Introduce StackArgumentsAccessor class for X64

src/x64/macro-assembler-x64.h

Index: src/x64/macro-assembler-x64.h
diff --git a/src/x64/macro-assembler-x64.h b/src/x64/macro-assembler-x64.h
index 9d5d2a31c5ceee61652cd923ca83e8a13d1388ca..2ce78e5c182f269f1e2a9f539c9e9fb0e280c531 100644
--- a/src/x64/macro-assembler-x64.h
+++ b/src/x64/macro-assembler-x64.h
@@ -1518,6 +1518,23 @@ inline Operand StackSpaceOperand(int index) {
 }
 
 
+// Assumes the return address size equals an argument size.
+// Considers receiver as argument 0.
+inline Operand StackOperandForArgument(int32_t disp) {
+  // Adjusts the disp with kPCOnStackSize - kPointerSize.
+  return Operand(rsp, disp + kPCOnStackSize - kPointerSize);

[danno, 2013/07/31 07:48:37]

Does it make sense to use an index rather than displacement? It would simplify
the usage sites. i.e.:

return Operand(rsp, (index * kPointerSize) + kPCOnStackSize - kPointerSize +
extra_disp);

extra_disp can be a default parameter with value 0

[haitao.feng, 2013/07/31 09:25:20]

I have thought about this. I did not use it as index actually is counted from
stack pointer, not from argument0. The reader might think
StackOperandForArgument(index) is accessing the ith argument.

How about defining this function as:
inline Operand StackOperandForReversedArgument(int index) {
  return Operand(rsp, (index * kPointerSize) + kPCOnStackSize);
}
Index is counted from the argument n (rsp + kPCOnStackSize), instead of argument
0 or rsp. If we want it from argument 0, we might need two arguments (one index,
one argc). 

inline Operand StackOperandForReceiver(int argc) {
  return StackOperandForReversedArgument(argc);
}

If you are OK with this, I will start updating the codes to use this interface. 

+}
+
+
+// Assumes the return address size equals an argument size.
+// Considers receiver as argument 0.
+inline Operand StackOperandForArgument(Register index,
+                                       ScaleFactor scale,
+                                       int32_t disp) {

[danno, 2013/07/31 07:48:37]

Same here (index rather than displacement)?

+  // Adjusts the disp with kPCOnStackSize - kPointerSize.
+  return Operand(rsp, index, scale, disp + kPCOnStackSize - kPointerSize);
+}
+
 
 #ifdef GENERATED_CODE_COVERAGE
 extern void LogGeneratedCodeCoverage(const char* file_line);