// Copyright (c) 2020, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

#include "vm/compiler/runtime_api.h"
#include "vm/flags.h"
#include "vm/globals.h"

// For `StubCodeCompiler::GenerateAllocateUnhandledExceptionStub`
#include "vm/compiler/backend/il.h"

#define SHOULD_NOT_INCLUDE_RUNTIME

#include "vm/compiler/stub_code_compiler.h"

#include "vm/compiler/api/type_check_mode.h"
#include "vm/compiler/assembler/assembler.h"
#include "vm/stack_frame.h"

#define __ assembler->

namespace dart {
namespace compiler {

intptr_t StubCodeCompiler::WordOffsetFromFpToCpuRegister(
    Register cpu_register) {
  ASSERT(RegisterSet::Contains(kDartAvailableCpuRegs, cpu_register));

  intptr_t slots_from_fp = target::frame_layout.param_end_from_fp + 1;
  for (intptr_t i = 0; i < kNumberOfCpuRegisters; i++) {
    Register reg = static_cast<Register>(i);
    if (reg == cpu_register) break;
    if (RegisterSet::Contains(kDartAvailableCpuRegs, reg)) {
      slots_from_fp++;
    }
  }
  return slots_from_fp;
}

void StubCodeCompiler::GenerateInitStaticFieldStub(Assembler* assembler) {
  __ EnterStubFrame();
  __ PushObject(NullObject());  // Make room for result.
  __ PushRegister(InitStaticFieldABI::kFieldReg);
  __ CallRuntime(kInitStaticFieldRuntimeEntry, /*argument_count=*/1);
  __ Drop(1);
  __ PopRegister(InitStaticFieldABI::kResultReg);
  __ LeaveStubFrame();
  __ Ret();
}

void StubCodeCompiler::GenerateInitLateStaticFieldStub(Assembler* assembler,
                                                       bool is_final) {
  const Register kResultReg = InitStaticFieldABI::kResultReg;
  const Register kFieldReg = InitStaticFieldABI::kFieldReg;
  const Register kAddressReg = InitLateStaticFieldInternalRegs::kAddressReg;
  const Register kScratchReg = InitLateStaticFieldInternalRegs::kScratchReg;

  __ EnterStubFrame();

  __ Comment("Calling initializer function");
  __ PushRegister(kFieldReg);
  __ LoadCompressedFieldFromOffset(
      FUNCTION_REG, kFieldReg, target::Field::initializer_function_offset());
  if (!FLAG_precompiled_mode) {
    __ LoadCompressedFieldFromOffset(CODE_REG, FUNCTION_REG,
                                     target::Function::code_offset());
    // Load a GC-safe value for the arguments descriptor (unused but tagged).
    __ LoadImmediate(ARGS_DESC_REG, 0);
  }
  __ Call(FieldAddress(FUNCTION_REG, target::Function::entry_point_offset()));
  __ MoveRegister(kResultReg, CallingConventions::kReturnReg);
  __ PopRegister(kFieldReg);
  __ LoadStaticFieldAddress(kAddressReg, kFieldReg, kScratchReg);

  Label throw_exception;
  if (is_final) {
    __ Comment("Checking that initializer did not set late final field");
    __ LoadFromOffset(kScratchReg, kAddressReg, 0);
    __ CompareObject(kScratchReg, SentinelObject());
    __ BranchIf(NOT_EQUAL, &throw_exception);
  }

  __ StoreToOffset(kResultReg, kAddressReg, 0);
  __ LeaveStubFrame();
  __ Ret();

  if (is_final) {
#if defined(TARGET_ARCH_ARM) || defined(TARGET_ARCH_ARM64)
    // We are jumping over LeaveStubFrame so restore LR state to match one
    // at the jump point.
    __ set_lr_state(compiler::LRState::OnEntry().EnterFrame());
#endif  // defined(TARGET_ARCH_ARM) || defined(TARGET_ARCH_ARM64)
    __ Bind(&throw_exception);
    __ PushObject(NullObject());  // Make room for (unused) result.
    __ PushRegister(kFieldReg);
    __ CallRuntime(kLateFieldAssignedDuringInitializationErrorRuntimeEntry,
                   /*argument_count=*/1);
    __ Breakpoint();
  }
}

void StubCodeCompiler::GenerateInitLateStaticFieldStub(Assembler* assembler) {
  GenerateInitLateStaticFieldStub(assembler, /*is_final=*/false);
}

void StubCodeCompiler::GenerateInitLateFinalStaticFieldStub(
    Assembler* assembler) {
  GenerateInitLateStaticFieldStub(assembler, /*is_final=*/true);
}

void StubCodeCompiler::GenerateInitInstanceFieldStub(Assembler* assembler) {
  __ EnterStubFrame();
  __ PushObject(NullObject());  // Make room for result.
  __ PushRegistersInOrder(
      {InitInstanceFieldABI::kInstanceReg, InitInstanceFieldABI::kFieldReg});
  __ CallRuntime(kInitInstanceFieldRuntimeEntry, /*argument_count=*/2);
  __ Drop(2);
  __ PopRegister(InitInstanceFieldABI::kResultReg);
  __ LeaveStubFrame();
  __ Ret();
}

void StubCodeCompiler::GenerateInitLateInstanceFieldStub(Assembler* assembler,
                                                         bool is_final) {
  const Register kInstanceReg = InitInstanceFieldABI::kInstanceReg;
  const Register kFieldReg = InitInstanceFieldABI::kFieldReg;
  const Register kAddressReg = InitLateInstanceFieldInternalRegs::kAddressReg;
  const Register kScratchReg = InitLateInstanceFieldInternalRegs::kScratchReg;

  __ EnterStubFrame();
  // Save kFieldReg and kInstanceReg for later.
  // Call initializer function.
  __ PushRegistersInOrder({kFieldReg, kInstanceReg, kInstanceReg});

  static_assert(
      InitInstanceFieldABI::kResultReg == CallingConventions::kReturnReg,
      "Result is a return value from initializer");

  __ LoadCompressedFieldFromOffset(
      FUNCTION_REG, InitInstanceFieldABI::kFieldReg,
      target::Field::initializer_function_offset());
  if (!FLAG_precompiled_mode) {
    __ LoadCompressedFieldFromOffset(CODE_REG, FUNCTION_REG,
                                     target::Function::code_offset());
    // Load a GC-safe value for the arguments descriptor (unused but tagged).
    __ LoadImmediate(ARGS_DESC_REG, 0);
  }
  __ Call(FieldAddress(FUNCTION_REG, target::Function::entry_point_offset()));
  __ Drop(1);  // Drop argument.

  __ PopRegisterPair(kInstanceReg, kFieldReg);
  __ LoadCompressedFieldFromOffset(
      kScratchReg, kFieldReg, target::Field::host_offset_or_field_id_offset());
#if defined(DART_COMPRESSED_POINTERS)
  // TODO(compressed-pointers): Variant of LoadFieldAddressForRegOffset that
  // ignores upper bits?
  __ SmiUntag(kScratchReg);
  __ SmiTag(kScratchReg);
#endif
  __ LoadCompressedFieldAddressForRegOffset(kAddressReg, kInstanceReg,
                                            kScratchReg);

  Label throw_exception;
  if (is_final) {
    __ LoadCompressed(kScratchReg, Address(kAddressReg, 0));
    __ CompareObject(kScratchReg, SentinelObject());
    __ BranchIf(NOT_EQUAL, &throw_exception);
  }

#if defined(TARGET_ARCH_IA32)
  // On IA32 StoreIntoObject clobbers value register, so scratch
  // register is used in StoreIntoObject to preserve kResultReg.
  __ MoveRegister(kScratchReg, InitInstanceFieldABI::kResultReg);
  __ StoreIntoObject(kInstanceReg, Address(kAddressReg, 0), kScratchReg);
#else
  __ StoreCompressedIntoObject(kInstanceReg, Address(kAddressReg, 0),
                               InitInstanceFieldABI::kResultReg);
#endif  // defined(TARGET_ARCH_IA32)

  __ LeaveStubFrame();
  __ Ret();

  if (is_final) {
#if defined(TARGET_ARCH_ARM) || defined(TARGET_ARCH_ARM64)
    // We are jumping over LeaveStubFrame so restore LR state to match one
    // at the jump point.
    __ set_lr_state(compiler::LRState::OnEntry().EnterFrame());
#endif  // defined(TARGET_ARCH_ARM) || defined(TARGET_ARCH_ARM64)
    __ Bind(&throw_exception);
    __ PushObject(NullObject());  // Make room for (unused) result.
    __ PushRegister(kFieldReg);
    __ CallRuntime(kLateFieldAssignedDuringInitializationErrorRuntimeEntry,
                   /*argument_count=*/1);
    __ Breakpoint();
  }
}

void StubCodeCompiler::GenerateInitLateInstanceFieldStub(Assembler* assembler) {
  GenerateInitLateInstanceFieldStub(assembler, /*is_final=*/false);
}

void StubCodeCompiler::GenerateInitLateFinalInstanceFieldStub(
    Assembler* assembler) {
  GenerateInitLateInstanceFieldStub(assembler, /*is_final=*/true);
}

void StubCodeCompiler::GenerateThrowStub(Assembler* assembler) {
  __ EnterStubFrame();
  __ PushObject(NullObject());  // Make room for (unused) result.
  __ PushRegister(ThrowABI::kExceptionReg);
  __ CallRuntime(kThrowRuntimeEntry, /*argument_count=*/1);
  __ Breakpoint();
}

void StubCodeCompiler::GenerateReThrowStub(Assembler* assembler) {
  __ EnterStubFrame();
  __ PushObject(NullObject());  // Make room for (unused) result.
  __ PushRegistersInOrder(
      {ReThrowABI::kExceptionReg, ReThrowABI::kStackTraceReg});
  __ CallRuntime(kReThrowRuntimeEntry, /*argument_count=*/2);
  __ Breakpoint();
}

void StubCodeCompiler::GenerateAssertBooleanStub(Assembler* assembler) {
  __ EnterStubFrame();
  __ PushObject(NullObject());  // Make room for (unused) result.
  __ PushRegister(AssertBooleanABI::kObjectReg);
  __ CallRuntime(kNonBoolTypeErrorRuntimeEntry, /*argument_count=*/1);
  __ Breakpoint();
}

void StubCodeCompiler::GenerateAssertSubtypeStub(Assembler* assembler) {
  __ EnterStubFrame();
  __ PushRegistersInOrder({AssertSubtypeABI::kInstantiatorTypeArgumentsReg,
                           AssertSubtypeABI::kFunctionTypeArgumentsReg,
                           AssertSubtypeABI::kSubTypeReg,
                           AssertSubtypeABI::kSuperTypeReg,
                           AssertSubtypeABI::kDstNameReg});
  __ CallRuntime(kSubtypeCheckRuntimeEntry, /*argument_count=*/5);
  __ Drop(5);  // Drop unused result as well as arguments.
  __ LeaveStubFrame();
  __ Ret();
}

void StubCodeCompiler::GenerateAssertAssignableStub(Assembler* assembler) {
#if !defined(TARGET_ARCH_IA32)
  __ Breakpoint();
#else
  __ EnterStubFrame();
  __ PushObject(Object::null_object());  // Make room for the result.
  __ pushl(Address(
      EBP, target::kWordSize * AssertAssignableStubABI::kInstanceSlotFromFp));
  __ pushl(Address(
      EBP, target::kWordSize * AssertAssignableStubABI::kDstTypeSlotFromFp));
  __ pushl(Address(
      EBP,
      target::kWordSize * AssertAssignableStubABI::kInstantiatorTAVSlotFromFp));
  __ pushl(Address(EBP, target::kWordSize *
                            AssertAssignableStubABI::kFunctionTAVSlotFromFp));
  __ PushRegistersInOrder({AssertAssignableStubABI::kDstNameReg,
                           AssertAssignableStubABI::kSubtypeTestReg});
  __ PushObject(Smi::ZoneHandle(Smi::New(kTypeCheckFromInline)));
  __ CallRuntime(kTypeCheckRuntimeEntry, /*argument_count=*/7);
  __ Drop(8);
  __ LeaveStubFrame();
  __ Ret();
#endif
}

static void BuildInstantiateTypeRuntimeCall(Assembler* assembler) {
  __ EnterStubFrame();
  __ PushObject(Object::null_object());
  __ PushRegistersInOrder({InstantiateTypeABI::kTypeReg,
                           InstantiateTypeABI::kInstantiatorTypeArgumentsReg,
                           InstantiateTypeABI::kFunctionTypeArgumentsReg});
  __ CallRuntime(kInstantiateTypeRuntimeEntry, /*argument_count=*/3);
  __ Drop(3);
  __ PopRegister(InstantiateTypeABI::kResultTypeReg);
  __ LeaveStubFrame();
  __ Ret();
}

static void BuildInstantiateTypeParameterStub(Assembler* assembler,
                                              Nullability nullability,
                                              bool is_function_parameter) {
  Label runtime_call, return_dynamic, type_parameter_value_is_not_type;

  if (is_function_parameter) {
    __ CompareObject(InstantiateTypeABI::kFunctionTypeArgumentsReg,
                     TypeArguments::null_object());
    __ BranchIf(EQUAL, &return_dynamic);
    __ LoadFieldFromOffset(
        InstantiateTypeABI::kResultTypeReg, InstantiateTypeABI::kTypeReg,
        target::TypeParameter::index_offset(), kUnsignedByte);
    __ LoadIndexedCompressed(InstantiateTypeABI::kResultTypeReg,
                             InstantiateTypeABI::kFunctionTypeArgumentsReg,
                             target::TypeArguments::types_offset(),
                             InstantiateTypeABI::kResultTypeReg);
  } else {
    __ CompareObject(InstantiateTypeABI::kInstantiatorTypeArgumentsReg,
                     TypeArguments::null_object());
    __ BranchIf(EQUAL, &return_dynamic);
    __ LoadFieldFromOffset(
        InstantiateTypeABI::kResultTypeReg, InstantiateTypeABI::kTypeReg,
        target::TypeParameter::index_offset(), kUnsignedByte);
    __ LoadIndexedCompressed(InstantiateTypeABI::kResultTypeReg,
                             InstantiateTypeABI::kInstantiatorTypeArgumentsReg,
                             target::TypeArguments::types_offset(),
                             InstantiateTypeABI::kResultTypeReg);
  }

  __ LoadClassId(InstantiateTypeABI::kScratchReg,
                 InstantiateTypeABI::kResultTypeReg);

  // The loaded value from the TAV can be [Type], [FunctionType] or [TypeRef].

  // Handle [Type]s.
  __ CompareImmediate(InstantiateTypeABI::kScratchReg, kTypeCid);
  __ BranchIf(NOT_EQUAL, &type_parameter_value_is_not_type);
  switch (nullability) {
    case Nullability::kNonNullable:
      __ Ret();
      break;
    case Nullability::kNullable:
      __ CompareTypeNullabilityWith(
          InstantiateTypeABI::kResultTypeReg,
          static_cast<int8_t>(Nullability::kNullable));
      __ BranchIf(NOT_EQUAL, &runtime_call);
      __ Ret();
      break;
    case Nullability::kLegacy:
      __ CompareTypeNullabilityWith(
          InstantiateTypeABI::kResultTypeReg,
          static_cast<int8_t>(Nullability::kNonNullable));
      __ BranchIf(EQUAL, &runtime_call);
      __ Ret();
  }

  // TODO(dartbug.com/49719)
  // Handle [FunctionType]s.
  __ Bind(&type_parameter_value_is_not_type);
  __ CompareImmediate(InstantiateTypeABI::kScratchReg, kFunctionTypeCid);
  __ BranchIf(NOT_EQUAL, &runtime_call);
  switch (nullability) {
    case Nullability::kNonNullable:
      __ Ret();
      break;
    case Nullability::kNullable:
      __ CompareFunctionTypeNullabilityWith(
          InstantiateTypeABI::kResultTypeReg,
          static_cast<int8_t>(Nullability::kNullable));
      __ BranchIf(NOT_EQUAL, &runtime_call);
      __ Ret();
      break;
    case Nullability::kLegacy:
      __ CompareFunctionTypeNullabilityWith(
          InstantiateTypeABI::kResultTypeReg,
          static_cast<int8_t>(Nullability::kNonNullable));
      __ BranchIf(EQUAL, &runtime_call);
      __ Ret();
  }

  // The TAV was null, so the value of the type parameter is "dynamic".
  __ Bind(&return_dynamic);
  __ LoadObject(InstantiateTypeABI::kResultTypeReg, Type::dynamic_type());
  __ Ret();

  __ Bind(&runtime_call);
  BuildInstantiateTypeRuntimeCall(assembler);
}

void StubCodeCompiler::GenerateInstantiateTypeNonNullableClassTypeParameterStub(
    Assembler* assembler) {
  BuildInstantiateTypeParameterStub(assembler, Nullability::kNonNullable,
                                    /*is_function_parameter=*/false);
}

void StubCodeCompiler::GenerateInstantiateTypeNullableClassTypeParameterStub(
    Assembler* assembler) {
  BuildInstantiateTypeParameterStub(assembler, Nullability::kNullable,
                                    /*is_function_parameter=*/false);
}

void StubCodeCompiler::GenerateInstantiateTypeLegacyClassTypeParameterStub(
    Assembler* assembler) {
  BuildInstantiateTypeParameterStub(assembler, Nullability::kLegacy,
                                    /*is_function_parameter=*/false);
}

void StubCodeCompiler::
    GenerateInstantiateTypeNonNullableFunctionTypeParameterStub(
        Assembler* assembler) {
  BuildInstantiateTypeParameterStub(assembler, Nullability::kNonNullable,
                                    /*is_function_parameter=*/true);
}

void StubCodeCompiler::GenerateInstantiateTypeNullableFunctionTypeParameterStub(
    Assembler* assembler) {
  BuildInstantiateTypeParameterStub(assembler, Nullability::kNullable,
                                    /*is_function_parameter=*/true);
}

void StubCodeCompiler::GenerateInstantiateTypeLegacyFunctionTypeParameterStub(
    Assembler* assembler) {
  BuildInstantiateTypeParameterStub(assembler, Nullability::kLegacy,
                                    /*is_function_parameter=*/true);
}

void StubCodeCompiler::GenerateInstantiateTypeStub(Assembler* assembler) {
  BuildInstantiateTypeRuntimeCall(assembler);
}

void StubCodeCompiler::GenerateInstanceOfStub(Assembler* assembler) {
  __ EnterStubFrame();
  __ PushObject(NullObject());  // Make room for the result.
  __ PushRegistersInOrder({TypeTestABI::kInstanceReg, TypeTestABI::kDstTypeReg,
                           TypeTestABI::kInstantiatorTypeArgumentsReg,
                           TypeTestABI::kFunctionTypeArgumentsReg,
                           TypeTestABI::kSubtypeTestCacheReg});
  __ CallRuntime(kInstanceofRuntimeEntry, /*argument_count=*/5);
  __ Drop(5);
  __ PopRegister(TypeTestABI::kInstanceOfResultReg);
  __ LeaveStubFrame();
  __ Ret();
}

// For use in GenerateTypeIsTopTypeForSubtyping and
// GenerateNullIsAssignableToType.
static void EnsureIsTypeOrFunctionTypeOrTypeParameter(Assembler* assembler,
                                                      Register type_reg,
                                                      Register scratch_reg) {
#if defined(DEBUG)
  compiler::Label is_type_param_or_type_or_function_type;
  __ LoadClassIdMayBeSmi(scratch_reg, type_reg);
  __ CompareImmediate(scratch_reg, kTypeParameterCid);
  __ BranchIf(EQUAL, &is_type_param_or_type_or_function_type,
              compiler::Assembler::kNearJump);
  __ CompareImmediate(scratch_reg, kTypeCid);
  __ BranchIf(EQUAL, &is_type_param_or_type_or_function_type,
              compiler::Assembler::kNearJump);
  __ CompareImmediate(scratch_reg, kFunctionTypeCid);
  __ BranchIf(EQUAL, &is_type_param_or_type_or_function_type,
              compiler::Assembler::kNearJump);
  // Type references show up in F-bounded polymorphism, which is limited
  // to classes. Thus, TypeRefs only appear in places like class type
  // arguments or the bounds of uninstantiated class type parameters.
  //
  // Since this stub is currently used only by the dynamic versions of
  // AssertSubtype and AssertAssignable, where kDstType is either the bound of
  // a function type parameter or the type of a function parameter
  // (respectively), we should never see a TypeRef here. This check is here
  // in case this changes and we need to update this stub.
  __ Stop("not a type or function type or type parameter");
  __ Bind(&is_type_param_or_type_or_function_type);
#endif
}

// Version of AbstractType::IsTopTypeForSubtyping() used when the type is not
// known at compile time. Must be kept in sync.
//
// Inputs:
// - TypeTestABI::kDstTypeReg: Destination type.
//
// Non-preserved scratch registers:
// - TypeTestABI::kScratchReg (only on non-IA32 architectures)
//
// Outputs:
// - TypeTestABI::kSubtypeTestCacheReg: 0 if the value is guaranteed assignable,
//   non-zero otherwise.
//
// All registers other than outputs and non-preserved scratches are preserved.
static void GenerateTypeIsTopTypeForSubtyping(Assembler* assembler,
                                              bool null_safety) {
  // The only case where the original value of kSubtypeTestCacheReg is needed
  // after the stub call is on IA32, where it's currently preserved on the stack
  // before calling the stub (as it's also CODE_REG on that architecture), so we
  // both use it as a scratch and clobber it for the return value.
  const Register scratch1_reg = TypeTestABI::kSubtypeTestCacheReg;
  // We reuse the first scratch register as the output register because we're
  // always guaranteed to have a type in it (starting with kDstType), and all
  // non-Smi ObjectPtrs are non-zero values.
  const Register output_reg = scratch1_reg;
#if defined(TARGET_ARCH_IA32)
  // The remaining scratch registers are preserved and restored before exit on
  // IA32. Because  we have few registers to choose from (which are all used in
  // TypeTestABI), use specific TestTypeABI registers.
  const Register scratch2_reg = TypeTestABI::kFunctionTypeArgumentsReg;
  // Preserve non-output scratch registers.
  __ PushRegister(scratch2_reg);
#else
  const Register scratch2_reg = TypeTestABI::kScratchReg;
#endif
  static_assert(scratch1_reg != scratch2_reg,
                "both scratch registers are the same");

  compiler::Label check_top_type, is_top_type, done;
  // Initialize scratch1_reg with the type to check (which also sets the
  // output register to a non-zero value). scratch1_reg (and thus the output
  // register) will always have a type in it from here on out.
  __ MoveRegister(scratch1_reg, TypeTestABI::kDstTypeReg);
  __ Bind(&check_top_type);
  // scratch1_reg: Current type to check.
  EnsureIsTypeOrFunctionTypeOrTypeParameter(assembler, scratch1_reg,
                                            scratch2_reg);
  compiler::Label is_type_ref;
  __ CompareClassId(scratch1_reg, kTypeCid, scratch2_reg);
  // Type parameters can't be top types themselves, though a particular
  // instantiation may result in a top type.
  // Function types cannot be top types.
  __ BranchIf(NOT_EQUAL, &done);
  __ LoadTypeClassId(scratch2_reg, scratch1_reg);
  __ CompareImmediate(scratch2_reg, kDynamicCid);
  __ BranchIf(EQUAL, &is_top_type, compiler::Assembler::kNearJump);
  __ CompareImmediate(scratch2_reg, kVoidCid);
  __ BranchIf(EQUAL, &is_top_type, compiler::Assembler::kNearJump);
  compiler::Label unwrap_future_or;
  __ CompareImmediate(scratch2_reg, kFutureOrCid);
  __ BranchIf(EQUAL, &unwrap_future_or, compiler::Assembler::kNearJump);
  __ CompareImmediate(scratch2_reg, kInstanceCid);
  __ BranchIf(NOT_EQUAL, &done, compiler::Assembler::kNearJump);
  if (null_safety) {
    // Instance type isn't a top type if non-nullable in null safe mode.
    __ CompareTypeNullabilityWith(
        scratch1_reg, static_cast<int8_t>(Nullability::kNonNullable));
    __ BranchIf(EQUAL, &done, compiler::Assembler::kNearJump);
  }
  __ Bind(&is_top_type);
  __ LoadImmediate(output_reg, 0);
  __ Bind(&done);
#if defined(TARGET_ARCH_IA32)
  // Restore preserved scratch registers.
  __ PopRegister(scratch2_reg);
#endif
  __ Ret();
  // An uncommon case, so off the main trunk of the function.
  __ Bind(&unwrap_future_or);
  __ LoadCompressedField(
      scratch2_reg,
      compiler::FieldAddress(scratch1_reg,
                             compiler::target::Type::arguments_offset()));
  __ CompareObject(scratch2_reg, Object::null_object());
  // If the arguments are null, then unwrapping gives dynamic, a top type.
  __ BranchIf(EQUAL, &is_top_type, compiler::Assembler::kNearJump);
  __ LoadCompressedField(
      scratch1_reg,
      compiler::FieldAddress(
          scratch2_reg, compiler::target::TypeArguments::type_at_offset(0)));
  __ Jump(&check_top_type, compiler::Assembler::kNearJump);
}

void StubCodeCompiler::GenerateTypeIsTopTypeForSubtypingStub(
    Assembler* assembler) {
  GenerateTypeIsTopTypeForSubtyping(assembler,
                                    /*null_safety=*/false);
}

void StubCodeCompiler::GenerateTypeIsTopTypeForSubtypingNullSafeStub(
    Assembler* assembler) {
  GenerateTypeIsTopTypeForSubtyping(assembler,
                                    /*null_safety=*/true);
}

// Version of Instance::NullIsAssignableTo(other, inst_tav, fun_tav) used when
// the destination type was not known at compile time. Must be kept in sync.
//
// Inputs:
// - TypeTestABI::kInstanceReg: Object to check for assignability.
// - TypeTestABI::kDstTypeReg: Destination type.
// - TypeTestABI::kInstantiatorTypeArgumentsReg: Instantiator TAV.
// - TypeTestABI::kFunctionTypeArgumentsReg: Function TAV.
//
// Non-preserved non-output scratch registers:
// - TypeTestABI::kScratchReg (only on non-IA32 architectures)
//
// Outputs:
// - TypeTestABI::kSubtypeTestCacheReg: 0 if the value is guaranteed assignable,
//   non-zero otherwise.
//
// All registers other than outputs and non-preserved scratches are preserved.
static void GenerateNullIsAssignableToType(Assembler* assembler,
                                           bool null_safety) {
  // The only case where the original value of kSubtypeTestCacheReg is needed
  // after the stub call is on IA32, where it's currently preserved on the stack
  // before calling the stub (as it's also CODE_REG on that architecture), so we
  // both use it as a scratch to hold the current type to inspect and also
  // clobber it for the return value.
  const Register kCurrentTypeReg = TypeTestABI::kSubtypeTestCacheReg;
  // We reuse the first scratch register as the output register because we're
  // always guaranteed to have a type in it (starting with the contents of
  // kDstTypeReg), and all non-Smi ObjectPtrs are non-zero values.
  const Register kOutputReg = kCurrentTypeReg;
#if defined(TARGET_ARCH_IA32)
  // The remaining scratch registers are preserved and restored before exit on
  // IA32. Because  we have few registers to choose from (which are all used in
  // TypeTestABI), use specific TestTypeABI registers.
  const Register kScratchReg = TypeTestABI::kFunctionTypeArgumentsReg;
  // Preserve non-output scratch registers.
  __ PushRegister(kScratchReg);
#else
  const Register kScratchReg = TypeTestABI::kScratchReg;
#endif
  static_assert(kCurrentTypeReg != kScratchReg,
                "code assumes distinct scratch registers");

  compiler::Label is_assignable, done;
  // Initialize the first scratch register (and thus the output register) with
  // the destination type. We do this before the check to ensure the output
  // register has a non-zero value if !null_safety and kInstanceReg is not null.
  __ MoveRegister(kCurrentTypeReg, TypeTestABI::kDstTypeReg);
  __ CompareObject(TypeTestABI::kInstanceReg, Object::null_object());
  if (null_safety) {
    compiler::Label check_null_assignable;
    // Skip checking the type if not null.
    __ BranchIf(NOT_EQUAL, &done);
    __ Bind(&check_null_assignable);
    // scratch1_reg: Current type to check.
    EnsureIsTypeOrFunctionTypeOrTypeParameter(assembler, kCurrentTypeReg,
                                              kScratchReg);
    compiler::Label is_not_type;
    __ CompareClassId(kCurrentTypeReg, kTypeCid, kScratchReg);
    __ BranchIf(NOT_EQUAL, &is_not_type, compiler::Assembler::kNearJump);
    __ CompareTypeNullabilityWith(
        kCurrentTypeReg, static_cast<int8_t>(Nullability::kNonNullable));
    __ BranchIf(NOT_EQUAL, &is_assignable);
    // FutureOr is a special case because it may have the non-nullable bit set,
    // but FutureOr<T> functions as the union of T and Future<T>, so it must be
    // unwrapped to see if T is nullable.
    __ LoadTypeClassId(kScratchReg, kCurrentTypeReg);
    __ CompareImmediate(kScratchReg, kFutureOrCid);
    __ BranchIf(NOT_EQUAL, &done);
    __ LoadCompressedField(
        kScratchReg,
        compiler::FieldAddress(kCurrentTypeReg,
                               compiler::target::Type::arguments_offset()));
    __ CompareObject(kScratchReg, Object::null_object());
    // If the arguments are null, then unwrapping gives the dynamic type,
    // which can take null.
    __ BranchIf(EQUAL, &is_assignable);
    __ LoadCompressedField(
        kCurrentTypeReg,
        compiler::FieldAddress(
            kScratchReg, compiler::target::TypeArguments::type_at_offset(0)));
    __ Jump(&check_null_assignable, compiler::Assembler::kNearJump);
    __ Bind(&is_not_type);
    // Null is assignable to a type parameter only if it is nullable or if the
    // instantiation is nullable.
    __ LoadFieldFromOffset(
        kScratchReg, kCurrentTypeReg,
        compiler::target::TypeParameter::nullability_offset(), kByte);
    __ CompareImmediate(kScratchReg,
                        static_cast<int8_t>(Nullability::kNonNullable));
    __ BranchIf(NOT_EQUAL, &is_assignable);

    // Don't set kScratchReg in here as on IA32, that's the function TAV reg.
    auto handle_case = [&](Register tav) {
      // We can reuse kCurrentTypeReg to hold the index because we no longer
      // need the type parameter afterwards.
      auto const kIndexReg = kCurrentTypeReg;
      // If the TAV is null, resolving gives the (nullable) dynamic type.
      __ CompareObject(tav, NullObject());
      __ BranchIf(EQUAL, &is_assignable, Assembler::kNearJump);
      // Resolve the type parameter to its instantiated type and loop.
      __ LoadFieldFromOffset(kIndexReg, kCurrentTypeReg,
                             target::TypeParameter::index_offset(),
                             kUnsignedByte);
      __ LoadIndexedCompressed(kCurrentTypeReg, tav,
                               target::TypeArguments::types_offset(),
                               kIndexReg);
      __ Jump(&check_null_assignable);
    };

    Label function_type_param;
    __ LoadFieldFromOffset(
        kScratchReg, kCurrentTypeReg,
        target::TypeParameter::parameterized_class_id_offset(),
        kUnsignedTwoBytes);
    __ CompareImmediate(kScratchReg, kFunctionCid);
    __ BranchIf(EQUAL, &function_type_param, Assembler::kNearJump);
    handle_case(TypeTestABI::kInstantiatorTypeArgumentsReg);
    __ Bind(&function_type_param);
#if defined(TARGET_ARCH_IA32)
    // Function TAV is on top of stack because we're using that register as
    // kScratchReg.
    __ LoadFromStack(TypeTestABI::kFunctionTypeArgumentsReg, 0);
#endif
    handle_case(TypeTestABI::kFunctionTypeArgumentsReg);
  } else {
    // Null in non-null-safe mode is always assignable.
    __ BranchIf(NOT_EQUAL, &done, compiler::Assembler::kNearJump);
  }
  __ Bind(&is_assignable);
  __ LoadImmediate(kOutputReg, 0);
  __ Bind(&done);
#if defined(TARGET_ARCH_IA32)
  // Restore preserved scratch registers.
  __ PopRegister(kScratchReg);
#endif
  __ Ret();
}

void StubCodeCompiler::GenerateNullIsAssignableToTypeStub(
    Assembler* assembler) {
  GenerateNullIsAssignableToType(assembler,
                                 /*null_safety=*/false);
}

void StubCodeCompiler::GenerateNullIsAssignableToTypeNullSafeStub(
    Assembler* assembler) {
  GenerateNullIsAssignableToType(assembler,
                                 /*null_safety=*/true);
}
#if !defined(TARGET_ARCH_IA32)
// The <X>TypeTestStubs are used to test whether a given value is of a given
// type. All variants have the same calling convention:
//
// Inputs (from TypeTestABI struct):
//   - kSubtypeTestCacheReg: RawSubtypeTestCache
//   - kInstanceReg: instance to test against.
//   - kInstantiatorTypeArgumentsReg : instantiator type arguments (if needed).
//   - kFunctionTypeArgumentsReg : function type arguments (if needed).
//
// See GenerateSubtypeNTestCacheStub for registers that may need saving by the
// caller.
//
// Output (from TypeTestABI struct):
//   - kResultReg: checked instance.
//
// Throws if the check is unsuccessful.
//
// Note of warning: The caller will not populate CODE_REG and we have therefore
// no access to the pool.
void StubCodeCompiler::GenerateDefaultTypeTestStub(Assembler* assembler) {
  __ LoadFromOffset(CODE_REG, THR,
                    target::Thread::slow_type_test_stub_offset());
  __ Jump(FieldAddress(CODE_REG, target::Code::entry_point_offset()));
}

// Used instead of DefaultTypeTestStub when null is assignable.
void StubCodeCompiler::GenerateDefaultNullableTypeTestStub(
    Assembler* assembler) {
  Label done;

  // Fast case for 'null'.
  __ CompareObject(TypeTestABI::kInstanceReg, NullObject());
  __ BranchIf(EQUAL, &done);

  __ LoadFromOffset(CODE_REG, THR,
                    target::Thread::slow_type_test_stub_offset());
  __ Jump(FieldAddress(CODE_REG, target::Code::entry_point_offset()));

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

void StubCodeCompiler::GenerateTopTypeTypeTestStub(Assembler* assembler) {
  __ Ret();
}

void StubCodeCompiler::GenerateUnreachableTypeTestStub(Assembler* assembler) {
  __ Breakpoint();
}

static void BuildTypeParameterTypeTestStub(Assembler* assembler,
                                           bool allow_null) {
  Label done;

  if (allow_null) {
    __ CompareObject(TypeTestABI::kInstanceReg, NullObject());
    __ BranchIf(EQUAL, &done, Assembler::kNearJump);
  }

  auto handle_case = [&](Register tav) {
    // If the TAV is null, then resolving the type parameter gives the dynamic
    // type, which is a top type.
    __ CompareObject(tav, NullObject());
    __ BranchIf(EQUAL, &done, Assembler::kNearJump);
    // Resolve the type parameter to its instantiated type and tail call the
    // instantiated type's TTS.
    __ LoadFieldFromOffset(TypeTestABI::kScratchReg, TypeTestABI::kDstTypeReg,
                           target::TypeParameter::index_offset(),
                           kUnsignedByte);
    __ LoadIndexedCompressed(TypeTestABI::kScratchReg, tav,
                             target::TypeArguments::types_offset(),
                             TypeTestABI::kScratchReg);
    __ Jump(FieldAddress(
        TypeTestABI::kScratchReg,
        target::AbstractType::type_test_stub_entry_point_offset()));
  };

  Label function_type_param;
  __ LoadFieldFromOffset(TypeTestABI::kScratchReg, TypeTestABI::kDstTypeReg,
                         target::TypeParameter::parameterized_class_id_offset(),
                         kUnsignedTwoBytes);
  __ CompareImmediate(TypeTestABI::kScratchReg, kFunctionCid);
  __ BranchIf(EQUAL, &function_type_param, Assembler::kNearJump);
  handle_case(TypeTestABI::kInstantiatorTypeArgumentsReg);
  __ Bind(&function_type_param);
  handle_case(TypeTestABI::kFunctionTypeArgumentsReg);
  __ Bind(&done);
  __ Ret();
}

void StubCodeCompiler::GenerateNullableTypeParameterTypeTestStub(
    Assembler* assembler) {
  BuildTypeParameterTypeTestStub(assembler, /*allow_null=*/true);
}

void StubCodeCompiler::GenerateTypeParameterTypeTestStub(Assembler* assembler) {
  BuildTypeParameterTypeTestStub(assembler, /*allow_null=*/false);
}

static void InvokeTypeCheckFromTypeTestStub(Assembler* assembler,
                                            TypeCheckMode mode) {
  __ PushObject(NullObject());  // Make room for result.
  __ PushRegistersInOrder({TypeTestABI::kInstanceReg, TypeTestABI::kDstTypeReg,
                           TypeTestABI::kInstantiatorTypeArgumentsReg,
                           TypeTestABI::kFunctionTypeArgumentsReg});
  __ PushObject(NullObject());
  __ PushRegister(TypeTestABI::kSubtypeTestCacheReg);
  __ PushImmediate(target::ToRawSmi(mode));
  __ CallRuntime(kTypeCheckRuntimeEntry, 7);
  __ Drop(1);  // mode
  __ PopRegister(TypeTestABI::kSubtypeTestCacheReg);
  __ Drop(1);  // dst_name
  __ PopRegister(TypeTestABI::kFunctionTypeArgumentsReg);
  __ PopRegister(TypeTestABI::kInstantiatorTypeArgumentsReg);
  __ PopRegister(TypeTestABI::kDstTypeReg);
  __ PopRegister(TypeTestABI::kInstanceReg);
  __ Drop(1);  // Discard return value.
}

void StubCodeCompiler::GenerateLazySpecializeTypeTestStub(
    Assembler* assembler) {
  __ LoadFromOffset(CODE_REG, THR,
                    target::Thread::lazy_specialize_type_test_stub_offset());
  __ EnterStubFrame();
  InvokeTypeCheckFromTypeTestStub(assembler, kTypeCheckFromLazySpecializeStub);
  __ LeaveStubFrame();
  __ Ret();
}

// Used instead of LazySpecializeTypeTestStub when null is assignable.
void StubCodeCompiler::GenerateLazySpecializeNullableTypeTestStub(
    Assembler* assembler) {
  Label done;

  __ CompareObject(TypeTestABI::kInstanceReg, NullObject());
  __ BranchIf(EQUAL, &done);

  __ LoadFromOffset(CODE_REG, THR,
                    target::Thread::lazy_specialize_type_test_stub_offset());
  __ EnterStubFrame();
  InvokeTypeCheckFromTypeTestStub(assembler, kTypeCheckFromLazySpecializeStub);
  __ LeaveStubFrame();

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

void StubCodeCompiler::GenerateSlowTypeTestStub(Assembler* assembler) {
  Label done, call_runtime;

  if (!FLAG_precompiled_mode) {
    __ LoadFromOffset(CODE_REG, THR,
                      target::Thread::slow_type_test_stub_offset());
  }
  __ EnterStubFrame();

  // If the subtype-cache is null, it needs to be lazily-created by the runtime.
  __ CompareObject(TypeTestABI::kSubtypeTestCacheReg, NullObject());
  __ BranchIf(EQUAL, &call_runtime, Assembler::kNearJump);

  // If this is not a [Type] object, we'll use wider SubtypeTestCache.
  Label is_simple_case, is_complex_case;
  __ LoadClassId(TypeTestABI::kScratchReg, TypeTestABI::kDstTypeReg);
  __ CompareImmediate(TypeTestABI::kScratchReg, kTypeCid);
  __ BranchIf(NOT_EQUAL, &is_complex_case, Assembler::kNearJump);

  // Check whether this [Type] is instantiated/uninstantiated.
  __ LoadFieldFromOffset(TypeTestABI::kScratchReg, TypeTestABI::kDstTypeReg,
                         target::Type::type_state_offset(), kByte);
  __ CompareImmediate(
      TypeTestABI::kScratchReg,
      target::UntaggedAbstractType::kTypeStateFinalizedInstantiated);
  __ BranchIf(NOT_EQUAL, &is_complex_case, Assembler::kNearJump);

  // This [Type] could be a FutureOr. Subtype2TestCache does not support Smi.
  __ BranchIfSmi(TypeTestABI::kInstanceReg, &is_complex_case);

  // Fall through to &is_simple_case

  const RegisterSet caller_saved_registers(
      TypeTestABI::kSubtypeTestCacheStubCallerSavedRegisters,
      /*fpu_registers=*/0);

  __ Bind(&is_simple_case);
  {
    __ PushRegisters(caller_saved_registers);
    __ Call(StubCodeSubtype3TestCache());
    __ CompareObject(TypeTestABI::kSubtypeTestCacheResultReg,
                     CastHandle<Object>(TrueObject()));
    __ PopRegisters(caller_saved_registers);
    __ BranchIf(EQUAL, &done);  // Cache said: yes.
    __ Jump(&call_runtime, Assembler::kNearJump);
  }

  __ Bind(&is_complex_case);
  {
    __ PushRegisters(caller_saved_registers);
    __ Call(StubCodeSubtype7TestCache());
    __ CompareObject(TypeTestABI::kSubtypeTestCacheResultReg,
                     CastHandle<Object>(TrueObject()));
    __ PopRegisters(caller_saved_registers);
    __ BranchIf(EQUAL, &done);  // Cache said: yes.
    // Fall through to runtime_call
  }

  __ Bind(&call_runtime);

  InvokeTypeCheckFromTypeTestStub(assembler, kTypeCheckFromSlowStub);

  __ Bind(&done);
  __ LeaveStubFrame();
  __ Ret();
}
#else
// Type testing stubs are not implemented on IA32.
#define GENERATE_BREAKPOINT_STUB(Name)                                         \
  void StubCodeCompiler::Generate##Name##Stub(Assembler* assembler) {          \
    __ Breakpoint();                                                           \
  }

VM_TYPE_TESTING_STUB_CODE_LIST(GENERATE_BREAKPOINT_STUB)

#undef GENERATE_BREAKPOINT_STUB
#endif  // !defined(TARGET_ARCH_IA32)

// Called for inline allocation of closure.
// Input (preserved):
//   AllocateClosureABI::kFunctionReg: closure function.
// Output:
//   AllocateClosureABI::kResultReg: new allocated Closure object.
// Clobbered:
//   AllocateClosureABI::kScratchReg
void StubCodeCompiler::GenerateAllocateClosureStub(Assembler* assembler) {
  const intptr_t instance_size =
      target::RoundedAllocationSize(target::Closure::InstanceSize());
  __ EnsureHasClassIdInDEBUG(kFunctionCid, AllocateClosureABI::kFunctionReg,
                             AllocateClosureABI::kScratchReg);
  __ EnsureHasClassIdInDEBUG(kContextCid, AllocateClosureABI::kContextReg,
                             AllocateClosureABI::kScratchReg,
                             /*can_be_null=*/true);
  if (!FLAG_use_slow_path && FLAG_inline_alloc) {
    Label slow_case;
    __ Comment("Inline allocation of uninitialized closure");
#if defined(DEBUG)
    // Need to account for the debug checks added by StoreToSlotNoBarrier.
    const auto distance = Assembler::kFarJump;
#else
    const auto distance = Assembler::kNearJump;
#endif
    __ TryAllocateObject(kClosureCid, instance_size, &slow_case, distance,
                         AllocateClosureABI::kResultReg,
                         AllocateClosureABI::kScratchReg);

    __ Comment("Inline initialization of allocated closure");
    // Put null in the scratch register for initializing most boxed fields.
    // We initialize the fields in offset order below.
    // Since the TryAllocateObject above did not go to the slow path, we're
    // guaranteed an object in new space here, and thus no barriers are needed.
    __ LoadObject(AllocateClosureABI::kScratchReg, NullObject());
    __ StoreToSlotNoBarrier(AllocateClosureABI::kScratchReg,
                            AllocateClosureABI::kResultReg,
                            Slot::Closure_instantiator_type_arguments());
    __ StoreToSlotNoBarrier(AllocateClosureABI::kScratchReg,
                            AllocateClosureABI::kResultReg,
                            Slot::Closure_function_type_arguments());
    __ StoreToSlotNoBarrier(AllocateClosureABI::kScratchReg,
                            AllocateClosureABI::kResultReg,
                            Slot::Closure_delayed_type_arguments());
    __ StoreToSlotNoBarrier(AllocateClosureABI::kFunctionReg,
                            AllocateClosureABI::kResultReg,
                            Slot::Closure_function());
    __ StoreToSlotNoBarrier(AllocateClosureABI::kContextReg,
                            AllocateClosureABI::kResultReg,
                            Slot::Closure_context());
    __ StoreToSlotNoBarrier(AllocateClosureABI::kScratchReg,
                            AllocateClosureABI::kResultReg,
                            Slot::Closure_hash());
#if defined(DART_PRECOMPILER) && !defined(TARGET_ARCH_IA32)
    if (FLAG_precompiled_mode) {
      // Set the closure entry point in precompiled mode, either to the function
      // entry point in bare instructions mode or to 0 otherwise (to catch
      // misuse). This overwrites the scratch register, but there are no more
      // boxed fields.
      __ LoadFromSlot(AllocateClosureABI::kScratchReg,
                      AllocateClosureABI::kFunctionReg,
                      Slot::Function_entry_point());
      __ StoreToSlotNoBarrier(AllocateClosureABI::kScratchReg,
                              AllocateClosureABI::kResultReg,
                              Slot::Closure_entry_point());
    }
#endif

    // AllocateClosureABI::kResultReg: new object.
    __ Ret();

    __ Bind(&slow_case);
  }

  __ Comment("Closure allocation via runtime");
  __ EnterStubFrame();
  __ PushObject(NullObject());  // Space on the stack for the return value.
  __ PushRegistersInOrder(
      {AllocateClosureABI::kFunctionReg, AllocateClosureABI::kContextReg});
  __ CallRuntime(kAllocateClosureRuntimeEntry, 2);
  __ PopRegister(AllocateClosureABI::kContextReg);
  __ PopRegister(AllocateClosureABI::kFunctionReg);
  __ PopRegister(AllocateClosureABI::kResultReg);
  ASSERT(target::WillAllocateNewOrRememberedObject(instance_size));
  EnsureIsNewOrRemembered(assembler, /*preserve_registers=*/false);
  __ LeaveStubFrame();

  // AllocateClosureABI::kResultReg: new object
  __ Ret();
}

// Generates allocation stub for _GrowableList class.
// This stub exists solely for performance reasons: default allocation
// stub is slower as it doesn't use specialized inline allocation.
void StubCodeCompiler::GenerateAllocateGrowableArrayStub(Assembler* assembler) {
#if defined(TARGET_ARCH_IA32)
  // This stub is not used on IA32 because IA32 version of
  // StubCodeCompiler::GenerateAllocationStubForClass uses inline
  // allocation. Also, AllocateObjectSlow stub is not generated on IA32.
  __ Breakpoint();
#else
  const intptr_t instance_size = target::RoundedAllocationSize(
      target::GrowableObjectArray::InstanceSize());

  if (!FLAG_use_slow_path && FLAG_inline_alloc) {
    Label slow_case;
    __ Comment("Inline allocation of GrowableList");
    __ TryAllocateObject(kGrowableObjectArrayCid, instance_size, &slow_case,
                         Assembler::kNearJump, AllocateObjectABI::kResultReg,
                         /*temp_reg=*/AllocateObjectABI::kTagsReg);
    __ StoreIntoObjectNoBarrier(
        AllocateObjectABI::kResultReg,
        FieldAddress(AllocateObjectABI::kResultReg,
                     target::GrowableObjectArray::type_arguments_offset()),
        AllocateObjectABI::kTypeArgumentsReg);

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

  const uword tags = target::MakeTagWordForNewSpaceObject(
      kGrowableObjectArrayCid, instance_size);
  __ LoadImmediate(AllocateObjectABI::kTagsReg, tags);
  __ Jump(
      Address(THR, target::Thread::allocate_object_slow_entry_point_offset()));
#endif  // defined(TARGET_ARCH_IA32)
}

void StubCodeCompiler::GenerateAllocateRecordStub(Assembler* assembler) {
  const Register result_reg = AllocateRecordABI::kResultReg;
  const Register num_fields_reg = AllocateRecordABI::kNumFieldsReg;
  const Register field_names_reg = AllocateRecordABI::kFieldNamesReg;
  const Register temp_reg = AllocateRecordABI::kTemp1Reg;
  const Register new_top_reg = AllocateRecordABI::kTemp2Reg;
  Label slow_case;

  // Check for allocation tracing.
  NOT_IN_PRODUCT(__ MaybeTraceAllocation(kRecordCid, &slow_case, temp_reg));

  // Compute the rounded instance size.
  const intptr_t fixed_size_plus_alignment_padding =
      (target::Record::field_offset(0) +
       target::ObjectAlignment::kObjectAlignment - 1);
  __ AddScaled(temp_reg, num_fields_reg, TIMES_COMPRESSED_WORD_SIZE,
               fixed_size_plus_alignment_padding);
  __ AndImmediate(temp_reg, -target::ObjectAlignment::kObjectAlignment);

  // Now allocate the object.
  __ LoadFromOffset(result_reg, Address(THR, target::Thread::top_offset()));
  __ MoveRegister(new_top_reg, temp_reg);
  __ AddRegisters(new_top_reg, result_reg);
  // Check if the allocation fits into the remaining space.
  __ CompareWithMemoryValue(new_top_reg,
                            Address(THR, target::Thread::end_offset()));
  __ BranchIf(UNSIGNED_GREATER_EQUAL, &slow_case);

  // Successfully allocated the object, now update top to point to
  // next object start and initialize the object.
  __ StoreToOffset(new_top_reg, Address(THR, target::Thread::top_offset()));
  __ AddImmediate(result_reg, kHeapObjectTag);

  // Calculate the size tag.
  {
    Label size_tag_overflow, done;
    __ CompareImmediate(temp_reg, target::UntaggedObject::kSizeTagMaxSizeTag);
    __ BranchIf(UNSIGNED_GREATER, &size_tag_overflow, Assembler::kNearJump);
    __ LslImmediate(temp_reg,
                    target::UntaggedObject::kTagBitsSizeTagPos -
                        target::ObjectAlignment::kObjectAlignmentLog2);
    __ Jump(&done, Assembler::kNearJump);

    __ Bind(&size_tag_overflow);
    // Set overflow size tag value.
    __ LoadImmediate(temp_reg, 0);

    __ Bind(&done);
    uword tags = target::MakeTagWordForNewSpaceObject(kRecordCid, 0);
    __ OrImmediate(temp_reg, tags);
    __ StoreToOffset(
        temp_reg,
        FieldAddress(result_reg, target::Object::tags_offset()));  // Tags.
  }

  __ StoreToOffset(
      num_fields_reg,
      FieldAddress(result_reg, target::Record::num_fields_offset()),
      kFourBytes);

  __ StoreCompressedIntoObjectNoBarrier(
      result_reg,
      FieldAddress(result_reg, target::Record::field_names_offset()),
      field_names_reg);

  // Initialize the remaining words of the object.
  {
    const Register field_reg = field_names_reg;
#if defined(TARGET_ARCH_ARM64) || defined(TARGET_ARCH_RISCV32) ||              \
    defined(TARGET_ARCH_RISCV64)
    const Register null_reg = NULL_REG;
#else
    const Register null_reg = temp_reg;
    __ LoadObject(null_reg, NullObject());
#endif

    Label loop, done;
    __ AddImmediate(field_reg, result_reg, target::Record::field_offset(0));
    __ CompareRegisters(field_reg, new_top_reg);
    __ BranchIf(UNSIGNED_GREATER_EQUAL, &done, Assembler::kNearJump);

    __ Bind(&loop);
    for (intptr_t offset = 0; offset < target::kObjectAlignment;
         offset += target::kCompressedWordSize) {
      __ StoreCompressedIntoObjectNoBarrier(
          result_reg, FieldAddress(field_reg, offset), null_reg);
    }
    // Safe to only check every kObjectAlignment bytes instead of each word.
    ASSERT(kAllocationRedZoneSize >= target::kObjectAlignment);
    __ AddImmediate(field_reg, target::kObjectAlignment);
    __ CompareRegisters(field_reg, new_top_reg);
    __ BranchIf(UNSIGNED_LESS, &loop, Assembler::kNearJump);
    __ Bind(&done);
  }

  __ Ret();

  __ Bind(&slow_case);

  __ EnterStubFrame();
  __ PushObject(NullObject());  // Space on the stack for the return value.
  __ SmiTag(num_fields_reg);
  __ PushRegistersInOrder({num_fields_reg, field_names_reg});
  __ CallRuntime(kAllocateRecordRuntimeEntry, 2);
  __ Drop(2);
  __ PopRegister(AllocateRecordABI::kResultReg);

  EnsureIsNewOrRemembered(assembler, /*preserve_registers=*/false);
  __ LeaveStubFrame();
  __ Ret();
}

// The UnhandledException class lives in the VM isolate, so it cannot cache
// an allocation stub for itself. Instead, we cache it in the stub code list.
void StubCodeCompiler::GenerateAllocateUnhandledExceptionStub(
    Assembler* assembler) {
  Thread* thread = Thread::Current();
  auto class_table = thread->isolate_group()->class_table();
  ASSERT(class_table->HasValidClassAt(kUnhandledExceptionCid));
  const auto& cls = Class::ZoneHandle(thread->zone(),
                                      class_table->At(kUnhandledExceptionCid));
  ASSERT(!cls.IsNull());

  GenerateAllocationStubForClass(assembler, nullptr, cls,
                                 Code::Handle(Code::null()),
                                 Code::Handle(Code::null()));
}

#define TYPED_DATA_ALLOCATION_STUB(clazz)                                      \
  void StubCodeCompiler::GenerateAllocate##clazz##Stub(Assembler* assembler) { \
    GenerateAllocateTypedDataArrayStub(assembler, kTypedData##clazz##Cid);     \
  }
CLASS_LIST_TYPED_DATA(TYPED_DATA_ALLOCATION_STUB)
#undef TYPED_DATA_ALLOCATION_STUB

void StubCodeCompiler::GenerateLateInitializationError(Assembler* assembler,
                                                       bool with_fpu_regs) {
  auto perform_runtime_call = [&]() {
    __ PushRegister(LateInitializationErrorABI::kFieldReg);
    __ CallRuntime(kLateFieldNotInitializedErrorRuntimeEntry,
                   /*argument_count=*/1);
  };
  GenerateSharedStubGeneric(
      assembler, /*save_fpu_registers=*/with_fpu_regs,
      with_fpu_regs
          ? target::Thread::
                late_initialization_error_shared_with_fpu_regs_stub_offset()
          : target::Thread::
                late_initialization_error_shared_without_fpu_regs_stub_offset(),
      /*allow_return=*/false, perform_runtime_call);
}

void StubCodeCompiler::GenerateLateInitializationErrorSharedWithoutFPURegsStub(
    Assembler* assembler) {
  GenerateLateInitializationError(assembler, /*with_fpu_regs=*/false);
}

void StubCodeCompiler::GenerateLateInitializationErrorSharedWithFPURegsStub(
    Assembler* assembler) {
  GenerateLateInitializationError(assembler, /*with_fpu_regs=*/true);
}

void StubCodeCompiler::GenerateNullErrorSharedWithoutFPURegsStub(
    Assembler* assembler) {
  GenerateSharedStub(
      assembler, /*save_fpu_registers=*/false, &kNullErrorRuntimeEntry,
      target::Thread::null_error_shared_without_fpu_regs_stub_offset(),
      /*allow_return=*/false);
}

void StubCodeCompiler::GenerateNullErrorSharedWithFPURegsStub(
    Assembler* assembler) {
  GenerateSharedStub(
      assembler, /*save_fpu_registers=*/true, &kNullErrorRuntimeEntry,
      target::Thread::null_error_shared_with_fpu_regs_stub_offset(),
      /*allow_return=*/false);
}

void StubCodeCompiler::GenerateNullArgErrorSharedWithoutFPURegsStub(
    Assembler* assembler) {
  GenerateSharedStub(
      assembler, /*save_fpu_registers=*/false, &kArgumentNullErrorRuntimeEntry,
      target::Thread::null_arg_error_shared_without_fpu_regs_stub_offset(),
      /*allow_return=*/false);
}

void StubCodeCompiler::GenerateNullArgErrorSharedWithFPURegsStub(
    Assembler* assembler) {
  GenerateSharedStub(
      assembler, /*save_fpu_registers=*/true, &kArgumentNullErrorRuntimeEntry,
      target::Thread::null_arg_error_shared_with_fpu_regs_stub_offset(),
      /*allow_return=*/false);
}

void StubCodeCompiler::GenerateNullCastErrorSharedWithoutFPURegsStub(
    Assembler* assembler) {
  GenerateSharedStub(
      assembler, /*save_fpu_registers=*/false, &kNullCastErrorRuntimeEntry,
      target::Thread::null_cast_error_shared_without_fpu_regs_stub_offset(),
      /*allow_return=*/false);
}

void StubCodeCompiler::GenerateNullCastErrorSharedWithFPURegsStub(
    Assembler* assembler) {
  GenerateSharedStub(
      assembler, /*save_fpu_registers=*/true, &kNullCastErrorRuntimeEntry,
      target::Thread::null_cast_error_shared_with_fpu_regs_stub_offset(),
      /*allow_return=*/false);
}

void StubCodeCompiler::GenerateStackOverflowSharedWithoutFPURegsStub(
    Assembler* assembler) {
  GenerateSharedStub(
      assembler, /*save_fpu_registers=*/false,
      &kInterruptOrStackOverflowRuntimeEntry,
      target::Thread::stack_overflow_shared_without_fpu_regs_stub_offset(),
      /*allow_return=*/true);
}

void StubCodeCompiler::GenerateStackOverflowSharedWithFPURegsStub(
    Assembler* assembler) {
  GenerateSharedStub(
      assembler, /*save_fpu_registers=*/true,
      &kInterruptOrStackOverflowRuntimeEntry,
      target::Thread::stack_overflow_shared_with_fpu_regs_stub_offset(),
      /*allow_return=*/true);
}

void StubCodeCompiler::GenerateRangeErrorSharedWithoutFPURegsStub(
    Assembler* assembler) {
  GenerateRangeError(assembler, /*with_fpu_regs=*/false);
}

void StubCodeCompiler::GenerateRangeErrorSharedWithFPURegsStub(
    Assembler* assembler) {
  GenerateRangeError(assembler, /*with_fpu_regs=*/true);
}

void StubCodeCompiler::GenerateWriteErrorSharedWithoutFPURegsStub(
    Assembler* assembler) {
  GenerateWriteError(assembler, /*with_fpu_regs=*/false);
}

void StubCodeCompiler::GenerateWriteErrorSharedWithFPURegsStub(
    Assembler* assembler) {
  GenerateWriteError(assembler, /*with_fpu_regs=*/true);
}

void StubCodeCompiler::GenerateFrameAwaitingMaterializationStub(
    Assembler* assembler) {
  __ Breakpoint();  // Marker stub.
}

void StubCodeCompiler::GenerateAsynchronousGapMarkerStub(Assembler* assembler) {
  __ Breakpoint();  // Marker stub.
}

void StubCodeCompiler::GenerateUnknownDartCodeStub(Assembler* assembler) {
  // Enter frame to include caller into the backtrace.
  __ EnterStubFrame();
  __ Breakpoint();  // Marker stub.
}

void StubCodeCompiler::GenerateNotLoadedStub(Assembler* assembler) {
  __ EnterStubFrame();
  __ CallRuntime(kNotLoadedRuntimeEntry, 0);
  __ Breakpoint();
}

#define EMIT_BOX_ALLOCATION(Name)                                              \
  void StubCodeCompiler::GenerateAllocate##Name##Stub(Assembler* assembler) {  \
    Label call_runtime;                                                        \
    if (!FLAG_use_slow_path && FLAG_inline_alloc) {                            \
      __ TryAllocate(compiler::Name##Class(), &call_runtime,                   \
                     Assembler::kNearJump, AllocateBoxABI::kResultReg,         \
                     AllocateBoxABI::kTempReg);                                \
      __ Ret();                                                                \
    }                                                                          \
    __ Bind(&call_runtime);                                                    \
    __ EnterStubFrame();                                                       \
    __ PushObject(NullObject()); /* Make room for result. */                   \
    __ CallRuntime(kAllocate##Name##RuntimeEntry, 0);                          \
    __ PopRegister(AllocateBoxABI::kResultReg);                                \
    __ LeaveStubFrame();                                                       \
    __ Ret();                                                                  \
  }

EMIT_BOX_ALLOCATION(Mint)
EMIT_BOX_ALLOCATION(Double)
EMIT_BOX_ALLOCATION(Float32x4)
EMIT_BOX_ALLOCATION(Float64x2)
EMIT_BOX_ALLOCATION(Int32x4)

#undef EMIT_BOX_ALLOCATION

static void GenerateBoxFpuValueStub(Assembler* assembler,
                                    const dart::Class& cls,
                                    const RuntimeEntry& runtime_entry,
                                    void (Assembler::*store_value)(FpuRegister,
                                                                   Register,
                                                                   int32_t)) {
  Label call_runtime;
  if (!FLAG_use_slow_path && FLAG_inline_alloc) {
    __ TryAllocate(cls, &call_runtime, compiler::Assembler::kFarJump,
                   BoxDoubleStubABI::kResultReg, BoxDoubleStubABI::kTempReg);
    (assembler->*store_value)(
        BoxDoubleStubABI::kValueReg, BoxDoubleStubABI::kResultReg,
        compiler::target::Double::value_offset() - kHeapObjectTag);
    __ Ret();
  }
  __ Bind(&call_runtime);
  __ EnterStubFrame();
  __ PushObject(NullObject()); /* Make room for result. */
  (assembler->*store_value)(BoxDoubleStubABI::kValueReg, THR,
                            target::Thread::unboxed_runtime_arg_offset());
  __ CallRuntime(runtime_entry, 0);
  __ PopRegister(BoxDoubleStubABI::kResultReg);
  __ LeaveStubFrame();
  __ Ret();
}

void StubCodeCompiler::GenerateBoxDoubleStub(Assembler* assembler) {
  GenerateBoxFpuValueStub(assembler, compiler::DoubleClass(),
                          kBoxDoubleRuntimeEntry,
                          &Assembler::StoreUnboxedDouble);
}

void StubCodeCompiler::GenerateBoxFloat32x4Stub(Assembler* assembler) {
#if !defined(TARGET_ARCH_RISCV32) && !defined(TARGET_ARCH_RISCV64)
  GenerateBoxFpuValueStub(assembler, compiler::Float32x4Class(),
                          kBoxFloat32x4RuntimeEntry,
                          &Assembler::StoreUnboxedSimd128);
#else
  __ Stop("Not supported on RISC-V.");
#endif
}

void StubCodeCompiler::GenerateBoxFloat64x2Stub(Assembler* assembler) {
#if !defined(TARGET_ARCH_RISCV32) && !defined(TARGET_ARCH_RISCV64)
  GenerateBoxFpuValueStub(assembler, compiler::Float64x2Class(),
                          kBoxFloat64x2RuntimeEntry,
                          &Assembler::StoreUnboxedSimd128);
#else
  __ Stop("Not supported on RISC-V.");
#endif
}

void StubCodeCompiler::GenerateDoubleToIntegerStub(Assembler* assembler) {
  __ EnterStubFrame();
  __ StoreUnboxedDouble(DoubleToIntegerStubABI::kInputReg, THR,
                        target::Thread::unboxed_runtime_arg_offset());
  __ PushObject(NullObject()); /* Make room for result. */
  __ PushRegister(DoubleToIntegerStubABI::kRecognizedKindReg);
  __ CallRuntime(kDoubleToIntegerRuntimeEntry, 1);
  __ Drop(1);
  __ PopRegister(DoubleToIntegerStubABI::kResultReg);
  __ LeaveStubFrame();
  __ Ret();
}

static intptr_t SuspendStateFpOffset() {
  return compiler::target::frame_layout.FrameSlotForVariableIndex(
             SuspendState::kSuspendStateVarIndex) *
         compiler::target::kWordSize;
}

static void CallDartCoreLibraryFunction(
    Assembler* assembler,
    intptr_t entry_point_offset_in_thread,
    intptr_t function_offset_in_object_store,
    bool uses_args_desc = false) {
  if (FLAG_precompiled_mode) {
    __ Call(Address(THR, entry_point_offset_in_thread));
  } else {
    __ LoadIsolateGroup(FUNCTION_REG);
    __ LoadFromOffset(
        FUNCTION_REG,
        Address(FUNCTION_REG, target::IsolateGroup::object_store_offset()));
    __ LoadFromOffset(FUNCTION_REG,
                      Address(FUNCTION_REG, function_offset_in_object_store));
    __ LoadCompressedFieldFromOffset(CODE_REG, FUNCTION_REG,
                                     target::Function::code_offset());
    if (!uses_args_desc) {
      // Load a GC-safe value for the arguments descriptor (unused but tagged).
      __ LoadImmediate(ARGS_DESC_REG, 0);
    }
    __ Call(FieldAddress(FUNCTION_REG, target::Function::entry_point_offset()));
  }
}

// Helper to generate allocation of _SuspendState instance.
// Initializes tags, frame_capacity and frame_size.
// Other fields are not initialized.
//
// Input:
//   frame_size_reg: size of the frame payload in bytes.
// Output:
//   result_reg: allocated instance.
// Clobbers:
//   result_reg, temp_reg.
static void GenerateAllocateSuspendState(Assembler* assembler,
                                         Label* slow_case,
                                         Register result_reg,
                                         Register frame_size_reg,
                                         Register temp_reg) {
  // Check for allocation tracing.
  NOT_IN_PRODUCT(
      __ MaybeTraceAllocation(kSuspendStateCid, slow_case, temp_reg));

  // Compute the rounded instance size.
  const intptr_t fixed_size_plus_alignment_padding =
      (target::SuspendState::HeaderSize() +
       target::SuspendState::FrameSizeGrowthGap() * target::kWordSize +
       target::ObjectAlignment::kObjectAlignment - 1);
  __ AddImmediate(temp_reg, frame_size_reg, fixed_size_plus_alignment_padding);
  __ AndImmediate(temp_reg, -target::ObjectAlignment::kObjectAlignment);

  // Now allocate the object.
  __ LoadFromOffset(result_reg, Address(THR, target::Thread::top_offset()));
  __ AddRegisters(temp_reg, result_reg);
  // Check if the allocation fits into the remaining space.
  __ CompareWithMemoryValue(temp_reg,
                            Address(THR, target::Thread::end_offset()));
  __ BranchIf(UNSIGNED_GREATER_EQUAL, slow_case);

  // Successfully allocated the object, now update top to point to
  // next object start and initialize the object.
  __ StoreToOffset(temp_reg, Address(THR, target::Thread::top_offset()));
  __ SubRegisters(temp_reg, result_reg);
  __ AddImmediate(result_reg, kHeapObjectTag);

  if (!FLAG_precompiled_mode) {
    // Use rounded object size to calculate and save frame capacity.
    __ AddImmediate(temp_reg, temp_reg,
                    -target::SuspendState::payload_offset());
    __ StoreToOffset(
        temp_reg, FieldAddress(result_reg,
                               target::SuspendState::frame_capacity_offset()));
    // Restore rounded object size.
    __ AddImmediate(temp_reg, temp_reg, target::SuspendState::payload_offset());
  }

  // Calculate the size tag.
  {
    Label size_tag_overflow, done;
    __ CompareImmediate(temp_reg, target::UntaggedObject::kSizeTagMaxSizeTag);
    __ BranchIf(UNSIGNED_GREATER, &size_tag_overflow, Assembler::kNearJump);
    __ LslImmediate(temp_reg,
                    target::UntaggedObject::kTagBitsSizeTagPos -
                        target::ObjectAlignment::kObjectAlignmentLog2);
    __ Jump(&done, Assembler::kNearJump);

    __ Bind(&size_tag_overflow);
    // Set overflow size tag value.
    __ LoadImmediate(temp_reg, 0);

    __ Bind(&done);
    uword tags = target::MakeTagWordForNewSpaceObject(kSuspendStateCid, 0);
    __ OrImmediate(temp_reg, tags);
    __ StoreToOffset(
        temp_reg,
        FieldAddress(result_reg, target::Object::tags_offset()));  // Tags.
  }

  __ StoreToOffset(
      frame_size_reg,
      FieldAddress(result_reg, target::SuspendState::frame_size_offset()));
}

void StubCodeCompiler::GenerateSuspendStub(
    Assembler* assembler,
    bool call_suspend_function,
    intptr_t suspend_entry_point_offset_in_thread,
    intptr_t suspend_function_offset_in_object_store) {
  const Register kArgument = SuspendStubABI::kArgumentReg;
  const Register kTemp = SuspendStubABI::kTempReg;
  const Register kFrameSize = SuspendStubABI::kFrameSizeReg;
  const Register kSuspendState = SuspendStubABI::kSuspendStateReg;
  const Register kFunctionData = SuspendStubABI::kFunctionDataReg;
  const Register kSrcFrame = SuspendStubABI::kSrcFrameReg;
  const Register kDstFrame = SuspendStubABI::kDstFrameReg;
  Label alloc_slow_case, alloc_done, init_done, resize_suspend_state,
      old_gen_object, call_dart;

#if defined(TARGET_ARCH_ARM) || defined(TARGET_ARCH_ARM64)
  SPILLS_LR_TO_FRAME({});  // Simulate entering the caller (Dart) frame.
#endif

  __ LoadFromOffset(kSuspendState, Address(FPREG, SuspendStateFpOffset()));

  __ AddImmediate(
      kFrameSize, FPREG,
      -target::frame_layout.last_param_from_entry_sp * target::kWordSize);
  __ SubRegisters(kFrameSize, SPREG);

  __ EnterStubFrame();

  __ CompareClassId(kSuspendState, kSuspendStateCid, kTemp);

  if (FLAG_precompiled_mode) {
    __ BranchIf(EQUAL, &init_done);
  } else {
    Label alloc_suspend_state;
    __ BranchIf(NOT_EQUAL, &alloc_suspend_state);

    __ CompareWithMemoryValue(
        kFrameSize,
        FieldAddress(kSuspendState,
                     target::SuspendState::frame_capacity_offset()));
    __ BranchIf(UNSIGNED_GREATER, &resize_suspend_state);

    __ StoreToOffset(
        kFrameSize,
        FieldAddress(kSuspendState, target::SuspendState::frame_size_offset()));
    __ Jump(&init_done);

    __ Bind(&alloc_suspend_state);
  }

  __ Comment("Allocate SuspendState");
  __ MoveRegister(kFunctionData, kSuspendState);

  GenerateAllocateSuspendState(assembler, &alloc_slow_case, kSuspendState,
                               kFrameSize, kTemp);

  __ StoreCompressedIntoObjectNoBarrier(
      kSuspendState,
      FieldAddress(kSuspendState, target::SuspendState::function_data_offset()),
      kFunctionData);

  {
#if defined(TARGET_ARCH_ARM64) || defined(TARGET_ARCH_RISCV32) ||              \
    defined(TARGET_ARCH_RISCV64)
    const Register kNullReg = NULL_REG;
#else
    const Register kNullReg = kTemp;
    __ LoadObject(kNullReg, NullObject());
#endif
    __ StoreCompressedIntoObjectNoBarrier(
        kSuspendState,
        FieldAddress(kSuspendState,
                     target::SuspendState::then_callback_offset()),
        kNullReg);
    __ StoreCompressedIntoObjectNoBarrier(
        kSuspendState,
        FieldAddress(kSuspendState,
                     target::SuspendState::error_callback_offset()),
        kNullReg);
  }

  __ Bind(&alloc_done);

  __ Comment("Save SuspendState to frame");
  __ LoadFromOffset(
      kTemp, Address(FPREG, kSavedCallerFpSlotFromFp * target::kWordSize));
  __ StoreToOffset(kSuspendState, Address(kTemp, SuspendStateFpOffset()));

  __ Bind(&init_done);
  __ Comment("Copy frame to SuspendState");

#ifdef DEBUG
  {
    // Verify that SuspendState.frame_size == kFrameSize.
    Label okay;
    __ LoadFromOffset(
        kTemp,
        FieldAddress(kSuspendState, target::SuspendState::frame_size_offset()));
    __ CompareRegisters(kTemp, kFrameSize);
    __ BranchIf(EQUAL, &okay);
    __ Breakpoint();
    __ Bind(&okay);
  }
#endif

  __ LoadFromOffset(
      kTemp, Address(FPREG, kSavedCallerPcSlotFromFp * target::kWordSize));
  __ StoreToOffset(
      kTemp, FieldAddress(kSuspendState, target::SuspendState::pc_offset()));

  if (kSrcFrame == THR) {
    __ PushRegister(THR);
  }
  __ AddImmediate(kSrcFrame, FPREG, kCallerSpSlotFromFp * target::kWordSize);
  __ AddImmediate(kDstFrame, kSuspendState,
                  target::SuspendState::payload_offset() - kHeapObjectTag);
  __ CopyMemoryWords(kSrcFrame, kDstFrame, kFrameSize, kTemp);
  if (kSrcFrame == THR) {
    __ PopRegister(THR);
  }

#ifdef DEBUG
  {
    // Verify that kSuspendState matches :suspend_state in the copied stack
    // frame.
    Label okay;
    __ LoadFromOffset(
        kTemp,
        FieldAddress(kSuspendState, target::SuspendState::frame_size_offset()));
    __ AddRegisters(kTemp, kSuspendState);
    __ LoadFromOffset(
        kTemp, FieldAddress(kTemp, target::SuspendState::payload_offset() +
                                       SuspendStateFpOffset()));
    __ CompareRegisters(kTemp, kSuspendState);
    __ BranchIf(EQUAL, &okay);
    __ Breakpoint();
    __ Bind(&okay);
  }
#endif

  if (call_suspend_function) {
    // Push arguments for suspend Dart function early to preserve them
    // across write barrier.
    __ PushRegistersInOrder({kSuspendState, kArgument});
  }

  // Write barrier.
  __ BranchIfBit(kSuspendState, target::ObjectAlignment::kNewObjectBitPosition,
                 ZERO, &old_gen_object);

  __ Bind(&call_dart);
  if (call_suspend_function) {
    __ Comment("Call suspend Dart function");
    CallDartCoreLibraryFunction(assembler, suspend_entry_point_offset_in_thread,
                                suspend_function_offset_in_object_store);
  } else {
    // SuspendStub returns either the result of Dart callback,
    // or SuspendStub argument (if Dart callback is not used).
    // The latter is used by yield/yield* in sync* functions
    // to indicate that iteration should be continued.
    __ MoveRegister(CallingConventions::kReturnReg, kArgument);
  }

  __ LeaveStubFrame();

#if !defined(TARGET_ARCH_X64) && !defined(TARGET_ARCH_IA32)
  // Drop caller frame on all architectures except x86 (X64/IA32) which
  // needs to maintain call/return balance to avoid performance regressions.
  __ LeaveDartFrame();
#elif defined(TARGET_ARCH_X64)
  // Restore PP in JIT mode on x64 as epilogue following SuspendStub call
  // will only unwind frame and return.
  if (!FLAG_precompiled_mode) {
    __ LoadFromOffset(
        PP, Address(FPREG, target::frame_layout.saved_caller_pp_from_fp *
                               target::kWordSize));
  }
#endif
  __ Ret();

#if defined(TARGET_ARCH_ARM) || defined(TARGET_ARCH_ARM64)
  // Slow path is executed with Dart and stub frames still on the stack.
  SPILLS_LR_TO_FRAME({});
  SPILLS_LR_TO_FRAME({});
#endif
  __ Bind(&alloc_slow_case);
  __ Comment("SuspendState Allocation slow case");
  // Save argument and frame size.
  __ PushRegistersInOrder({kArgument, kFrameSize});
  __ PushObject(NullObject());  // Make space on stack for the return value.
  __ SmiTag(kFrameSize);
  // Pass frame size and function data to runtime entry.
  __ PushRegistersInOrder({kFrameSize, kFunctionData});
  __ CallRuntime(kAllocateSuspendStateRuntimeEntry, 2);
  __ Drop(2);                     // Drop arguments
  __ PopRegister(kSuspendState);  // Get result.
  __ PopRegister(kFrameSize);     // Restore frame size.
  __ PopRegister(kArgument);      // Restore argument.
  __ Jump(&alloc_done);

  __ Bind(&resize_suspend_state);
  __ Comment("Resize SuspendState");
  // Save argument and frame size.
  __ PushRegistersInOrder({kArgument, kFrameSize});
  __ PushObject(NullObject());  // Make space on stack for the return value.
  __ SmiTag(kFrameSize);
  // Pass frame size and old suspend state to runtime entry.
  __ PushRegistersInOrder({kFrameSize, kSuspendState});
  // It's okay to call runtime for resizing SuspendState objects
  // as it can only happen in the unoptimized code if expression
  // stack grows between suspends, or once after OSR transition.
  __ CallRuntime(kAllocateSuspendStateRuntimeEntry, 2);
  __ Drop(2);                     // Drop arguments
  __ PopRegister(kSuspendState);  // Get result.
  __ PopRegister(kFrameSize);     // Restore frame size.
  __ PopRegister(kArgument);      // Restore argument.
  __ Jump(&alloc_done);

  __ Bind(&old_gen_object);
  __ Comment("Old gen SuspendState slow case");
  if (!call_suspend_function) {
    // Save kArgument which contains the return value
    // if suspend function is not called.
    __ PushRegister(kArgument);
  }
  {
#if defined(TARGET_ARCH_IA32)
    LeafRuntimeScope rt(assembler, /*frame_size=*/2 * target::kWordSize,
                        /*preserve_registers=*/false);
    __ movl(Address(ESP, 1 * target::kWordSize), THR);
    __ movl(Address(ESP, 0 * target::kWordSize), kSuspendState);
#else
    LeafRuntimeScope rt(assembler, /*frame_size=*/0,
                        /*preserve_registers=*/false);
    __ MoveRegister(CallingConventions::ArgumentRegisters[0], kSuspendState);
    __ MoveRegister(CallingConventions::ArgumentRegisters[1], THR);
#endif
    rt.Call(kEnsureRememberedAndMarkingDeferredRuntimeEntry, 2);
  }
  if (!call_suspend_function) {
    __ PopRegister(kArgument);
  }
  __ Jump(&call_dart);
}

void StubCodeCompiler::GenerateAwaitStub(Assembler* assembler) {
  GenerateSuspendStub(assembler,
                      /*call_suspend_function=*/true,
                      target::Thread::suspend_state_await_entry_point_offset(),
                      target::ObjectStore::suspend_state_await_offset());
}

void StubCodeCompiler::GenerateYieldAsyncStarStub(Assembler* assembler) {
  GenerateSuspendStub(
      assembler,
      /*call_suspend_function=*/true,
      target::Thread::suspend_state_yield_async_star_entry_point_offset(),
      target::ObjectStore::suspend_state_yield_async_star_offset());
}

void StubCodeCompiler::GenerateSuspendSyncStarAtStartStub(
    Assembler* assembler) {
  GenerateSuspendStub(
      assembler,
      /*call_suspend_function=*/true,
      target::Thread::
          suspend_state_suspend_sync_star_at_start_entry_point_offset(),
      target::ObjectStore::suspend_state_suspend_sync_star_at_start_offset());
}

void StubCodeCompiler::GenerateSuspendSyncStarAtYieldStub(
    Assembler* assembler) {
  GenerateSuspendStub(assembler,
                      /*call_suspend_function=*/false, -1, -1);
}

void StubCodeCompiler::GenerateInitSuspendableFunctionStub(
    Assembler* assembler,
    intptr_t init_entry_point_offset_in_thread,
    intptr_t init_function_offset_in_object_store) {
  const Register kTypeArgs = InitSuspendableFunctionStubABI::kTypeArgsReg;

  __ EnterStubFrame();
  __ LoadObject(ARGS_DESC_REG, ArgumentsDescriptorBoxed(/*type_args_len=*/1,
                                                        /*num_arguments=*/0));
  __ PushRegister(kTypeArgs);
  CallDartCoreLibraryFunction(assembler, init_entry_point_offset_in_thread,
                              init_function_offset_in_object_store,
                              /*uses_args_desc=*/true);
  __ LeaveStubFrame();

  // Set :suspend_state in the caller frame.
  __ StoreToOffset(CallingConventions::kReturnReg,
                   Address(FPREG, SuspendStateFpOffset()));
  __ Ret();
}

void StubCodeCompiler::GenerateInitAsyncStub(Assembler* assembler) {
  GenerateInitSuspendableFunctionStub(
      assembler, target::Thread::suspend_state_init_async_entry_point_offset(),
      target::ObjectStore::suspend_state_init_async_offset());
}

void StubCodeCompiler::GenerateInitAsyncStarStub(Assembler* assembler) {
  GenerateInitSuspendableFunctionStub(
      assembler,
      target::Thread::suspend_state_init_async_star_entry_point_offset(),
      target::ObjectStore::suspend_state_init_async_star_offset());
}

void StubCodeCompiler::GenerateInitSyncStarStub(Assembler* assembler) {
  GenerateInitSuspendableFunctionStub(
      assembler,
      target::Thread::suspend_state_init_sync_star_entry_point_offset(),
      target::ObjectStore::suspend_state_init_sync_star_offset());
}

void StubCodeCompiler::GenerateResumeStub(Assembler* assembler) {
  const Register kSuspendState = ResumeStubABI::kSuspendStateReg;
  const Register kTemp = ResumeStubABI::kTempReg;
  const Register kFrameSize = ResumeStubABI::kFrameSizeReg;
  const Register kSrcFrame = ResumeStubABI::kSrcFrameReg;
  const Register kDstFrame = ResumeStubABI::kDstFrameReg;
  const Register kResumePc = ResumeStubABI::kResumePcReg;
  const Register kException = ResumeStubABI::kExceptionReg;
  const Register kStackTrace = ResumeStubABI::kStackTraceReg;
  Label call_runtime;

  // Top of the stack on entry:
  // ... [SuspendState] [value] [exception] [stackTrace] [ReturnAddress]

  __ EnterDartFrame(0);

  const intptr_t param_offset =
      target::frame_layout.param_end_from_fp * target::kWordSize;
  __ LoadFromOffset(kSuspendState,
                    Address(FPREG, param_offset + 4 * target::kWordSize));
#ifdef DEBUG
  {
    Label okay;
    __ CompareClassId(kSuspendState, kSuspendStateCid, kTemp);
    __ BranchIf(EQUAL, &okay);
    __ Breakpoint();
    __ Bind(&okay);
  }
  {
    Label okay;
    __ LoadFromOffset(
        kTemp, FieldAddress(kSuspendState, target::SuspendState::pc_offset()));
    __ CompareImmediate(kTemp, 0);
    __ BranchIf(NOT_EQUAL, &okay);
    __ Breakpoint();
    __ Bind(&okay);
  }
#endif

  __ LoadFromOffset(
      kFrameSize,
      FieldAddress(kSuspendState, target::SuspendState::frame_size_offset()));
#ifdef DEBUG
  {
    Label okay;
    __ MoveRegister(kTemp, kFrameSize);
    __ AddRegisters(kTemp, kSuspendState);
    __ LoadFromOffset(
        kTemp, FieldAddress(kTemp, target::SuspendState::payload_offset() +
                                       SuspendStateFpOffset()));
    __ CompareRegisters(kTemp, kSuspendState);
    __ BranchIf(EQUAL, &okay);
    __ Breakpoint();
    __ Bind(&okay);
  }
#endif
  if (!FLAG_precompiled_mode) {
    // Copy Code object (part of the fixed frame which is not copied below)
    // and restore pool pointer.
    __ MoveRegister(kTemp, kSuspendState);
    __ AddRegisters(kTemp, kFrameSize);
    __ LoadFromOffset(
        CODE_REG,
        Address(kTemp,
                target::SuspendState::payload_offset() - kHeapObjectTag +
                    target::frame_layout.code_from_fp * target::kWordSize));
    __ StoreToOffset(
        CODE_REG,
        Address(FPREG, target::frame_layout.code_from_fp * target::kWordSize));
#if !defined(TARGET_ARCH_IA32)
    __ LoadPoolPointer(PP);
#endif
  }
  // Do not copy fixed frame between the first local and FP.
  __ AddImmediate(kFrameSize, (target::frame_layout.first_local_from_fp + 1) *
                                  target::kWordSize);
  __ SubRegisters(SPREG, kFrameSize);

  __ Comment("Copy frame from SuspendState");
  intptr_t num_saved_regs = 0;
  if (kSrcFrame == THR) {
    __ PushRegister(THR);
    ++num_saved_regs;
  }
  if (kDstFrame == CODE_REG) {
    __ PushRegister(CODE_REG);
    ++num_saved_regs;
  }
  __ AddImmediate(kSrcFrame, kSuspendState,
                  target::SuspendState::payload_offset() - kHeapObjectTag);
  __ AddImmediate(kDstFrame, SPREG, num_saved_regs * target::kWordSize);
  __ CopyMemoryWords(kSrcFrame, kDstFrame, kFrameSize, kTemp);
  if (kDstFrame == CODE_REG) {
    __ PopRegister(CODE_REG);
  }
  if (kSrcFrame == THR) {
    __ PopRegister(THR);
  }

  __ Comment("Transfer control");

  __ LoadFromOffset(kResumePc, FieldAddress(kSuspendState,
                                            target::SuspendState::pc_offset()));
  __ StoreZero(FieldAddress(kSuspendState, target::SuspendState::pc_offset()),
               kTemp);

#if defined(TARGET_ARCH_X64) || defined(TARGET_ARCH_IA32)
  // Adjust resume PC to skip extra epilogue generated on x86
  // right after the call to suspend stub in order to maintain
  // call/return balance.
  __ AddImmediate(kResumePc, SuspendStubABI::kResumePcDistance);
#endif

  static_assert((kException != CODE_REG) && (kException != PP),
                "should not interfere");
  __ LoadFromOffset(kException,
                    Address(FPREG, param_offset + 2 * target::kWordSize));
  __ CompareObject(kException, NullObject());
  __ BranchIf(NOT_EQUAL, &call_runtime);

  if (!FLAG_precompiled_mode) {
    // Check if Code is disabled.
    __ LoadFromOffset(
        kTemp, FieldAddress(CODE_REG, target::Code::instructions_offset()));
    __ CompareWithMemoryValue(
        kTemp,
        FieldAddress(CODE_REG, target::Code::active_instructions_offset()));
    __ BranchIf(NOT_EQUAL, &call_runtime);

#if !defined(PRODUCT)
    // Check if there is a breakpoint at resumption.
    __ LoadIsolate(kTemp);
    __ LoadFromOffset(
        kTemp,
        Address(kTemp, target::Isolate::has_resumption_breakpoints_offset()),
        kUnsignedByte);
    __ CompareImmediate(kTemp, 0);
    __ BranchIf(NOT_EQUAL, &call_runtime);
#endif
  }

  __ LoadFromOffset(CallingConventions::kReturnReg,
                    Address(FPREG, param_offset + 3 * target::kWordSize));

  __ Jump(kResumePc);

  __ Comment("Call runtime to throw exception or deopt");
  __ Bind(&call_runtime);

  __ LoadFromOffset(kStackTrace,
                    Address(FPREG, param_offset + 1 * target::kWordSize));
  static_assert((kStackTrace != CODE_REG) && (kStackTrace != PP),
                "should not interfere");

  // Set return address as if suspended Dart function called
  // stub with kResumePc as a return address.
  __ SetReturnAddress(kResumePc);

  if (!FLAG_precompiled_mode) {
    __ LoadFromOffset(CODE_REG, THR, target::Thread::resume_stub_offset());
  }
#if !defined(TARGET_ARCH_IA32)
  __ set_constant_pool_allowed(false);
#endif
  __ EnterStubFrame();
  __ PushObject(NullObject());  // Make room for (unused) result.
  __ PushRegistersInOrder({kException, kStackTrace});
  __ CallRuntime(kResumeFrameRuntimeEntry, /*argument_count=*/2);

  if (FLAG_precompiled_mode) {
    __ Breakpoint();
  } else {
    __ LeaveStubFrame();
    __ LoadFromOffset(CallingConventions::kReturnReg,
                      Address(FPREG, param_offset + 3 * target::kWordSize));
    // Lazy deoptimize.
    __ Ret();
  }
}

void StubCodeCompiler::GenerateReturnStub(
    Assembler* assembler,
    intptr_t return_entry_point_offset_in_thread,
    intptr_t return_function_offset_in_object_store,
    intptr_t return_stub_offset_in_thread) {
  const Register kSuspendState = ReturnStubABI::kSuspendStateReg;

#if defined(TARGET_ARCH_ARM) || defined(TARGET_ARCH_ARM64)
  SPILLS_LR_TO_FRAME({});  // Simulate entering the caller (Dart) frame.
#endif

  __ LoadFromOffset(kSuspendState, Address(FPREG, SuspendStateFpOffset()));
#ifdef DEBUG
  {
    Label okay;
    __ CompareObject(kSuspendState, NullObject());
    __ BranchIf(NOT_EQUAL, &okay);
    __ Breakpoint();
    __ Bind(&okay);
  }
#endif
  __ LeaveDartFrame();
  if (!FLAG_precompiled_mode) {
    __ LoadFromOffset(CODE_REG, THR, return_stub_offset_in_thread);
  }
  __ EnterStubFrame();
  __ PushRegistersInOrder({kSuspendState, CallingConventions::kReturnReg});
  CallDartCoreLibraryFunction(assembler, return_entry_point_offset_in_thread,
                              return_function_offset_in_object_store);
  __ LeaveStubFrame();
  __ Ret();
}

void StubCodeCompiler::GenerateReturnAsyncStub(Assembler* assembler) {
  GenerateReturnStub(
      assembler,
      target::Thread::suspend_state_return_async_entry_point_offset(),
      target::ObjectStore::suspend_state_return_async_offset(),
      target::Thread::return_async_stub_offset());
}

void StubCodeCompiler::GenerateReturnAsyncNotFutureStub(Assembler* assembler) {
  GenerateReturnStub(
      assembler,
      target::Thread::
          suspend_state_return_async_not_future_entry_point_offset(),
      target::ObjectStore::suspend_state_return_async_not_future_offset(),
      target::Thread::return_async_not_future_stub_offset());
}

void StubCodeCompiler::GenerateReturnAsyncStarStub(Assembler* assembler) {
  GenerateReturnStub(
      assembler,
      target::Thread::suspend_state_return_async_star_entry_point_offset(),
      target::ObjectStore::suspend_state_return_async_star_offset(),
      target::Thread::return_async_star_stub_offset());
}

void StubCodeCompiler::GenerateAsyncExceptionHandlerStub(Assembler* assembler) {
  const Register kSuspendState = AsyncExceptionHandlerStubABI::kSuspendStateReg;
  ASSERT(kSuspendState != kExceptionObjectReg);
  ASSERT(kSuspendState != kStackTraceObjectReg);
  Label rethrow_exception;

#if defined(TARGET_ARCH_ARM) || defined(TARGET_ARCH_ARM64)
  SPILLS_LR_TO_FRAME({});  // Simulate entering the caller (Dart) frame.
#endif

  __ LoadFromOffset(kSuspendState, Address(FPREG, SuspendStateFpOffset()));

  // Check if suspend_state is initialized. Otherwise
  // exception was thrown from the prologue code and
  // should be synchronuously propagated.
  __ CompareObject(kSuspendState, NullObject());
  __ BranchIf(EQUAL, &rethrow_exception);

  __ LeaveDartFrame();
  if (!FLAG_precompiled_mode) {
    __ LoadFromOffset(CODE_REG, THR,
                      target::Thread::async_exception_handler_stub_offset());
  }
  __ EnterStubFrame();
  __ PushRegistersInOrder(
      {kSuspendState, kExceptionObjectReg, kStackTraceObjectReg});
  CallDartCoreLibraryFunction(
      assembler,
      target::Thread::suspend_state_handle_exception_entry_point_offset(),
      target::ObjectStore::suspend_state_handle_exception_offset());
  __ LeaveStubFrame();
  __ Ret();

#if defined(TARGET_ARCH_ARM) || defined(TARGET_ARCH_ARM64)
  // Rethrow case is used when Dart frame is still on the stack.
  SPILLS_LR_TO_FRAME({});
#endif
  __ Comment("Rethrow exception");
  __ Bind(&rethrow_exception);
  __ LeaveDartFrame();
  if (!FLAG_precompiled_mode) {
    __ LoadFromOffset(CODE_REG, THR,
                      target::Thread::async_exception_handler_stub_offset());
  }
  __ EnterStubFrame();
  __ PushObject(NullObject());  // Make room for (unused) result.
  __ PushRegistersInOrder({kExceptionObjectReg, kStackTraceObjectReg});
  __ CallRuntime(kReThrowRuntimeEntry, /*argument_count=*/2);
  __ Breakpoint();
}

void StubCodeCompiler::GenerateCloneSuspendStateStub(Assembler* assembler) {
  const Register kSource = CloneSuspendStateStubABI::kSourceReg;
  const Register kDestination = CloneSuspendStateStubABI::kDestinationReg;
  const Register kTemp = CloneSuspendStateStubABI::kTempReg;
  const Register kFrameSize = CloneSuspendStateStubABI::kFrameSizeReg;
  const Register kSrcFrame = CloneSuspendStateStubABI::kSrcFrameReg;
  const Register kDstFrame = CloneSuspendStateStubABI::kDstFrameReg;
  Label alloc_slow_case;

#ifdef DEBUG
  {
    // Can only clone _SuspendState objects with copied frames.
    Label okay;
    __ LoadFromOffset(kTemp,
                      FieldAddress(kSource, target::SuspendState::pc_offset()));
    __ CompareImmediate(kTemp, 0);
    __ BranchIf(NOT_EQUAL, &okay);
    __ Breakpoint();
    __ Bind(&okay);
  }
#endif

  __ LoadFromOffset(
      kFrameSize,
      FieldAddress(kSource, target::SuspendState::frame_size_offset()));

  GenerateAllocateSuspendState(assembler, &alloc_slow_case, kDestination,
                               kFrameSize, kTemp);

  // Copy pc.
  __ LoadFromOffset(kTemp,
                    FieldAddress(kSource, target::SuspendState::pc_offset()));
  __ StoreToOffset(
      kTemp, FieldAddress(kDestination, target::SuspendState::pc_offset()));

  // Copy function_data.
  __ LoadCompressedFieldFromOffset(
      kTemp, kSource, target::SuspendState::function_data_offset());
  __ StoreCompressedIntoObjectNoBarrier(
      kDestination,
      FieldAddress(kDestination, target::SuspendState::function_data_offset()),
      kTemp);

  // Copy then_callback.
  __ LoadCompressedFieldFromOffset(
      kTemp, kSource, target::SuspendState::then_callback_offset());
  __ StoreCompressedIntoObjectNoBarrier(
      kDestination,
      FieldAddress(kDestination, target::SuspendState::then_callback_offset()),
      kTemp);

  // Copy error_callback.
  __ LoadCompressedFieldFromOffset(
      kTemp, kSource, target::SuspendState::error_callback_offset());
  __ StoreCompressedIntoObjectNoBarrier(
      kDestination,
      FieldAddress(kDestination, target::SuspendState::error_callback_offset()),
      kTemp);

  // Copy payload frame.
  if (kSrcFrame == THR) {
    __ PushRegister(THR);
  }
  const uword offset = target::SuspendState::payload_offset() - kHeapObjectTag;
  __ AddImmediate(kSrcFrame, kSource, offset);
  __ AddImmediate(kDstFrame, kDestination, offset);
  __ CopyMemoryWords(kSrcFrame, kDstFrame, kFrameSize, kTemp);
  if (kSrcFrame == THR) {
    __ PopRegister(THR);
  }

  // Update value of :suspend_state variable in the copied frame
  // for the new SuspendState.
  __ LoadFromOffset(
      kTemp,
      FieldAddress(kDestination, target::SuspendState::frame_size_offset()));
  __ AddRegisters(kTemp, kDestination);
  __ StoreToOffset(kDestination,
                   FieldAddress(kTemp, target::SuspendState::payload_offset() +
                                           SuspendStateFpOffset()));

  __ MoveRegister(CallingConventions::kReturnReg, kDestination);
  __ Ret();

  __ Bind(&alloc_slow_case);
  __ Comment("CloneSuspendState slow case");
  __ EnterStubFrame();
  __ PushObject(NullObject());  // Make space on stack for the return value.
  __ PushRegister(kSource);
  __ CallRuntime(kCloneSuspendStateRuntimeEntry, 1);
  __ Drop(1);                                      // Drop argument
  __ PopRegister(CallingConventions::kReturnReg);  // Get result.
  __ LeaveStubFrame();
  __ Ret();
}

}  // namespace compiler

}  // namespace dart