ia32 StringAddStub: fast two character case.

src/ia32/macro-assembler-ia32.cc

Index: src/ia32/macro-assembler-ia32.cc
diff --git a/src/ia32/macro-assembler-ia32.cc b/src/ia32/macro-assembler-ia32.cc
index c215142409b16997e464b0c2ae9fb500b69897cb..ff3810023e9b3de72f06453a6281f4b8279cec64 100644
--- a/src/ia32/macro-assembler-ia32.cc
+++ b/src/ia32/macro-assembler-ia32.cc
@@ -782,6 +782,30 @@ void MacroAssembler::AllocateAsciiString(Register result,
 }
 
 
+void MacroAssembler::AllocateAsciiString(Register result,
+                                         int length,
+                                         Register scratch,

[Søren Thygesen Gjesse, 2010/09/01 11:19:31]

Maybe add another scratch register and pass that as no_reg, leaving the option
of avoiding the object reference in the reloc info to the caller.

[Vitaly Repeshko, 2010/09/01 17:21:51]

Done.

+                                         Label* gc_required) {
+  ASSERT(length > 0);
+
+  // Allocate ascii string in new space.
+  AllocateInNewSpace(SeqAsciiString::SizeFor(length),
+                     result,
+                     scratch,
+                     no_reg,
+                     gc_required,
+                     TAG_OBJECT);
+
+  // Set the map, length and hash field.
+  mov(FieldOperand(result, HeapObject::kMapOffset),
+      Immediate(Factory::ascii_string_map()));
+  mov(FieldOperand(result, String::kLengthOffset),
+      Immediate(Smi::FromInt(length)));
+  mov(FieldOperand(result, String::kHashFieldOffset),
+      Immediate(String::kEmptyHashField));
+}
+
+
 void MacroAssembler::AllocateConsString(Register result,
                                         Register scratch1,
                                         Register scratch2,