src/x64/assembler-x64-inl.h

// 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.

#ifndef V8_X64_ASSEMBLER_X64_INL_H_
#define V8_X64_ASSEMBLER_X64_INL_H_

#include "src/x64/assembler-x64.h"

#include "src/base/cpu.h"
#include "src/debug.h"
#include "src/v8memory.h"

namespace v8 {
namespace internal {

bool CpuFeatures::SupportsCrankshaft() { return true; }


// -----------------------------------------------------------------------------
// Implementation of Assembler


static const byte kCallOpcode = 0xE8;
// The length of pushq(rbp), movp(rbp, rsp), Push(rsi) and Push(rdi).
static const int kNoCodeAgeSequenceLength = kPointerSize == kInt64Size ? 6 : 17;


void Assembler::emitl(uint32_t x) {
  Memory::uint32_at(pc_) = x;
  pc_ += sizeof(uint32_t);
}


void Assembler::emitp(void* x, RelocInfo::Mode rmode) {
  uintptr_t value = reinterpret_cast<uintptr_t>(x);
  Memory::uintptr_at(pc_) = value;
  if (!RelocInfo::IsNone(rmode)) {
    RecordRelocInfo(rmode, value);
  }
  pc_ += sizeof(uintptr_t);
}


void Assembler::emitq(uint64_t x) {
  Memory::uint64_at(pc_) = x;
  pc_ += sizeof(uint64_t);
}


void Assembler::emitw(uint16_t x) {
  Memory::uint16_at(pc_) = x;
  pc_ += sizeof(uint16_t);
}


void Assembler::emit_code_target(Handle<Code> target,
                                 RelocInfo::Mode rmode,
                                 TypeFeedbackId ast_id) {
  DCHECK(RelocInfo::IsCodeTarget(rmode) ||
      rmode == RelocInfo::CODE_AGE_SEQUENCE);
  if (rmode == RelocInfo::CODE_TARGET && !ast_id.IsNone()) {
    RecordRelocInfo(RelocInfo::CODE_TARGET_WITH_ID, ast_id.ToInt());
  } else {
    RecordRelocInfo(rmode);
  }
  int current = code_targets_.length();
  if (current > 0 && code_targets_.last().is_identical_to(target)) {
    // Optimization if we keep jumping to the same code target.
    emitl(current - 1);
  } else {
    code_targets_.Add(target);
    emitl(current);
  }
}


void Assembler::emit_runtime_entry(Address entry, RelocInfo::Mode rmode) {
  DCHECK(RelocInfo::IsRuntimeEntry(rmode));
  RecordRelocInfo(rmode);
  emitl(static_cast<uint32_t>(entry - isolate()->code_range()->start()));
}


void Assembler::emit_rex_64(Register reg, Register rm_reg) {
  emit(0x48 | reg.high_bit() << 2 | rm_reg.high_bit());
}


void Assembler::emit_rex_64(XMMRegister reg, Register rm_reg) {
  emit(0x48 | (reg.code() & 0x8) >> 1 | rm_reg.code() >> 3);
}


void Assembler::emit_rex_64(Register reg, XMMRegister rm_reg) {
  emit(0x48 | (reg.code() & 0x8) >> 1 | rm_reg.code() >> 3);
}


void Assembler::emit_rex_64(Register reg, const Operand& op) {
  emit(0x48 | reg.high_bit() << 2 | op.rex_);
}


void Assembler::emit_rex_64(XMMRegister reg, const Operand& op) {
  emit(0x48 | (reg.code() & 0x8) >> 1 | op.rex_);
}


void Assembler::emit_rex_64(Register rm_reg) {
  DCHECK_EQ(rm_reg.code() & 0xf, rm_reg.code());
  emit(0x48 | rm_reg.high_bit());
}


void Assembler::emit_rex_64(const Operand& op) {
  emit(0x48 | op.rex_);
}


void Assembler::emit_rex_32(Register reg, Register rm_reg) {
  emit(0x40 | reg.high_bit() << 2 | rm_reg.high_bit());
}


void Assembler::emit_rex_32(Register reg, const Operand& op) {
  emit(0x40 | reg.high_bit() << 2  | op.rex_);
}


void Assembler::emit_rex_32(Register rm_reg) {
  emit(0x40 | rm_reg.high_bit());
}


void Assembler::emit_rex_32(const Operand& op) {
  emit(0x40 | op.rex_);
}


void Assembler::emit_optional_rex_32(Register reg, Register rm_reg) {
  byte rex_bits = reg.high_bit() << 2 | rm_reg.high_bit();
  if (rex_bits != 0) emit(0x40 | rex_bits);
}


void Assembler::emit_optional_rex_32(Register reg, const Operand& op) {
  byte rex_bits =  reg.high_bit() << 2 | op.rex_;
  if (rex_bits != 0) emit(0x40 | rex_bits);
}


void Assembler::emit_optional_rex_32(XMMRegister reg, const Operand& op) {
  byte rex_bits =  (reg.code() & 0x8) >> 1 | op.rex_;
  if (rex_bits != 0) emit(0x40 | rex_bits);
}


void Assembler::emit_optional_rex_32(XMMRegister reg, XMMRegister base) {
  byte rex_bits =  (reg.code() & 0x8) >> 1 | (base.code() & 0x8) >> 3;
  if (rex_bits != 0) emit(0x40 | rex_bits);
}


void Assembler::emit_optional_rex_32(XMMRegister reg, Register base) {
  byte rex_bits =  (reg.code() & 0x8) >> 1 | (base.code() & 0x8) >> 3;
  if (rex_bits != 0) emit(0x40 | rex_bits);
}


void Assembler::emit_optional_rex_32(Register reg, XMMRegister base) {
  byte rex_bits =  (reg.code() & 0x8) >> 1 | (base.code() & 0x8) >> 3;
  if (rex_bits != 0) emit(0x40 | rex_bits);
}


void Assembler::emit_optional_rex_32(Register rm_reg) {
  if (rm_reg.high_bit()) emit(0x41);
}


void Assembler::emit_optional_rex_32(const Operand& op) {
  if (op.rex_ != 0) emit(0x40 | op.rex_);
}


Address Assembler::target_address_at(Address pc,
                                     ConstantPoolArray* constant_pool) {
  return Memory::int32_at(pc) + pc + 4;
}


void Assembler::set_target_address_at(Address pc,
                                      ConstantPoolArray* constant_pool,
                                      Address target,
                                      ICacheFlushMode icache_flush_mode) {
  Memory::int32_at(pc) = static_cast<int32_t>(target - pc - 4);
  if (icache_flush_mode != SKIP_ICACHE_FLUSH) {
    CpuFeatures::FlushICache(pc, sizeof(int32_t));
  }
}


Address Assembler::target_address_from_return_address(Address pc) {
  return pc - kCallTargetAddressOffset;
}


Address Assembler::break_address_from_return_address(Address pc) {
  return pc - Assembler::kPatchDebugBreakSlotReturnOffset;
}


Handle<Object> Assembler::code_target_object_handle_at(Address pc) {
  return code_targets_[Memory::int32_at(pc)];
}


Address Assembler::runtime_entry_at(Address pc) {
  return Memory::int32_at(pc) + isolate()->code_range()->start();
}

// -----------------------------------------------------------------------------
// Implementation of RelocInfo

// The modes possibly affected by apply must be in kApplyMask.
void RelocInfo::apply(intptr_t delta, ICacheFlushMode icache_flush_mode) {
  bool flush_icache = icache_flush_mode != SKIP_ICACHE_FLUSH;
  if (IsInternalReference(rmode_)) {
    // absolute code pointer inside code object moves with the code object.
    Memory::Address_at(pc_) += static_cast<int32_t>(delta);
    if (flush_icache) CpuFeatures::FlushICache(pc_, sizeof(Address));
  } else if (IsCodeTarget(rmode_) || IsRuntimeEntry(rmode_)) {
    Memory::int32_at(pc_) -= static_cast<int32_t>(delta);
    if (flush_icache) CpuFeatures::FlushICache(pc_, sizeof(int32_t));
  } else if (rmode_ == CODE_AGE_SEQUENCE) {
    if (*pc_ == kCallOpcode) {
      int32_t* p = reinterpret_cast<int32_t*>(pc_ + 1);
      *p -= static_cast<int32_t>(delta);  // Relocate entry.
      if (flush_icache) CpuFeatures::FlushICache(p, sizeof(uint32_t));
    }
  }
}


Address RelocInfo::target_address() {
  DCHECK(IsCodeTarget(rmode_) || IsRuntimeEntry(rmode_));
  return Assembler::target_address_at(pc_, host_);
}


Address RelocInfo::target_address_address() {
  DCHECK(IsCodeTarget(rmode_) || IsRuntimeEntry(rmode_)
                              || rmode_ == EMBEDDED_OBJECT
                              || rmode_ == EXTERNAL_REFERENCE);
  return reinterpret_cast<Address>(pc_);
}


Address RelocInfo::constant_pool_entry_address() {
  UNREACHABLE();
  return NULL;
}


int RelocInfo::target_address_size() {
  if (IsCodedSpecially()) {
    return Assembler::kSpecialTargetSize;
  } else {
    return kPointerSize;
  }
}


void RelocInfo::set_target_address(Address target,
                                   WriteBarrierMode write_barrier_mode,
                                   ICacheFlushMode icache_flush_mode) {
  DCHECK(IsCodeTarget(rmode_) || IsRuntimeEntry(rmode_));
  Assembler::set_target_address_at(pc_, host_, target, icache_flush_mode);
  if (write_barrier_mode == UPDATE_WRITE_BARRIER && host() != NULL &&
      IsCodeTarget(rmode_)) {
    Object* target_code = Code::GetCodeFromTargetAddress(target);
    host()->GetHeap()->incremental_marking()->RecordWriteIntoCode(
        host(), this, HeapObject::cast(target_code));
  }
}


Object* RelocInfo::target_object() {
  DCHECK(IsCodeTarget(rmode_) || rmode_ == EMBEDDED_OBJECT);
  return Memory::Object_at(pc_);
}


Handle<Object> RelocInfo::target_object_handle(Assembler* origin) {
  DCHECK(IsCodeTarget(rmode_) || rmode_ == EMBEDDED_OBJECT);
  if (rmode_ == EMBEDDED_OBJECT) {
    return Memory::Object_Handle_at(pc_);
  } else {
    return origin->code_target_object_handle_at(pc_);
  }
}


Address RelocInfo::target_reference() {
  DCHECK(rmode_ == RelocInfo::EXTERNAL_REFERENCE);
  return Memory::Address_at(pc_);
}


void RelocInfo::set_target_object(Object* target,
                                  WriteBarrierMode write_barrier_mode,
                                  ICacheFlushMode icache_flush_mode) {
  DCHECK(IsCodeTarget(rmode_) || rmode_ == EMBEDDED_OBJECT);
  Memory::Object_at(pc_) = target;
  if (icache_flush_mode != SKIP_ICACHE_FLUSH) {
    CpuFeatures::FlushICache(pc_, sizeof(Address));
  }
  if (write_barrier_mode == UPDATE_WRITE_BARRIER &&
      host() != NULL &&
      target->IsHeapObject()) {
    host()->GetHeap()->incremental_marking()->RecordWrite(
        host(), &Memory::Object_at(pc_), HeapObject::cast(target));
  }
}


Address RelocInfo::target_runtime_entry(Assembler* origin) {
  DCHECK(IsRuntimeEntry(rmode_));
  return origin->runtime_entry_at(pc_);
}


void RelocInfo::set_target_runtime_entry(Address target,
                                         WriteBarrierMode write_barrier_mode,
                                         ICacheFlushMode icache_flush_mode) {
  DCHECK(IsRuntimeEntry(rmode_));
  if (target_address() != target) {
    set_target_address(target, write_barrier_mode, icache_flush_mode);
  }
}


Handle<Cell> RelocInfo::target_cell_handle() {
  DCHECK(rmode_ == RelocInfo::CELL);
  Address address = Memory::Address_at(pc_);
  return Handle<Cell>(reinterpret_cast<Cell**>(address));
}


Cell* RelocInfo::target_cell() {
  DCHECK(rmode_ == RelocInfo::CELL);
  return Cell::FromValueAddress(Memory::Address_at(pc_));
}


void RelocInfo::set_target_cell(Cell* cell,
                                WriteBarrierMode write_barrier_mode,
                                ICacheFlushMode icache_flush_mode) {
  DCHECK(rmode_ == RelocInfo::CELL);
  Address address = cell->address() + Cell::kValueOffset;
  Memory::Address_at(pc_) = address;
  if (icache_flush_mode != SKIP_ICACHE_FLUSH) {
    CpuFeatures::FlushICache(pc_, sizeof(Address));
  }
  if (write_barrier_mode == UPDATE_WRITE_BARRIER &&
      host() != NULL) {
    // TODO(1550) We are passing NULL as a slot because cell can never be on
    // evacuation candidate.
    host()->GetHeap()->incremental_marking()->RecordWrite(
        host(), NULL, cell);
  }
}


void RelocInfo::WipeOut() {
  if (IsEmbeddedObject(rmode_) || IsExternalReference(rmode_)) {
    Memory::Address_at(pc_) = NULL;
  } else if (IsCodeTarget(rmode_) || IsRuntimeEntry(rmode_)) {
    // Effectively write zero into the relocation.
    Assembler::set_target_address_at(pc_, host_, pc_ + sizeof(int32_t));
  } else {
    UNREACHABLE();
  }
}


bool RelocInfo::IsPatchedReturnSequence() {
  // The recognized call sequence is:
  //  movq(kScratchRegister, address); call(kScratchRegister);
  // It only needs to be distinguished from a return sequence
  //  movq(rsp, rbp); pop(rbp); ret(n); int3 *6
  // The 11th byte is int3 (0xCC) in the return sequence and
  // REX.WB (0x48+register bit) for the call sequence.
  return pc_[Assembler::kMoveAddressIntoScratchRegisterInstructionLength] !=
         0xCC;
}


bool RelocInfo::IsPatchedDebugBreakSlotSequence() {
  return !Assembler::IsNop(pc());
}


Handle<Object> RelocInfo::code_age_stub_handle(Assembler* origin) {
  DCHECK(rmode_ == RelocInfo::CODE_AGE_SEQUENCE);
  DCHECK(*pc_ == kCallOpcode);
  return origin->code_target_object_handle_at(pc_ + 1);
}


Code* RelocInfo::code_age_stub() {
  DCHECK(rmode_ == RelocInfo::CODE_AGE_SEQUENCE);
  DCHECK(*pc_ == kCallOpcode);
  return Code::GetCodeFromTargetAddress(
      Assembler::target_address_at(pc_ + 1, host_));
}


void RelocInfo::set_code_age_stub(Code* stub,
                                  ICacheFlushMode icache_flush_mode) {
  DCHECK(*pc_ == kCallOpcode);
  DCHECK(rmode_ == RelocInfo::CODE_AGE_SEQUENCE);
  Assembler::set_target_address_at(pc_ + 1, host_, stub->instruction_start(),
                                   icache_flush_mode);
}


Address RelocInfo::call_address() {
  DCHECK((IsJSReturn(rmode()) && IsPatchedReturnSequence()) ||
         (IsDebugBreakSlot(rmode()) && IsPatchedDebugBreakSlotSequence()));
  return Memory::Address_at(
      pc_ + Assembler::kRealPatchReturnSequenceAddressOffset);
}


void RelocInfo::set_call_address(Address target) {
  DCHECK((IsJSReturn(rmode()) && IsPatchedReturnSequence()) ||
         (IsDebugBreakSlot(rmode()) && IsPatchedDebugBreakSlotSequence()));
  Memory::Address_at(pc_ + Assembler::kRealPatchReturnSequenceAddressOffset) =
      target;
  CpuFeatures::FlushICache(
      pc_ + Assembler::kRealPatchReturnSequenceAddressOffset, sizeof(Address));
  if (host() != NULL) {
    Object* target_code = Code::GetCodeFromTargetAddress(target);
    host()->GetHeap()->incremental_marking()->RecordWriteIntoCode(
        host(), this, HeapObject::cast(target_code));
  }
}


Object* RelocInfo::call_object() {
  return *call_object_address();
}


void RelocInfo::set_call_object(Object* target) {
  *call_object_address() = target;
}


Object** RelocInfo::call_object_address() {
  DCHECK((IsJSReturn(rmode()) && IsPatchedReturnSequence()) ||
         (IsDebugBreakSlot(rmode()) && IsPatchedDebugBreakSlotSequence()));
  return reinterpret_cast<Object**>(
      pc_ + Assembler::kPatchReturnSequenceAddressOffset);
}


void RelocInfo::Visit(Isolate* isolate, ObjectVisitor* visitor) {
  RelocInfo::Mode mode = rmode();
  if (mode == RelocInfo::EMBEDDED_OBJECT) {
    visitor->VisitEmbeddedPointer(this);
    CpuFeatures::FlushICache(pc_, sizeof(Address));
  } else if (RelocInfo::IsCodeTarget(mode)) {
    visitor->VisitCodeTarget(this);
  } else if (mode == RelocInfo::CELL) {
    visitor->VisitCell(this);
  } else if (mode == RelocInfo::EXTERNAL_REFERENCE) {
    visitor->VisitExternalReference(this);
    CpuFeatures::FlushICache(pc_, sizeof(Address));
  } else if (RelocInfo::IsCodeAgeSequence(mode)) {
    visitor->VisitCodeAgeSequence(this);
  } else if (((RelocInfo::IsJSReturn(mode) &&
              IsPatchedReturnSequence()) ||
             (RelocInfo::IsDebugBreakSlot(mode) &&
              IsPatchedDebugBreakSlotSequence())) &&
             isolate->debug()->has_break_points()) {
    visitor->VisitDebugTarget(this);
  } else if (RelocInfo::IsRuntimeEntry(mode)) {
    visitor->VisitRuntimeEntry(this);
  }
}


template<typename StaticVisitor>
void RelocInfo::Visit(Heap* heap) {
  RelocInfo::Mode mode = rmode();
  if (mode == RelocInfo::EMBEDDED_OBJECT) {
    StaticVisitor::VisitEmbeddedPointer(heap, this);
    CpuFeatures::FlushICache(pc_, sizeof(Address));
  } else if (RelocInfo::IsCodeTarget(mode)) {
    StaticVisitor::VisitCodeTarget(heap, this);
  } else if (mode == RelocInfo::CELL) {
    StaticVisitor::VisitCell(heap, this);
  } else if (mode == RelocInfo::EXTERNAL_REFERENCE) {
    StaticVisitor::VisitExternalReference(this);
    CpuFeatures::FlushICache(pc_, sizeof(Address));
  } else if (RelocInfo::IsCodeAgeSequence(mode)) {
    StaticVisitor::VisitCodeAgeSequence(heap, this);
  } else if (heap->isolate()->debug()->has_break_points() &&
             ((RelocInfo::IsJSReturn(mode) &&
              IsPatchedReturnSequence()) ||
             (RelocInfo::IsDebugBreakSlot(mode) &&
              IsPatchedDebugBreakSlotSequence()))) {
    StaticVisitor::VisitDebugTarget(heap, this);
  } else if (RelocInfo::IsRuntimeEntry(mode)) {
    StaticVisitor::VisitRuntimeEntry(this);
  }
}


// -----------------------------------------------------------------------------
// Implementation of Operand

void Operand::set_modrm(int mod, Register rm_reg) {
  DCHECK(is_uint2(mod));
  buf_[0] = mod << 6 | rm_reg.low_bits();
  // Set REX.B to the high bit of rm.code().
  rex_ |= rm_reg.high_bit();
}


void Operand::set_sib(ScaleFactor scale, Register index, Register base) {
  DCHECK(len_ == 1);
  DCHECK(is_uint2(scale));
  // Use SIB with no index register only for base rsp or r12. Otherwise we
  // would skip the SIB byte entirely.
  DCHECK(!index.is(rsp) || base.is(rsp) || base.is(r12));
  buf_[1] = (scale << 6) | (index.low_bits() << 3) | base.low_bits();
  rex_ |= index.high_bit() << 1 | base.high_bit();
  len_ = 2;
}

void Operand::set_disp8(int disp) {
  DCHECK(is_int8(disp));
  DCHECK(len_ == 1 || len_ == 2);
  int8_t* p = reinterpret_cast<int8_t*>(&buf_[len_]);
  *p = disp;
  len_ += sizeof(int8_t);
}

void Operand::set_disp32(int disp) {
  DCHECK(len_ == 1 || len_ == 2);
  int32_t* p = reinterpret_cast<int32_t*>(&buf_[len_]);
  *p = disp;
  len_ += sizeof(int32_t);
}


} }  // namespace v8::internal

#endif  // V8_X64_ASSEMBLER_X64_INL_H_