Revert "[ptr-cage] Reserve base registers on x64 (r14) and arm64 (x28)"

This reverts commit 0c63aa9e.

Reason for revert: Breaking clusterfuzz builds

Original change's description:
> [ptr-cage] Reserve base registers on x64 (r14) and arm64 (x28)
>
> Also add a V8_COMPRESS_POINTERS_IN_SHARED_CAGE define when pointer
> compression is enabled.
>
> This CL is to get performance numbers for reserving an extra register.
> There is no actual pointer cage yet, and the base register will always
> have the same value as the root register. The pointer decompression code
> is switched to using the base register instead of the root register.
>
> Bug: v8:11460
> Change-Id: I40bae556c2098608fb6fc193a52694e3f54754bd
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2716075
> Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
> Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
> Reviewed-by: Leszek Swirski <leszeks@chromium.org>
> Commit-Queue: Shu-yu Guo <syg@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#73204}

Bug: v8:11460
Change-Id: Idebf1fc6eeeda880a21d65b6f2c674fa58690bfa
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2737812
Auto-Submit: Shu-yu Guo <syg@chromium.org>
Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#73205}

BUILD.gn

@@ -108,7 +108,6 @@ declare_args() {
 
   # Enable pointer compression (sets -dV8_COMPRESS_POINTERS).
   v8_enable_pointer_compression = ""
-  v8_enable_pointer_compression_shared_cage = ""
   v8_enable_31bit_smis_on_64bit_arch = false
 
   # Sets -dOBJECT_PRINT.
@@ -325,9 +324,6 @@ if (v8_enable_pointer_compression == "") {
   v8_enable_pointer_compression =
       v8_current_cpu == "arm64" || v8_current_cpu == "x64"
 }
-if (v8_enable_pointer_compression_shared_cage == "") {
-  v8_enable_pointer_compression_shared_cage = v8_enable_pointer_compression
-}
 if (v8_enable_fast_torque == "") {
   v8_enable_fast_torque = v8_enable_fast_mksnapshot
 }
@@ -392,10 +388,6 @@ assert(!v8_use_multi_snapshots || !v8_control_flow_integrity,
 assert(!v8_enable_heap_sandbox || v8_enable_pointer_compression,
        "V8 Heap Sandbox requires pointer compression")
 
-assert(
-    !v8_enable_pointer_compression_shared_cage || v8_enable_pointer_compression,
-    "Can't share a pointer compression cage if pointers aren't compressed")
-
 assert(!v8_enable_unconditional_write_barriers || !v8_disable_write_barriers,
        "Write barriers can't be both enabled and disabled")
 
@@ -535,7 +527,6 @@ config("external_startup_data") {
 external_v8_defines = [
   "V8_ENABLE_CHECKS",
   "V8_COMPRESS_POINTERS",
-  "V8_COMPRESS_POINTERS_IN_SHARED_CAGE",
   "V8_31BIT_SMIS_ON_64BIT_ARCH",
   "V8_COMPRESS_ZONES",
   "V8_HEAP_SANDBOX",
@@ -553,9 +544,6 @@ if (v8_enable_v8_checks) {
 if (v8_enable_pointer_compression) {
   enabled_external_v8_defines += [ "V8_COMPRESS_POINTERS" ]
 }
-if (v8_enable_pointer_compression_shared_cage) {
-  enabled_external_v8_defines += [ "V8_COMPRESS_POINTERS_IN_SHARED_CAGE" ]
-}
 if (v8_enable_pointer_compression || v8_enable_31bit_smis_on_64bit_arch) {
   enabled_external_v8_defines += [ "V8_31BIT_SMIS_ON_64BIT_ARCH" ]
 }

src/baseline/x64/baseline-assembler-x64-inl.h

@@ -17,7 +17,7 @@ namespace detail {
 
 // Avoid using kScratchRegister(==r10) since the macro-assembler doesn't use
 // this scope and will conflict.
-static constexpr Register kScratchRegisters[] = {r8, r9, r11, r12, r15};
+static constexpr Register kScratchRegisters[] = {r8, r9, r11, r12, r14, r15};
 static constexpr int kNumScratchRegisters = arraysize(kScratchRegisters);
 
 }  // namespace detail

src/builtins/arm64/builtins-arm64.cc

@@ -632,11 +632,6 @@ void Generate_JSEntryVariant(MacroAssembler* masm, StackFrame::Type type,
     // Initialize the root register.
     // C calling convention. The first argument is passed in x0.
     __ Mov(kRootRegister, x0);
-
-#ifdef V8_COMPRESS_POINTERS_IN_SHARED_CAGE
-    // Initialize the pointer cage base register.
-    __ Mov(kPointerCageBaseRegister, x0);
-#endif
   }
 
   // Set up fp. It points to the {fp, lr} pair pushed as the last step in
@@ -915,13 +910,10 @@ static void Generate_JSEntryTrampolineHelper(MacroAssembler* masm,
     __ Mov(x23, x19);
     __ Mov(x24, x19);
     __ Mov(x25, x19);
-#ifndef V8_COMPRESS_POINTERS_IN_SHARED_CAGE
     __ Mov(x28, x19);
-#endif
     // Don't initialize the reserved registers.
     // x26 : root register (kRootRegister).
     // x27 : context pointer (cp).
-    // x28 : pointer cage base register (kPointerCageBaseRegister).
     // x29 : frame pointer (fp).
 
     Handle<Code> builtin = is_construct

src/builtins/x64/builtins-x64.cc

@@ -377,12 +377,6 @@ void Generate_JSEntryVariant(MacroAssembler* masm, StackFrame::Type type,
     // Initialize the root register.
     // C calling convention. The first argument is passed in arg_reg_1.
     __ movq(kRootRegister, arg_reg_1);
-
-#ifdef V8_COMPRESS_POINTERS_IN_SHARED_CAGE
-    // Initialize the pointer cage base register.
-    // TODO(syg): Actually make a cage.
-    __ movq(kPointerCageBaseRegister, arg_reg_1);
-#endif
   }
 
   // Save copies of the top frame descriptor on the stack.
@@ -1639,7 +1633,7 @@ void Builtins::Generate_BaselineOutOfLinePrologue(MacroAssembler* masm) {
   __ incl(
       FieldOperand(feedback_vector, FeedbackVector::kInvocationCountOffset));
 
-  Register return_address = r15;
+  Register return_address = r12;
 
   __ RecordComment("[ Frame Setup");
   // Save the return address, so that we can push it to the end of the newly
@@ -2816,8 +2810,8 @@ void Builtins::Generate_CEntry(MacroAssembler* masm, int result_size,
     DCHECK(save_doubles == kDontSaveFPRegs);
     DCHECK(!builtin_exit_frame);
     __ EnterApiExitFrame(arg_stack_space);
-    // Move argc into r12 (argv is already in r15).
-    __ movq(r12, rax);
+    // Move argc into r14 (argv is already in r15).
+    __ movq(r14, rax);
   } else {
     __ EnterExitFrame(
         arg_stack_space, save_doubles == kSaveFPRegs,
@@ -2827,7 +2821,7 @@ void Builtins::Generate_CEntry(MacroAssembler* masm, int result_size,
   // rbx: pointer to builtin function  (C callee-saved).
   // rbp: frame pointer of exit frame  (restored after C call).
   // rsp: stack pointer (restored after C call).
-  // r12: number of arguments including receiver (C callee-saved).
+  // r14: number of arguments including receiver (C callee-saved).
   // r15: argv pointer (C callee-saved).
 
   // Check stack alignment.
@@ -2840,7 +2834,7 @@ void Builtins::Generate_CEntry(MacroAssembler* masm, int result_size,
   if (result_size <= kMaxRegisterResultSize) {
     // Pass a pointer to the Arguments object as the first argument.
     // Return result in single register (rax), or a register pair (rax, rdx).
-    __ movq(kCCallArg0, r12);  // argc.
+    __ movq(kCCallArg0, r14);  // argc.
     __ movq(kCCallArg1, r15);  // argv.
     __ Move(kCCallArg2, ExternalReference::isolate_address(masm->isolate()));
   } else {
@@ -2848,7 +2842,7 @@ void Builtins::Generate_CEntry(MacroAssembler* masm, int result_size,
     // Pass a pointer to the result location as the first argument.
     __ leaq(kCCallArg0, StackSpaceOperand(kArgExtraStackSpace));
     // Pass a pointer to the Arguments object as the second argument.
-    __ movq(kCCallArg1, r12);  // argc.
+    __ movq(kCCallArg1, r14);  // argc.
     __ movq(kCCallArg2, r15);  // argv.
     __ Move(kCCallArg3, ExternalReference::isolate_address(masm->isolate()));
   }
@@ -2872,12 +2866,12 @@ void Builtins::Generate_CEntry(MacroAssembler* masm, int result_size,
   // should have returned the exception sentinel.
   if (FLAG_debug_code) {
     Label okay;
-    __ LoadRoot(kScratchRegister, RootIndex::kTheHoleValue);
+    __ LoadRoot(r14, RootIndex::kTheHoleValue);
     ExternalReference pending_exception_address = ExternalReference::Create(
         IsolateAddressId::kPendingExceptionAddress, masm->isolate());
     Operand pending_exception_operand =
         masm->ExternalReferenceAsOperand(pending_exception_address);
-    __ cmp_tagged(kScratchRegister, pending_exception_operand);
+    __ cmp_tagged(r14, pending_exception_operand);
     __ j(equal, &okay, Label::kNear);
     __ int3();
     __ bind(&okay);
@@ -3218,7 +3212,7 @@ void Builtins::Generate_GenericJSToWasmWrapper(MacroAssembler* masm) {
       kLastSpillOffset - kSystemPointerSize;
   // For Integer section.
   // Set the current_int_param_slot to point to the start of the section.
-  Register current_int_param_slot = r10;
+  Register current_int_param_slot = r14;
   __ leaq(current_int_param_slot, MemOperand(rsp, -kSystemPointerSize));
   Register params_size = param_count;
   param_count = no_reg;
@@ -3332,7 +3326,7 @@ void Builtins::Generate_GenericJSToWasmWrapper(MacroAssembler* masm) {
   // ----------- S t a t e -------------
   //  -- r8  : start_int_section
   //  -- rdi : start_float_section
-  //  -- r10 : current_int_param_slot
+  //  -- r14 : current_int_param_slot
   //  -- r15 : current_float_param_slot
   //  -- r11 : valuetypes_array_ptr
   //  -- r12 : valuetype
@@ -3764,7 +3758,7 @@ int Offset(ExternalReference ref0, ExternalReference ref1) {
 }
 
 // Calls an API function.  Allocates HandleScope, extracts returned value
-// from handle and propagates exceptions.  Clobbers r12, r15, rbx and
+// from handle and propagates exceptions.  Clobbers r14, r15, rbx and
 // caller-save registers.  Restores context.  On return removes
 // stack_space * kSystemPointerSize (GCed).
 void CallApiFunctionAndReturn(MacroAssembler* masm, Register function_address,
@@ -3791,7 +3785,7 @@ void CallApiFunctionAndReturn(MacroAssembler* masm, Register function_address,
 
   DCHECK(rdx == function_address || r8 == function_address);
   // Allocate HandleScope in callee-save registers.
-  Register prev_next_address_reg = r12;
+  Register prev_next_address_reg = r14;
   Register prev_limit_reg = rbx;
   Register base_reg = r15;
   __ Move(base_reg, next_address);

src/codegen/arm64/macro-assembler-arm64-inl.h

@@ -1036,9 +1036,6 @@ void TurboAssembler::Uxtw(const Register& rd, const Register& rn) {
 void TurboAssembler::InitializeRootRegister() {
   ExternalReference isolate_root = ExternalReference::isolate_root(isolate());
   Mov(kRootRegister, Operand(isolate_root));
-#ifdef V8_COMPRESS_POINTERS_IN_SHARED_CAGE
-  Mov(kPointerCageBaseRegister, Operand(isolate_root));
-#endif
 }
 
 void MacroAssembler::SmiTag(Register dst, Register src) {

src/codegen/arm64/macro-assembler-arm64.cc

@@ -2816,14 +2816,14 @@ void TurboAssembler::DecompressTaggedPointer(const Register& destination,
                                              const MemOperand& field_operand) {
   RecordComment("[ DecompressTaggedPointer");
   Ldr(destination.W(), field_operand);
-  Add(destination, kPointerCageBaseRegister, destination);
+  Add(destination, kRootRegister, destination);
   RecordComment("]");
 }
 
 void TurboAssembler::DecompressTaggedPointer(const Register& destination,
                                              const Register& source) {
   RecordComment("[ DecompressTaggedPointer");
-  Add(destination, kPointerCageBaseRegister, Operand(source, UXTW));
+  Add(destination, kRootRegister, Operand(source, UXTW));
   RecordComment("]");
 }
 
@@ -2831,7 +2831,7 @@ void TurboAssembler::DecompressAnyTagged(const Register& destination,
                                          const MemOperand& field_operand) {
   RecordComment("[ DecompressAnyTagged");
   Ldr(destination.W(), field_operand);
-  Add(destination, kPointerCageBaseRegister, destination);
+  Add(destination, kRootRegister, destination);
   RecordComment("]");
 }
 

src/codegen/arm64/register-arm64.h

@@ -30,21 +30,11 @@ namespace internal {
 
 // x18 is the platform register and is reserved for the use of platform ABIs.
 // It is known to be reserved by the OS at least on Windows and iOS.
-#define ALWAYS_ALLOCATABLE_GENERAL_REGISTERS(R)                  \
+#define ALLOCATABLE_GENERAL_REGISTERS(R)                  \
   R(x0)  R(x1)  R(x2)  R(x3)  R(x4)  R(x5)  R(x6)  R(x7)  \
   R(x8)  R(x9)  R(x10) R(x11) R(x12) R(x13) R(x14) R(x15) \
          R(x19) R(x20) R(x21) R(x22) R(x23) R(x24) R(x25) \
-  R(x27)
-
-#ifdef V8_COMPRESS_POINTERS_IN_SHARED_CAGE
-#define MAYBE_ALLOCATABLE_GENERAL_REGISTERS(R)
-#else
-#define MAYBE_ALLOCATABLE_GENERAL_REGISTERS(R) R(x28)
-#endif
-
-#define ALLOCATABLE_GENERAL_REGISTERS(V)  \
-  ALWAYS_ALLOCATABLE_GENERAL_REGISTERS(V) \
-  MAYBE_ALLOCATABLE_GENERAL_REGISTERS(V)
+  R(x27) R(x28)
 
 #define FLOAT_REGISTERS(V)                                \
   V(s0)  V(s1)  V(s2)  V(s3)  V(s4)  V(s5)  V(s6)  V(s7)  \
@@ -468,12 +458,6 @@ ALIAS_REGISTER(Register, wip1, w17);
 // Root register.
 ALIAS_REGISTER(Register, kRootRegister, x26);
 ALIAS_REGISTER(Register, rr, x26);
-// Pointer cage base register.
-#ifdef V8_COMPRESS_POINTERS_IN_SHARED_CAGE
-ALIAS_REGISTER(Register, kPointerCageBaseRegister, x28);
-#else
-ALIAS_REGISTER(Register, kPointerCageBaseRegister, kRootRegister);
-#endif
 // Context pointer register.
 ALIAS_REGISTER(Register, cp, x27);
 ALIAS_REGISTER(Register, fp, x29);

src/codegen/interface-descriptors.cc

@@ -25,9 +25,6 @@ void CallInterfaceDescriptorData::InitializePlatformSpecific(
     // within the calling convention are disallowed.
 #ifdef DEBUG
     CHECK_NE(registers[i], kRootRegister);
-#ifdef V8_COMPRESS_POINTERS_IN_SHARED_CAGE
-    CHECK_NE(registers[i], kPointerCageBaseRegister);
-#endif
     // Check for duplicated registers.
     for (int j = i + 1; j < register_parameter_count; j++) {
       CHECK_NE(registers[i], registers[j]);

src/codegen/x64/macro-assembler-x64.cc

@@ -288,7 +288,7 @@ void TurboAssembler::DecompressTaggedPointer(Register destination,
                                              Operand field_operand) {
   RecordComment("[ DecompressTaggedPointer");
   movl(destination, field_operand);
-  addq(destination, kPointerCageBaseRegister);
+  addq(destination, kRootRegister);
   RecordComment("]");
 }
 
@@ -296,7 +296,7 @@ void TurboAssembler::DecompressTaggedPointer(Register destination,
                                              Register source) {
   RecordComment("[ DecompressTaggedPointer");
   movl(destination, source);
-  addq(destination, kPointerCageBaseRegister);
+  addq(destination, kRootRegister);
   RecordComment("]");
 }
 
@@ -304,7 +304,7 @@ void TurboAssembler::DecompressAnyTagged(Register destination,
                                          Operand field_operand) {
   RecordComment("[ DecompressAnyTagged");
   movl(destination, field_operand);
-  addq(destination, kPointerCageBaseRegister);
+  addq(destination, kRootRegister);
   RecordComment("]");
 }
 
@@ -3379,7 +3379,7 @@ void TurboAssembler::AllocateStackSpace(int bytes) {
 }
 #endif
 
-void MacroAssembler::EnterExitFramePrologue(Register saved_rax_reg,
+void MacroAssembler::EnterExitFramePrologue(bool save_rax,
                                             StackFrame::Type frame_type) {
   DCHECK(frame_type == StackFrame::EXIT ||
          frame_type == StackFrame::BUILTIN_EXIT);
@@ -3399,8 +3399,8 @@ void MacroAssembler::EnterExitFramePrologue(Register saved_rax_reg,
   Push(Immediate(0));  // Saved entry sp, patched before call.
 
   // Save the frame pointer and the context in top.
-  if (saved_rax_reg != no_reg) {
-    movq(saved_rax_reg, rax);  // Backup rax in callee-save register.
+  if (save_rax) {
+    movq(r14, rax);  // Backup rax in callee-save register.
   }
 
   Store(
@@ -3449,19 +3449,18 @@ void MacroAssembler::EnterExitFrameEpilogue(int arg_stack_space,
 
 void MacroAssembler::EnterExitFrame(int arg_stack_space, bool save_doubles,
                                     StackFrame::Type frame_type) {
-  Register saved_rax_reg = r12;
-  EnterExitFramePrologue(saved_rax_reg, frame_type);
+  EnterExitFramePrologue(true, frame_type);
 
   // Set up argv in callee-saved register r15. It is reused in LeaveExitFrame,
   // so it must be retained across the C-call.
   int offset = StandardFrameConstants::kCallerSPOffset - kSystemPointerSize;
-  leaq(r15, Operand(rbp, saved_rax_reg, times_system_pointer_size, offset));
+  leaq(r15, Operand(rbp, r14, times_system_pointer_size, offset));
 
   EnterExitFrameEpilogue(arg_stack_space, save_doubles);
 }
 
 void MacroAssembler::EnterApiExitFrame(int arg_stack_space) {
-  EnterExitFramePrologue(no_reg, StackFrame::EXIT);
+  EnterExitFramePrologue(false, StackFrame::EXIT);
   EnterExitFrameEpilogue(arg_stack_space, false);
 }
 

src/codegen/x64/macro-assembler-x64.h

@@ -704,9 +704,6 @@ class V8_EXPORT_PRIVATE TurboAssembler : public TurboAssemblerBase {
   void InitializeRootRegister() {
     ExternalReference isolate_root = ExternalReference::isolate_root(isolate());
     Move(kRootRegister, isolate_root);
-#ifdef V8_COMPRESS_POINTERS_IN_SHARED_CAGE
-    Move(kPointerCageBaseRegister, isolate_root);
-#endif
   }
 
   void SaveRegisters(RegList registers);
@@ -1149,8 +1146,7 @@ class V8_EXPORT_PRIVATE MacroAssembler : public TurboAssembler {
                       Register actual_parameter_count, Label* done,
                       InvokeFlag flag);
 
-  void EnterExitFramePrologue(Register saved_rax_reg,
-                              StackFrame::Type frame_type);
+  void EnterExitFramePrologue(bool save_rax, StackFrame::Type frame_type);
 
   // Allocates arg_stack_space * kSystemPointerSize memory (not GCed) on the
   // stack accessible via StackSpaceOperand.

src/codegen/x64/register-x64.h

@@ -29,7 +29,7 @@ namespace internal {
   V(r14)                     \
   V(r15)
 
-#define ALWAYS_ALLOCATABLE_GENERAL_REGISTERS(V) \
+#define ALLOCATABLE_GENERAL_REGISTERS(V) \
   V(rax)                                 \
   V(rbx)                                 \
   V(rdx)                                 \
@@ -40,18 +40,9 @@ namespace internal {
   V(r9)                                  \
   V(r11)                                 \
   V(r12)                                 \
+  V(r14)                                 \
   V(r15)
 
-#ifdef V8_COMPRESS_POINTERS_IN_SHARED_CAGE
-#define MAYBE_ALLOCATABLE_GENERAL_REGISTERS(V)
-#else
-#define MAYBE_ALLOCATABLE_GENERAL_REGISTERS(V) V(r14)
-#endif
-
-#define ALLOCATABLE_GENERAL_REGISTERS(V)  \
-  ALWAYS_ALLOCATABLE_GENERAL_REGISTERS(V) \
-  MAYBE_ALLOCATABLE_GENERAL_REGISTERS(V)
-
 enum RegisterCode {
 #define REGISTER_CODE(R) kRegCode_##R,
   GENERAL_REGISTERS(REGISTER_CODE)
@@ -210,7 +201,7 @@ constexpr Register kAllocateSizeRegister = rdx;
 constexpr Register kSpeculationPoisonRegister = r12;
 constexpr Register kInterpreterAccumulatorRegister = rax;
 constexpr Register kInterpreterBytecodeOffsetRegister = r9;
-constexpr Register kInterpreterBytecodeArrayRegister = r12;
+constexpr Register kInterpreterBytecodeArrayRegister = r14;
 constexpr Register kInterpreterDispatchTableRegister = r15;
 
 constexpr Register kJavaScriptCallArgCountRegister = rax;
@@ -230,11 +221,6 @@ constexpr Register kWasmInstanceRegister = rsi;
 constexpr Register kScratchRegister = r10;
 constexpr XMMRegister kScratchDoubleReg = xmm15;
 constexpr Register kRootRegister = r13;  // callee save
-#ifdef V8_COMPRESS_POINTERS_IN_SHARED_CAGE
-constexpr Register kPointerCageBaseRegister = r14;  // callee save
-#else
-constexpr Register kPointerCageBaseRegister = kRootRegister;
-#endif
 
 constexpr Register kOffHeapTrampolineRegister = kScratchRegister;
 

src/deoptimizer/deoptimizer.cc

@@ -962,10 +962,6 @@ void Deoptimizer::DoComputeOutputFrames() {
   FrameDescription* topmost = output_[count - 1];
   topmost->GetRegisterValues()->SetRegister(kRootRegister.code(),
                                             isolate()->isolate_root());
-#ifdef V8_COMPRESS_POINTERS_IN_SHARED_CAGE
-  topmost->GetRegisterValues()->SetRegister(kPointerCageBaseRegister.code(),
-                                            isolate()->isolate_root());
-#endif
 
   // Print some helpful diagnostic information.
   if (verbose_tracing_enabled()) {

src/wasm/baseline/liftoff-assembler-defs.h

@@ -58,15 +58,11 @@ constexpr RegList kLiftoffAssemblerFpCacheRegs = LowDwVfpRegister::ListOf(
 
 #elif V8_TARGET_ARCH_ARM64
 
-// x16: ip0, x17: ip1, x18: platform register, x26: root, x27: cp, x8: base,
-// x29: fp, x30: lr, x31: xzr.
+// x16: ip0, x17: ip1, x18: platform register, x26: root, x27: cp, x29: fp,
+// x30: lr, x31: xzr.
 constexpr RegList kLiftoffAssemblerGpCacheRegs =
     CPURegister::ListOf(x0, x1, x2, x3, x4, x5, x6, x7, x8, x9, x10, x11, x12,
-#ifdef V8_COMPRESS_POINTERS_IN_SHARED_CAGE
-                        x13, x14, x15, x19, x20, x21, x22, x23, x24, x25);
-#else
                         x13, x14, x15, x19, x20, x21, x22, x23, x24, x25, x28);
-#endif
 
 // d15: fp_zero, d30-d31: macro-assembler scratch V Registers.
 constexpr RegList kLiftoffAssemblerFpCacheRegs = CPURegister::ListOf(

test/cctest/test-macro-assembler-x64.cc

@@ -60,18 +60,10 @@ using F0 = int();
 static void EntryCode(MacroAssembler* masm) {
   // Smi constant register is callee save.
   __ pushq(kRootRegister);
-#ifdef V8_COMPRESS_POINTERS_IN_SHARED_CAGE
-  __ pushq(kPointerCageBaseRegister);
-#endif
   __ InitializeRootRegister();
 }
 
-static void ExitCode(MacroAssembler* masm) {
-#ifdef V8_COMPRESS_POINTERS_IN_SHARED_CAGE
-  __ popq(kPointerCageBaseRegister);
-#endif
-  __ popq(kRootRegister);
-}
+static void ExitCode(MacroAssembler* masm) { __ popq(kRootRegister); }
 
 TEST(Smi) {
   // Check that C++ Smi operations work as expected.