Make some constants' meaning clear for X64

R=danno@chromium.org

Review URL: https://codereview.chromium.org/21721002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16061 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/x64/assembler-x64-inl.h

@@ -373,13 +373,14 @@ void RelocInfo::set_target_cell(Cell* cell, WriteBarrierMode mode) {
 
 bool RelocInfo::IsPatchedReturnSequence() {
   // The recognized call sequence is:
-  //  movq(kScratchRegister, immediate64); call(kScratchRegister);
+  //  movq(kScratchRegister, address); call(kScratchRegister);
   // It only needs to be distinguished from a return sequence
   //  movq(rsp, rbp); pop(rbp); ret(n); int3 *6
   // The 11th byte is int3 (0xCC) in the return sequence and
   // REX.WB (0x48+register bit) for the call sequence.
 #ifdef ENABLE_DEBUGGER_SUPPORT
-  return pc_[2 + kPointerSize] != 0xCC;
+  return pc_[Assembler::kMoveAddressIntoScratchRegisterInstructionLength] !=
+         0xCC;
 #else
   return false;
 #endif

src/x64/assembler-x64.cc

@@ -164,10 +164,7 @@ void CpuFeatures::Probe() {
 // Patch the code at the current PC with a call to the target address.
 // Additional guard int3 instructions can be added if required.
 void RelocInfo::PatchCodeWithCall(Address target, int guard_bytes) {
-  // Load register with immediate 64 and call through a register instructions
+  int code_size = Assembler::kCallSequenceLength + guard_bytes;
-  // takes up 13 bytes and int3 takes up one byte.
-  static const int kCallCodeSize = 13;
-  int code_size = kCallCodeSize + guard_bytes;
 
   // Create a code patcher.
   CodePatcher patcher(pc_, code_size);
@@ -183,7 +180,7 @@ void RelocInfo::PatchCodeWithCall(Address target, int guard_bytes) {
   patcher.masm()->call(r10);
 
   // Check that the size of the code generated is as expected.
-  ASSERT_EQ(kCallCodeSize,
+  ASSERT_EQ(Assembler::kCallSequenceLength,
             patcher.masm()->SizeOfCodeGeneratedSince(&check_codesize));
 
   // Add the requested number of int3 instructions after the call.

src/x64/assembler-x64.h

@@ -579,29 +579,36 @@ class Assembler : public AssemblerBase {
   // Distance between the address of the code target in the call instruction
   // and the return address pushed on the stack.
   static const int kCallTargetAddressOffset = 4;  // Use 32-bit displacement.
-  // Distance between the start of the JS return sequence and where the
+  // The length of call(kScratchRegister).
-  // 32-bit displacement of a near call would be, relative to the pushed
+  static const int kCallScratchRegisterInstructionLength = 3;
-  // return address.  TODO: Use return sequence length instead.
+  // The length of call(Immediate32).
-  // Should equal Debug::kX64JSReturnSequenceLength - kCallTargetAddressOffset;
-  static const int kPatchReturnSequenceAddressOffset = 13 - 4;
-  // Distance between start of patched debug break slot and where the
-  // 32-bit displacement of a near call would be, relative to the pushed
-  // return address.  TODO: Use return sequence length instead.
-  // Should equal Debug::kX64JSReturnSequenceLength - kCallTargetAddressOffset;
-  static const int kPatchDebugBreakSlotAddressOffset = 13 - 4;
-  // TODO(X64): Rename this, removing the "Real", after changing the above.
-  static const int kRealPatchReturnSequenceAddressOffset = 2;
-
-  // Some x64 JS code is padded with int3 to make it large
-  // enough to hold an instruction when the debugger patches it.
-  static const int kJumpInstructionLength = 13;
-  static const int kCallInstructionLength = 13;
-  static const int kJSReturnSequenceLength = 13;
   static const int kShortCallInstructionLength = 5;
-  static const int kPatchDebugBreakSlotReturnOffset = 4;
+  // The length of movq(kScratchRegister, address).
+  static const int kMoveAddressIntoScratchRegisterInstructionLength =
+      2 + kPointerSize;
+  // The length of movq(kScratchRegister, address) and call(kScratchRegister).
+  static const int kCallSequenceLength =
+      kMoveAddressIntoScratchRegisterInstructionLength +
+      kCallScratchRegisterInstructionLength;
 
-  // The debug break slot must be able to contain a call instruction.
+  // The js return and debug break slot must be able to contain an indirect
-  static const int kDebugBreakSlotLength = kCallInstructionLength;
+  // call sequence, some x64 JS code is padded with int3 to make it large
+  // enough to hold an instruction when the debugger patches it.
+  static const int kJSReturnSequenceLength = kCallSequenceLength;
+  static const int kDebugBreakSlotLength = kCallSequenceLength;
+  static const int kPatchDebugBreakSlotReturnOffset = kCallTargetAddressOffset;
+  // Distance between the start of the JS return sequence and where the
+  // 32-bit displacement of a short call would be. The short call is from
+  // SetDebugBreakAtIC from debug-x64.cc.
+  static const int kPatchReturnSequenceAddressOffset =
+      kJSReturnSequenceLength - kPatchDebugBreakSlotReturnOffset;
+  // Distance between the start of the JS return sequence and where the
+  // 32-bit displacement of a short call would be. The short call is from
+  // SetDebugBreakAtIC from debug-x64.cc.
+  static const int kPatchDebugBreakSlotAddressOffset =
+      kDebugBreakSlotLength - kPatchDebugBreakSlotReturnOffset;
+  static const int kRealPatchReturnSequenceAddressOffset =
+      kMoveAddressIntoScratchRegisterInstructionLength - kPointerSize;
 
   // One byte opcode for test eax,0xXXXXXXXX.
   static const byte kTestEaxByte = 0xA9;

src/x64/debug-x64.cc

@@ -48,11 +48,10 @@ bool BreakLocationIterator::IsDebugBreakAtReturn()  {
 // CodeGenerator::VisitReturnStatement and VirtualFrame::Exit in codegen-x64.cc
 // for the precise return instructions sequence.
 void BreakLocationIterator::SetDebugBreakAtReturn()  {
-  ASSERT(Assembler::kJSReturnSequenceLength >=
+  ASSERT(Assembler::kJSReturnSequenceLength >= Assembler::kCallSequenceLength);
-         Assembler::kCallInstructionLength);
   rinfo()->PatchCodeWithCall(
       Isolate::Current()->debug()->debug_break_return()->entry(),
-      Assembler::kJSReturnSequenceLength - Assembler::kCallInstructionLength);
+      Assembler::kJSReturnSequenceLength - Assembler::kCallSequenceLength);
 }
 
 
@@ -82,7 +81,7 @@ void BreakLocationIterator::SetDebugBreakAtSlot() {
   ASSERT(IsDebugBreakSlot());
   rinfo()->PatchCodeWithCall(
       Isolate::Current()->debug()->debug_break_slot()->entry(),
-      Assembler::kDebugBreakSlotLength - Assembler::kCallInstructionLength);
+      Assembler::kDebugBreakSlotLength - Assembler::kCallSequenceLength);
 }
 
 

src/x64/deoptimizer-x64.cc

@@ -42,7 +42,7 @@ const int Deoptimizer::table_entry_size_ = 10;
 
 
 int Deoptimizer::patch_size() {
-  return Assembler::kCallInstructionLength;
+  return Assembler::kCallSequenceLength;
 }
 
 
@@ -69,7 +69,7 @@ void Deoptimizer::PatchCodeForDeoptimization(Isolate* isolate, Code* code) {
     Address call_address = instruction_start + deopt_data->Pc(i)->value();
     // There is room enough to write a long call instruction because we pad
     // LLazyBailout instructions with nops if necessary.
-    CodePatcher patcher(call_address, Assembler::kCallInstructionLength);
+    CodePatcher patcher(call_address, Assembler::kCallSequenceLength);
     patcher.masm()->Call(GetDeoptimizationEntry(isolate, i, LAZY),
                          RelocInfo::NONE64);
     ASSERT(prev_call_address == NULL ||

src/x64/macro-assembler-x64.cc

@@ -155,7 +155,7 @@ int MacroAssembler::LoadAddressSize(ExternalReference source) {
     }
   }
   // Size of movq(destination, src);
-  return 10;
+  return Assembler::kMoveAddressIntoScratchRegisterInstructionLength;
 }
 
 
@@ -2511,8 +2511,8 @@ void MacroAssembler::Jump(Handle<Code> code_object, RelocInfo::Mode rmode) {
 
 int MacroAssembler::CallSize(ExternalReference ext) {
   // Opcode for call kScratchRegister is: Rex.B FF D4 (three bytes).
-  const int kCallInstructionSize = 3;
+  return LoadAddressSize(ext) +
-  return LoadAddressSize(ext) + kCallInstructionSize;
+         Assembler::kCallScratchRegisterInstructionLength;
 }
 
 

src/x64/macro-assembler-x64.h

@@ -841,7 +841,7 @@ class MacroAssembler: public Assembler {
 
   // The size of the code generated for different call instructions.
   int CallSize(Address destination, RelocInfo::Mode rmode) {
-    return kCallInstructionLength;
+    return kCallSequenceLength;
   }
   int CallSize(ExternalReference ext);
   int CallSize(Handle<Code> code_object) {