// Copyright 2013 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#if V8_TARGET_ARCH_ARM64

#include "src/api-arguments.h"
#include "src/arm64/assembler-arm64-inl.h"
#include "src/arm64/macro-assembler-arm64-inl.h"
#include "src/bootstrapper.h"
#include "src/code-stubs.h"
#include "src/counters.h"
#include "src/frame-constants.h"
#include "src/frames.h"
#include "src/heap/heap-inl.h"
#include "src/ic/ic.h"
#include "src/ic/stub-cache.h"
#include "src/isolate.h"
#include "src/objects/regexp-match-info.h"
#include "src/regexp/jsregexp.h"
#include "src/regexp/regexp-macro-assembler.h"
#include "src/runtime/runtime.h"

#include "src/arm64/code-stubs-arm64.h"  // Cannot be the first include.

namespace v8 {
namespace internal {

#define __ ACCESS_MASM(masm)

void ArrayNArgumentsConstructorStub::Generate(MacroAssembler* masm) {
  __ Mov(x5, Operand(x0, LSL, kPointerSizeLog2));
  __ Str(x1, MemOperand(__ StackPointer(), x5));
  __ Push(x1, x2);
  __ Add(x0, x0, Operand(3));
  __ TailCallRuntime(Runtime::kNewArray);
}


void DoubleToIStub::Generate(MacroAssembler* masm) {
  Label done;
  Register result = destination();

  DCHECK(result.Is64Bits());

  UseScratchRegisterScope temps(masm);
  Register scratch1 = temps.AcquireX();
  Register scratch2 = temps.AcquireX();
  DoubleRegister double_scratch = temps.AcquireD();

  __ Peek(double_scratch, 0);
  // Try to convert with a FPU convert instruction.  This handles all
  // non-saturating cases.
  __ TryConvertDoubleToInt64(result, double_scratch, &done);
  __ Fmov(result, double_scratch);

  // If we reach here we need to manually convert the input to an int32.

  // Extract the exponent.
  Register exponent = scratch1;
  __ Ubfx(exponent, result, HeapNumber::kMantissaBits,
          HeapNumber::kExponentBits);

  // It the exponent is >= 84 (kMantissaBits + 32), the result is always 0 since
  // the mantissa gets shifted completely out of the int32_t result.
  __ Cmp(exponent, HeapNumber::kExponentBias + HeapNumber::kMantissaBits + 32);
  __ CzeroX(result, ge);
  __ B(ge, &done);

  // The Fcvtzs sequence handles all cases except where the conversion causes
  // signed overflow in the int64_t target. Since we've already handled
  // exponents >= 84, we can guarantee that 63 <= exponent < 84.

  if (masm->emit_debug_code()) {
    __ Cmp(exponent, HeapNumber::kExponentBias + 63);
    // Exponents less than this should have been handled by the Fcvt case.
    __ Check(ge, AbortReason::kUnexpectedValue);
  }

  // Isolate the mantissa bits, and set the implicit '1'.
  Register mantissa = scratch2;
  __ Ubfx(mantissa, result, 0, HeapNumber::kMantissaBits);
  __ Orr(mantissa, mantissa, 1UL << HeapNumber::kMantissaBits);

  // Negate the mantissa if necessary.
  __ Tst(result, kXSignMask);
  __ Cneg(mantissa, mantissa, ne);

  // Shift the mantissa bits in the correct place. We know that we have to shift
  // it left here, because exponent >= 63 >= kMantissaBits.
  __ Sub(exponent, exponent,
         HeapNumber::kExponentBias + HeapNumber::kMantissaBits);
  __ Lsl(result, mantissa, exponent);

  __ Bind(&done);
  __ Ret();
}


void MathPowStub::Generate(MacroAssembler* masm) {
  // Stack on entry:
  // sp[0]: Exponent (as a tagged value).
  // sp[1]: Base (as a tagged value).
  //
  // The (tagged) result will be returned in x0, as a heap number.

  Register exponent_tagged = MathPowTaggedDescriptor::exponent();
  DCHECK(exponent_tagged.is(x11));
  Register exponent_integer = MathPowIntegerDescriptor::exponent();
  DCHECK(exponent_integer.is(x12));
  Register saved_lr = x19;
  VRegister result_double = d0;
  VRegister base_double = d0;
  VRegister exponent_double = d1;
  VRegister base_double_copy = d2;
  VRegister scratch1_double = d6;
  VRegister scratch0_double = d7;

  // A fast-path for integer exponents.
  Label exponent_is_smi, exponent_is_integer;
  // Allocate a heap number for the result, and return it.
  Label done;

  // Unpack the inputs.
  if (exponent_type() == TAGGED) {
    __ JumpIfSmi(exponent_tagged, &exponent_is_smi);
    __ Ldr(exponent_double,
           FieldMemOperand(exponent_tagged, HeapNumber::kValueOffset));
  }

  // Handle double (heap number) exponents.
  if (exponent_type() != INTEGER) {
    // Detect integer exponents stored as doubles and handle those in the
    // integer fast-path.
    __ TryRepresentDoubleAsInt64(exponent_integer, exponent_double,
                                 scratch0_double, &exponent_is_integer);

    {
      AllowExternalCallThatCantCauseGC scope(masm);
      __ Mov(saved_lr, lr);
      __ CallCFunction(
          ExternalReference::power_double_double_function(isolate()), 0, 2);
      __ Mov(lr, saved_lr);
      __ B(&done);
    }

    // Handle SMI exponents.
    __ Bind(&exponent_is_smi);
    //  x10   base_tagged       The tagged base (input).
    //  x11   exponent_tagged   The tagged exponent (input).
    //  d1    base_double       The base as a double.
    __ SmiUntag(exponent_integer, exponent_tagged);
  }

  __ Bind(&exponent_is_integer);
  //  x10   base_tagged       The tagged base (input).
  //  x11   exponent_tagged   The tagged exponent (input).
  //  x12   exponent_integer  The exponent as an integer.
  //  d1    base_double       The base as a double.

  // Find abs(exponent). For negative exponents, we can find the inverse later.
  Register exponent_abs = x13;
  __ Cmp(exponent_integer, 0);
  __ Cneg(exponent_abs, exponent_integer, mi);
  //  x13   exponent_abs      The value of abs(exponent_integer).

  // Repeatedly multiply to calculate the power.
  //  result = 1.0;
  //  For each bit n (exponent_integer{n}) {
  //    if (exponent_integer{n}) {
  //      result *= base;
  //    }
  //    base *= base;
  //    if (remaining bits in exponent_integer are all zero) {
  //      break;
  //    }
  //  }
  Label power_loop, power_loop_entry, power_loop_exit;
  __ Fmov(scratch1_double, base_double);
  __ Fmov(base_double_copy, base_double);
  __ Fmov(result_double, 1.0);
  __ B(&power_loop_entry);

  __ Bind(&power_loop);
  __ Fmul(scratch1_double, scratch1_double, scratch1_double);
  __ Lsr(exponent_abs, exponent_abs, 1);
  __ Cbz(exponent_abs, &power_loop_exit);

  __ Bind(&power_loop_entry);
  __ Tbz(exponent_abs, 0, &power_loop);
  __ Fmul(result_double, result_double, scratch1_double);
  __ B(&power_loop);

  __ Bind(&power_loop_exit);

  // If the exponent was positive, result_double holds the result.
  __ Tbz(exponent_integer, kXSignBit, &done);

  // The exponent was negative, so find the inverse.
  __ Fmov(scratch0_double, 1.0);
  __ Fdiv(result_double, scratch0_double, result_double);
  // ECMA-262 only requires Math.pow to return an 'implementation-dependent
  // approximation' of base^exponent. However, mjsunit/math-pow uses Math.pow
  // to calculate the subnormal value 2^-1074. This method of calculating
  // negative powers doesn't work because 2^1074 overflows to infinity. To
  // catch this corner-case, we bail out if the result was 0. (This can only
  // occur if the divisor is infinity or the base is zero.)
  __ Fcmp(result_double, 0.0);
  __ B(&done, ne);

  AllowExternalCallThatCantCauseGC scope(masm);
  __ Mov(saved_lr, lr);
  __ Fmov(base_double, base_double_copy);
  __ Scvtf(exponent_double, exponent_integer);
  __ CallCFunction(ExternalReference::power_double_double_function(isolate()),
                   0, 2);
  __ Mov(lr, saved_lr);
  __ Bind(&done);
  __ Ret();
}

void CodeStub::GenerateStubsAheadOfTime(Isolate* isolate) {
  // It is important that the following stubs are generated in this order
  // because pregenerated stubs can only call other pregenerated stubs.
  CEntryStub::GenerateAheadOfTime(isolate);
  CommonArrayConstructorStub::GenerateStubsAheadOfTime(isolate);
  StoreFastElementStub::GenerateAheadOfTime(isolate);
}


void CodeStub::GenerateFPStubs(Isolate* isolate) {
  // Floating-point code doesn't get special handling in ARM64, so there's
  // nothing to do here.
  USE(isolate);
}

Movability CEntryStub::NeedsImmovableCode() {
  // CEntryStub stores the return address on the stack before calling into
  // C++ code. In some cases, the VM accesses this address, but it is not used
  // when the C++ code returns to the stub because LR holds the return address
  // in AAPCS64. If the stub is moved (perhaps during a GC), we could end up
  // returning to dead code.
  // TODO(jbramley): Whilst this is the only analysis that makes sense, I can't
  // find any comment to confirm this, and I don't hit any crashes whatever
  // this function returns. The anaylsis should be properly confirmed.
  return kImmovable;
}


void CEntryStub::GenerateAheadOfTime(Isolate* isolate) {
  CEntryStub stub(isolate, 1, kDontSaveFPRegs);
  stub.GetCode();
  CEntryStub stub_fp(isolate, 1, kSaveFPRegs);
  stub_fp.GetCode();
}


void CEntryStub::Generate(MacroAssembler* masm) {
  // The Abort mechanism relies on CallRuntime, which in turn relies on
  // CEntryStub, so until this stub has been generated, we have to use a
  // fall-back Abort mechanism.
  //
  // Note that this stub must be generated before any use of Abort.
  MacroAssembler::NoUseRealAbortsScope no_use_real_aborts(masm);

  ASM_LOCATION("CEntryStub::Generate entry");
  ProfileEntryHookStub::MaybeCallEntryHook(masm);

  // Register parameters:
  //    x0: argc (including receiver, untagged)
  //    x1: target
  // If argv_in_register():
  //    x11: argv (pointer to first argument)
  //
  // The stack on entry holds the arguments and the receiver, with the receiver
  // at the highest address:
  //
  //    sp]argc-1]: receiver
  //    sp[argc-2]: arg[argc-2]
  //    ...           ...
  //    sp[1]:      arg[1]
  //    sp[0]:      arg[0]
  //
  // The arguments are in reverse order, so that arg[argc-2] is actually the
  // first argument to the target function and arg[0] is the last.
  const Register& argc_input = x0;
  const Register& target_input = x1;

  // Calculate argv, argc and the target address, and store them in
  // callee-saved registers so we can retry the call without having to reload
  // these arguments.
  // TODO(jbramley): If the first call attempt succeeds in the common case (as
  // it should), then we might be better off putting these parameters directly
  // into their argument registers, rather than using callee-saved registers and
  // preserving them on the stack.
  const Register& argv = x21;
  const Register& argc = x22;
  const Register& target = x23;

  // Derive argv from the stack pointer so that it points to the first argument
  // (arg[argc-2]), or just below the receiver in case there are no arguments.
  //  - Adjust for the arg[] array.
  Register temp_argv = x11;
  if (!argv_in_register()) {
    __ SlotAddress(temp_argv, x0);
    //  - Adjust for the receiver.
    __ Sub(temp_argv, temp_argv, 1 * kPointerSize);
  }

  // Reserve three slots to preserve x21-x23 callee-saved registers.
  int extra_stack_space = 3;
  // Enter the exit frame.
  FrameScope scope(masm, StackFrame::MANUAL);
  __ EnterExitFrame(
      save_doubles(), x10, extra_stack_space,
      is_builtin_exit() ? StackFrame::BUILTIN_EXIT : StackFrame::EXIT);
  DCHECK(csp.Is(__ StackPointer()));

  // Poke callee-saved registers into reserved space.
  __ Poke(argv, 1 * kPointerSize);
  __ Poke(argc, 2 * kPointerSize);
  __ Poke(target, 3 * kPointerSize);

  // We normally only keep tagged values in callee-saved registers, as they
  // could be pushed onto the stack by called stubs and functions, and on the
  // stack they can confuse the GC. However, we're only calling C functions
  // which can push arbitrary data onto the stack anyway, and so the GC won't
  // examine that part of the stack.
  __ Mov(argc, argc_input);
  __ Mov(target, target_input);
  __ Mov(argv, temp_argv);

  // x21 : argv
  // x22 : argc
  // x23 : call target
  //
  // The stack (on entry) holds the arguments and the receiver, with the
  // receiver at the highest address:
  //
  //         argv[8]:     receiver
  // argv -> argv[0]:     arg[argc-2]
  //         ...          ...
  //         argv[...]:   arg[1]
  //         argv[...]:   arg[0]
  //
  // Immediately below (after) this is the exit frame, as constructed by
  // EnterExitFrame:
  //         fp[8]:    CallerPC (lr)
  //   fp -> fp[0]:    CallerFP (old fp)
  //         fp[-8]:   Space reserved for SPOffset.
  //         fp[-16]:  CodeObject()
  //         csp[...]: Saved doubles, if saved_doubles is true.
  //         csp[32]:  Alignment padding, if necessary.
  //         csp[24]:  Preserved x23 (used for target).
  //         csp[16]:  Preserved x22 (used for argc).
  //         csp[8]:   Preserved x21 (used for argv).
  //  csp -> csp[0]:   Space reserved for the return address.
  //
  // After a successful call, the exit frame, preserved registers (x21-x23) and
  // the arguments (including the receiver) are dropped or popped as
  // appropriate. The stub then returns.
  //
  // After an unsuccessful call, the exit frame and suchlike are left
  // untouched, and the stub either throws an exception by jumping to one of
  // the exception_returned label.

  DCHECK(csp.Is(__ StackPointer()));

  // Prepare AAPCS64 arguments to pass to the builtin.
  __ Mov(x0, argc);
  __ Mov(x1, argv);
  __ Mov(x2, ExternalReference::isolate_address(isolate()));

  Label return_location;
  __ Adr(x12, &return_location);
  __ Poke(x12, 0);

  if (__ emit_debug_code()) {
    // Verify that the slot below fp[kSPOffset]-8 points to the return location
    // (currently in x12).
    UseScratchRegisterScope temps(masm);
    Register temp = temps.AcquireX();
    __ Ldr(temp, MemOperand(fp, ExitFrameConstants::kSPOffset));
    __ Ldr(temp, MemOperand(temp, -static_cast<int64_t>(kXRegSize)));
    __ Cmp(temp, x12);
    __ Check(eq, AbortReason::kReturnAddressNotFoundInFrame);
  }

  // Call the builtin.
  __ Blr(target);
  __ Bind(&return_location);

  // Result returned in x0 or x1:x0 - do not destroy these registers!

  //  x0    result0      The return code from the call.
  //  x1    result1      For calls which return ObjectPair.
  //  x21   argv
  //  x22   argc
  //  x23   target
  const Register& result = x0;

  // Check result for exception sentinel.
  Label exception_returned;
  __ CompareRoot(result, Heap::kExceptionRootIndex);
  __ B(eq, &exception_returned);

  // The call succeeded, so unwind the stack and return.

  // Restore callee-saved registers x21-x23.
  __ Mov(x11, argc);

  __ Peek(argv, 1 * kPointerSize);
  __ Peek(argc, 2 * kPointerSize);
  __ Peek(target, 3 * kPointerSize);

  __ LeaveExitFrame(save_doubles(), x10, x9);
  if (!argv_in_register()) {
    // Drop the remaining stack slots and return from the stub.
    __ DropArguments(x11);
  }
  __ AssertFPCRState();
  __ Ret();

  // Handling of exception.
  __ Bind(&exception_returned);

  ExternalReference pending_handler_context_address(
      IsolateAddressId::kPendingHandlerContextAddress, isolate());
  ExternalReference pending_handler_entrypoint_address(
      IsolateAddressId::kPendingHandlerEntrypointAddress, isolate());
  ExternalReference pending_handler_fp_address(
      IsolateAddressId::kPendingHandlerFPAddress, isolate());
  ExternalReference pending_handler_sp_address(
      IsolateAddressId::kPendingHandlerSPAddress, isolate());

  // Ask the runtime for help to determine the handler. This will set x0 to
  // contain the current pending exception, don't clobber it.
  ExternalReference find_handler(Runtime::kUnwindAndFindExceptionHandler,
                                 isolate());
  DCHECK(csp.Is(masm->StackPointer()));
  {
    FrameScope scope(masm, StackFrame::MANUAL);
    __ Mov(x0, 0);  // argc.
    __ Mov(x1, 0);  // argv.
    __ Mov(x2, ExternalReference::isolate_address(isolate()));
    __ CallCFunction(find_handler, 3);
  }

  // Retrieve the handler context, SP and FP.
  __ Mov(cp, Operand(pending_handler_context_address));
  __ Ldr(cp, MemOperand(cp));
  {
    UseScratchRegisterScope temps(masm);
    Register scratch = temps.AcquireX();
    __ Mov(scratch, Operand(pending_handler_sp_address));
    __ Ldr(scratch, MemOperand(scratch));
    __ Mov(csp, scratch);
  }
  __ Mov(fp, Operand(pending_handler_fp_address));
  __ Ldr(fp, MemOperand(fp));

  // If the handler is a JS frame, restore the context to the frame. Note that
  // the context will be set to (cp == 0) for non-JS frames.
  Label not_js_frame;
  __ Cbz(cp, &not_js_frame);
  __ Str(cp, MemOperand(fp, StandardFrameConstants::kContextOffset));
  __ Bind(&not_js_frame);

  // Compute the handler entry address and jump to it.
  __ Mov(x10, Operand(pending_handler_entrypoint_address));
  __ Ldr(x10, MemOperand(x10));
  __ Br(x10);
}

// This is the entry point from C++. 5 arguments are provided in x0-x4.
// See use of the JSEntryFunction for example in src/execution.cc.
// Input:
//   x0: code entry.
//   x1: function.
//   x2: receiver.
//   x3: argc.
//   x4: argv.
// Output:
//   x0: result.
void JSEntryStub::Generate(MacroAssembler* masm) {
  Register code_entry = x0;

  // Enable instruction instrumentation. This only works on the simulator, and
  // will have no effect on the model or real hardware.
  __ EnableInstrumentation();

  Label invoke, handler_entry, exit;

  __ PushCalleeSavedRegisters();

  ProfileEntryHookStub::MaybeCallEntryHook(masm);

  // Set up the reserved register for 0.0.
  __ Fmov(fp_zero, 0.0);

  // Initialize the root array register
  __ InitializeRootRegister();

  // Build an entry frame (see layout below).
  StackFrame::Type marker = type();
  int64_t bad_frame_pointer = -1L;  // Bad frame pointer to fail if it is used.
  __ Mov(x13, bad_frame_pointer);
  __ Mov(x12, StackFrame::TypeToMarker(marker));
  __ Mov(x11, ExternalReference(IsolateAddressId::kCEntryFPAddress, isolate()));
  __ Ldr(x10, MemOperand(x11));

  __ Push(x13, x12, xzr, x10);
  // Set up fp.
  __ Sub(fp, __ StackPointer(), EntryFrameConstants::kCallerFPOffset);

  // Push the JS entry frame marker. Also set js_entry_sp if this is the
  // outermost JS call.
  Label non_outermost_js, done;
  ExternalReference js_entry_sp(IsolateAddressId::kJSEntrySPAddress, isolate());
  __ Mov(x10, ExternalReference(js_entry_sp));
  __ Ldr(x11, MemOperand(x10));

  // Select between the inner and outermost frame marker, based on the JS entry
  // sp. We assert that the inner marker is zero, so we can use xzr to save a
  // move instruction.
  DCHECK_EQ(StackFrame::INNER_JSENTRY_FRAME, 0);
  __ Cmp(x11, 0);  // If x11 is zero, this is the outermost frame.
  __ Csel(x12, xzr, StackFrame::OUTERMOST_JSENTRY_FRAME, ne);
  __ B(ne, &done);
  __ Str(fp, MemOperand(x10));

  __ Bind(&done);
  __ Push(x12, padreg);

  // The frame set up looks like this:
  // sp[0] : padding.
  // sp[1] : JS entry frame marker.
  // sp[2] : C entry FP.
  // sp[3] : stack frame marker.
  // sp[4] : stack frame marker.
  // sp[5] : bad frame pointer 0xFFF...FF   <- fp points here.

  // Jump to a faked try block that does the invoke, with a faked catch
  // block that sets the pending exception.
  __ B(&invoke);

  // Prevent the constant pool from being emitted between the record of the
  // handler_entry position and the first instruction of the sequence here.
  // There is no risk because Assembler::Emit() emits the instruction before
  // checking for constant pool emission, but we do not want to depend on
  // that.
  {
    Assembler::BlockPoolsScope block_pools(masm);
    __ bind(&handler_entry);
    handler_offset_ = handler_entry.pos();
    // Caught exception: Store result (exception) in the pending exception
    // field in the JSEnv and return a failure sentinel. Coming in here the
    // fp will be invalid because the PushTryHandler below sets it to 0 to
    // signal the existence of the JSEntry frame.
    __ Mov(x10, Operand(ExternalReference(
                    IsolateAddressId::kPendingExceptionAddress, isolate())));
  }
  __ Str(code_entry, MemOperand(x10));
  __ LoadRoot(x0, Heap::kExceptionRootIndex);
  __ B(&exit);

  // Invoke: Link this frame into the handler chain.
  __ Bind(&invoke);

  // Push new stack handler.
  static_assert(StackHandlerConstants::kSize == 2 * kPointerSize,
                "Unexpected offset for StackHandlerConstants::kSize");
  static_assert(StackHandlerConstants::kNextOffset == 0 * kPointerSize,
                "Unexpected offset for StackHandlerConstants::kNextOffset");

  // Link the current handler as the next handler.
  __ Mov(x11, ExternalReference(IsolateAddressId::kHandlerAddress, isolate()));
  __ Ldr(x10, MemOperand(x11));
  __ Push(padreg, x10);

  // Set this new handler as the current one.
  {
    UseScratchRegisterScope temps(masm);
    Register scratch = temps.AcquireX();
    __ Mov(scratch, __ StackPointer());
    __ Str(scratch, MemOperand(x11));
  }

  // If an exception not caught by another handler occurs, this handler
  // returns control to the code after the B(&invoke) above, which
  // restores all callee-saved registers (including cp and fp) to their
  // saved values before returning a failure to C.

  // Invoke the function by calling through the JS entry trampoline builtin.
  // Notice that we cannot store a reference to the trampoline code directly in
  // this stub, because runtime stubs are not traversed when doing GC.

  // Expected registers by Builtins::JSEntryTrampoline
  // x0: code entry.
  // x1: function.
  // x2: receiver.
  // x3: argc.
  // x4: argv.
  __ Call(EntryTrampoline(), RelocInfo::CODE_TARGET);

  // Pop the stack handler and unlink this frame from the handler chain.
  static_assert(StackHandlerConstants::kNextOffset == 0 * kPointerSize,
                "Unexpected offset for StackHandlerConstants::kNextOffset");
  __ Pop(x10, padreg);
  __ Mov(x11, ExternalReference(IsolateAddressId::kHandlerAddress, isolate()));
  __ Drop(StackHandlerConstants::kSlotCount - 2);
  __ Str(x10, MemOperand(x11));

  __ Bind(&exit);
  // x0 holds the result.
  // The stack pointer points to the top of the entry frame pushed on entry from
  // C++ (at the beginning of this stub):
  // sp[0] : padding.
  // sp[1] : JS entry frame marker.
  // sp[2] : C entry FP.
  // sp[3] : stack frame marker.
  // sp[4] : stack frame marker.
  // sp[5] : bad frame pointer 0xFFF...FF   <- fp points here.

  // Check if the current stack frame is marked as the outermost JS frame.
  Label non_outermost_js_2;
  {
    Register c_entry_fp = x11;
    __ PeekPair(x10, c_entry_fp, 1 * kPointerSize);
    __ Cmp(x10, StackFrame::OUTERMOST_JSENTRY_FRAME);
    __ B(ne, &non_outermost_js_2);
    __ Mov(x12, ExternalReference(js_entry_sp));
    __ Str(xzr, MemOperand(x12));
    __ Bind(&non_outermost_js_2);

    // Restore the top frame descriptors from the stack.
    __ Mov(x12,
           ExternalReference(IsolateAddressId::kCEntryFPAddress, isolate()));
    __ Str(c_entry_fp, MemOperand(x12));
  }

  // Reset the stack to the callee saved registers.
  static_assert(EntryFrameConstants::kFixedFrameSize % (2 * kPointerSize) == 0,
                "Size of entry frame is not a multiple of 16 bytes");
  __ Drop(EntryFrameConstants::kFixedFrameSize / kPointerSize);
  // Restore the callee-saved registers and return.
  __ PopCalleeSavedRegisters();
  __ Ret();
}

// The entry hook is a Push (stp) instruction, followed by a call.
static const unsigned int kProfileEntryHookCallSize =
    (1 * kInstructionSize) + Assembler::kCallSizeWithRelocation;

void ProfileEntryHookStub::MaybeCallEntryHookDelayed(TurboAssembler* tasm,
                                                     Zone* zone) {
  if (tasm->isolate()->function_entry_hook() != nullptr) {
    Assembler::BlockConstPoolScope no_const_pools(tasm);
    DontEmitDebugCodeScope no_debug_code(tasm);
    Label entry_hook_call_start;
    tasm->Bind(&entry_hook_call_start);
    tasm->Push(padreg, lr);
    tasm->CallStubDelayed(new (zone) ProfileEntryHookStub(nullptr));
    DCHECK_EQ(tasm->SizeOfCodeGeneratedSince(&entry_hook_call_start),
              kProfileEntryHookCallSize);
    tasm->Pop(lr, padreg);
  }
}

void ProfileEntryHookStub::MaybeCallEntryHook(MacroAssembler* masm) {
  if (masm->isolate()->function_entry_hook() != nullptr) {
    ProfileEntryHookStub stub(masm->isolate());
    Assembler::BlockConstPoolScope no_const_pools(masm);
    DontEmitDebugCodeScope no_debug_code(masm);
    Label entry_hook_call_start;
    __ Bind(&entry_hook_call_start);
    __ Push(padreg, lr);
    __ CallStub(&stub);
    DCHECK_EQ(masm->SizeOfCodeGeneratedSince(&entry_hook_call_start),
              kProfileEntryHookCallSize);
    __ Pop(lr, padreg);
  }
}


void ProfileEntryHookStub::Generate(MacroAssembler* masm) {
  MacroAssembler::NoUseRealAbortsScope no_use_real_aborts(masm);

  // Save all kCallerSaved registers (including lr), since this can be called
  // from anywhere.
  // TODO(jbramley): What about FP registers?
  __ PushCPURegList(kCallerSaved);
  DCHECK(kCallerSaved.IncludesAliasOf(lr));
  const int kNumSavedRegs = kCallerSaved.Count();
  DCHECK_EQ(kNumSavedRegs % 2, 0);

  // Compute the function's address as the first argument.
  __ Sub(x0, lr, kProfileEntryHookCallSize);

#if V8_HOST_ARCH_ARM64
  uintptr_t entry_hook =
      reinterpret_cast<uintptr_t>(isolate()->function_entry_hook());
  __ Mov(x10, entry_hook);
#else
  // Under the simulator we need to indirect the entry hook through a trampoline
  // function at a known address.
  ApiFunction dispatcher(FUNCTION_ADDR(EntryHookTrampoline));
  __ Mov(x10, Operand(ExternalReference(&dispatcher,
                                        ExternalReference::BUILTIN_CALL,
                                        isolate())));
  // It additionally takes an isolate as a third parameter
  __ Mov(x2, ExternalReference::isolate_address(isolate()));
#endif

  // The caller's return address is above the saved temporaries.
  // Grab its location for the second argument to the hook.
  __ SlotAddress(x1, kNumSavedRegs);

  {
    // Create a dummy frame, as CallCFunction requires this.
    FrameScope frame(masm, StackFrame::MANUAL);
    __ CallCFunction(x10, 2, 0);
  }

  __ PopCPURegList(kCallerSaved);
  __ Ret();
}


void DirectCEntryStub::Generate(MacroAssembler* masm) {
  // Put return address on the stack (accessible to GC through exit frame pc).
  __ Poke(lr, 0);
  // Call the C++ function.
  __ Blr(x10);
  // Return to calling code.
  __ Peek(lr, 0);
  __ AssertFPCRState();
  __ Ret();
}

void DirectCEntryStub::GenerateCall(MacroAssembler* masm,
                                    Register target) {
  // Make sure the caller configured the stack pointer (see comment in
  // DirectCEntryStub::Generate).
  DCHECK(csp.Is(__ StackPointer()));

  intptr_t code =
      reinterpret_cast<intptr_t>(GetCode().location());
  __ Mov(lr, Operand(code, RelocInfo::CODE_TARGET));
  __ Mov(x10, target);
  // Branch to the stub.
  __ Blr(lr);
}

template<class T>
static void CreateArrayDispatch(MacroAssembler* masm,
                                AllocationSiteOverrideMode mode) {
  ASM_LOCATION("CreateArrayDispatch");
  if (mode == DISABLE_ALLOCATION_SITES) {
    T stub(masm->isolate(), GetInitialFastElementsKind(), mode);
     __ TailCallStub(&stub);

  } else if (mode == DONT_OVERRIDE) {
    Register kind = x3;
    int last_index =
        GetSequenceIndexFromFastElementsKind(TERMINAL_FAST_ELEMENTS_KIND);
    for (int i = 0; i <= last_index; ++i) {
      Label next;
      ElementsKind candidate_kind = GetFastElementsKindFromSequenceIndex(i);
      // TODO(jbramley): Is this the best way to handle this? Can we make the
      // tail calls conditional, rather than hopping over each one?
      __ CompareAndBranch(kind, candidate_kind, ne, &next);
      T stub(masm->isolate(), candidate_kind);
      __ TailCallStub(&stub);
      __ Bind(&next);
    }

    // If we reached this point there is a problem.
    __ Abort(AbortReason::kUnexpectedElementsKindInArrayConstructor);

  } else {
    UNREACHABLE();
  }
}


// TODO(jbramley): If this needs to be a special case, make it a proper template
// specialization, and not a separate function.
static void CreateArrayDispatchOneArgument(MacroAssembler* masm,
                                           AllocationSiteOverrideMode mode) {
  ASM_LOCATION("CreateArrayDispatchOneArgument");
  // x0 - argc
  // x1 - constructor?
  // x2 - allocation site (if mode != DISABLE_ALLOCATION_SITES)
  // x3 - kind (if mode != DISABLE_ALLOCATION_SITES)
  // sp[0] - last argument

  Register allocation_site = x2;
  Register kind = x3;

  STATIC_ASSERT(PACKED_SMI_ELEMENTS == 0);
  STATIC_ASSERT(HOLEY_SMI_ELEMENTS == 1);
  STATIC_ASSERT(PACKED_ELEMENTS == 2);
  STATIC_ASSERT(HOLEY_ELEMENTS == 3);
  STATIC_ASSERT(PACKED_DOUBLE_ELEMENTS == 4);
  STATIC_ASSERT(HOLEY_DOUBLE_ELEMENTS == 5);

  if (mode == DISABLE_ALLOCATION_SITES) {
    ElementsKind initial = GetInitialFastElementsKind();
    ElementsKind holey_initial = GetHoleyElementsKind(initial);

    ArraySingleArgumentConstructorStub stub_holey(masm->isolate(),
                                                  holey_initial,
                                                  DISABLE_ALLOCATION_SITES);
    __ TailCallStub(&stub_holey);
  } else if (mode == DONT_OVERRIDE) {
    // Is the low bit set? If so, the array is holey.
    Label normal_sequence;
    __ Tbnz(kind, 0, &normal_sequence);

    // We are going to create a holey array, but our kind is non-holey.
    // Fix kind and retry (only if we have an allocation site in the slot).
    __ Orr(kind, kind, 1);

    if (FLAG_debug_code) {
      __ Ldr(x10, FieldMemOperand(allocation_site, 0));
      __ JumpIfNotRoot(x10, Heap::kAllocationSiteMapRootIndex,
                       &normal_sequence);
      __ Assert(eq, AbortReason::kExpectedAllocationSite);
    }

    // Save the resulting elements kind in type info. We can't just store 'kind'
    // in the AllocationSite::transition_info field because elements kind is
    // restricted to a portion of the field; upper bits need to be left alone.
    STATIC_ASSERT(AllocationSite::ElementsKindBits::kShift == 0);
    __ Ldr(x11,
           FieldMemOperand(allocation_site,
                           AllocationSite::kTransitionInfoOrBoilerplateOffset));
    __ Add(x11, x11, Smi::FromInt(kFastElementsKindPackedToHoley));
    __ Str(x11,
           FieldMemOperand(allocation_site,
                           AllocationSite::kTransitionInfoOrBoilerplateOffset));

    __ Bind(&normal_sequence);
    int last_index =
        GetSequenceIndexFromFastElementsKind(TERMINAL_FAST_ELEMENTS_KIND);
    for (int i = 0; i <= last_index; ++i) {
      Label next;
      ElementsKind candidate_kind = GetFastElementsKindFromSequenceIndex(i);
      __ CompareAndBranch(kind, candidate_kind, ne, &next);
      ArraySingleArgumentConstructorStub stub(masm->isolate(), candidate_kind);
      __ TailCallStub(&stub);
      __ Bind(&next);
    }

    // If we reached this point there is a problem.
    __ Abort(AbortReason::kUnexpectedElementsKindInArrayConstructor);
  } else {
    UNREACHABLE();
  }
}


template<class T>
static void ArrayConstructorStubAheadOfTimeHelper(Isolate* isolate) {
  int to_index =
      GetSequenceIndexFromFastElementsKind(TERMINAL_FAST_ELEMENTS_KIND);
  for (int i = 0; i <= to_index; ++i) {
    ElementsKind kind = GetFastElementsKindFromSequenceIndex(i);
    T stub(isolate, kind);
    stub.GetCode();
    if (AllocationSite::ShouldTrack(kind)) {
      T stub1(isolate, kind, DISABLE_ALLOCATION_SITES);
      stub1.GetCode();
    }
  }
}

void CommonArrayConstructorStub::GenerateStubsAheadOfTime(Isolate* isolate) {
  ArrayConstructorStubAheadOfTimeHelper<ArrayNoArgumentConstructorStub>(
      isolate);
  ArrayConstructorStubAheadOfTimeHelper<ArraySingleArgumentConstructorStub>(
      isolate);
  ArrayNArgumentsConstructorStub stub(isolate);
  stub.GetCode();
  ElementsKind kinds[2] = {PACKED_ELEMENTS, HOLEY_ELEMENTS};
  for (int i = 0; i < 2; i++) {
    // For internal arrays we only need a few things
    InternalArrayNoArgumentConstructorStub stubh1(isolate, kinds[i]);
    stubh1.GetCode();
    InternalArraySingleArgumentConstructorStub stubh2(isolate, kinds[i]);
    stubh2.GetCode();
  }
}


void ArrayConstructorStub::GenerateDispatchToArrayStub(
    MacroAssembler* masm,
    AllocationSiteOverrideMode mode) {
  Register argc = x0;
  Label zero_case, n_case;
  __ Cbz(argc, &zero_case);
  __ Cmp(argc, 1);
  __ B(ne, &n_case);

  // One argument.
  CreateArrayDispatchOneArgument(masm, mode);

  __ Bind(&zero_case);
  // No arguments.
  CreateArrayDispatch<ArrayNoArgumentConstructorStub>(masm, mode);

  __ Bind(&n_case);
  // N arguments.
  ArrayNArgumentsConstructorStub stub(masm->isolate());
  __ TailCallStub(&stub);
}


void ArrayConstructorStub::Generate(MacroAssembler* masm) {
  ASM_LOCATION("ArrayConstructorStub::Generate");
  // ----------- S t a t e -------------
  //  -- x0 : argc (only if argument_count() is ANY or MORE_THAN_ONE)
  //  -- x1 : constructor
  //  -- x2 : AllocationSite or undefined
  //  -- x3 : new target
  //  -- sp[0] : last argument
  // -----------------------------------
  Register constructor = x1;
  Register allocation_site = x2;
  Register new_target = x3;

  if (FLAG_debug_code) {
    // The array construct code is only set for the global and natives
    // builtin Array functions which always have maps.

    Label unexpected_map, map_ok;
    // Initial map for the builtin Array function should be a map.
    __ Ldr(x10, FieldMemOperand(constructor,
                                JSFunction::kPrototypeOrInitialMapOffset));
    // Will both indicate a nullptr and a Smi.
    __ JumpIfSmi(x10, &unexpected_map);
    __ JumpIfObjectType(x10, x10, x11, MAP_TYPE, &map_ok);
    __ Bind(&unexpected_map);
    __ Abort(AbortReason::kUnexpectedInitialMapForArrayFunction);
    __ Bind(&map_ok);

    // We should either have undefined in the allocation_site register or a
    // valid AllocationSite.
    __ AssertUndefinedOrAllocationSite(allocation_site);
  }

  // Enter the context of the Array function.
  __ Ldr(cp, FieldMemOperand(x1, JSFunction::kContextOffset));

  Label subclassing;
  __ Cmp(new_target, constructor);
  __ B(ne, &subclassing);

  Register kind = x3;
  Label no_info;
  // Get the elements kind and case on that.
  __ JumpIfRoot(allocation_site, Heap::kUndefinedValueRootIndex, &no_info);

  __ Ldrsw(kind, UntagSmiFieldMemOperand(
                     allocation_site,
                     AllocationSite::kTransitionInfoOrBoilerplateOffset));
  __ And(kind, kind, AllocationSite::ElementsKindBits::kMask);
  GenerateDispatchToArrayStub(masm, DONT_OVERRIDE);

  __ Bind(&no_info);
  GenerateDispatchToArrayStub(masm, DISABLE_ALLOCATION_SITES);

  // Subclassing support.
  __ Bind(&subclassing);
  __ Poke(constructor, Operand(x0, LSL, kPointerSizeLog2));
  __ Add(x0, x0, Operand(3));
  __ Push(new_target, allocation_site);
  __ JumpToExternalReference(ExternalReference(Runtime::kNewArray, isolate()));
}


void InternalArrayConstructorStub::GenerateCase(
    MacroAssembler* masm, ElementsKind kind) {
  Label zero_case, n_case;
  Register argc = x0;

  __ Cbz(argc, &zero_case);
  __ CompareAndBranch(argc, 1, ne, &n_case);

  // One argument.
  if (IsFastPackedElementsKind(kind)) {
    Label packed_case;

    // We might need to create a holey array; look at the first argument.
    __ Peek(x10, 0);
    __ Cbz(x10, &packed_case);

    InternalArraySingleArgumentConstructorStub
        stub1_holey(isolate(), GetHoleyElementsKind(kind));
    __ TailCallStub(&stub1_holey);

    __ Bind(&packed_case);
  }
  InternalArraySingleArgumentConstructorStub stub1(isolate(), kind);
  __ TailCallStub(&stub1);

  __ Bind(&zero_case);
  // No arguments.
  InternalArrayNoArgumentConstructorStub stub0(isolate(), kind);
  __ TailCallStub(&stub0);

  __ Bind(&n_case);
  // N arguments.
  ArrayNArgumentsConstructorStub stubN(isolate());
  __ TailCallStub(&stubN);
}


void InternalArrayConstructorStub::Generate(MacroAssembler* masm) {
  // ----------- S t a t e -------------
  //  -- x0 : argc
  //  -- x1 : constructor
  //  -- sp[0] : return address
  //  -- sp[4] : last argument
  // -----------------------------------

  Register constructor = x1;

  if (FLAG_debug_code) {
    // The array construct code is only set for the global and natives
    // builtin Array functions which always have maps.

    Label unexpected_map, map_ok;
    // Initial map for the builtin Array function should be a map.
    __ Ldr(x10, FieldMemOperand(constructor,
                                JSFunction::kPrototypeOrInitialMapOffset));
    // Will both indicate a nullptr and a Smi.
    __ JumpIfSmi(x10, &unexpected_map);
    __ JumpIfObjectType(x10, x10, x11, MAP_TYPE, &map_ok);
    __ Bind(&unexpected_map);
    __ Abort(AbortReason::kUnexpectedInitialMapForArrayFunction);
    __ Bind(&map_ok);
  }

  Register kind = w3;
  // Figure out the right elements kind
  __ Ldr(x10, FieldMemOperand(constructor,
                              JSFunction::kPrototypeOrInitialMapOffset));

  // Retrieve elements_kind from map.
  __ LoadElementsKindFromMap(kind, x10);

  if (FLAG_debug_code) {
    Label done;
    __ Cmp(x3, PACKED_ELEMENTS);
    __ Ccmp(x3, HOLEY_ELEMENTS, ZFlag, ne);
    __ Assert(
        eq,
        AbortReason::kInvalidElementsKindForInternalArrayOrInternalPackedArray);
  }

  Label fast_elements_case;
  __ CompareAndBranch(kind, PACKED_ELEMENTS, eq, &fast_elements_case);
  GenerateCase(masm, HOLEY_ELEMENTS);

  __ Bind(&fast_elements_case);
  GenerateCase(masm, PACKED_ELEMENTS);
}

// The number of register that CallApiFunctionAndReturn will need to save on
// the stack. The space for these registers need to be allocated in the
// ExitFrame before calling CallApiFunctionAndReturn.
static const int kCallApiFunctionSpillSpace = 4;


static int AddressOffset(ExternalReference ref0, ExternalReference ref1) {
  return static_cast<int>(ref0.address() - ref1.address());
}

// Calls an API function. Allocates HandleScope, extracts returned value
// from handle and propagates exceptions.
// 'stack_space' is the space to be unwound on exit (includes the call JS
// arguments space and the additional space allocated for the fast call).
// 'spill_offset' is the offset from the stack pointer where
// CallApiFunctionAndReturn can spill registers.
static void CallApiFunctionAndReturn(MacroAssembler* masm,
                                     Register function_address,
                                     ExternalReference thunk_ref,
                                     int stack_space, int spill_offset,
                                     MemOperand return_value_operand) {
  ASM_LOCATION("CallApiFunctionAndReturn");
  Isolate* isolate = masm->isolate();
  ExternalReference next_address =
      ExternalReference::handle_scope_next_address(isolate);
  const int kNextOffset = 0;
  const int kLimitOffset = AddressOffset(
      ExternalReference::handle_scope_limit_address(isolate), next_address);
  const int kLevelOffset = AddressOffset(
      ExternalReference::handle_scope_level_address(isolate), next_address);

  DCHECK(function_address.is(x1) || function_address.is(x2));

  Label profiler_disabled;
  Label end_profiler_check;
  __ Mov(x10, ExternalReference::is_profiling_address(isolate));
  __ Ldrb(w10, MemOperand(x10));
  __ Cbz(w10, &profiler_disabled);
  __ Mov(x3, thunk_ref);
  __ B(&end_profiler_check);

  __ Bind(&profiler_disabled);
  __ Mov(x3, function_address);
  __ Bind(&end_profiler_check);

  // Save the callee-save registers we are going to use.
  // TODO(all): Is this necessary? ARM doesn't do it.
  STATIC_ASSERT(kCallApiFunctionSpillSpace == 4);
  __ Poke(x19, (spill_offset + 0) * kXRegSize);
  __ Poke(x20, (spill_offset + 1) * kXRegSize);
  __ Poke(x21, (spill_offset + 2) * kXRegSize);
  __ Poke(x22, (spill_offset + 3) * kXRegSize);

  // Allocate HandleScope in callee-save registers.
  // We will need to restore the HandleScope after the call to the API function,
  // by allocating it in callee-save registers they will be preserved by C code.
  Register handle_scope_base = x22;
  Register next_address_reg = x19;
  Register limit_reg = x20;
  Register level_reg = w21;

  __ Mov(handle_scope_base, next_address);
  __ Ldr(next_address_reg, MemOperand(handle_scope_base, kNextOffset));
  __ Ldr(limit_reg, MemOperand(handle_scope_base, kLimitOffset));
  __ Ldr(level_reg, MemOperand(handle_scope_base, kLevelOffset));
  __ Add(level_reg, level_reg, 1);
  __ Str(level_reg, MemOperand(handle_scope_base, kLevelOffset));

  if (FLAG_log_timer_events) {
    FrameScope frame(masm, StackFrame::MANUAL);
    __ PushSafepointRegisters();
    __ Mov(x0, ExternalReference::isolate_address(isolate));
    __ CallCFunction(ExternalReference::log_enter_external_function(isolate),
                     1);
    __ PopSafepointRegisters();
  }

  // Native call returns to the DirectCEntry stub which redirects to the
  // return address pushed on stack (could have moved after GC).
  // DirectCEntry stub itself is generated early and never moves.
  DirectCEntryStub stub(isolate);
  stub.GenerateCall(masm, x3);

  if (FLAG_log_timer_events) {
    FrameScope frame(masm, StackFrame::MANUAL);
    __ PushSafepointRegisters();
    __ Mov(x0, ExternalReference::isolate_address(isolate));
    __ CallCFunction(ExternalReference::log_leave_external_function(isolate),
                     1);
    __ PopSafepointRegisters();
  }

  Label promote_scheduled_exception;
  Label delete_allocated_handles;
  Label leave_exit_frame;
  Label return_value_loaded;

  // Load value from ReturnValue.
  __ Ldr(x0, return_value_operand);
  __ Bind(&return_value_loaded);
  // No more valid handles (the result handle was the last one). Restore
  // previous handle scope.
  __ Str(next_address_reg, MemOperand(handle_scope_base, kNextOffset));
  if (__ emit_debug_code()) {
    __ Ldr(w1, MemOperand(handle_scope_base, kLevelOffset));
    __ Cmp(w1, level_reg);
    __ Check(eq, AbortReason::kUnexpectedLevelAfterReturnFromApiCall);
  }
  __ Sub(level_reg, level_reg, 1);
  __ Str(level_reg, MemOperand(handle_scope_base, kLevelOffset));
  __ Ldr(x1, MemOperand(handle_scope_base, kLimitOffset));
  __ Cmp(limit_reg, x1);
  __ B(ne, &delete_allocated_handles);

  // Leave the API exit frame.
  __ Bind(&leave_exit_frame);
  // Restore callee-saved registers.
  __ Peek(x19, (spill_offset + 0) * kXRegSize);
  __ Peek(x20, (spill_offset + 1) * kXRegSize);
  __ Peek(x21, (spill_offset + 2) * kXRegSize);
  __ Peek(x22, (spill_offset + 3) * kXRegSize);

  __ LeaveExitFrame(false, x1, x5);

  // Check if the function scheduled an exception.
  __ Mov(x5, ExternalReference::scheduled_exception_address(isolate));
  __ Ldr(x5, MemOperand(x5));
  __ JumpIfNotRoot(x5, Heap::kTheHoleValueRootIndex,
                   &promote_scheduled_exception);

  __ DropSlots(stack_space);
  __ Ret();

  // Re-throw by promoting a scheduled exception.
  __ Bind(&promote_scheduled_exception);
  __ TailCallRuntime(Runtime::kPromoteScheduledException);

  // HandleScope limit has changed. Delete allocated extensions.
  __ Bind(&delete_allocated_handles);
  __ Str(limit_reg, MemOperand(handle_scope_base, kLimitOffset));
  // Save the return value in a callee-save register.
  Register saved_result = x19;
  __ Mov(saved_result, x0);
  __ Mov(x0, ExternalReference::isolate_address(isolate));
  __ CallCFunction(ExternalReference::delete_handle_scope_extensions(isolate),
                   1);
  __ Mov(x0, saved_result);
  __ B(&leave_exit_frame);
}

void CallApiCallbackStub::Generate(MacroAssembler* masm) {
  // ----------- S t a t e -------------
  //  -- x4                  : call_data
  //  -- x2                  : holder
  //  -- x1                  : api_function_address
  //  -- cp                  : context
  //  --
  //  -- sp[0]               : last argument
  //  -- ...
  //  -- sp[(argc - 1) * 8]  : first argument
  //  -- sp[argc * 8]        : receiver
  // -----------------------------------

  Register call_data = x4;
  Register holder = x2;
  Register api_function_address = x1;

  typedef FunctionCallbackArguments FCA;

  STATIC_ASSERT(FCA::kArgsLength == 6);
  STATIC_ASSERT(FCA::kNewTargetIndex == 5);
  STATIC_ASSERT(FCA::kDataIndex == 4);
  STATIC_ASSERT(FCA::kReturnValueOffset == 3);
  STATIC_ASSERT(FCA::kReturnValueDefaultValueIndex == 2);
  STATIC_ASSERT(FCA::kIsolateIndex == 1);
  STATIC_ASSERT(FCA::kHolderIndex == 0);

  Register undef = x7;
  __ LoadRoot(undef, Heap::kUndefinedValueRootIndex);

  // Push new target, call data.
  __ Push(undef, call_data);

  Register isolate_reg = x5;
  __ Mov(isolate_reg, ExternalReference::isolate_address(masm->isolate()));

  // FunctionCallbackArguments:
  //    return value, return value default, isolate, holder.
  __ Push(undef, undef, isolate_reg, holder);

  // Prepare arguments.
  Register args = x6;
  __ Mov(args, masm->StackPointer());

  // Allocate the v8::Arguments structure in the arguments' space, since it's
  // not controlled by GC.
  const int kApiStackSpace = 3;

  // Allocate space so that CallApiFunctionAndReturn can store some scratch
  // registers on the stack.
  const int kCallApiFunctionSpillSpace = 4;

  FrameScope frame_scope(masm, StackFrame::MANUAL);
  __ EnterExitFrame(false, x10, kApiStackSpace + kCallApiFunctionSpillSpace);

  DCHECK(!AreAliased(x0, api_function_address));
  // x0 = FunctionCallbackInfo&
  // Arguments is after the return address.
  __ SlotAddress(x0, 1);
  // FunctionCallbackInfo::implicit_args_ and FunctionCallbackInfo::values_
  __ Add(x10, args, Operand((FCA::kArgsLength - 1 + argc()) * kPointerSize));
  __ Stp(args, x10, MemOperand(x0, 0 * kPointerSize));
  // FunctionCallbackInfo::length_ = argc
  __ Mov(x10, argc());
  __ Str(x10, MemOperand(x0, 2 * kPointerSize));

  ExternalReference thunk_ref =
      ExternalReference::invoke_function_callback(masm->isolate());

  AllowExternalCallThatCantCauseGC scope(masm);
  // Stores return the first js argument
  int return_value_offset = 2 + FCA::kReturnValueOffset;
  MemOperand return_value_operand(fp, return_value_offset * kPointerSize);
  // The number of arguments might be odd, but will be padded when calling the
  // stub. We do not round up stack_space to account for odd argc here, this
  // will be done in CallApiFunctionAndReturn.
  const int stack_space = (argc() + 1) + FCA::kArgsLength;

  // The current frame needs to be aligned.
  DCHECK_EQ((stack_space - (argc() + 1)) % 2, 0);
  const int spill_offset = 1 + kApiStackSpace;
  CallApiFunctionAndReturn(masm, api_function_address, thunk_ref, stack_space,
                           spill_offset, return_value_operand);
}


void CallApiGetterStub::Generate(MacroAssembler* masm) {
  STATIC_ASSERT(PropertyCallbackArguments::kShouldThrowOnErrorIndex == 0);
  STATIC_ASSERT(PropertyCallbackArguments::kHolderIndex == 1);
  STATIC_ASSERT(PropertyCallbackArguments::kIsolateIndex == 2);
  STATIC_ASSERT(PropertyCallbackArguments::kReturnValueDefaultValueIndex == 3);
  STATIC_ASSERT(PropertyCallbackArguments::kReturnValueOffset == 4);
  STATIC_ASSERT(PropertyCallbackArguments::kDataIndex == 5);
  STATIC_ASSERT(PropertyCallbackArguments::kThisIndex == 6);
  STATIC_ASSERT(PropertyCallbackArguments::kArgsLength == 7);

  Register receiver = ApiGetterDescriptor::ReceiverRegister();
  Register holder = ApiGetterDescriptor::HolderRegister();
  Register callback = ApiGetterDescriptor::CallbackRegister();
  Register data = x4;
  Register undef = x5;
  Register isolate_address = x6;
  Register name = x7;
  DCHECK(!AreAliased(receiver, holder, callback, data, undef, isolate_address,
                     name));

  __ Ldr(data, FieldMemOperand(callback, AccessorInfo::kDataOffset));
  __ LoadRoot(undef, Heap::kUndefinedValueRootIndex);
  __ Mov(isolate_address,
         Operand(ExternalReference::isolate_address(isolate())));
  __ Ldr(name, FieldMemOperand(callback, AccessorInfo::kNameOffset));

  // PropertyCallbackArguments:
  //   receiver, data, return value, return value default, isolate, holder,
  //   should_throw_on_error
  // These are followed by the property name, which is also pushed below the
  // exit frame to make the GC aware of it.
  __ Push(receiver, data, undef, undef, isolate_address, holder, xzr, name);

  // v8::PropertyCallbackInfo::args_ array and name handle.
  static const int kStackUnwindSpace =
      PropertyCallbackArguments::kArgsLength + 1;
  static_assert(kStackUnwindSpace % 2 == 0,
                "slots must be a multiple of 2 for stack pointer alignment");

  // Load address of v8::PropertyAccessorInfo::args_ array and name handle.
  __ Mov(x0, masm->StackPointer());  // x0 = Handle<Name>
  __ Add(x1, x0, 1 * kPointerSize);  // x1 = v8::PCI::args_

  const int kApiStackSpace = 1;

  // Allocate space so that CallApiFunctionAndReturn can store some scratch
  // registers on the stack.
  const int kCallApiFunctionSpillSpace = 4;

  FrameScope frame_scope(masm, StackFrame::MANUAL);
  __ EnterExitFrame(false, x10, kApiStackSpace + kCallApiFunctionSpillSpace);

  // Create v8::PropertyCallbackInfo object on the stack and initialize
  // it's args_ field.
  __ Poke(x1, 1 * kPointerSize);
  __ SlotAddress(x1, 1);
  // x1 = v8::PropertyCallbackInfo&

  ExternalReference thunk_ref =
      ExternalReference::invoke_accessor_getter_callback(isolate());

  Register api_function_address = x2;
  Register js_getter = x4;
  __ Ldr(js_getter, FieldMemOperand(callback, AccessorInfo::kJsGetterOffset));
  __ Ldr(api_function_address,
         FieldMemOperand(js_getter, Foreign::kForeignAddressOffset));

  const int spill_offset = 1 + kApiStackSpace;
  // +3 is to skip prolog, return address and name handle.
  MemOperand return_value_operand(
      fp, (PropertyCallbackArguments::kReturnValueOffset + 3) * kPointerSize);
  CallApiFunctionAndReturn(masm, api_function_address, thunk_ref,
                           kStackUnwindSpace, spill_offset,
                           return_value_operand);
}

#undef __

}  // namespace internal
}  // namespace v8

#endif  // V8_TARGET_ARCH_ARM64