[cleanup] Remove obsolete {ExitFrame::code_slot} mechanism.

This slot has become obsolete now that all CEntry stubs are builtins
(which are part of the rootset) and no longer need to be kept alive
explicitly by a slot in the frame.

R=verwaest@chromium.org
BUG=v8:8834

Change-Id: I7b791cc509ef800bcf7aa5faab31ddf35370f944
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1520725Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60267}

src/arm/frame-constants-arm.h

@@ -26,8 +26,7 @@ class EntryFrameConstants : public AllStatic {
 class ExitFrameConstants : public TypedFrameConstants {
  public:
   static constexpr int kSPOffset = TYPED_FRAME_PUSHED_VALUE_OFFSET(0);
-  static constexpr int kCodeOffset = TYPED_FRAME_PUSHED_VALUE_OFFSET(1);
-  DEFINE_TYPED_FRAME_SIZES(2);
+  DEFINE_TYPED_FRAME_SIZES(1);
 
   // The caller fields are below the frame pointer on the stack.
   static constexpr int kCallerFPOffset = 0 * kPointerSize;

src/arm/macro-assembler-arm.cc

@@ -1308,14 +1308,12 @@ void MacroAssembler::EnterExitFrame(bool save_doubles, int stack_space,
   DCHECK_EQ(0 * kPointerSize, ExitFrameConstants::kCallerFPOffset);
   mov(scratch, Operand(StackFrame::TypeToMarker(frame_type)));
   PushCommonFrame(scratch);
-  // Reserve room for saved entry sp and code object.
+  // Reserve room for saved entry sp.
   sub(sp, fp, Operand(ExitFrameConstants::kFixedFrameSizeFromFp));
   if (emit_debug_code()) {
     mov(scratch, Operand::Zero());
     str(scratch, MemOperand(fp, ExitFrameConstants::kSPOffset));
   }
-  Move(scratch, CodeObject());
-  str(scratch, MemOperand(fp, ExitFrameConstants::kCodeOffset));
 
   // Save the frame pointer and the context in top.
   Move(scratch, ExternalReference::Create(IsolateAddressId::kCEntryFPAddress,

src/arm64/frame-constants-arm64.h

@@ -44,10 +44,8 @@ class EntryFrameConstants : public AllStatic {
 class ExitFrameConstants : public TypedFrameConstants {
  public:
   static constexpr int kSPOffset = TYPED_FRAME_PUSHED_VALUE_OFFSET(0);
-  static constexpr int kCodeOffset = TYPED_FRAME_PUSHED_VALUE_OFFSET(1);
-  static constexpr int kPaddingOffset = TYPED_FRAME_PUSHED_VALUE_OFFSET(2);
-  DEFINE_TYPED_FRAME_SIZES(3);
-  static constexpr int kLastExitFrameField = kPaddingOffset;
+  DEFINE_TYPED_FRAME_SIZES(1);
+  static constexpr int kLastExitFrameField = kSPOffset;
 
   static constexpr int kConstantPoolOffset = 0;  // Not used
 };

src/arm64/macro-assembler-arm64.cc

@@ -2585,14 +2585,10 @@ void MacroAssembler::EnterExitFrame(bool save_doubles, const Register& scratch,
   Mov(fp, sp);
   Mov(scratch, StackFrame::TypeToMarker(frame_type));
   Push(scratch, xzr);
-  Mov(scratch, CodeObject());
-  Push(scratch, padreg);
   //          fp[8]: CallerPC (lr)
   //    fp -> fp[0]: CallerFP (old fp)
   //          fp[-8]: STUB marker
-  //          fp[-16]: Space reserved for SPOffset.
-  //          fp[-24]: CodeObject()
-  //    sp -> fp[-32]: padding
+  //    sp -> fp[-16]: Space reserved for SPOffset.
   STATIC_ASSERT((2 * kSystemPointerSize) ==
                 ExitFrameConstants::kCallerSPOffset);
   STATIC_ASSERT((1 * kSystemPointerSize) ==
@@ -2600,9 +2596,6 @@ void MacroAssembler::EnterExitFrame(bool save_doubles, const Register& scratch,
   STATIC_ASSERT((0 * kSystemPointerSize) ==
                 ExitFrameConstants::kCallerFPOffset);
   STATIC_ASSERT((-2 * kSystemPointerSize) == ExitFrameConstants::kSPOffset);
-  STATIC_ASSERT((-3 * kSystemPointerSize) == ExitFrameConstants::kCodeOffset);
-  STATIC_ASSERT((-4 * kSystemPointerSize) ==
-                ExitFrameConstants::kPaddingOffset);
 
   // Save the frame pointer and context pointer in the top frame.
   Mov(scratch,
@@ -2612,7 +2605,7 @@ void MacroAssembler::EnterExitFrame(bool save_doubles, const Register& scratch,
       ExternalReference::Create(IsolateAddressId::kContextAddress, isolate()));
   Str(cp, MemOperand(scratch));
 
-  STATIC_ASSERT((-4 * kSystemPointerSize) ==
+  STATIC_ASSERT((-2 * kSystemPointerSize) ==
                 ExitFrameConstants::kLastExitFrameField);
   if (save_doubles) {
     ExitFramePreserveFPRegs();
@@ -2629,8 +2622,7 @@ void MacroAssembler::EnterExitFrame(bool save_doubles, const Register& scratch,
   //   fp -> fp[0]: CallerFP (old fp)
   //         fp[-8]: STUB marker
   //         fp[-16]: Space reserved for SPOffset.
-  //         fp[-24]: CodeObject()
-  //         fp[-24 - fp_size]: Saved doubles (if save_doubles is true).
+  //         fp[-16 - fp_size]: Saved doubles (if save_doubles is true).
   //         sp[8]: Extra space reserved for caller (if extra_space != 0).
   //   sp -> sp[0]: Space reserved for the return address.
 

src/frames.cc

@@ -614,14 +614,7 @@ Code ConstructEntryFrame::unchecked_code() const {
   return isolate()->heap()->builtin(Builtins::kJSConstructEntry);
 }
 
-Address& ExitFrame::code_slot() const {
-  const int offset = ExitFrameConstants::kCodeOffset;
-  return Memory<Address>(fp() + offset);
-}
-
-Code ExitFrame::unchecked_code() const {
-  return Code::unchecked_cast(Object(code_slot()));
-}
+Code ExitFrame::unchecked_code() const { UNREACHABLE(); }
 
 void ExitFrame::ComputeCallerState(State* state) const {
   // Set up the caller state.
@@ -641,7 +634,6 @@ void ExitFrame::Iterate(RootVisitor* v) const {
   // The arguments are traversed as part of the expression stack of
   // the calling frame.
   IteratePc(v, pc_address(), constant_pool_address(), LookupCode());
-  v->VisitRootPointer(Root::kTop, nullptr, FullObjectSlot(&code_slot()));
 }
 
 

src/frames.h

@@ -384,8 +384,6 @@ class ExitFrame: public StackFrame {
 
   Code unchecked_code() const override;
 
-  Address& code_slot() const;
-
   // Garbage collection support.
   void Iterate(RootVisitor* v) const override;
 

src/ia32/frame-constants-ia32.h

@@ -35,8 +35,7 @@ class EntryFrameConstants : public AllStatic {
 class ExitFrameConstants : public TypedFrameConstants {
  public:
   static constexpr int kSPOffset = TYPED_FRAME_PUSHED_VALUE_OFFSET(0);
-  static constexpr int kCodeOffset = TYPED_FRAME_PUSHED_VALUE_OFFSET(1);
-  DEFINE_TYPED_FRAME_SIZES(2);
+  DEFINE_TYPED_FRAME_SIZES(1);
 
   static constexpr int kCallerFPOffset = 0 * kSystemPointerSize;
   static constexpr int kCallerPCOffset = +1 * kSystemPointerSize;

src/ia32/macro-assembler-ia32.cc

@@ -810,13 +810,10 @@ void MacroAssembler::EnterExitFramePrologue(StackFrame::Type frame_type,
   push(ebp);
   mov(ebp, esp);
 
-  // Reserve room for entry stack pointer and push the code object.
+  // Reserve room for entry stack pointer.
   push(Immediate(StackFrame::TypeToMarker(frame_type)));
   DCHECK_EQ(-2 * kSystemPointerSize, ExitFrameConstants::kSPOffset);
   push(Immediate(0));  // Saved entry sp, patched before call.
-  DCHECK_EQ(-3 * kSystemPointerSize, ExitFrameConstants::kCodeOffset);
-  Move(scratch, CodeObject());
-  push(scratch);  // Accessed from ExitFrame::code_slot.
 
   STATIC_ASSERT(edx == kRuntimeCallFunctionRegister);
   STATIC_ASSERT(esi == kContextRegister);

src/mips/frame-constants-mips.h

@@ -26,8 +26,7 @@ class EntryFrameConstants : public AllStatic {
 class ExitFrameConstants : public TypedFrameConstants {
  public:
   static constexpr int kSPOffset = TYPED_FRAME_PUSHED_VALUE_OFFSET(0);
-  static constexpr int kCodeOffset = TYPED_FRAME_PUSHED_VALUE_OFFSET(1);
-  DEFINE_TYPED_FRAME_SIZES(2);
+  DEFINE_TYPED_FRAME_SIZES(1);
 
   // The caller fields are below the frame pointer on the stack.
   static constexpr int kCallerFPOffset = +0 * kPointerSize;

src/mips/macro-assembler-mips.cc

@@ -4816,11 +4816,10 @@ void MacroAssembler::EnterExitFrame(bool save_doubles, int stack_space,
   // [fp + 0 (==kCallerFPOffset)] - saved old fp
   // [fp - 1 StackFrame::EXIT Smi
   // [fp - 2 (==kSPOffset)] - sp of the called function
-  // [fp - 3 (==kCodeOffset)] - CodeObject
   // fp - (2 + stack_space + alignment) == sp == [fp - kSPOffset] - top of the
   //   new stack (will contain saved ra)
 
-  // Save registers and reserve room for saved entry sp and code object.
+  // Save registers and reserve room for saved entry sp.
   addiu(sp, sp, -2 * kPointerSize - ExitFrameConstants::kFixedFrameSizeFromFp);
   sw(ra, MemOperand(sp, 4 * kPointerSize));
   sw(fp, MemOperand(sp, 3 * kPointerSize));
@@ -4837,10 +4836,6 @@ void MacroAssembler::EnterExitFrame(bool save_doubles, int stack_space,
     sw(zero_reg, MemOperand(fp, ExitFrameConstants::kSPOffset));
   }
 
-  // Accessed from ExitFrame::code_slot.
-  li(t8, CodeObject(), CONSTANT_SIZE);
-  sw(t8, MemOperand(fp, ExitFrameConstants::kCodeOffset));
-
   // Save the frame pointer and the context in top.
   li(t8,
      ExternalReference::Create(IsolateAddressId::kCEntryFPAddress, isolate()));

src/mips64/frame-constants-mips64.h

@@ -22,8 +22,7 @@ class EntryFrameConstants : public AllStatic {
 class ExitFrameConstants : public TypedFrameConstants {
  public:
   static constexpr int kSPOffset = TYPED_FRAME_PUSHED_VALUE_OFFSET(0);
-  static constexpr int kCodeOffset = TYPED_FRAME_PUSHED_VALUE_OFFSET(1);
-  DEFINE_TYPED_FRAME_SIZES(2);
+  DEFINE_TYPED_FRAME_SIZES(1);
 
   // The caller fields are below the frame pointer on the stack.
   static constexpr int kCallerFPOffset = +0 * kPointerSize;

src/mips64/macro-assembler-mips64.cc

@@ -5168,11 +5168,10 @@ void MacroAssembler::EnterExitFrame(bool save_doubles, int stack_space,
   // [fp + 0 (==kCallerFPOffset)] - saved old fp
   // [fp - 1 StackFrame::EXIT Smi
   // [fp - 2 (==kSPOffset)] - sp of the called function
-  // [fp - 3 (==kCodeOffset)] - CodeObject
   // fp - (2 + stack_space + alignment) == sp == [fp - kSPOffset] - top of the
   //   new stack (will contain saved ra)
 
-  // Save registers and reserve room for saved entry sp and code object.
+  // Save registers and reserve room for saved entry sp.
   daddiu(sp, sp, -2 * kPointerSize - ExitFrameConstants::kFixedFrameSizeFromFp);
   Sd(ra, MemOperand(sp, 4 * kPointerSize));
   Sd(fp, MemOperand(sp, 3 * kPointerSize));
@@ -5191,10 +5190,6 @@ void MacroAssembler::EnterExitFrame(bool save_doubles, int stack_space,
 
   {
     BlockTrampolinePoolScope block_trampoline_pool(this);
-    // Accessed from ExitFrame::code_slot.
-    li(t8, CodeObject(), CONSTANT_SIZE);
-    Sd(t8, MemOperand(fp, ExitFrameConstants::kCodeOffset));
-
     // Save the frame pointer and the context in top.
     li(t8, ExternalReference::Create(IsolateAddressId::kCEntryFPAddress,
                                      isolate()));

src/ppc/frame-constants-ppc.h

@@ -20,8 +20,7 @@ class EntryFrameConstants : public AllStatic {
 class ExitFrameConstants : public TypedFrameConstants {
  public:
   static constexpr int kSPOffset = TYPED_FRAME_PUSHED_VALUE_OFFSET(0);
-  static constexpr int kCodeOffset = TYPED_FRAME_PUSHED_VALUE_OFFSET(1);
-  DEFINE_TYPED_FRAME_SIZES(2);
+  DEFINE_TYPED_FRAME_SIZES(1);
 
   // The caller fields are below the frame pointer on the stack.
   static constexpr int kCallerFPOffset = 0 * kPointerSize;

src/ppc/macro-assembler-ppc.cc

@@ -997,7 +997,6 @@ int TurboAssembler::LeaveFrame(StackFrame::Type type, int stack_adjustment) {
 //
 //  SP -> previousSP
 //        LK reserved
-//        code
 //        sp_on_exit (for debug?)
 // oldSP->prev SP
 //        LK
@@ -1025,7 +1024,7 @@ void MacroAssembler::EnterExitFrame(bool save_doubles, int stack_space,
 
   mov(ip, Operand(StackFrame::TypeToMarker(frame_type)));
   PushCommonFrame(ip);
-  // Reserve room for saved entry sp and code object.
+  // Reserve room for saved entry sp.
   subi(sp, fp, Operand(ExitFrameConstants::kFixedFrameSizeFromFp));
 
   if (emit_debug_code()) {
@@ -1036,8 +1035,6 @@ void MacroAssembler::EnterExitFrame(bool save_doubles, int stack_space,
     StoreP(kConstantPoolRegister,
            MemOperand(fp, ExitFrameConstants::kConstantPoolOffset));
   }
-  Move(r8, CodeObject());
-  StoreP(r8, MemOperand(fp, ExitFrameConstants::kCodeOffset));
 
   // Save the frame pointer and the context in top.
   Move(r8, ExternalReference::Create(IsolateAddressId::kCEntryFPAddress,

src/s390/frame-constants-s390.h

@@ -22,8 +22,7 @@ class EntryFrameConstants : public AllStatic {
 class ExitFrameConstants : public TypedFrameConstants {
  public:
   static constexpr int kSPOffset = TYPED_FRAME_PUSHED_VALUE_OFFSET(0);
-  static constexpr int kCodeOffset = TYPED_FRAME_PUSHED_VALUE_OFFSET(1);
-  DEFINE_TYPED_FRAME_SIZES(2);
+  DEFINE_TYPED_FRAME_SIZES(1);
 
   // The caller fields are below the frame pointer on the stack.
   static constexpr int kCallerFPOffset = 0 * kPointerSize;

src/s390/macro-assembler-s390.cc

@@ -1049,7 +1049,6 @@ int TurboAssembler::LeaveFrame(StackFrame::Type type, int stack_adjustment) {
 //
 //  SP -> previousSP
 //        LK reserved
-//        code
 //        sp_on_exit (for debug?)
 // oldSP->prev SP
 //        LK
@@ -1064,7 +1063,6 @@ int TurboAssembler::LeaveFrame(StackFrame::Type type, int stack_adjustment) {
 // r14
 // oldFP <- newFP
 // SP
-// Code
 // Floats
 // gaps
 // Args
@@ -1085,14 +1083,12 @@ void MacroAssembler::EnterExitFrame(bool save_doubles, int stack_space,
   CleanseP(r14);
   Load(r1, Operand(StackFrame::TypeToMarker(frame_type)));
   PushCommonFrame(r1);
-  // Reserve room for saved entry sp and code object.
+  // Reserve room for saved entry sp.
   lay(sp, MemOperand(fp, -ExitFrameConstants::kFixedFrameSizeFromFp));
 
   if (emit_debug_code()) {
     StoreP(MemOperand(fp, ExitFrameConstants::kSPOffset), Operand::Zero(), r1);
   }
-  Move(r1, CodeObject());
-  StoreP(r1, MemOperand(fp, ExitFrameConstants::kCodeOffset));
 
   // Save the frame pointer and the context in top.
   Move(r1, ExternalReference::Create(IsolateAddressId::kCEntryFPAddress,

src/x64/frame-constants-x64.h

@@ -44,8 +44,7 @@ class EntryFrameConstants : public AllStatic {
 class ExitFrameConstants : public TypedFrameConstants {
  public:
   static constexpr int kSPOffset = TYPED_FRAME_PUSHED_VALUE_OFFSET(0);
-  static constexpr int kCodeOffset = TYPED_FRAME_PUSHED_VALUE_OFFSET(1);
-  DEFINE_TYPED_FRAME_SIZES(2);
+  DEFINE_TYPED_FRAME_SIZES(1);
 
   static constexpr int kCallerFPOffset = +0 * kSystemPointerSize;
   static constexpr int kCallerPCOffset = kFPOnStackSize;

src/x64/macro-assembler-x64.cc

@@ -2422,12 +2422,10 @@ void MacroAssembler::EnterExitFramePrologue(bool save_rax,
   pushq(rbp);
   movq(rbp, rsp);
 
-  // Reserve room for entry stack pointer and push the code object.
+  // Reserve room for entry stack pointer.
   Push(Immediate(StackFrame::TypeToMarker(frame_type)));
   DCHECK_EQ(-2 * kSystemPointerSize, ExitFrameConstants::kSPOffset);
   Push(Immediate(0));  // Saved entry sp, patched before call.
-  Move(kScratchRegister, CodeObject(), RelocInfo::EMBEDDED_OBJECT);
-  Push(kScratchRegister);  // Accessed from ExitFrame::code_slot.
 
   // Save the frame pointer and the context in top.
   if (save_rax) {