Introduce StackArgumentsAccessor class for X64

src/x64/macro-assembler-x64.h

 // 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 1461 matching lines @@
   // Macro assembler to emit code.
   MacroAssembler* masm() { return &masm_; }
 
  private:
   byte* address_;  // The address of the code being patched.
   int size_;  // Number of bytes of the expected patch size.
   MacroAssembler masm_;  // Macro assembler used to generate the code.
 };
 
 
+class StackArguments BASE_EMBEDDED {

[danno, 2013/08/05 15:17:56]

I would call this StackArgumentsAccessor

[haitao.feng, 2013/08/06 11:49:55]

Done.

+ public:
+  // argc could be an immediate or in a register.
+  // extra is 1 when the receiver is considered as argument[0].
+  // disp is the displacement between rsp and return address.
+  StackArguments(int immediate, int extra = 0, int disp = 0)
+      : reg_(no_reg), immediate_(immediate), extra_(extra), disp_(disp) { }
+
+  StackArguments(Register reg, int extra = 0, int disp = 0)

[danno, 2013/08/05 15:17:56]

I find all the math with extra and disp a bit confusing. How about adding an
enum for the receiver mode:

StackArgumentsAccessorReceiverMode {
  ARGUMENTS_CONTAIN_RECEIVER,
  ARGUMENTS_DONT_CONTAIN_RECEIVER
};

The default should be ARGUMENTS_CONTAIN_RECEIVER since you more often than not
pass 1 for extra currently. You can then turn this into receiver_size_ that is
used in the math calculations below.

Also, call disp and disp_ dispacement_to_sp and dispacement_to_sp_,
respectively, this make the comment superfluous.

[haitao.feng, 2013/08/06 11:49:55]

Done.

+      : reg_(reg), immediate_(0), extra_(extra), disp_(disp) { }
+
+  StackArguments(const ParameterCount& parameter_count,
+                 int extra = 0,
+                 int disp = 0)
+      : reg_(parameter_count.is_reg() ? parameter_count.reg() : no_reg),
+        immediate_(parameter_count.is_immediate() ?
+                   parameter_count.immediate() : 0),
+        extra_(extra),
+        disp_(disp) { }
+
+  Operand operator[] (int index) {

[danno, 2013/08/05 15:17:56]

I think it's better to not overide the [] operator, since StackArgumentsAccessor
isn't a container per se. I think it would be better to call this 

GetArgumentOperand(int index) { ... } 

[haitao.feng, 2013/08/06 11:49:55]

Done.

+    if (index >= 0) {
+      if (reg_.is(no_reg)) {
+        // argument[0] is at rsp + disp + kPCOnSackSize +
+        // (immediate_ + extra_ - 1) * kPointerSize.
+        ASSERT(immediate_ + extra_ > 0);
+        return Operand(rsp, disp_ + kPCOnStackSize +
+                       (immediate_ + extra_ - 1 - index) * kPointerSize);
+      } else {
+        // argument[0] is at rsp + disp + kPCOnSackSize +
+        // reg_ * times_pointer_size + (extra_ - 1) * kPointerSize.
+        return Operand(rsp, reg_, times_pointer_size, disp_ + kPCOnStackSize +
+                       (extra_ - 1 - index) * kPointerSize);
+      }
+    } else {

[danno, 2013/08/05 15:17:56]

I think the handling of negative arguments is pretty confusing. Do you really
need to support them?

[haitao.feng, 2013/08/06 11:49:55]

Done.

+      // Reverse order, argument[-1] is at rsp + disp + kPCOnSackSize.
+      ASSERT(reg_.is(no_reg) || (-index <= immediate_));
+      return Operand(rsp, disp_ + kPCOnStackSize + (-index - 1) * kPointerSize);
+    }
+  }
+
+  Operand GetReceiver() {

[danno, 2013/08/05 15:17:56]

... and this GetReceiverOperand()

[haitao.feng, 2013/08/06 11:49:55]

Done.

+    ASSERT(extra_ == 1);
+    return (*this)[0];
+  }
+
+ private:
+  const Register reg_;
+  const int immediate_;
+  const int extra_;
+  const int disp_;
+};
+
+
 // -----------------------------------------------------------------------------
 // Static helper functions.
 
 // Generate an Operand for loading a field from an object.
 inline Operand FieldOperand(Register object, int offset) {
   return Operand(object, offset - kHeapObjectTag);
 }
 
 
 // Generate an Operand for loading an indexed field from an object.
@@ skipping 24 matching lines @@
   return Operand(rsp, index * kPointerSize);
 #endif
 }
 
 
 inline Operand StackOperandForReturnAddress(int32_t disp) {
   return Operand(rsp, disp);
 }
 
 
+// Computes the argument address from the argument 0 (might be receiver)

[danno, 2013/08/05 15:17:56]

Do you need any of these here and below any more?

[haitao.feng, 2013/08/06 11:49:55]

Done. Sorry, I remembered I removed all of them. Maybe I did not commit it.

+// 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
 #define CODE_COVERAGE_TOSTRING(x) CODE_COVERAGE_STRINGIFY(x)
 #define __FILE_LINE__ __FILE__ ":" CODE_COVERAGE_TOSTRING(__LINE__)
 #define ACCESS_MASM(masm) {                                                  \
     Address x64_coverage_function = FUNCTION_ADDR(LogGeneratedCodeCoverage); \
     masm->pushfq();                                                          \
     masm->Pushad();                                                          \
     masm->push(Immediate(reinterpret_cast<int>(&__FILE_LINE__)));            \
     masm->Call(x64_coverage_function, RelocInfo::EXTERNAL_REFERENCE);        \
     masm->pop(rax);                                                          \
     masm->Popad();                                                           \
     masm->popfq();                                                           \
   }                                                                          \
   masm->
 #else
 #define ACCESS_MASM(masm) masm->
 #endif
 
 } }  // namespace v8::internal
 
 #endif  // V8_X64_MACRO_ASSEMBLER_X64_H_