src/arm/code-stubs-arm.cc

// Copyright 2012 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_ARM

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

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

namespace v8 {
namespace internal {

#define __ ACCESS_MASM(masm)

void JSEntryStub::Generate(MacroAssembler* masm) {
  // r0: code entry
  // r1: function
  // r2: receiver
  // r3: argc
  // [sp+0]: argv

  Label invoke, handler_entry, exit;

  {
    NoRootArrayScope no_root_array(masm);

    ProfileEntryHookStub::MaybeCallEntryHook(masm);

    // Called from C, so do not pop argc and args on exit (preserve sp)
    // No need to save register-passed args
    // Save callee-saved registers (incl. cp and fp), sp, and lr
    __ stm(db_w, sp, kCalleeSaved | lr.bit());

    // Save callee-saved vfp registers.
    __ vstm(db_w, sp, kFirstCalleeSavedDoubleReg, kLastCalleeSavedDoubleReg);
    // Set up the reserved register for 0.0.
    __ vmov(kDoubleRegZero, Double(0.0));

    __ InitializeRootRegister();
  }

  // Get address of argv, see stm above.
  // r0: code entry
  // r1: function
  // r2: receiver
  // r3: argc

  // Set up argv in r4.
  int offset_to_argv = (kNumCalleeSaved + 1) * kPointerSize;
  offset_to_argv += kNumDoubleCalleeSaved * kDoubleSize;
  __ ldr(r4, MemOperand(sp, offset_to_argv));

  // Push a frame with special values setup to mark it as an entry frame.
  // r0: code entry
  // r1: function
  // r2: receiver
  // r3: argc
  // r4: argv
  StackFrame::Type marker = type();
  __ mov(r7, Operand(StackFrame::TypeToMarker(marker)));
  __ mov(r6, Operand(StackFrame::TypeToMarker(marker)));
  __ mov(r5, Operand(ExternalReference::Create(
                 IsolateAddressId::kCEntryFPAddress, isolate())));
  __ ldr(r5, MemOperand(r5));
  {
    UseScratchRegisterScope temps(masm);
    Register scratch = temps.Acquire();

    // Push a bad frame pointer to fail if it is used.
    __ mov(scratch, Operand(-1));
    __ stm(db_w, sp, r5.bit() | r6.bit() | r7.bit() | scratch.bit());
  }

  Register scratch = r6;

  // Set up frame pointer for the frame to be pushed.
  __ add(fp, sp, Operand(-EntryFrameConstants::kCallerFPOffset));

  // If this is the outermost JS call, set js_entry_sp value.
  Label non_outermost_js;
  ExternalReference js_entry_sp =
      ExternalReference::Create(IsolateAddressId::kJSEntrySPAddress, isolate());
  __ mov(r5, Operand(ExternalReference(js_entry_sp)));
  __ ldr(scratch, MemOperand(r5));
  __ cmp(scratch, Operand::Zero());
  __ b(ne, &non_outermost_js);
  __ str(fp, MemOperand(r5));
  __ mov(scratch, Operand(StackFrame::OUTERMOST_JSENTRY_FRAME));
  Label cont;
  __ b(&cont);
  __ bind(&non_outermost_js);
  __ mov(scratch, Operand(StackFrame::INNER_JSENTRY_FRAME));
  __ bind(&cont);
  __ push(scratch);

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

  // Block literal pool emission whilst taking the position of the handler
  // entry. This avoids making the assumption that literal pools are always
  // emitted after an instruction is emitted, rather than before.
  {
    Assembler::BlockConstPoolScope block_const_pool(masm);
    __ bind(&handler_entry);
    handler_offset_ = handler_entry.pos();
    // Caught exception: Store result (exception) in the pending exception
    // field in the JSEnv and return a failure sentinel.  Coming in here the
    // fp will be invalid because the PushStackHandler below sets it to 0 to
    // signal the existence of the JSEntry frame.
    __ mov(scratch,
           Operand(ExternalReference::Create(
               IsolateAddressId::kPendingExceptionAddress, isolate())));
  }
  __ str(r0, MemOperand(scratch));
  __ LoadRoot(r0, Heap::kExceptionRootIndex);
  __ b(&exit);

  // Invoke: Link this frame into the handler chain.
  __ bind(&invoke);
  // Must preserve r0-r4, r5-r6 are available.
  __ PushStackHandler();
  // If an exception not caught by another handler occurs, this handler
  // returns control to the code after the bl(&invoke) above, which
  // restores all kCalleeSaved registers (including cp and fp) to their
  // saved values before returning a failure to C.

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

  // Expected registers by Builtins::JSEntryTrampoline
  // r0: code entry
  // r1: function
  // r2: receiver
  // r3: argc
  // r4: argv
  __ Call(EntryTrampoline(), RelocInfo::CODE_TARGET);

  // Unlink this frame from the handler chain.
  __ PopStackHandler();

  __ bind(&exit);  // r0 holds result
  // Check if the current stack frame is marked as the outermost JS frame.
  Label non_outermost_js_2;
  __ pop(r5);
  __ cmp(r5, Operand(StackFrame::OUTERMOST_JSENTRY_FRAME));
  __ b(ne, &non_outermost_js_2);
  __ mov(r6, Operand::Zero());
  __ mov(r5, Operand(ExternalReference(js_entry_sp)));
  __ str(r6, MemOperand(r5));
  __ bind(&non_outermost_js_2);

  // Restore the top frame descriptors from the stack.
  __ pop(r3);
  __ mov(scratch, Operand(ExternalReference::Create(
                      IsolateAddressId::kCEntryFPAddress, isolate())));
  __ str(r3, MemOperand(scratch));

  // Reset the stack to the callee saved registers.
  __ add(sp, sp, Operand(-EntryFrameConstants::kCallerFPOffset));

  // Restore callee-saved registers and return.
#ifdef DEBUG
  if (FLAG_debug_code) {
    __ mov(lr, Operand(pc));
  }
#endif

  // Restore callee-saved vfp registers.
  __ vldm(ia_w, sp, kFirstCalleeSavedDoubleReg, kLastCalleeSavedDoubleReg);

  __ ldm(ia_w, sp, kCalleeSaved | pc.bit());
}

void DirectCEntryStub::Generate(MacroAssembler* masm) {
  // Place the return address on the stack, making the call
  // GC safe. The RegExp backend also relies on this.
  __ str(lr, MemOperand(sp, 0));
  __ blx(ip);  // Call the C++ function.
  __ ldr(pc, MemOperand(sp, 0));
}


void DirectCEntryStub::GenerateCall(MacroAssembler* masm,
                                    Register target) {
  if (FLAG_embedded_builtins) {
    if (masm->root_array_available() &&
        isolate()->ShouldLoadConstantsFromRootList()) {
      // This is basically an inlined version of Call(Handle<Code>) that loads
      // the code object into lr instead of ip.
      __ Move(ip, target);
      __ IndirectLoadConstant(lr, GetCode());
      __ add(lr, lr, Operand(Code::kHeaderSize - kHeapObjectTag));
      __ blx(lr);
      return;
    }
  }
  intptr_t code =
      reinterpret_cast<intptr_t>(GetCode().location());
  __ Move(ip, target);
  __ mov(lr, Operand(code, RelocInfo::CODE_TARGET));
  __ blx(lr);  // Call the stub.
}


void ProfileEntryHookStub::MaybeCallEntryHookDelayed(TurboAssembler* tasm,
                                                     Zone* zone) {
  if (tasm->isolate()->function_entry_hook() != nullptr) {
    tasm->MaybeCheckConstPool();
    PredictableCodeSizeScope predictable(
        tasm, TurboAssembler::kCallStubSize + 2 * kInstrSize);
    tasm->push(lr);
    tasm->CallStubDelayed(new (zone) ProfileEntryHookStub(nullptr));
    tasm->pop(lr);
  }
}

void ProfileEntryHookStub::MaybeCallEntryHook(MacroAssembler* masm) {
  if (masm->isolate()->function_entry_hook() != nullptr) {
    ProfileEntryHookStub stub(masm->isolate());
    masm->MaybeCheckConstPool();
    PredictableCodeSizeScope predictable(
        masm, TurboAssembler::kCallStubSize + 2 * kInstrSize);
    __ push(lr);
    __ CallStub(&stub);
    __ pop(lr);
  }
}


void ProfileEntryHookStub::Generate(MacroAssembler* masm) {
  // The entry hook is a "push lr" instruction, followed by a call.
  const int32_t kReturnAddressDistanceFromFunctionStart = 3 * kInstrSize;

  // This should contain all kCallerSaved registers.
  const RegList kSavedRegs =
      1 <<  0 |  // r0
      1 <<  1 |  // r1
      1 <<  2 |  // r2
      1 <<  3 |  // r3
      1 <<  5 |  // r5
      1 <<  9;   // r9
  // We also save lr, so the count here is one higher than the mask indicates.
  const int32_t kNumSavedRegs = 7;

  DCHECK_EQ(kCallerSaved & kSavedRegs, kCallerSaved);

  // Save all caller-save registers as this may be called from anywhere.
  __ stm(db_w, sp, kSavedRegs | lr.bit());

  // Compute the function's address for the first argument.
  __ sub(r0, lr, Operand(kReturnAddressDistanceFromFunctionStart));

  // The caller's return address is above the saved temporaries.
  // Grab that for the second argument to the hook.
  __ add(r1, sp, Operand(kNumSavedRegs * kPointerSize));

  // Align the stack if necessary.
  int frame_alignment = masm->ActivationFrameAlignment();
  if (frame_alignment > kPointerSize) {
    __ mov(r5, sp);
    DCHECK(base::bits::IsPowerOfTwo(frame_alignment));
    __ and_(sp, sp, Operand(-frame_alignment));
  }

  {
    UseScratchRegisterScope temps(masm);
    Register scratch = temps.Acquire();

#if V8_HOST_ARCH_ARM
    int32_t entry_hook =
        reinterpret_cast<int32_t>(isolate()->function_entry_hook());
    __ mov(scratch, Operand(entry_hook));
#else
    // Under the simulator we need to indirect the entry hook through a
    // trampoline function at a known address.
    // It additionally takes an isolate as a third parameter
    __ mov(r2, Operand(ExternalReference::isolate_address(isolate())));

    ApiFunction dispatcher(FUNCTION_ADDR(EntryHookTrampoline));
    __ mov(scratch, Operand(ExternalReference::Create(
                        &dispatcher, ExternalReference::BUILTIN_CALL)));
#endif
    __ Call(scratch);
  }

  // Restore the stack pointer if needed.
  if (frame_alignment > kPointerSize) {
    __ mov(sp, r5);
  }

  // Also pop pc to get Ret(0).
  __ ldm(ia_w, sp, kSavedRegs | pc.bit());
}

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


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

  DCHECK(function_address == r1 || function_address == r2);

  Label profiler_disabled;
  Label end_profiler_check;
  __ Move(r9, ExternalReference::is_profiling_address(isolate));
  __ ldrb(r9, MemOperand(r9, 0));
  __ cmp(r9, Operand(0));
  __ b(eq, &profiler_disabled);

  // Additional parameter is the address of the actual callback.
  __ Move(r3, thunk_ref);
  __ jmp(&end_profiler_check);

  __ bind(&profiler_disabled);
  __ Move(r3, function_address);
  __ bind(&end_profiler_check);

  // Allocate HandleScope in callee-save registers.
  __ Move(r9, next_address);
  __ ldr(r4, MemOperand(r9, kNextOffset));
  __ ldr(r5, MemOperand(r9, kLimitOffset));
  __ ldr(r6, MemOperand(r9, kLevelOffset));
  __ add(r6, r6, Operand(1));
  __ str(r6, MemOperand(r9, kLevelOffset));

  if (FLAG_log_timer_events) {
    FrameScope frame(masm, StackFrame::MANUAL);
    __ PushSafepointRegisters();
    __ PrepareCallCFunction(1);
    __ Move(r0, ExternalReference::isolate_address(isolate));
    __ CallCFunction(ExternalReference::log_enter_external_function(), 1);
    __ PopSafepointRegisters();
  }

  // Native call returns to the DirectCEntry stub which redirects to the
  // return address pushed on stack (could have moved after GC).
  // DirectCEntry stub itself is generated early and never moves.
  DirectCEntryStub stub(isolate);
  stub.GenerateCall(masm, r3);

  if (FLAG_log_timer_events) {
    FrameScope frame(masm, StackFrame::MANUAL);
    __ PushSafepointRegisters();
    __ PrepareCallCFunction(1);
    __ Move(r0, ExternalReference::isolate_address(isolate));
    __ CallCFunction(ExternalReference::log_leave_external_function(), 1);
    __ PopSafepointRegisters();
  }

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

  // load value from ReturnValue
  __ ldr(r0, return_value_operand);
  __ bind(&return_value_loaded);
  // No more valid handles (the result handle was the last one). Restore
  // previous handle scope.
  __ str(r4, MemOperand(r9, kNextOffset));
  if (__ emit_debug_code()) {
    __ ldr(r1, MemOperand(r9, kLevelOffset));
    __ cmp(r1, r6);
    __ Check(eq, AbortReason::kUnexpectedLevelAfterReturnFromApiCall);
  }
  __ sub(r6, r6, Operand(1));
  __ str(r6, MemOperand(r9, kLevelOffset));
  __ ldr(r6, MemOperand(r9, kLimitOffset));
  __ cmp(r5, r6);
  __ b(ne, &delete_allocated_handles);

  // Leave the API exit frame.
  __ bind(&leave_exit_frame);
  // LeaveExitFrame expects unwind space to be in a register.
  if (stack_space_operand != nullptr) {
    __ ldr(r4, *stack_space_operand);
  } else {
    __ mov(r4, Operand(stack_space));
  }
  __ LeaveExitFrame(false, r4, stack_space_operand != nullptr);

  // Check if the function scheduled an exception.
  __ LoadRoot(r4, Heap::kTheHoleValueRootIndex);
  __ Move(r6, ExternalReference::scheduled_exception_address(isolate));
  __ ldr(r5, MemOperand(r6));
  __ cmp(r4, r5);
  __ b(ne, &promote_scheduled_exception);

  __ mov(pc, lr);

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

  // HandleScope limit has changed. Delete allocated extensions.
  __ bind(&delete_allocated_handles);
  __ str(r5, MemOperand(r9, kLimitOffset));
  __ mov(r4, r0);
  __ PrepareCallCFunction(1);
  __ Move(r0, ExternalReference::isolate_address(isolate));
  __ CallCFunction(ExternalReference::delete_handle_scope_extensions(), 1);
  __ mov(r0, r4);
  __ jmp(&leave_exit_frame);
}

void CallApiCallbackStub::Generate(MacroAssembler* masm) {
  // ----------- S t a t e -------------
  //  -- r4                  : call_data
  //  -- r2                  : holder
  //  -- r1                  : api_function_address
  //  -- cp                  : context
  //  --
  //  -- sp[0]               : last argument
  //  -- ...
  //  -- sp[(argc - 1) * 4]  : first argument
  //  -- sp[argc * 4]        : receiver
  // -----------------------------------

  Register call_data = r4;
  Register holder = r2;
  Register api_function_address = r1;

  typedef FunctionCallbackArguments FCA;

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

  // new target
  __ PushRoot(Heap::kUndefinedValueRootIndex);

  // call data
  __ push(call_data);

  Register scratch0 = call_data;
  Register scratch1 = r5;
  __ LoadRoot(scratch0, Heap::kUndefinedValueRootIndex);
  // return value
  __ push(scratch0);
  // return value default
  __ push(scratch0);
  // isolate
  __ Move(scratch1, ExternalReference::isolate_address(masm->isolate()));
  __ push(scratch1);
  // holder
  __ push(holder);

  // Prepare arguments.
  __ mov(scratch0, sp);

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

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

  DCHECK(api_function_address != r0 && scratch0 != r0);
  // r0 = FunctionCallbackInfo&
  // Arguments is after the return address.
  __ add(r0, sp, Operand(1 * kPointerSize));
  // FunctionCallbackInfo::implicit_args_
  __ str(scratch0, MemOperand(r0, 0 * kPointerSize));
  // FunctionCallbackInfo::values_
  __ add(scratch1, scratch0,
         Operand((FCA::kArgsLength - 1 + argc()) * kPointerSize));
  __ str(scratch1, MemOperand(r0, 1 * kPointerSize));
  // FunctionCallbackInfo::length_ = argc
  __ mov(scratch0, Operand(argc()));
  __ str(scratch0, MemOperand(r0, 2 * kPointerSize));

  ExternalReference thunk_ref = ExternalReference::invoke_function_callback();

  AllowExternalCallThatCantCauseGC scope(masm);
  // Stores return the first js argument
  int return_value_offset = 2 + FCA::kReturnValueOffset;
  MemOperand return_value_operand(fp, return_value_offset * kPointerSize);
  const int stack_space = argc() + FCA::kArgsLength + 1;
  MemOperand* stack_space_operand = nullptr;

  CallApiFunctionAndReturn(masm, api_function_address, thunk_ref, stack_space,
                           stack_space_operand, return_value_operand);
}


void CallApiGetterStub::Generate(MacroAssembler* masm) {
  // Build v8::PropertyCallbackInfo::args_ array on the stack and push property
  // name below the exit frame to make GC aware of them.
  STATIC_ASSERT(PropertyCallbackArguments::kShouldThrowOnErrorIndex == 0);
  STATIC_ASSERT(PropertyCallbackArguments::kHolderIndex == 1);
  STATIC_ASSERT(PropertyCallbackArguments::kIsolateIndex == 2);
  STATIC_ASSERT(PropertyCallbackArguments::kReturnValueDefaultValueIndex == 3);
  STATIC_ASSERT(PropertyCallbackArguments::kReturnValueOffset == 4);
  STATIC_ASSERT(PropertyCallbackArguments::kDataIndex == 5);
  STATIC_ASSERT(PropertyCallbackArguments::kThisIndex == 6);
  STATIC_ASSERT(PropertyCallbackArguments::kArgsLength == 7);

  Register receiver = ApiGetterDescriptor::ReceiverRegister();
  Register holder = ApiGetterDescriptor::HolderRegister();
  Register callback = ApiGetterDescriptor::CallbackRegister();
  Register scratch = r4;
  DCHECK(!AreAliased(receiver, holder, callback, scratch));

  Register api_function_address = r2;

  __ push(receiver);
  // Push data from AccessorInfo.
  __ ldr(scratch, FieldMemOperand(callback, AccessorInfo::kDataOffset));
  __ push(scratch);
  __ LoadRoot(scratch, Heap::kUndefinedValueRootIndex);
  __ Push(scratch, scratch);
  __ Move(scratch, ExternalReference::isolate_address(isolate()));
  __ Push(scratch, holder);
  __ Push(Smi::kZero);  // should_throw_on_error -> false
  __ ldr(scratch, FieldMemOperand(callback, AccessorInfo::kNameOffset));
  __ push(scratch);
  // v8::PropertyCallbackInfo::args_ array and name handle.
  const int kStackUnwindSpace = PropertyCallbackArguments::kArgsLength + 1;

  // Load address of v8::PropertyAccessorInfo::args_ array and name handle.
  __ mov(r0, sp);                             // r0 = Handle<Name>
  __ add(r1, r0, Operand(1 * kPointerSize));  // r1 = v8::PCI::args_

  const int kApiStackSpace = 1;
  FrameScope frame_scope(masm, StackFrame::MANUAL);
  __ EnterExitFrame(false, kApiStackSpace);

  // Create v8::PropertyCallbackInfo object on the stack and initialize
  // it's args_ field.
  __ str(r1, MemOperand(sp, 1 * kPointerSize));
  __ add(r1, sp, Operand(1 * kPointerSize));  // r1 = v8::PropertyCallbackInfo&

  ExternalReference thunk_ref =
      ExternalReference::invoke_accessor_getter_callback();

  __ ldr(scratch, FieldMemOperand(callback, AccessorInfo::kJsGetterOffset));
  __ ldr(api_function_address,
         FieldMemOperand(scratch, Foreign::kForeignAddressOffset));

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

#undef __

}  // namespace internal
}  // namespace v8

#endif  // V8_TARGET_ARCH_ARM