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

src/ia32/lithium-ia32.cc

Index: src/ia32/lithium-ia32.cc
diff --git a/src/ia32/lithium-ia32.cc b/src/ia32/lithium-ia32.cc
index 9951d2540bb1cab9136db7c2acf028cc04584473..6622cc9f051cab3af09acd1ff1bc3e5b151f96f2 100644
--- a/src/ia32/lithium-ia32.cc
+++ b/src/ia32/lithium-ia32.cc
@@ -2057,10 +2057,12 @@ LInstruction* LChunkBuilder::DoStringAdd(HStringAdd* 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)));
 }