text: // 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/arm64/frames-arm64.h"
  #include "src/codegen.h"
  #include "src/debug/debug.h"
  #include "src/deoptimizer.h"
  #include "src/full-codegen/full-codegen.h"
  #include "src/runtime/runtime.h"
  
  namespace v8 {
  namespace internal {
  
  
  #define __ ACCESS_MASM(masm)
  
  
  // Load the built-in Array function from the current context.
  static void GenerateLoadArrayFunction(MacroAssembler* masm, Register result) {
    // Load the native context.
    __ Ldr(result, GlobalObjectMemOperand());
    __ Ldr(result,
           FieldMemOperand(result, GlobalObject::kNativeContextOffset));
    // Load the InternalArray function from the native context.
    __ Ldr(result,
           MemOperand(result,
                      Context::SlotOffset(Context::ARRAY_FUNCTION_INDEX)));
  }
  
  
  // Load the built-in InternalArray function from the current context.
  static void GenerateLoadInternalArrayFunction(MacroAssembler* masm,
                                                Register result) {
    // Load the native context.
    __ Ldr(result, GlobalObjectMemOperand());
    __ Ldr(result,
           FieldMemOperand(result, GlobalObject::kNativeContextOffset));
    // Load the InternalArray function from the native context.
    __ Ldr(result, ContextMemOperand(result,
                                     Context::INTERNAL_ARRAY_FUNCTION_INDEX));
  }
  
  
  void Builtins::Generate_Adaptor(MacroAssembler* masm,
                                  CFunctionId id,
                                  BuiltinExtraArguments extra_args) {
    // ----------- S t a t e -------------
    //  -- x0                 : number of arguments excluding receiver
    //  -- x1                 : called function (only guaranteed when
    //                          extra_args requires it)
    //  -- cp                 : context
    //  -- sp[0]              : last argument
    //  -- ...
    //  -- sp[4 * (argc - 1)] : first argument (argc == x0)
    //  -- sp[4 * argc]       : receiver
    // -----------------------------------
  
    // Insert extra arguments.
    int num_extra_args = 0;
    if (extra_args == NEEDS_CALLED_FUNCTION) {
      num_extra_args = 1;
      __ Push(x1);
    } else {
      DCHECK(extra_args == NO_EXTRA_ARGUMENTS);
    }
  
    // JumpToExternalReference expects x0 to contain the number of arguments
    // including the receiver and the extra arguments.
    __ Add(x0, x0, num_extra_args + 1);
    __ JumpToExternalReference(ExternalReference(id, masm->isolate()));
  }
  
  
  void Builtins::Generate_InternalArrayCode(MacroAssembler* masm) {
    // ----------- S t a t e -------------
    //  -- x0     : number of arguments
    //  -- lr     : return address
    //  -- sp[...]: constructor arguments
    // -----------------------------------
    ASM_LOCATION("Builtins::Generate_InternalArrayCode");
    Label generic_array_code;
  
    // Get the InternalArray function.
    GenerateLoadInternalArrayFunction(masm, x1);
  
    if (FLAG_debug_code) {
      // Initial map for the builtin InternalArray functions should be maps.
      __ Ldr(x10, FieldMemOperand(x1, JSFunction::kPrototypeOrInitialMapOffset));
      __ Tst(x10, kSmiTagMask);
      __ Assert(ne, kUnexpectedInitialMapForInternalArrayFunction);
      __ CompareObjectType(x10, x11, x12, MAP_TYPE);
      __ Assert(eq, kUnexpectedInitialMapForInternalArrayFunction);
    }
  
    // Run the native code for the InternalArray function called as a normal
    // function.
    InternalArrayConstructorStub stub(masm->isolate());
    __ TailCallStub(&stub);
  }
  
  
  void Builtins::Generate_ArrayCode(MacroAssembler* masm) {
    // ----------- S t a t e -------------
    //  -- x0     : number of arguments
    //  -- lr     : return address
    //  -- sp[...]: constructor arguments
    // -----------------------------------
    ASM_LOCATION("Builtins::Generate_ArrayCode");
    Label generic_array_code, one_or_more_arguments, two_or_more_arguments;
  
    // Get the Array function.
    GenerateLoadArrayFunction(masm, x1);
  
    if (FLAG_debug_code) {
      // Initial map for the builtin Array functions should be maps.
      __ Ldr(x10, FieldMemOperand(x1, JSFunction::kPrototypeOrInitialMapOffset));
      __ Tst(x10, kSmiTagMask);
      __ Assert(ne, kUnexpectedInitialMapForArrayFunction);
      __ CompareObjectType(x10, x11, x12, MAP_TYPE);
      __ Assert(eq, kUnexpectedInitialMapForArrayFunction);
    }
  
    // Run the native code for the Array function called as a normal function.
    __ LoadRoot(x2, Heap::kUndefinedValueRootIndex);
    __ Mov(x3, x1);
    ArrayConstructorStub stub(masm->isolate());
    __ TailCallStub(&stub);
  }
  
  
  void Builtins::Generate_StringConstructCode(MacroAssembler* masm) {
    // ----------- S t a t e -------------
    //  -- x0                     : number of arguments
    //  -- x1                     : constructor function
    //  -- lr                     : return address
    //  -- sp[(argc - n - 1) * 8] : arg[n] (zero based)
    //  -- sp[argc * 8]           : receiver
    // -----------------------------------
    ASM_LOCATION("Builtins::Generate_StringConstructCode");
    Counters* counters = masm->isolate()->counters();
    __ IncrementCounter(counters->string_ctor_calls(), 1, x10, x11);
  
    Register argc = x0;
    Register function = x1;
    if (FLAG_debug_code) {
      __ LoadGlobalFunction(Context::STRING_FUNCTION_INDEX, x10);
      __ Cmp(function, x10);
      __ Assert(eq, kUnexpectedStringFunction);
    }
  
    // Load the first arguments in x0 and get rid of the rest.
    Label no_arguments;
    __ Cbz(argc, &no_arguments);
    // First args = sp[(argc - 1) * 8].
    __ Sub(argc, argc, 1);
    __ Drop(argc, kXRegSize);
    // jssp now point to args[0], load and drop args[0] + receiver.
    Register arg = argc;
    __ Ldr(arg, MemOperand(jssp, 2 * kPointerSize, PostIndex));
    argc = NoReg;
  
    Register argument = x2;
    Label not_cached, argument_is_string;
    __ LookupNumberStringCache(arg,        // Input.
                               argument,   // Result.
                               x10,        // Scratch.
                               x11,        // Scratch.
                               x12,        // Scratch.
                               &not_cached);
    __ IncrementCounter(counters->string_ctor_cached_number(), 1, x10, x11);
    __ Bind(&argument_is_string);
  
    // ----------- S t a t e -------------
    //  -- x2     : argument converted to string
    //  -- x1     : constructor function
    //  -- lr     : return address
    // -----------------------------------
  
    Label gc_required;
    Register new_obj = x0;
    __ Allocate(JSValue::kSize, new_obj, x10, x11, &gc_required, TAG_OBJECT);
  
    // Initialize the String object.
    Register map = x3;
    __ LoadGlobalFunctionInitialMap(function, map, x10);
    if (FLAG_debug_code) {
      __ Ldrb(x4, FieldMemOperand(map, Map::kInstanceSizeOffset));
      __ Cmp(x4, JSValue::kSize >> kPointerSizeLog2);
      __ Assert(eq, kUnexpectedStringWrapperInstanceSize);
      __ Ldrb(x4, FieldMemOperand(map, Map::kUnusedPropertyFieldsOffset));
      __ Cmp(x4, 0);
      __ Assert(eq, kUnexpectedUnusedPropertiesOfStringWrapper);
    }
    __ Str(map, FieldMemOperand(new_obj, HeapObject::kMapOffset));
  
    Register empty = x3;
    __ LoadRoot(empty, Heap::kEmptyFixedArrayRootIndex);
    __ Str(empty, FieldMemOperand(new_obj, JSObject::kPropertiesOffset));
    __ Str(empty, FieldMemOperand(new_obj, JSObject::kElementsOffset));
  
    __ Str(argument, FieldMemOperand(new_obj, JSValue::kValueOffset));
  
    // Ensure the object is fully initialized.
    STATIC_ASSERT(JSValue::kSize == (4 * kPointerSize));
  
    __ Ret();
  
    // The argument was not found in the number to string cache. Check
    // if it's a string already before calling the conversion builtin.
    Label convert_argument;
    __ Bind(&not_cached);
    __ JumpIfSmi(arg, &convert_argument);
  
    // Is it a String?
    __ Ldr(x10, FieldMemOperand(x0, HeapObject::kMapOffset));
    __ Ldrb(x11, FieldMemOperand(x10, Map::kInstanceTypeOffset));
    __ Tbnz(x11, MaskToBit(kIsNotStringMask), &convert_argument);
    __ Mov(argument, arg);
    __ IncrementCounter(counters->string_ctor_string_value(), 1, x10, x11);
    __ B(&argument_is_string);
  
    // Invoke the conversion builtin and put the result into x2.
    __ Bind(&convert_argument);
    __ Push(function);  // Preserve the function.
    __ IncrementCounter(counters->string_ctor_conversions(), 1, x10, x11);
    {
      FrameScope scope(masm, StackFrame::INTERNAL);
      ToStringStub stub(masm->isolate());
      __ CallStub(&stub);
    }
    __ Pop(function);
    __ Mov(argument, x0);
    __ B(&argument_is_string);
  
    // Load the empty string into x2, remove the receiver from the
    // stack, and jump back to the case where the argument is a string.
    __ Bind(&no_arguments);
    __ LoadRoot(argument, Heap::kempty_stringRootIndex);
    __ Drop(1);
    __ B(&argument_is_string);
  
    // At this point the argument is already a string. Call runtime to create a
    // string wrapper.
    __ Bind(&gc_required);
    __ IncrementCounter(counters->string_ctor_gc_required(), 1, x10, x11);
    {
      FrameScope scope(masm, StackFrame::INTERNAL);
      __ Push(argument);
      __ CallRuntime(Runtime::kNewStringWrapper, 1);
    }
    __ Ret();
  }
  
  
  static void CallRuntimePassFunction(MacroAssembler* masm,
                                      Runtime::FunctionId function_id) {
    FrameScope scope(masm, StackFrame::INTERNAL);
    //   - Push a copy of the function onto the stack.
    //   - Push another copy as a parameter to the runtime call.
    __ Push(x1, x1);
  
    __ CallRuntime(function_id, 1);
  
    //   - Restore receiver.
    __ Pop(x1);
  }
  
  
  static void GenerateTailCallToSharedCode(MacroAssembler* masm) {
    __ Ldr(x2, FieldMemOperand(x1, JSFunction::kSharedFunctionInfoOffset));
    __ Ldr(x2, FieldMemOperand(x2, SharedFunctionInfo::kCodeOffset));
    __ Add(x2, x2, Code::kHeaderSize - kHeapObjectTag);
    __ Br(x2);
  }
  
  
  static void GenerateTailCallToReturnedCode(MacroAssembler* masm) {
    __ Add(x0, x0, Code::kHeaderSize - kHeapObjectTag);
    __ Br(x0);
  }
  
  
  void Builtins::Generate_InOptimizationQueue(MacroAssembler* masm) {
    // Checking whether the queued function is ready for install is optional,
    // since we come across interrupts and stack checks elsewhere. However, not
    // checking may delay installing ready functions, and always checking would be
    // quite expensive. A good compromise is to first check against stack limit as
    // a cue for an interrupt signal.
    Label ok;
    __ CompareRoot(masm->StackPointer(), Heap::kStackLimitRootIndex);
    __ B(hs, &ok);
  
    CallRuntimePassFunction(masm, Runtime::kTryInstallOptimizedCode);
    GenerateTailCallToReturnedCode(masm);
  
    __ Bind(&ok);
    GenerateTailCallToSharedCode(masm);
  }
  
  
  static void Generate_JSConstructStubHelper(MacroAssembler* masm,
                                             bool is_api_function,
                                             bool create_memento) {
    // ----------- S t a t e -------------
    //  -- x0     : number of arguments
    //  -- x1     : constructor function
    //  -- x2     : allocation site or undefined
    //  -- x3    : original constructor
    //  -- lr     : return address
    //  -- sp[...]: constructor arguments
    // -----------------------------------
  
    ASM_LOCATION("Builtins::Generate_JSConstructStubHelper");
    // Should never create mementos for api functions.
    DCHECK(!is_api_function || !create_memento);
  
    Isolate* isolate = masm->isolate();
  
    // Enter a construct frame.
    {
      FrameScope scope(masm, StackFrame::CONSTRUCT);
  
      // Preserve the four incoming parameters on the stack.
      Register argc = x0;
      Register constructor = x1;
      Register allocation_site = x2;
      Register original_constructor = x3;
  
      // Preserve the incoming parameters on the stack.
      __ AssertUndefinedOrAllocationSite(allocation_site, x10);
      __ SmiTag(argc);
      __ Push(allocation_site, argc, constructor, original_constructor);
      // sp[0]: new.target
      // sp[1]: Constructor function.
      // sp[2]: number of arguments (smi-tagged)
      // sp[3]: allocation site
  
      // Try to allocate the object without transitioning into C code. If any of
      // the preconditions is not met, the code bails out to the runtime call.
      Label rt_call, allocated;
      if (FLAG_inline_new) {
        ExternalReference debug_step_in_fp =
            ExternalReference::debug_step_in_fp_address(isolate);
        __ Mov(x2, Operand(debug_step_in_fp));
        __ Ldr(x2, MemOperand(x2));
        __ Cbnz(x2, &rt_call);
  
        // Fall back to runtime if the original constructor and function differ.
        __ Cmp(constructor, original_constructor);
        __ B(ne, &rt_call);
  
        // Load the initial map and verify that it is in fact a map.
        Register init_map = x2;
        __ Ldr(init_map,
               FieldMemOperand(constructor,
                               JSFunction::kPrototypeOrInitialMapOffset));
        __ JumpIfSmi(init_map, &rt_call);
        __ JumpIfNotObjectType(init_map, x10, x11, MAP_TYPE, &rt_call);
  
        // Check that the constructor is not constructing a JSFunction (see
        // comments in Runtime_NewObject in runtime.cc). In which case the initial
        // map's instance type would be JS_FUNCTION_TYPE.
        __ CompareInstanceType(init_map, x10, JS_FUNCTION_TYPE);
        __ B(eq, &rt_call);
  
        Register constructon_count = x14;
        if (!is_api_function) {
          Label allocate;
          MemOperand bit_field3 =
              FieldMemOperand(init_map, Map::kBitField3Offset);
          // Check if slack tracking is enabled.
          __ Ldr(x4, bit_field3);
          __ DecodeField<Map::Counter>(constructon_count, x4);
          __ Cmp(constructon_count, Operand(Map::kSlackTrackingCounterEnd));
          __ B(lt, &allocate);
          // Decrease generous allocation count.
          __ Subs(x4, x4, Operand(1 << Map::Counter::kShift));
          __ Str(x4, bit_field3);
          __ Cmp(constructon_count, Operand(Map::kSlackTrackingCounterEnd));
          __ B(ne, &allocate);
  
          // Push the constructor and map to the stack, and the constructor again
          // as argument to the runtime call.
          __ Push(constructor, init_map, constructor);
          __ CallRuntime(Runtime::kFinalizeInstanceSize, 1);
          __ Pop(init_map, constructor);
          __ Mov(constructon_count, Operand(Map::kSlackTrackingCounterEnd - 1));
          __ Bind(&allocate);
        }
  
        // Now allocate the JSObject on the heap.
        Label rt_call_reload_new_target;
        Register obj_size = x3;
        Register new_obj = x4;
        __ Ldrb(obj_size, FieldMemOperand(init_map, Map::kInstanceSizeOffset));
        if (create_memento) {
          __ Add(x7, obj_size,
                 Operand(AllocationMemento::kSize / kPointerSize));
          __ Allocate(x7, new_obj, x10, x11, &rt_call_reload_new_target,
                      SIZE_IN_WORDS);
        } else {
          __ Allocate(obj_size, new_obj, x10, x11, &rt_call_reload_new_target,
                      SIZE_IN_WORDS);
        }
  
        // Allocated the JSObject, now initialize the fields. Map is set to
        // initial map and properties and elements are set to empty fixed array.
        // NB. the object pointer is not tagged, so MemOperand is used.
        Register empty = x5;
        __ LoadRoot(empty, Heap::kEmptyFixedArrayRootIndex);
        __ Str(init_map, MemOperand(new_obj, JSObject::kMapOffset));
        STATIC_ASSERT(JSObject::kElementsOffset ==
            (JSObject::kPropertiesOffset + kPointerSize));
        __ Stp(empty, empty, MemOperand(new_obj, JSObject::kPropertiesOffset));
  
        Register first_prop = x5;
        __ Add(first_prop, new_obj, JSObject::kHeaderSize);
  
        // Fill all of the in-object properties with the appropriate filler.
        Register filler = x7;
        __ LoadRoot(filler, Heap::kUndefinedValueRootIndex);
  
        // Obtain number of pre-allocated property fields and in-object
        // properties.
        Register unused_props = x10;
        Register inobject_props = x11;
        Register inst_sizes_or_attrs = x11;
        Register prealloc_fields = x10;
        __ Ldr(inst_sizes_or_attrs,
               FieldMemOperand(init_map, Map::kInstanceAttributesOffset));
        __ Ubfx(unused_props, inst_sizes_or_attrs,
                Map::kUnusedPropertyFieldsByte * kBitsPerByte, kBitsPerByte);
        __ Ldr(inst_sizes_or_attrs,
               FieldMemOperand(init_map, Map::kInstanceSizesOffset));
        __ Ubfx(
            inobject_props, inst_sizes_or_attrs,
            Map::kInObjectPropertiesOrConstructorFunctionIndexByte * kBitsPerByte,
            kBitsPerByte);
        __ Sub(prealloc_fields, inobject_props, unused_props);
  
        // Calculate number of property fields in the object.
        Register prop_fields = x6;
        __ Sub(prop_fields, obj_size, JSObject::kHeaderSize / kPointerSize);
  
        if (!is_api_function) {
          Label no_inobject_slack_tracking;
  
          // Check if slack tracking is enabled.
          __ Cmp(constructon_count, Operand(Map::kSlackTrackingCounterEnd));
          __ B(lt, &no_inobject_slack_tracking);
          constructon_count = NoReg;
  
          // Fill the pre-allocated fields with undef.
          __ FillFields(first_prop, prealloc_fields, filler);
  
          // Update first_prop register to be the offset of the first field after
          // pre-allocated fields.
          __ Add(first_prop, first_prop,
                 Operand(prealloc_fields, LSL, kPointerSizeLog2));
  
          if (FLAG_debug_code) {
            Register obj_end = x14;
            __ Add(obj_end, new_obj, Operand(obj_size, LSL, kPointerSizeLog2));
            __ Cmp(first_prop, obj_end);
            __ Assert(le, kUnexpectedNumberOfPreAllocatedPropertyFields);
          }
  
          // Fill the remaining fields with one pointer filler map.
          __ LoadRoot(filler, Heap::kOnePointerFillerMapRootIndex);
          __ Sub(prop_fields, prop_fields, prealloc_fields);
  
          __ bind(&no_inobject_slack_tracking);
        }
        if (create_memento) {
          // Fill the pre-allocated fields with undef.
          __ FillFields(first_prop, prop_fields, filler);
          __ Add(first_prop, new_obj, Operand(obj_size, LSL, kPointerSizeLog2));
          __ LoadRoot(x14, Heap::kAllocationMementoMapRootIndex);
          DCHECK_EQ(0 * kPointerSize, AllocationMemento::kMapOffset);
          __ Str(x14, MemOperand(first_prop, kPointerSize, PostIndex));
          // Load the AllocationSite
          __ Peek(x14, 3 * kXRegSize);
          __ AssertUndefinedOrAllocationSite(x14, x10);
          DCHECK_EQ(1 * kPointerSize, AllocationMemento::kAllocationSiteOffset);
          __ Str(x14, MemOperand(first_prop, kPointerSize, PostIndex));
          first_prop = NoReg;
        } else {
          // Fill all of the property fields with undef.
          __ FillFields(first_prop, prop_fields, filler);
          first_prop = NoReg;
          prop_fields = NoReg;
        }
  
        // Add the object tag to make the JSObject real, so that we can continue
        // and jump into the continuation code at any time from now on.
        __ Add(new_obj, new_obj, kHeapObjectTag);
  
        // Continue with JSObject being successfully allocated.
        __ B(&allocated);
  
        // Reload the original constructor and fall-through.
        __ Bind(&rt_call_reload_new_target);
        __ Peek(x3, 0 * kXRegSize);
      }
  
      // Allocate the new receiver object using the runtime call.
      // x1: constructor function
      // x3: original constructor
      __ Bind(&rt_call);
      Label count_incremented;
      if (create_memento) {
        // Get the cell or allocation site.
        __ Peek(x4, 3 * kXRegSize);
        __ Push(x4, constructor, original_constructor);  // arguments 1-3
        __ CallRuntime(Runtime::kNewObjectWithAllocationSite, 3);
        __ Mov(x4, x0);
        // If we ended up using the runtime, and we want a memento, then the
        // runtime call made it for us, and we shouldn't do create count
        // increment.
        __ B(&count_incremented);
      } else {
        __ Push(constructor, original_constructor);  // arguments 1-2
        __ CallRuntime(Runtime::kNewObject, 2);
        __ Mov(x4, x0);
      }
  
      // Receiver for constructor call allocated.
      // x4: JSObject
      __ Bind(&allocated);
  
      if (create_memento) {
        __ Peek(x10, 3 * kXRegSize);
        __ JumpIfRoot(x10, Heap::kUndefinedValueRootIndex, &count_incremented);
        // r2 is an AllocationSite. We are creating a memento from it, so we
        // need to increment the memento create count.
        __ Ldr(x5, FieldMemOperand(x10,
                                   AllocationSite::kPretenureCreateCountOffset));
        __ Add(x5, x5, Operand(Smi::FromInt(1)));
        __ Str(x5, FieldMemOperand(x10,
                                   AllocationSite::kPretenureCreateCountOffset));
        __ bind(&count_incremented);
      }
  
      // Restore the parameters.
      __ Pop(original_constructor);
      __ Pop(constructor);
  
      // Reload the number of arguments from the stack.
      // Set it up in x0 for the function call below.
      // jssp[0]: number of arguments (smi-tagged)
      __ Peek(argc, 0);  // Load number of arguments.
      __ SmiUntag(argc);
  
      __ Push(original_constructor, x4, x4);
  
      // Set up pointer to last argument.
      __ Add(x2, fp, StandardFrameConstants::kCallerSPOffset);
  
      // Copy arguments and receiver to the expression stack.
      // Copy 2 values every loop to use ldp/stp.
      // x0: number of arguments
      // x1: constructor function
      // x2: address of last argument (caller sp)
      // jssp[0]: receiver
      // jssp[1]: receiver
      // jssp[2]: new.target
      // jssp[3]: number of arguments (smi-tagged)
      // Compute the start address of the copy in x3.
      __ Add(x3, x2, Operand(argc, LSL, kPointerSizeLog2));
      Label loop, entry, done_copying_arguments;
      __ B(&entry);
      __ Bind(&loop);
      __ Ldp(x10, x11, MemOperand(x3, -2 * kPointerSize, PreIndex));
      __ Push(x11, x10);
      __ Bind(&entry);
      __ Cmp(x3, x2);
      __ B(gt, &loop);
      // Because we copied values 2 by 2 we may have copied one extra value.
      // Drop it if that is the case.
      __ B(eq, &done_copying_arguments);
      __ Drop(1);
      __ Bind(&done_copying_arguments);
  
      // Call the function.
      // x0: number of arguments
      // x1: constructor function
      if (is_api_function) {
        __ Ldr(cp, FieldMemOperand(constructor, JSFunction::kContextOffset));
        Handle<Code> code =
            masm->isolate()->builtins()->HandleApiCallConstruct();
        __ Call(code, RelocInfo::CODE_TARGET);
      } else {
        ParameterCount actual(argc);
        __ InvokeFunction(constructor, actual, CALL_FUNCTION, NullCallWrapper());
      }
  
      // Store offset of return address for deoptimizer.
      if (!is_api_function) {
        masm->isolate()->heap()->SetConstructStubDeoptPCOffset(masm->pc_offset());
      }
  
      // Restore the context from the frame.
      // x0: result
      // jssp[0]: receiver
      // jssp[1]: new.target
      // jssp[2]: number of arguments (smi-tagged)
      __ Ldr(cp, MemOperand(fp, StandardFrameConstants::kContextOffset));
  
      // If the result is an object (in the ECMA sense), we should get rid
      // of the receiver and use the result; see ECMA-262 section 13.2.2-7
      // on page 74.
      Label use_receiver, exit;
  
      // If the result is a smi, it is *not* an object in the ECMA sense.
      // x0: result
      // jssp[0]: receiver (newly allocated object)
      // jssp[1]: number of arguments (smi-tagged)
      __ JumpIfSmi(x0, &use_receiver);
  
      // If the type of the result (stored in its map) is less than
      // FIRST_SPEC_OBJECT_TYPE, it is not an object in the ECMA sense.
      __ JumpIfObjectType(x0, x1, x3, FIRST_SPEC_OBJECT_TYPE, &exit, ge);
  
      // Throw away the result of the constructor invocation and use the
      // on-stack receiver as the result.
      __ Bind(&use_receiver);
      __ Peek(x0, 0);
  
      // Remove the receiver from the stack, remove caller arguments, and
      // return.
      __ Bind(&exit);
      // x0: result
      // jssp[0]: receiver (newly allocated object)
      // jssp[1]: new.target (original constructor)
      // jssp[2]: number of arguments (smi-tagged)
      __ Peek(x1, 2 * kXRegSize);
  
      // Leave construct frame.
    }
  
    __ DropBySMI(x1);
    __ Drop(1);
    __ IncrementCounter(isolate->counters()->constructed_objects(), 1, x1, x2);
    __ Ret();
  }
  
  
  void Builtins::Generate_JSConstructStubGeneric(MacroAssembler* masm) {
    Generate_JSConstructStubHelper(masm, false, FLAG_pretenuring_call_new);
  }
  
  
  void Builtins::Generate_JSConstructStubApi(MacroAssembler* masm) {
    Generate_JSConstructStubHelper(masm, true, false);
  }
  
  
  void Builtins::Generate_JSConstructStubForDerived(MacroAssembler* masm) {
    // ----------- S t a t e -------------
    //  -- x0     : number of arguments
    //  -- x1     : constructor function
    //  -- x2     : allocation site or undefined
    //  -- x3    : original constructor
    //  -- lr     : return address
    //  -- sp[...]: constructor arguments
    // -----------------------------------
    ASM_LOCATION("Builtins::Generate_JSConstructStubForDerived");
  
    {
      FrameScope frame_scope(masm, StackFrame::CONSTRUCT);
  
      __ AssertUndefinedOrAllocationSite(x2, x10);
      __ Mov(x4, x0);
      __ SmiTag(x4);
      __ LoadRoot(x10, Heap::kTheHoleValueRootIndex);
      __ Push(x2, x4, x3, x10);
      // sp[0]: receiver (the hole)
      // sp[1]: new.target
      // sp[2]: number of arguments
      // sp[3]: allocation site
  
      // Set up pointer to last argument.
      __ Add(x2, fp, StandardFrameConstants::kCallerSPOffset);
  
      // Copy arguments and receiver to the expression stack.
      // Copy 2 values every loop to use ldp/stp.
      // x0: number of arguments
      // x1: constructor function
      // x2: address of last argument (caller sp)
      // jssp[0]: receiver
      // jssp[1]: new.target
      // jssp[2]: number of arguments (smi-tagged)
      // Compute the start address of the copy in x4.
      __ Add(x4, x2, Operand(x0, LSL, kPointerSizeLog2));
      Label loop, entry, done_copying_arguments;
      __ B(&entry);
      __ Bind(&loop);
      __ Ldp(x10, x11, MemOperand(x4, -2 * kPointerSize, PreIndex));
      __ Push(x11, x10);
      __ Bind(&entry);
      __ Cmp(x4, x2);
      __ B(gt, &loop);
      // Because we copied values 2 by 2 we may have copied one extra value.
      // Drop it if that is the case.
      __ B(eq, &done_copying_arguments);
      __ Drop(1);
      __ Bind(&done_copying_arguments);
  
      // Handle step in.
      Label skip_step_in;
      ExternalReference debug_step_in_fp =
          ExternalReference::debug_step_in_fp_address(masm->isolate());
      __ Mov(x2, Operand(debug_step_in_fp));
      __ Ldr(x2, MemOperand(x2));
      __ Cbz(x2, &skip_step_in);
  
      __ Push(x0, x1, x1);
      __ CallRuntime(Runtime::kHandleStepInForDerivedConstructors, 1);
      __ Pop(x1, x0);
  
      __ bind(&skip_step_in);
  
      // Call the function.
      // x0: number of arguments
      // x1: constructor function
      ParameterCount actual(x0);
      __ InvokeFunction(x1, actual, CALL_FUNCTION, NullCallWrapper());
  
  
      // Restore the context from the frame.
      // x0: result
      // jssp[0]: number of arguments (smi-tagged)
      __ Ldr(cp, MemOperand(fp, StandardFrameConstants::kContextOffset));
  
      // Load number of arguments (smi), skipping over new.target.
      __ Peek(x1, kPointerSize);
  
      // Leave construct frame
    }
  
    __ DropBySMI(x1);
    __ Drop(1);
    __ Ret();
  }
  
  
  enum IsTagged { kArgcIsSmiTagged, kArgcIsUntaggedInt };
  
  
  // Clobbers x10, x15; preserves all other registers.
  static void Generate_CheckStackOverflow(MacroAssembler* masm,
                                          const int calleeOffset, Register argc,
                                          IsTagged argc_is_tagged) {
    Register function = x15;
  
    // Check the stack for overflow.
    // We are not trying to catch interruptions (e.g. debug break and
    // preemption) here, so the "real stack limit" is checked.
    Label enough_stack_space;
    __ LoadRoot(x10, Heap::kRealStackLimitRootIndex);
    __ Ldr(function, MemOperand(fp, calleeOffset));
    // Make x10 the space we have left. The stack might already be overflowed
    // here which will cause x10 to become negative.
    // TODO(jbramley): Check that the stack usage here is safe.
    __ Sub(x10, jssp, x10);
    // Check if the arguments will overflow the stack.
    if (argc_is_tagged == kArgcIsSmiTagged) {
      __ Cmp(x10, Operand::UntagSmiAndScale(argc, kPointerSizeLog2));
    } else {
      DCHECK(argc_is_tagged == kArgcIsUntaggedInt);
      __ Cmp(x10, Operand(argc, LSL, kPointerSizeLog2));
    }
    __ B(gt, &enough_stack_space);
    // There is not enough stack space, so use a builtin to throw an appropriate
    // error.
    if (argc_is_tagged == kArgcIsUntaggedInt) {
      __ SmiTag(argc);
    }
    __ Push(function, argc);
    __ InvokeBuiltin(Context::STACK_OVERFLOW_BUILTIN_INDEX, CALL_FUNCTION);
    // We should never return from the APPLY_OVERFLOW builtin.
    if (__ emit_debug_code()) {
      __ Unreachable();
    }
  
    __ Bind(&enough_stack_space);
  }
  
  
  // Input:
  //   x0: code entry.
  //   x1: function.
  //   x2: receiver.
  //   x3: argc.
  //   x4: argv.
  // Output:
  //   x0: result.
  static void Generate_JSEntryTrampolineHelper(MacroAssembler* masm,
                                               bool is_construct) {
    // Called from JSEntryStub::GenerateBody().
    Register function = x1;
    Register receiver = x2;
    Register argc = x3;
    Register argv = x4;
  
    ProfileEntryHookStub::MaybeCallEntryHook(masm);
  
    // Clear the context before we push it when entering the internal frame.
    __ Mov(cp, 0);
  
    {
      // Enter an internal frame.
      FrameScope scope(masm, StackFrame::INTERNAL);
  
      // Set up the context from the function argument.
      __ Ldr(cp, FieldMemOperand(function, JSFunction::kContextOffset));
  
      __ InitializeRootRegister();
  
      // Push the function and the receiver onto the stack.
      __ Push(function, receiver);
  
      // Check if we have enough stack space to push all arguments.
      // The function is the first thing that was pushed above after entering
      // the internal frame.
      const int kFunctionOffset =
          InternalFrameConstants::kCodeOffset - kPointerSize;
      // Expects argument count in eax. Clobbers ecx, edx, edi.
      Generate_CheckStackOverflow(masm, kFunctionOffset, argc,
                                  kArgcIsUntaggedInt);
  
      // Copy arguments to the stack in a loop, in reverse order.
      // x3: argc.
      // x4: argv.
      Label loop, entry;
      // Compute the copy end address.
      __ Add(x10, argv, Operand(argc, LSL, kPointerSizeLog2));
  
      __ B(&entry);
      __ Bind(&loop);
      __ Ldr(x11, MemOperand(argv, kPointerSize, PostIndex));
      __ Ldr(x12, MemOperand(x11));  // Dereference the handle.
      __ Push(x12);  // Push the argument.
      __ Bind(&entry);
      __ Cmp(x10, argv);
      __ B(ne, &loop);
  
      // Initialize all JavaScript callee-saved registers, since they will be seen
      // by the garbage collector as part of handlers.
      // The original values have been saved in JSEntryStub::GenerateBody().
      __ LoadRoot(x19, Heap::kUndefinedValueRootIndex);
      __ Mov(x20, x19);
      __ Mov(x21, x19);
      __ Mov(x22, x19);
      __ Mov(x23, x19);
      __ Mov(x24, x19);
      __ Mov(x25, x19);
      // Don't initialize the reserved registers.
      // x26 : root register (root).
      // x27 : context pointer (cp).
      // x28 : JS stack pointer (jssp).
      // x29 : frame pointer (fp).
  
      __ Mov(x0, argc);
      if (is_construct) {
        // No type feedback cell is available.
        __ LoadRoot(x2, Heap::kUndefinedValueRootIndex);
  
        CallConstructStub stub(masm->isolate(), NO_CALL_CONSTRUCTOR_FLAGS);
        __ CallStub(&stub);
      } else {
        ParameterCount actual(x0);
        __ InvokeFunction(function, actual, CALL_FUNCTION, NullCallWrapper());
      }
      // Exit the JS internal frame and remove the parameters (except function),
      // and return.
    }
  
    // Result is in x0. Return.
    __ Ret();
  }
  
  
  void Builtins::Generate_JSEntryTrampoline(MacroAssembler* masm) {
    Generate_JSEntryTrampolineHelper(masm, false);
  }
  
  
  void Builtins::Generate_JSConstructEntryTrampoline(MacroAssembler* masm) {
    Generate_JSEntryTrampolineHelper(masm, true);
  }
  
  
  // Generate code for entering a JS function with the interpreter.
  // On entry to the function the receiver and arguments have been pushed on the
  // stack left to right.  The actual argument count matches the formal parameter
  // count expected by the function.
  //
  // The live registers are:
  //   - x1: the JS function object being called.
  //   - cp: our context.
  //   - fp: our caller's frame pointer.
  //   - jssp: stack pointer.
  //   - lr: return address.
  //
  // The function builds a JS frame.  Please see JavaScriptFrameConstants in
  // frames-arm64.h for its layout.
  // TODO(rmcilroy): We will need to include the current bytecode pointer in the
  // frame.
  void Builtins::Generate_InterpreterEntryTrampoline(MacroAssembler* masm) {
    // Open a frame scope to indicate that there is a frame on the stack.  The
    // MANUAL indicates that the scope shouldn't actually generate code to set up
    // the frame (that is done below).
    FrameScope frame_scope(masm, StackFrame::MANUAL);
    __ Push(lr, fp, cp, x1);
    __ Add(fp, jssp, StandardFrameConstants::kFixedFrameSizeFromFp);
  
    // Get the bytecode array from the function object and load the pointer to the
    // first entry into kInterpreterBytecodeRegister.
    __ Ldr(x0, FieldMemOperand(x1, JSFunction::kSharedFunctionInfoOffset));
    __ Ldr(kInterpreterBytecodeArrayRegister,
           FieldMemOperand(x0, SharedFunctionInfo::kFunctionDataOffset));
  
    if (FLAG_debug_code) {
      // Check function data field is actually a BytecodeArray object.
      __ AssertNotSmi(kInterpreterBytecodeArrayRegister,
                      kFunctionDataShouldBeBytecodeArrayOnInterpreterEntry);
      __ CompareObjectType(kInterpreterBytecodeArrayRegister, x0, x0,
                           BYTECODE_ARRAY_TYPE);
      __ Assert(eq, kFunctionDataShouldBeBytecodeArrayOnInterpreterEntry);
    }
  
    // Allocate the local and temporary register file on the stack.
    {
      // Load frame size from the BytecodeArray object.
      __ Ldr(w11, FieldMemOperand(kInterpreterBytecodeArrayRegister,
                                  BytecodeArray::kFrameSizeOffset));
  
      // Do a stack check to ensure we don't go over the limit.
      Label ok;
      DCHECK(jssp.Is(__ StackPointer()));
      __ Sub(x10, jssp, Operand(x11));
      __ CompareRoot(x10, Heap::kRealStackLimitRootIndex);
      __ B(hs, &ok);
      __ InvokeBuiltin(Context::STACK_OVERFLOW_BUILTIN_INDEX, CALL_FUNCTION);
      __ Bind(&ok);
  
      // If ok, push undefined as the initial value for all register file entries.
      // Note: there should always be at least one stack slot for the return
      // register in the register file.
      Label loop_header;
      __ LoadRoot(x10, Heap::kUndefinedValueRootIndex);
      // TODO(rmcilroy): Ensure we always have an even number of registers to
      // allow stack to be 16 bit aligned (and remove need for jssp).
      __ Lsr(x11, x11, kPointerSizeLog2);
      __ PushMultipleTimes(x10, x11);
      __ Bind(&loop_header);
    }
  
    // TODO(rmcilroy): List of things not currently dealt with here but done in
    // fullcodegen's prologue:
    //  - Support profiler (specifically profiling_counter).
    //  - Call ProfileEntryHookStub when isolate has a function_entry_hook.
    //  - Allow simulator stop operations if FLAG_stop_at is set.
    //  - Deal with sloppy mode functions which need to replace the
    //    receiver with the global proxy when called as functions (without an
    //    explicit receiver object).
    //  - Code aging of the BytecodeArray object.
    //  - Supporting FLAG_trace.
    //
    // The following items are also not done here, and will probably be done using
    // explicit bytecodes instead:
    //  - Allocating a new local context if applicable.
    //  - Setting up a local binding to the this function, which is used in
    //    derived constructors with super calls.
    //  - Setting new.target if required.
    //  - Dealing with REST parameters (only if
    //    https://codereview.chromium.org/1235153006 doesn't land by then).
    //  - Dealing with argument objects.
  
    // Perform stack guard check.
    {
      Label ok;
      __ CompareRoot(jssp, Heap::kStackLimitRootIndex);
      __ B(hs, &ok);
      __ CallRuntime(Runtime::kStackGuard, 0);
      __ Bind(&ok);
    }
  
    // Load accumulator, register file, bytecode offset, dispatch table into
    // registers.
    __ LoadRoot(kInterpreterAccumulatorRegister, Heap::kUndefinedValueRootIndex);
    __ Sub(kInterpreterRegisterFileRegister, fp,
           Operand(kPointerSize + StandardFrameConstants::kFixedFrameSizeFromFp));
    __ Mov(kInterpreterBytecodeOffsetRegister,
           Operand(BytecodeArray::kHeaderSize - kHeapObjectTag));
    __ LoadRoot(kInterpreterDispatchTableRegister,
                Heap::kInterpreterTableRootIndex);
    __ Add(kInterpreterDispatchTableRegister, kInterpreterDispatchTableRegister,
           Operand(FixedArray::kHeaderSize - kHeapObjectTag));
  
    // Dispatch to the first bytecode handler for the function.
    __ Ldrb(x1, MemOperand(kInterpreterBytecodeArrayRegister,
                           kInterpreterBytecodeOffsetRegister));
    __ Mov(x1, Operand(x1, LSL, kPointerSizeLog2));
    __ Ldr(ip0, MemOperand(kInterpreterDispatchTableRegister, x1));
    // TODO(rmcilroy): Make dispatch table point to code entrys to avoid untagging
    // and header removal.
    __ Add(ip0, ip0, Operand(Code::kHeaderSize - kHeapObjectTag));
    __ Call(ip0);
  }
  
  
  void Builtins::Generate_InterpreterExitTrampoline(MacroAssembler* masm) {
    // TODO(rmcilroy): List of things not currently dealt with here but done in
    // fullcodegen's EmitReturnSequence.
    //  - Supporting FLAG_trace for Runtime::TraceExit.
    //  - Support profiler (specifically decrementing profiling_counter
    //    appropriately and calling out to HandleInterrupts if necessary).
  
    // The return value is in accumulator, which is already in x0.
  
    // Leave the frame (also dropping the register file).
    __ LeaveFrame(StackFrame::JAVA_SCRIPT);
  
    // Drop receiver + arguments and return.
    __ Ldr(w1, FieldMemOperand(kInterpreterBytecodeArrayRegister,
                               BytecodeArray::kParameterSizeOffset));
    __ Drop(x1, 1);
    __ Ret();
  }
  
  
  void Builtins::Generate_CompileLazy(MacroAssembler* masm) {
    CallRuntimePassFunction(masm, Runtime::kCompileLazy);
    GenerateTailCallToReturnedCode(masm);
  }
  
  
  static void CallCompileOptimized(MacroAssembler* masm, bool concurrent) {
    FrameScope scope(masm, StackFrame::INTERNAL);
    Register function = x1;
  
    // Preserve function. At the same time, push arguments for
    // kCompileOptimized.
    __ LoadObject(x10, masm->isolate()->factory()->ToBoolean(concurrent));
    __ Push(function, function, x10);
  
    __ CallRuntime(Runtime::kCompileOptimized, 2);
  
    // Restore receiver.
    __ Pop(function);
  }
  
  
  void Builtins::Generate_CompileOptimized(MacroAssembler* masm) {
    CallCompileOptimized(masm, false);
    GenerateTailCallToReturnedCode(masm);
  }
  
  
  void Builtins::Generate_CompileOptimizedConcurrent(MacroAssembler* masm) {
    CallCompileOptimized(masm, true);
    GenerateTailCallToReturnedCode(masm);
  }
  
  
  static void GenerateMakeCodeYoungAgainCommon(MacroAssembler* masm) {
    // For now, we are relying on the fact that make_code_young doesn't do any
    // garbage collection which allows us to save/restore the registers without
    // worrying about which of them contain pointers. We also don't build an
    // internal frame to make the code fast, since we shouldn't have to do stack
    // crawls in MakeCodeYoung. This seems a bit fragile.
  
    // The following caller-saved registers must be saved and restored when
    // calling through to the runtime:
    //   x0 - The address from which to resume execution.
    //   x1 - isolate
    //   lr - The return address for the JSFunction itself. It has not yet been
    //        preserved on the stack because the frame setup code was replaced
    //        with a call to this stub, to handle code ageing.
    {
      FrameScope scope(masm, StackFrame::MANUAL);
      __ Push(x0, x1, fp, lr);
      __ Mov(x1, ExternalReference::isolate_address(masm->isolate()));
      __ CallCFunction(
          ExternalReference::get_make_code_young_function(masm->isolate()), 2);
      __ Pop(lr, fp, x1, x0);
    }
  
    // The calling function has been made young again, so return to execute the
    // real frame set-up code.
    __ Br(x0);
  }
  
  #define DEFINE_CODE_AGE_BUILTIN_GENERATOR(C)                 \
  void Builtins::Generate_Make##C##CodeYoungAgainEvenMarking(  \
      MacroAssembler* masm) {                                  \
    GenerateMakeCodeYoungAgainCommon(masm);                    \
  }                                                            \
  void Builtins::Generate_Make##C##CodeYoungAgainOddMarking(   \
      MacroAssembler* masm) {                                  \
    GenerateMakeCodeYoungAgainCommon(masm);                    \
  }
  CODE_AGE_LIST(DEFINE_CODE_AGE_BUILTIN_GENERATOR)
  #undef DEFINE_CODE_AGE_BUILTIN_GENERATOR
  
  
  void Builtins::Generate_MarkCodeAsExecutedOnce(MacroAssembler* masm) {
    // For now, as in GenerateMakeCodeYoungAgainCommon, we are relying on the fact
    // that make_code_young doesn't do any garbage collection which allows us to
    // save/restore the registers without worrying about which of them contain
    // pointers.
  
    // The following caller-saved registers must be saved and restored when
    // calling through to the runtime:
    //   x0 - The address from which to resume execution.
    //   x1 - isolate
    //   lr - The return address for the JSFunction itself. It has not yet been
    //        preserved on the stack because the frame setup code was replaced
    //        with a call to this stub, to handle code ageing.
    {
      FrameScope scope(masm, StackFrame::MANUAL);
      __ Push(x0, x1, fp, lr);
      __ Mov(x1, ExternalReference::isolate_address(masm->isolate()));
      __ CallCFunction(
          ExternalReference::get_mark_code_as_executed_function(
              masm->isolate()), 2);
      __ Pop(lr, fp, x1, x0);
  
      // Perform prologue operations usually performed by the young code stub.
      __ EmitFrameSetupForCodeAgePatching(masm);
    }
  
    // Jump to point after the code-age stub.
    __ Add(x0, x0, kNoCodeAgeSequenceLength);
    __ Br(x0);
  }
  
  
  void Builtins::Generate_MarkCodeAsExecutedTwice(MacroAssembler* masm) {
    GenerateMakeCodeYoungAgainCommon(masm);
  }
  
  
  void Builtins::Generate_MarkCodeAsToBeExecutedOnce(MacroAssembler* masm) {
    Generate_MarkCodeAsExecutedOnce(masm);
  }
  
  
  static void Generate_NotifyStubFailureHelper(MacroAssembler* masm,
                                               SaveFPRegsMode save_doubles) {
    {
      FrameScope scope(masm, StackFrame::INTERNAL);
  
      // Preserve registers across notification, this is important for compiled
      // stubs that tail call the runtime on deopts passing their parameters in
      // registers.
      // TODO(jbramley): Is it correct (and appropriate) to use safepoint
      // registers here? According to the comment above, we should only need to
      // preserve the registers with parameters.
      __ PushXRegList(kSafepointSavedRegisters);
      // Pass the function and deoptimization type to the runtime system.
      __ CallRuntime(Runtime::kNotifyStubFailure, 0, save_doubles);
      __ PopXRegList(kSafepointSavedRegisters);
    }
  
    // Ignore state (pushed by Deoptimizer::EntryGenerator::Generate).
    __ Drop(1);
  
    // Jump to the miss handler. Deoptimizer::EntryGenerator::Generate loads this
    // into lr before it jumps here.
    __ Br(lr);
  }
  
  
  void Builtins::Generate_NotifyStubFailure(MacroAssembler* masm) {
    Generate_NotifyStubFailureHelper(masm, kDontSaveFPRegs);
  }
  
  
  void Builtins::Generate_NotifyStubFailureSaveDoubles(MacroAssembler* masm) {
    Generate_NotifyStubFailureHelper(masm, kSaveFPRegs);
  }
  
  
  static void Generate_NotifyDeoptimizedHelper(MacroAssembler* masm,
                                               Deoptimizer::BailoutType type) {
    {
      FrameScope scope(masm, StackFrame::INTERNAL);
      // Pass the deoptimization type to the runtime system.
      __ Mov(x0, Smi::FromInt(static_cast<int>(type)));
      __ Push(x0);
      __ CallRuntime(Runtime::kNotifyDeoptimized, 1);
    }
  
    // Get the full codegen state from the stack and untag it.
    Register state = x6;
    __ Peek(state, 0);
    __ SmiUntag(state);
  
    // Switch on the state.
    Label with_tos_register, unknown_state;
    __ CompareAndBranch(
        state, FullCodeGenerator::NO_REGISTERS, ne, &with_tos_register);
    __ Drop(1);  // Remove state.
    __ Ret();
  
    __ Bind(&with_tos_register);
    // Reload TOS register.
    __ Peek(x0, kPointerSize);
    __ CompareAndBranch(state, FullCodeGenerator::TOS_REG, ne, &unknown_state);
    __ Drop(2);  // Remove state and TOS.
    __ Ret();
  
    __ Bind(&unknown_state);
    __ Abort(kInvalidFullCodegenState);
  }
  
  
  void Builtins::Generate_NotifyDeoptimized(MacroAssembler* masm) {
    Generate_NotifyDeoptimizedHelper(masm, Deoptimizer::EAGER);
  }
  
  
  void Builtins::Generate_NotifyLazyDeoptimized(MacroAssembler* masm) {
    Generate_NotifyDeoptimizedHelper(masm, Deoptimizer::LAZY);
  }
  
  
  void Builtins::Generate_NotifySoftDeoptimized(MacroAssembler* masm) {
    Generate_NotifyDeoptimizedHelper(masm, Deoptimizer::SOFT);
  }
  
  
  void Builtins::Generate_OnStackReplacement(MacroAssembler* masm) {
    // Lookup the function in the JavaScript frame.
    __ Ldr(x0, MemOperand(fp, JavaScriptFrameConstants::kFunctionOffset));
    {
      FrameScope scope(masm, StackFrame::INTERNAL);
      // Pass function as argument.
      __ Push(x0);
      __ CallRuntime(Runtime::kCompileForOnStackReplacement, 1);
    }
  
    // If the code object is null, just return to the unoptimized code.
    Label skip;
    __ CompareAndBranch(x0, Smi::FromInt(0), ne, &skip);
    __ Ret();
  
    __ Bind(&skip);
  
    // Load deoptimization data from the code object.
    // <deopt_data> = <code>[#deoptimization_data_offset]
    __ Ldr(x1, MemOperand(x0, Code::kDeoptimizationDataOffset - kHeapObjectTag));
  
    // Load the OSR entrypoint offset from the deoptimization data.
    // <osr_offset> = <deopt_data>[#header_size + #osr_pc_offset]
    __ Ldrsw(w1, UntagSmiFieldMemOperand(x1, FixedArray::OffsetOfElementAt(
        DeoptimizationInputData::kOsrPcOffsetIndex)));
  
    // Compute the target address = code_obj + header_size + osr_offset
    // <entry_addr> = <code_obj> + #header_size + <osr_offset>
    __ Add(x0, x0, x1);
    __ Add(lr, x0, Code::kHeaderSize - kHeapObjectTag);
  
    // And "return" to the OSR entry point of the function.
    __ Ret();
  }
  
  
  void Builtins::Generate_OsrAfterStackCheck(MacroAssembler* masm) {
    // We check the stack limit as indicator that recompilation might be done.
    Label ok;
    __ CompareRoot(jssp, Heap::kStackLimitRootIndex);
    __ B(hs, &ok);
    {
      FrameScope scope(masm, StackFrame::INTERNAL);
      __ CallRuntime(Runtime::kStackGuard, 0);
    }
    __ Jump(masm->isolate()->builtins()->OnStackReplacement(),
            RelocInfo::CODE_TARGET);
  
    __ Bind(&ok);
    __ Ret();
  }
  
  
  void Builtins::Generate_FunctionCall(MacroAssembler* masm) {
    enum {
      call_type_JS_func = 0,
      call_type_func_proxy = 1,
      call_type_non_func = 2
    };
    Register argc = x0;
    Register function = x1;
    Register call_type = x4;
    Register scratch1 = x10;
    Register scratch2 = x11;
    Register receiver_type = x13;
  
    ASM_LOCATION("Builtins::Generate_FunctionCall");
    // 1. Make sure we have at least one argument.
    { Label done;
      __ Cbnz(argc, &done);
      __ LoadRoot(scratch1, Heap::kUndefinedValueRootIndex);
      __ Push(scratch1);
      __ Mov(argc, 1);
      __ Bind(&done);
    }
  
    // 2. Get the function to call (passed as receiver) from the stack, check
    //    if it is a function.
    Label slow, non_function;
    __ Peek(function, Operand(argc, LSL, kXRegSizeLog2));
    __ JumpIfSmi(function, &non_function);
    __ JumpIfNotObjectType(function, scratch1, receiver_type,
                           JS_FUNCTION_TYPE, &slow);
  
    // 3a. Patch the first argument if necessary when calling a function.
    Label shift_arguments;
    __ Mov(call_type, static_cast<int>(call_type_JS_func));
    { Label convert_to_object, use_global_proxy, patch_receiver;
      // Change context eagerly in case we need the global receiver.
      __ Ldr(cp, FieldMemOperand(function, JSFunction::kContextOffset));
  
      // Do not transform the receiver for strict mode functions.
      // Also do not transform the receiver for native (Compilerhints already in
      // x3).
      __ Ldr(scratch1,
             FieldMemOperand(function, JSFunction::kSharedFunctionInfoOffset));
      __ Ldr(scratch2.W(),
             FieldMemOperand(scratch1, SharedFunctionInfo::kCompilerHintsOffset));
      __ TestAndBranchIfAnySet(
          scratch2.W(),
          (1 << SharedFunctionInfo::kStrictModeFunction) |
          (1 << SharedFunctionInfo::kNative),
          &shift_arguments);
  
      // Compute the receiver in sloppy mode.
      Register receiver = x2;
      __ Sub(scratch1, argc, 1);
      __ Peek(receiver, Operand(scratch1, LSL, kXRegSizeLog2));
      __ JumpIfSmi(receiver, &convert_to_object);
  
      __ JumpIfRoot(receiver, Heap::kUndefinedValueRootIndex,
                    &use_global_proxy);
      __ JumpIfRoot(receiver, Heap::kNullValueRootIndex, &use_global_proxy);
  
      STATIC_ASSERT(LAST_SPEC_OBJECT_TYPE == LAST_TYPE);
      __ JumpIfObjectType(receiver, scratch1, scratch2,
                          FIRST_SPEC_OBJECT_TYPE, &shift_arguments, ge);
  
      __ Bind(&convert_to_object);
  
      {
        // Enter an internal frame in order to preserve argument count.
        FrameScope scope(masm, StackFrame::INTERNAL);
        __ SmiTag(argc);
  
        __ Push(argc);
        __ Mov(x0, receiver);
        ToObjectStub stub(masm->isolate());
        __ CallStub(&stub);
        __ Mov(receiver, x0);
  
        __ Pop(argc);
        __ SmiUntag(argc);
  
        // Exit the internal frame.
      }
  
      // Restore the function and flag in the registers.
      __ Peek(function, Operand(argc, LSL, kXRegSizeLog2));
      __ Mov(call_type, static_cast<int>(call_type_JS_func));
      __ B(&patch_receiver);
  
      __ Bind(&use_global_proxy);
      __ Ldr(receiver, GlobalObjectMemOperand());
      __ Ldr(receiver,
             FieldMemOperand(receiver, GlobalObject::kGlobalProxyOffset));
  
  
      __ Bind(&patch_receiver);
      __ Sub(scratch1, argc, 1);
      __ Poke(receiver, Operand(scratch1, LSL, kXRegSizeLog2));
  
      __ B(&shift_arguments);
    }
  
    // 3b. Check for function proxy.
    __ Bind(&slow);
    __ Mov(call_type, static_cast<int>(call_type_func_proxy));
    __ Cmp(receiver_type, JS_FUNCTION_PROXY_TYPE);
    __ B(eq, &shift_arguments);
    __ Bind(&non_function);
    __ Mov(call_type, static_cast<int>(call_type_non_func));
  
    // 3c. Patch the first argument when calling a non-function.  The
    //     CALL_NON_FUNCTION builtin expects the non-function callee as
    //     receiver, so overwrite the first argument which will ultimately
    //     become the receiver.
    // call type (0: JS function, 1: function proxy, 2: non-function)
    __ Sub(scratch1, argc, 1);
    __ Poke(function, Operand(scratch1, LSL, kXRegSizeLog2));
  
    // 4. Shift arguments and return address one slot down on the stack
    //    (overwriting the original receiver).  Adjust argument count to make
    //    the original first argument the new receiver.
    // call type (0: JS function, 1: function proxy, 2: non-function)
    __ Bind(&shift_arguments);
    { Label loop;
      // Calculate the copy start address (destination). Copy end address is jssp.
      __ Add(scratch2, jssp, Operand(argc, LSL, kPointerSizeLog2));
      __ Sub(scratch1, scratch2, kPointerSize);
  
      __ Bind(&loop);
      __ Ldr(x12, MemOperand(scratch1, -kPointerSize, PostIndex));
      __ Str(x12, MemOperand(scratch2, -kPointerSize, PostIndex));
      __ Cmp(scratch1, jssp);
      __ B(ge, &loop);
      // Adjust the actual number of arguments and remove the top element
      // (which is a copy of the last argument).
      __ Sub(argc, argc, 1);
      __ Drop(1);
    }
  
    // 5a. Call non-function via tail call to CALL_NON_FUNCTION builtin,
    //     or a function proxy via CALL_FUNCTION_PROXY.
    // call type (0: JS function, 1: function proxy, 2: non-function)
    { Label js_function, non_proxy;
      __ Cbz(call_type, &js_function);
      // Expected number of arguments is 0 for CALL_NON_FUNCTION.
      __ Mov(x2, 0);
      __ Cmp(call_type, static_cast<int>(call_type_func_proxy));
      __ B(ne, &non_proxy);
  
      __ Push(function);  // Re-add proxy object as additional argument.
      __ Add(argc, argc, 1);
      __ GetBuiltinFunction(function, Context::CALL_FUNCTION_PROXY_BUILTIN_INDEX);
      __ Jump(masm->isolate()->builtins()->ArgumentsAdaptorTrampoline(),
              RelocInfo::CODE_TARGET);
  
      __ Bind(&non_proxy);
      __ GetBuiltinFunction(function, Context::CALL_NON_FUNCTION_BUILTIN_INDEX);
      __ Jump(masm->isolate()->builtins()->ArgumentsAdaptorTrampoline(),
              RelocInfo::CODE_TARGET);
      __ Bind(&js_function);
    }
  
    // 5b. Get the code to call from the function and check that the number of
    //     expected arguments matches what we're providing.  If so, jump
    //     (tail-call) to the code in register edx without checking arguments.
    __ Ldr(x3, FieldMemOperand(function, JSFunction::kSharedFunctionInfoOffset));
    __ Ldrsw(x2,
             FieldMemOperand(x3,
               SharedFunctionInfo::kFormalParameterCountOffset));
    Label dont_adapt_args;
    __ Cmp(x2, argc);  // Check formal and actual parameter counts.
    __ B(eq, &dont_adapt_args);
    __ Jump(masm->isolate()->builtins()->ArgumentsAdaptorTrampoline(),
            RelocInfo::CODE_TARGET);
    __ Bind(&dont_adapt_args);
  
    __ Ldr(x3, FieldMemOperand(function, JSFunction::kCodeEntryOffset));
    ParameterCount expected(0);
    __ InvokeCode(x3, expected, expected, JUMP_FUNCTION, NullCallWrapper());
  }
  
  
  static void Generate_PushAppliedArguments(MacroAssembler* masm,
                                            const int argumentsOffset,
                                            const int indexOffset,
                                            const int limitOffset) {
    Label entry, loop;
    Register receiver = LoadDescriptor::ReceiverRegister();
    Register key = LoadDescriptor::NameRegister();
    Register slot = LoadDescriptor::SlotRegister();
    Register vector = LoadWithVectorDescriptor::VectorRegister();
  
    __ Ldr(key, MemOperand(fp, indexOffset));
    __ B(&entry);
  
    // Load the current argument from the arguments array.
    __ Bind(&loop);
    __ Ldr(receiver, MemOperand(fp, argumentsOffset));
  
    // Use inline caching to speed up access to arguments.
    Code::Kind kinds[] = {Code::KEYED_LOAD_IC};
    FeedbackVectorSpec spec(0, 1, kinds);
    Handle<TypeFeedbackVector> feedback_vector =
        masm->isolate()->factory()->NewTypeFeedbackVector(&spec);
    int index = feedback_vector->GetIndex(FeedbackVectorICSlot(0));
    __ Mov(slot, Smi::FromInt(index));
    __ Mov(vector, feedback_vector);
    Handle<Code> ic =
        KeyedLoadICStub(masm->isolate(), LoadICState(kNoExtraICState)).GetCode();
    __ Call(ic, RelocInfo::CODE_TARGET);
  
    // Push the nth argument.
    __ Push(x0);
  
    __ Ldr(key, MemOperand(fp, indexOffset));
    __ Add(key, key, Smi::FromInt(1));
    __ Str(key, MemOperand(fp, indexOffset));
  
    // Test if the copy loop has finished copying all the elements from the
    // arguments object.
    __ Bind(&entry);
    __ Ldr(x1, MemOperand(fp, limitOffset));
    __ Cmp(key, x1);
    __ B(ne, &loop);
  
    // On exit, the pushed arguments count is in x0, untagged
    __ Mov(x0, key);
    __ SmiUntag(x0);
  }
  
  
  static void Generate_ApplyHelper(MacroAssembler* masm, bool targetIsArgument) {
    const int kFormalParameters = targetIsArgument ? 3 : 2;
    const int kStackSize = kFormalParameters + 1;
  
    {
      FrameScope frame_scope(masm, StackFrame::INTERNAL);
  
      const int kArgumentsOffset =  kFPOnStackSize + kPCOnStackSize;
      const int kReceiverOffset = kArgumentsOffset + kPointerSize;
      const int kFunctionOffset = kReceiverOffset + kPointerSize;
      const int kIndexOffset    =
          StandardFrameConstants::kExpressionsOffset - (2 * kPointerSize);
      const int kLimitOffset    =
          StandardFrameConstants::kExpressionsOffset - (1 * kPointerSize);
  
      Register args = x12;
      Register receiver = x14;
      Register function = x15;
  
      // Get the length of the arguments via a builtin call.
      __ Ldr(function, MemOperand(fp, kFunctionOffset));
      __ Ldr(args, MemOperand(fp, kArgumentsOffset));
      __ Push(function, args);
      if (targetIsArgument) {
        __ InvokeBuiltin(Context::REFLECT_APPLY_PREPARE_BUILTIN_INDEX,
                         CALL_FUNCTION);
      } else {
        __ InvokeBuiltin(Context::APPLY_PREPARE_BUILTIN_INDEX, CALL_FUNCTION);
      }
      Register argc = x0;
  
      Generate_CheckStackOverflow(masm, kFunctionOffset, argc, kArgcIsSmiTagged);
  
      // Push current limit and index.
      __ Mov(x1, 0);  // Initial index.
      __ Push(argc, x1);
  
      Label push_receiver;
      __ Ldr(receiver, MemOperand(fp, kReceiverOffset));
  
      // Check that the function is a JS function. Otherwise it must be a proxy.
      // When it is not the function proxy will be invoked later.
      __ JumpIfNotObjectType(function, x10, x11, JS_FUNCTION_TYPE,
                             &push_receiver);
  
      // Change context eagerly to get the right global object if necessary.
      __ Ldr(cp, FieldMemOperand(function, JSFunction::kContextOffset));
      // Load the shared function info.
      __ Ldr(x2, FieldMemOperand(function,
                                 JSFunction::kSharedFunctionInfoOffset));
  
      // Compute and push the receiver.
      // Do not transform the receiver for strict mode functions.
      Label convert_receiver_to_object, use_global_proxy;
      __ Ldr(w10, FieldMemOperand(x2, SharedFunctionInfo::kCompilerHintsOffset));
      __ Tbnz(x10, SharedFunctionInfo::kStrictModeFunction, &push_receiver);
      // Do not transform the receiver for native functions.
      __ Tbnz(x10, SharedFunctionInfo::kNative, &push_receiver);
  
      // Compute the receiver in sloppy mode.
      __ JumpIfSmi(receiver, &convert_receiver_to_object);
      __ JumpIfRoot(receiver, Heap::kNullValueRootIndex, &use_global_proxy);
      __ JumpIfRoot(receiver, Heap::kUndefinedValueRootIndex,
                    &use_global_proxy);
  
      // Check if the receiver is already a JavaScript object.
      STATIC_ASSERT(LAST_SPEC_OBJECT_TYPE == LAST_TYPE);
      __ JumpIfObjectType(receiver, x10, x11, FIRST_SPEC_OBJECT_TYPE,
                          &push_receiver, ge);
  
      // Call a builtin to convert the receiver to a regular object.
      __ Bind(&convert_receiver_to_object);
      __ Mov(x0, receiver);
      ToObjectStub stub(masm->isolate());
      __ CallStub(&stub);
      __ Mov(receiver, x0);
      __ B(&push_receiver);
  
      __ Bind(&use_global_proxy);
      __ Ldr(x10, GlobalObjectMemOperand());
      __ Ldr(receiver, FieldMemOperand(x10, GlobalObject::kGlobalProxyOffset));
  
      // Push the receiver
      __ Bind(&push_receiver);
      __ Push(receiver);
  
      // Copy all arguments from the array to the stack.
      Generate_PushAppliedArguments(
          masm, kArgumentsOffset, kIndexOffset, kLimitOffset);
  
      // At the end of the loop, the number of arguments is stored in 'current',
      // represented as a smi.
  
      function = x1;  // From now on we want the function to be kept in x1;
      __ Ldr(function, MemOperand(fp, kFunctionOffset));
  
      // Call the function.
      Label call_proxy;
      ParameterCount actual(x0);
      __ JumpIfNotObjectType(function, x10, x11, JS_FUNCTION_TYPE, &call_proxy);
      __ InvokeFunction(function, actual, CALL_FUNCTION, NullCallWrapper());
      frame_scope.GenerateLeaveFrame();
      __ Drop(kStackSize);
      __ Ret();
  
      // Call the function proxy.
      __ Bind(&call_proxy);
      // x0 : argc
      // x1 : function
      __ Push(function);  // Add function proxy as last argument.
      __ Add(x0, x0, 1);
      __ Mov(x2, 0);
      __ GetBuiltinFunction(x1, Context::CALL_FUNCTION_PROXY_BUILTIN_INDEX);
      __ Call(masm->isolate()->builtins()->ArgumentsAdaptorTrampoline(),
              RelocInfo::CODE_TARGET);
    }
    __ Drop(kStackSize);
    __ Ret();
  }
  
  
  static void Generate_ConstructHelper(MacroAssembler* masm) {
    const int kFormalParameters = 3;
    const int kStackSize = kFormalParameters + 1;
  
    {
      FrameScope frame_scope(masm, StackFrame::INTERNAL);
  
      const int kNewTargetOffset = kFPOnStackSize + kPCOnStackSize;
      const int kArgumentsOffset =  kNewTargetOffset + kPointerSize;
      const int kFunctionOffset = kArgumentsOffset + kPointerSize;
  
      const int kIndexOffset    =
          StandardFrameConstants::kExpressionsOffset - (2 * kPointerSize);
      const int kLimitOffset    =
          StandardFrameConstants::kExpressionsOffset - (1 * kPointerSize);
  
      // Is x11 safe to use?
      Register newTarget = x11;
      Register args = x12;
      Register function = x15;
  
      // If newTarget is not supplied, set it to constructor
      Label validate_arguments;
      __ Ldr(x0, MemOperand(fp, kNewTargetOffset));
      __ CompareRoot(x0, Heap::kUndefinedValueRootIndex);
      __ B(ne, &validate_arguments);
      __ Ldr(x0, MemOperand(fp, kFunctionOffset));
      __ Str(x0, MemOperand(fp, kNewTargetOffset));
  
      // Validate arguments
      __ Bind(&validate_arguments);
      __ Ldr(function, MemOperand(fp, kFunctionOffset));
      __ Ldr(args, MemOperand(fp, kArgumentsOffset));
      __ Ldr(newTarget, MemOperand(fp, kNewTargetOffset));
      __ Push(function, args, newTarget);
      __ InvokeBuiltin(Context::REFLECT_CONSTRUCT_PREPARE_BUILTIN_INDEX,
                       CALL_FUNCTION);
      Register argc = x0;
  
      Generate_CheckStackOverflow(masm, kFunctionOffset, argc, kArgcIsSmiTagged);
  
      // Push current limit and index & constructor function as callee.
      __ Mov(x1, 0);  // Initial index.
      __ Push(argc, x1, function);
  
      // Copy all arguments from the array to the stack.
      Generate_PushAppliedArguments(
          masm, kArgumentsOffset, kIndexOffset, kLimitOffset);
  
      // Use undefined feedback vector
      __ LoadRoot(x2, Heap::kUndefinedValueRootIndex);
      __ Ldr(x1, MemOperand(fp, kFunctionOffset));
      __ Ldr(x4, MemOperand(fp, kNewTargetOffset));
  
      // Call the function.
      CallConstructStub stub(masm->isolate(), SUPER_CONSTRUCTOR_CALL);
      __ Call(stub.GetCode(), RelocInfo::CONSTRUCT_CALL);
  
      // Leave internal frame.
    }
    __ Drop(kStackSize);
    __ Ret();
  }
  
  
  void Builtins::Generate_FunctionApply(MacroAssembler* masm) {
    ASM_LOCATION("Builtins::Generate_FunctionApply");
    Generate_ApplyHelper(masm, false);
  }
  
  
  void Builtins::Generate_ReflectApply(MacroAssembler* masm) {
    ASM_LOCATION("Builtins::Generate_ReflectApply");
    Generate_ApplyHelper(masm, true);
  }
  
  
  void Builtins::Generate_ReflectConstruct(MacroAssembler* masm) {
    ASM_LOCATION("Builtins::Generate_ReflectConstruct");
    Generate_ConstructHelper(masm);
  }
  
  
  static void ArgumentAdaptorStackCheck(MacroAssembler* masm,
                                        Label* stack_overflow) {
    // ----------- S t a t e -------------
    //  -- x0 : actual number of arguments
    //  -- x1 : function (passed through to callee)
    //  -- x2 : expected number of arguments
    // -----------------------------------
    // Check the stack for overflow.
    // We are not trying to catch interruptions (e.g. debug break and
    // preemption) here, so the "real stack limit" is checked.
    Label enough_stack_space;
    __ LoadRoot(x10, Heap::kRealStackLimitRootIndex);
    // Make x10 the space we have left. The stack might already be overflowed
    // here which will cause x10 to become negative.
    __ Sub(x10, jssp, x10);
    // Check if the arguments will overflow the stack.
    __ Cmp(x10, Operand(x2, LSL, kPointerSizeLog2));
    __ B(le, stack_overflow);
  }
  
  
  static void EnterArgumentsAdaptorFrame(MacroAssembler* masm) {
    __ SmiTag(x10, x0);
    __ Mov(x11, Smi::FromInt(StackFrame::ARGUMENTS_ADAPTOR));
    __ Push(lr, fp);
    __ Push(x11, x1, x10);
    __ Add(fp, jssp,
           StandardFrameConstants::kFixedFrameSizeFromFp + kPointerSize);
  }
  
  
  static void LeaveArgumentsAdaptorFrame(MacroAssembler* masm) {
    // ----------- S t a t e -------------
    //  -- x0 : result being passed through
    // -----------------------------------
    // Get the number of arguments passed (as a smi), tear down the frame and
    // then drop the parameters and the receiver.
    __ Ldr(x10, MemOperand(fp, -(StandardFrameConstants::kFixedFrameSizeFromFp +
                                 kPointerSize)));
    __ Mov(jssp, fp);
    __ Pop(fp, lr);
    __ DropBySMI(x10, kXRegSize);
    __ Drop(1);
  }
  
  
  void Builtins::Generate_ArgumentsAdaptorTrampoline(MacroAssembler* masm) {
    ASM_LOCATION("Builtins::Generate_ArgumentsAdaptorTrampoline");
    // ----------- S t a t e -------------
    //  -- x0 : actual number of arguments
    //  -- x1 : function (passed through to callee)
    //  -- x2 : expected number of arguments
    // -----------------------------------
  
    Label stack_overflow;
    ArgumentAdaptorStackCheck(masm, &stack_overflow);
  
    Register argc_actual = x0;  // Excluding the receiver.
    Register argc_expected = x2;  // Excluding the receiver.
    Register function = x1;
    Register code_entry = x3;
  
    Label invoke, dont_adapt_arguments;
  
    Label enough, too_few;
    __ Ldr(code_entry, FieldMemOperand(function, JSFunction::kCodeEntryOffset));
    __ Cmp(argc_actual, argc_expected);
    __ B(lt, &too_few);
    __ Cmp(argc_expected, SharedFunctionInfo::kDontAdaptArgumentsSentinel);
    __ B(eq, &dont_adapt_arguments);
  
    {  // Enough parameters: actual >= expected
      EnterArgumentsAdaptorFrame(masm);
  
      Register copy_start = x10;
      Register copy_end = x11;
      Register copy_to = x12;
      Register scratch1 = x13, scratch2 = x14;
  
      __ Lsl(scratch2, argc_expected, kPointerSizeLog2);
  
      // Adjust for fp, lr, and the receiver.
      __ Add(copy_start, fp, 3 * kPointerSize);
      __ Add(copy_start, copy_start, Operand(argc_actual, LSL, kPointerSizeLog2));
      __ Sub(copy_end, copy_start, scratch2);
      __ Sub(copy_end, copy_end, kPointerSize);
      __ Mov(copy_to, jssp);
  
      // Claim space for the arguments, the receiver, and one extra slot.
      // The extra slot ensures we do not write under jssp. It will be popped
      // later.
      __ Add(scratch1, scratch2, 2 * kPointerSize);
      __ Claim(scratch1, 1);
  
      // Copy the arguments (including the receiver) to the new stack frame.
      Label copy_2_by_2;
      __ Bind(&copy_2_by_2);
      __ Ldp(scratch1, scratch2,
             MemOperand(copy_start, - 2 * kPointerSize, PreIndex));
      __ Stp(scratch1, scratch2,
             MemOperand(copy_to, - 2 * kPointerSize, PreIndex));
      __ Cmp(copy_start, copy_end);
      __ B(hi, &copy_2_by_2);
  
      // Correct the space allocated for the extra slot.
      __ Drop(1);
  
      __ B(&invoke);
    }
  
    {  // Too few parameters: Actual < expected
      __ Bind(&too_few);
  
      Register copy_from = x10;
      Register copy_end = x11;
      Register copy_to = x12;
      Register scratch1 = x13, scratch2 = x14;
  
      // If the function is strong we need to throw an error.
      Label no_strong_error;
      __ Ldr(scratch1,
             FieldMemOperand(function, JSFunction::kSharedFunctionInfoOffset));
      __ Ldr(scratch2.W(),
             FieldMemOperand(scratch1, SharedFunctionInfo::kCompilerHintsOffset));
      __ TestAndBranchIfAllClear(scratch2.W(),
                                 (1 << SharedFunctionInfo::kStrongModeFunction),
                                 &no_strong_error);
  
      // What we really care about is the required number of arguments.
      DCHECK_EQ(kPointerSize, kInt64Size);
      __ Ldr(scratch2.W(),
             FieldMemOperand(scratch1, SharedFunctionInfo::kLengthOffset));
      __ Cmp(argc_actual, Operand(scratch2, LSR, 1));
      __ B(ge, &no_strong_error);
  
      {
        FrameScope frame(masm, StackFrame::MANUAL);
        EnterArgumentsAdaptorFrame(masm);
        __ CallRuntime(Runtime::kThrowStrongModeTooFewArguments, 0);
      }
  
      __ Bind(&no_strong_error);
      EnterArgumentsAdaptorFrame(masm);
  
      __ Lsl(scratch2, argc_expected, kPointerSizeLog2);
      __ Lsl(argc_actual, argc_actual, kPointerSizeLog2);
  
      // Adjust for fp, lr, and the receiver.
      __ Add(copy_from, fp, 3 * kPointerSize);
      __ Add(copy_from, copy_from, argc_actual);
      __ Mov(copy_to, jssp);
      __ Sub(copy_end, copy_to, 1 * kPointerSize);   // Adjust for the receiver.
      __ Sub(copy_end, copy_end, argc_actual);
  
      // Claim space for the arguments, the receiver, and one extra slot.
      // The extra slot ensures we do not write under jssp. It will be popped
      // later.
      __ Add(scratch1, scratch2, 2 * kPointerSize);
      __ Claim(scratch1, 1);
  
      // Copy the arguments (including the receiver) to the new stack frame.
      Label copy_2_by_2;
      __ Bind(&copy_2_by_2);
      __ Ldp(scratch1, scratch2,
             MemOperand(copy_from, - 2 * kPointerSize, PreIndex));
      __ Stp(scratch1, scratch2,
             MemOperand(copy_to, - 2 * kPointerSize, PreIndex));
      __ Cmp(copy_to, copy_end);
      __ B(hi, &copy_2_by_2);
  
      __ Mov(copy_to, copy_end);
  
      // Fill the remaining expected arguments with undefined.
      __ LoadRoot(scratch1, Heap::kUndefinedValueRootIndex);
      __ Add(copy_end, jssp, kPointerSize);
  
      Label fill;
      __ Bind(&fill);
      __ Stp(scratch1, scratch1,
             MemOperand(copy_to, - 2 * kPointerSize, PreIndex));
      __ Cmp(copy_to, copy_end);
      __ B(hi, &fill);
  
      // Correct the space allocated for the extra slot.
      __ Drop(1);
    }
  
    // Arguments have been adapted. Now call the entry point.
    __ Bind(&invoke);
    __ Mov(argc_actual, argc_expected);
    // x0 : expected number of arguments
    // x1 : function (passed through to callee)
    __ Call(code_entry);
  
    // Store offset of return address for deoptimizer.
    masm->isolate()->heap()->SetArgumentsAdaptorDeoptPCOffset(masm->pc_offset());
  
    // Exit frame and return.
    LeaveArgumentsAdaptorFrame(masm);
    __ Ret();
  
    // Call the entry point without adapting the arguments.
    __ Bind(&dont_adapt_arguments);
    __ Jump(code_entry);
  
    __ Bind(&stack_overflow);
    {
      FrameScope frame(masm, StackFrame::MANUAL);
      EnterArgumentsAdaptorFrame(masm);
      __ InvokeBuiltin(Context::STACK_OVERFLOW_BUILTIN_INDEX, CALL_FUNCTION);
      __ Unreachable();
    }
  }
  
  
  #undef __
  
  }  // namespace internal
  }  // namespace v8
  
  #endif  // V8_TARGET_ARCH_ARM
  