ia32 StringAddStub: fast two character case.

src/ia32/macro-assembler-ia32.cc

 // Copyright 2006-2009 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
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@@ skipping 764 matching lines @@
   mov(FieldOperand(result, HeapObject::kMapOffset),
       Immediate(Factory::ascii_string_map()));
   mov(scratch1, length);
   SmiTag(scratch1);
   mov(FieldOperand(result, String::kLengthOffset), scratch1);
   mov(FieldOperand(result, String::kHashFieldOffset),
       Immediate(String::kEmptyHashField));
 }
 
 
+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,
                                         Label* gc_required) {
   // Allocate heap number in new space.
   AllocateInNewSpace(ConsString::kSize,
                      result,
                      scratch1,
                      scratch2,
                      gc_required,
@@ skipping 834 matching lines @@
 
   // Check that the code was patched as expected.
   ASSERT(masm_.pc_ == address_ + size_);
   ASSERT(masm_.reloc_info_writer.pos() == address_ + size_ + Assembler::kGap);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32