@@ -5945,6 +5945,8 @@ void StringHelper::GenerateTwoCharacterSymbolTableProbe(MacroAssembler* masm,
     // If entry is undefined no string with this hash can be found.
     __ cmp(candidate, FACTORY->undefined_value());
     __ j(equal, not_found);
+    __ cmp(candidate, FACTORY->null_value());
+    __ j(equal, &next_probe[i]);
 
     // If length is not 2 the string is not a candidate.
     __ cmp(FieldOperand(candidate, String::kLengthOffset),
@@ -6313,59 +6315,6 @@ void StringCompareStub::Generate(MacroAssembler* masm) {
 }
 
 
-void StringCharAtStub::Generate(MacroAssembler* masm) {
-  // Expects two arguments (object, index) on the stack:
-
-  // Stack frame on entry.
-  //  esp[0]: return address
-  //  esp[4]: index
-  //  esp[8]: object
-
-  Register object = ebx;
-  Register index = eax;
-  Register scratch1 = ecx;
-  Register scratch2 = edx;
-  Register result = eax;
-
-  __ pop(scratch1);  // Return address.
-  __ pop(index);
-  __ pop(object);
-  __ push(scratch1);
-
-  Label need_conversion;
-  Label index_out_of_range;
-  Label done;
-  StringCharAtGenerator generator(object,
-                                  index,
-                                  scratch1,
-                                  scratch2,
-                                  result,
-                                  &need_conversion,
-                                  &need_conversion,
-                                  &index_out_of_range,
-                                  STRING_INDEX_IS_NUMBER);
-  generator.GenerateFast(masm);
-  __ jmp(&done);
-
-  __ bind(&index_out_of_range);
-  // When the index is out of range, the spec requires us to return
-  // the empty string.
-  __ Set(result, Immediate(FACTORY->empty_string()));
-  __ jmp(&done);
-
-  __ bind(&need_conversion);
-  // Move smi zero into the result register, which will trigger
-  // conversion.
-  __ Set(result, Immediate(Smi::FromInt(0)));
-  __ jmp(&done);
-
-  StubRuntimeCallHelper call_helper;
-  generator.GenerateSlow(masm, call_helper);
-
-  __ bind(&done);
-  __ ret(0);
-}
-
 void ICCompareStub::GenerateSmis(MacroAssembler* masm) {
   ASSERT(state_ == CompareIC::SMIS);
   NearLabel miss;