Fix DoubleStackSlot-to-DoubleStackSlot moves on ia32. Unify platform-independent code.

src/ia32/lithium-codegen-ia32.cc

 // Copyright 2012 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 531 matching lines @@
 
 bool LCodeGen::IsInteger32(LConstantOperand* op) const {
   return chunk_->LookupLiteralRepresentation(op).IsInteger32();
 }
 
 
 Operand LCodeGen::ToOperand(LOperand* op) const {
   if (op->IsRegister()) return Operand(ToRegister(op));
   if (op->IsDoubleRegister()) return Operand(ToDoubleRegister(op));
   ASSERT(op->IsStackSlot() || op->IsDoubleStackSlot());
-  int index = op->index();
-  if (index >= 0) {
-    // Local or spill slot. Skip the frame pointer, function, and
-    // context in the fixed part of the frame.
-    return Operand(ebp, -(index + 3) * kPointerSize);
-  } else {
-    // Incoming parameter. Skip the return address.
-    return Operand(ebp, -(index - 1) * kPointerSize);
-  }
+  return Operand(ebp, StackSlotOffset(op->index()));
 }
 
 
 Operand LCodeGen::HighOperand(LOperand* op) {
   ASSERT(op->IsDoubleStackSlot());
-  int index = op->index();
-  int offset = (index >= 0) ? index + 3 : index - 1;
-  return Operand(ebp, -offset * kPointerSize);
+  return Operand(ebp, StackSlotOffset(op->index()) + kPointerSize);
 }
 
 
 void LCodeGen::WriteTranslation(LEnvironment* environment,
                                 Translation* translation,
                                 int* arguments_index,
                                 int* arguments_count) {
   if (environment == NULL) return;
 
   // The translation includes one command per value in the environment.
@@ skipping 5599 matching lines @@
                               FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32