Tentative implementation of string slices (hidden under the flag --string-slices).

src/ia32/lithium-ia32.cc

 // Copyright 2011 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 2039 matching lines @@
 LInstruction* LChunkBuilder::DoStringAdd(HStringAdd* instr) {
   LOperand* context = UseFixed(instr->context(), esi);
   LOperand* left = UseOrConstantAtStart(instr->left());
   LOperand* right = UseOrConstantAtStart(instr->right());
   LStringAdd* string_add = new LStringAdd(context, left, right);
   return MarkAsCall(DefineFixed(string_add, eax), instr);
 }
 
 
 LInstruction* LChunkBuilder::DoStringCharCodeAt(HStringCharCodeAt* instr) {
-  LOperand* string = UseRegister(instr->string());
+  LOperand* string = UseTempRegister(instr->string());

[Vitaly Repeshko, 2011/08/12 19:01:00]

We can use 3 instead of 4 registers if we give up on special casing the const
index:
LOperand* string = UseTempRegister(instr->string());
LOperand* index = UseTempRegister(instr->string());
LOperand* context = UseAny(instr->context());
LStringCharCodeAt* result = new LStringCharCodeAt(context, string, index);

   LOperand* index = UseRegisterOrConstant(instr->index());
   LOperand* context = UseAny(instr->context());
-  LStringCharCodeAt* result = new LStringCharCodeAt(context, string, index);
+  LOperand* temp = TempRegister();
+  LStringCharCodeAt* result = new LStringCharCodeAt(context, string,
+                                                    index, temp);
   return AssignEnvironment(AssignPointerMap(DefineAsRegister(result)));
 }
 
 
 LInstruction* LChunkBuilder::DoStringCharFromCode(HStringCharFromCode* instr) {
   LOperand* char_code = UseRegister(instr->value());
   LOperand* context = UseAny(instr->context());
   LStringCharFromCode* result = new LStringCharFromCode(context, char_code);
   return AssignPointerMap(DefineAsRegister(result));
 }
@@ skipping 182 matching lines @@
   LOperand* key = UseOrConstantAtStart(instr->key());
   LOperand* object = UseOrConstantAtStart(instr->object());
   LIn* result = new LIn(context, key, object);
   return MarkAsCall(DefineFixed(result, eax), instr);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32