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 e611c8ae27999a9520d0aa07bfa050b51a0bb831..d003c8d1382584bc556e3297b137a5ec1aeeee62 100644
--- a/src/x64/macro-assembler-x64.h
+++ b/src/x64/macro-assembler-x64.h
@@ -1523,6 +1523,41 @@ inline Operand StackOperandForReturnAddress(int32_t disp) {
 }
 
 
+// Computes the argument address from the argument 0 (might be receiver)
+// at rsp + disp + kPCOnStackSize + (total - 1) * kPointerSize, disp is the
+// displacement between the rsp and the return address.
+inline Operand StackOperandForArgument(int index, int total, int disp = 0) {
+  return Operand(rsp, disp + kPCOnStackSize +
+                 (total - 1 - index) * kPointerSize);
+}
+
+
+// Computes the argument address in reverse order, i.e., from the last argument
+// at rsp + disp + kPCOnStackSize, disp is the displacement between the rsp
+// and the return address.
+inline Operand StackOperandForReversedArgument(int index, int disp = 0) {
+  return Operand(rsp, disp + kPCOnStackSize + index * kPointerSize);
+}
+
+
+inline Operand StackOperandForReversedArgument(Register index,
+                                               int offset,
+                                               int disp = 0) {
+  return Operand(rsp, index, times_pointer_size,
+                 disp + kPCOnStackSize + offset * kPointerSize);
+}
+
+
+inline Operand StackOperandForReceiver(int index, int disp = 0) {
+  return StackOperandForReversedArgument(index, disp);
+}
+
+
+inline Operand StackOperandForReceiver(Register index, int disp = 0) {
+  return StackOperandForReversedArgument(index, 0, disp);
+}
+
+
 #ifdef GENERATED_CODE_COVERAGE
 extern void LogGeneratedCodeCoverage(const char* file_line);
 #define CODE_COVERAGE_STRINGIFY(x) #x