assembler-arm-inl.h

// Copyright (c) 1994-2006 Sun Microsystems Inc.
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// The original source code covered by the above license above has been modified
// significantly by Google Inc.
// Copyright 2012 the V8 project authors. All rights reserved.

#ifndef V8_ARM_ASSEMBLER_ARM_INL_H_
#define V8_ARM_ASSEMBLER_ARM_INL_H_

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

#include "src/assembler.h"
#include "src/debug/debug.h"
#include "src/objects-inl.h"
#include "src/objects/smi.h"

namespace v8 {
namespace internal {

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

bool CpuFeatures::SupportsWasmSimd128() { return IsSupported(NEON); }

int DoubleRegister::NumRegisters() {
  return CpuFeatures::IsSupported(VFP32DREGS) ? 32 : 16;
}


void RelocInfo::apply(intptr_t delta) {
  if (RelocInfo::IsInternalReference(rmode_)) {
    // absolute code pointer inside code object moves with the code object.
    int32_t* p = reinterpret_cast<int32_t*>(pc_);
    *p += delta;  // relocate entry
  } else if (RelocInfo::IsRelativeCodeTarget(rmode_)) {
    Instruction* branch = Instruction::At(pc_);
    int32_t branch_offset = branch->GetBranchOffset() + delta;
    branch->SetBranchOffset(branch_offset);
  }
}


Address RelocInfo::target_address() {
  DCHECK(IsCodeTargetMode(rmode_) || IsRuntimeEntry(rmode_) ||
         IsWasmCall(rmode_));
  return Assembler::target_address_at(pc_, constant_pool_);
}

Address RelocInfo::target_address_address() {
  DCHECK(IsCodeTarget(rmode_) || IsRuntimeEntry(rmode_) || IsWasmCall(rmode_) ||
         IsEmbeddedObject(rmode_) || IsExternalReference(rmode_) ||
         IsOffHeapTarget(rmode_));
  if (Assembler::IsMovW(Memory<int32_t>(pc_))) {
    return pc_;
  } else {
    DCHECK(Assembler::IsLdrPcImmediateOffset(Memory<int32_t>(pc_)));
    return constant_pool_entry_address();
  }
}


Address RelocInfo::constant_pool_entry_address() {
  DCHECK(IsInConstantPool());
  return Assembler::constant_pool_entry_address(pc_, constant_pool_);
}


int RelocInfo::target_address_size() {
  return kPointerSize;
}

HeapObject* RelocInfo::target_object() {
  DCHECK(IsCodeTarget(rmode_) || rmode_ == EMBEDDED_OBJECT);
  return HeapObject::cast(reinterpret_cast<Object*>(
      Assembler::target_address_at(pc_, constant_pool_)));
}

Handle<HeapObject> RelocInfo::target_object_handle(Assembler* origin) {
  if (IsCodeTarget(rmode_) || rmode_ == EMBEDDED_OBJECT) {
    return Handle<HeapObject>(reinterpret_cast<Address*>(
        Assembler::target_address_at(pc_, constant_pool_)));
  }
  DCHECK(IsRelativeCodeTarget(rmode_));
  return origin->relative_code_target_object_handle_at(pc_);
}

void RelocInfo::set_target_object(Heap* heap, HeapObject* target,
                                  WriteBarrierMode write_barrier_mode,
                                  ICacheFlushMode icache_flush_mode) {
  DCHECK(IsCodeTarget(rmode_) || rmode_ == EMBEDDED_OBJECT);
  Assembler::set_target_address_at(pc_, constant_pool_,
                                   reinterpret_cast<Address>(target),
                                   icache_flush_mode);
  if (write_barrier_mode == UPDATE_WRITE_BARRIER && host() != nullptr) {
    WriteBarrierForCode(host(), this, target);
  }
}


Address RelocInfo::target_external_reference() {
  DCHECK(rmode_ == EXTERNAL_REFERENCE);
  return Assembler::target_address_at(pc_, constant_pool_);
}

void RelocInfo::set_target_external_reference(
    Address target, ICacheFlushMode icache_flush_mode) {
  DCHECK(rmode_ == RelocInfo::EXTERNAL_REFERENCE);
  Assembler::set_target_address_at(pc_, constant_pool_, target,
                                   icache_flush_mode);
}

Address RelocInfo::target_internal_reference() {
  DCHECK(rmode_ == INTERNAL_REFERENCE);
  return Memory<Address>(pc_);
}


Address RelocInfo::target_internal_reference_address() {
  DCHECK(rmode_ == INTERNAL_REFERENCE);
  return pc_;
}

Address RelocInfo::target_runtime_entry(Assembler* origin) {
  DCHECK(IsRuntimeEntry(rmode_));
  return target_address();
}

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);
}

Address RelocInfo::target_off_heap_target() {
  DCHECK(IsOffHeapTarget(rmode_));
  return Assembler::target_address_at(pc_, constant_pool_);
}

void RelocInfo::WipeOut() {
  DCHECK(IsEmbeddedObject(rmode_) || IsCodeTarget(rmode_) ||
         IsRuntimeEntry(rmode_) || IsExternalReference(rmode_) ||
         IsInternalReference(rmode_) || IsOffHeapTarget(rmode_));
  if (IsInternalReference(rmode_)) {
    Memory<Address>(pc_) = kNullAddress;
  } else {
    Assembler::set_target_address_at(pc_, constant_pool_, kNullAddress);
  }
}

Handle<Code> Assembler::relative_code_target_object_handle_at(
    Address pc) const {
  Instruction* branch = Instruction::At(pc);
  int code_target_index = branch->GetBranchOffset() / kInstrSize;
  return GetCodeTarget(code_target_index);
}

template <typename ObjectVisitor>
void RelocInfo::Visit(ObjectVisitor* visitor) {
  RelocInfo::Mode mode = rmode();
  if (mode == RelocInfo::EMBEDDED_OBJECT) {
    visitor->VisitEmbeddedPointer(host(), this);
  } else if (RelocInfo::IsCodeTargetMode(mode)) {
    visitor->VisitCodeTarget(host(), this);
  } else if (mode == RelocInfo::EXTERNAL_REFERENCE) {
    visitor->VisitExternalReference(host(), this);
  } else if (mode == RelocInfo::INTERNAL_REFERENCE) {
    visitor->VisitInternalReference(host(), this);
  } else if (RelocInfo::IsRuntimeEntry(mode)) {
    visitor->VisitRuntimeEntry(host(), this);
  } else if (RelocInfo::IsOffHeapTarget(mode)) {
    visitor->VisitOffHeapTarget(host(), this);
  }
}

Operand::Operand(int32_t immediate, RelocInfo::Mode rmode) : rmode_(rmode) {
  value_.immediate = immediate;
}

Operand Operand::Zero() { return Operand(static_cast<int32_t>(0)); }

Operand::Operand(const ExternalReference& f)
    : rmode_(RelocInfo::EXTERNAL_REFERENCE) {
  value_.immediate = static_cast<int32_t>(f.address());
}

Operand::Operand(Smi value) : rmode_(RelocInfo::NONE) {
  value_.immediate = static_cast<intptr_t>(value.ptr());
}

Operand::Operand(Register rm) : rm_(rm), shift_op_(LSL), shift_imm_(0) {}

void Assembler::CheckBuffer() {
  if (buffer_space() <= kGap) {
    GrowBuffer();
  }
  MaybeCheckConstPool();
}


void Assembler::emit(Instr x) {
  CheckBuffer();
  *reinterpret_cast<Instr*>(pc_) = x;
  pc_ += kInstrSize;
}


Address Assembler::target_address_from_return_address(Address pc) {
  // Returns the address of the call target from the return address that will
  // be returned to after a call.
  // Call sequence on V7 or later is:
  //  movw  ip, #... @ call address low 16
  //  movt  ip, #... @ call address high 16
  //  blx   ip
  //                      @ return address
  // For V6 when the constant pool is unavailable, it is:
  //  mov  ip, #...     @ call address low 8
  //  orr  ip, ip, #... @ call address 2nd 8
  //  orr  ip, ip, #... @ call address 3rd 8
  //  orr  ip, ip, #... @ call address high 8
  //  blx   ip
  //                      @ return address
  // In cases that need frequent patching, the address is in the
  // constant pool.  It could be a small constant pool load:
  //  ldr   ip, [pc, #...] @ call address
  //  blx   ip
  //                      @ return address
  Address candidate = pc - 2 * kInstrSize;
  Instr candidate_instr(Memory<int32_t>(candidate));
  if (IsLdrPcImmediateOffset(candidate_instr)) {
    return candidate;
  } else {
    if (CpuFeatures::IsSupported(ARMv7)) {
      candidate -= 1 * kInstrSize;
      DCHECK(IsMovW(Memory<int32_t>(candidate)) &&
             IsMovT(Memory<int32_t>(candidate + kInstrSize)));
    } else {
      candidate -= 3 * kInstrSize;
      DCHECK(IsMovImmed(Memory<int32_t>(candidate)) &&
             IsOrrImmed(Memory<int32_t>(candidate + kInstrSize)) &&
             IsOrrImmed(Memory<int32_t>(candidate + 2 * kInstrSize)) &&
             IsOrrImmed(Memory<int32_t>(candidate + 3 * kInstrSize)));
    }
    return candidate;
  }
}


Address Assembler::return_address_from_call_start(Address pc) {
  if (IsLdrPcImmediateOffset(Memory<int32_t>(pc))) {
    // Load from constant pool, small section.
    return pc + kInstrSize * 2;
  } else {
    if (CpuFeatures::IsSupported(ARMv7)) {
      DCHECK(IsMovW(Memory<int32_t>(pc)));
      DCHECK(IsMovT(Memory<int32_t>(pc + kInstrSize)));
      // A movw / movt load immediate.
      return pc + kInstrSize * 3;
    } else {
      DCHECK(IsMovImmed(Memory<int32_t>(pc)));
      DCHECK(IsOrrImmed(Memory<int32_t>(pc + kInstrSize)));
      DCHECK(IsOrrImmed(Memory<int32_t>(pc + 2 * kInstrSize)));
      DCHECK(IsOrrImmed(Memory<int32_t>(pc + 3 * kInstrSize)));
      // A mov / orr load immediate.
      return pc + kInstrSize * 5;
    }
  }
}

void Assembler::deserialization_set_special_target_at(
    Address constant_pool_entry, Code code, Address target) {
  Memory<Address>(constant_pool_entry) = target;
}

int Assembler::deserialization_special_target_size(Address location) {
  return kSpecialTargetSize;
}

void Assembler::deserialization_set_target_internal_reference_at(
    Address pc, Address target, RelocInfo::Mode mode) {
  Memory<Address>(pc) = target;
}


bool Assembler::is_constant_pool_load(Address pc) {
  return IsLdrPcImmediateOffset(Memory<int32_t>(pc));
}


Address Assembler::constant_pool_entry_address(Address pc,
                                               Address constant_pool) {
  DCHECK(Assembler::IsLdrPcImmediateOffset(Memory<int32_t>(pc)));
  Instr instr = Memory<int32_t>(pc);
  return pc + GetLdrRegisterImmediateOffset(instr) + Instruction::kPcLoadDelta;
}


Address Assembler::target_address_at(Address pc, Address constant_pool) {
  if (is_constant_pool_load(pc)) {
    // This is a constant pool lookup. Return the value in the constant pool.
    return Memory<Address>(constant_pool_entry_address(pc, constant_pool));
  } else if (CpuFeatures::IsSupported(ARMv7) && IsMovW(Memory<int32_t>(pc))) {
    // This is an movw / movt immediate load. Return the immediate.
    DCHECK(IsMovW(Memory<int32_t>(pc)) &&
           IsMovT(Memory<int32_t>(pc + kInstrSize)));
    Instruction* movw_instr = Instruction::At(pc);
    Instruction* movt_instr = Instruction::At(pc + kInstrSize);
    return static_cast<Address>((movt_instr->ImmedMovwMovtValue() << 16) |
                                movw_instr->ImmedMovwMovtValue());
  } else if (IsMovImmed(Memory<int32_t>(pc))) {
    // This is an mov / orr immediate load. Return the immediate.
    DCHECK(IsMovImmed(Memory<int32_t>(pc)) &&
           IsOrrImmed(Memory<int32_t>(pc + kInstrSize)) &&
           IsOrrImmed(Memory<int32_t>(pc + 2 * kInstrSize)) &&
           IsOrrImmed(Memory<int32_t>(pc + 3 * kInstrSize)));
    Instr mov_instr = instr_at(pc);
    Instr orr_instr_1 = instr_at(pc + kInstrSize);
    Instr orr_instr_2 = instr_at(pc + 2 * kInstrSize);
    Instr orr_instr_3 = instr_at(pc + 3 * kInstrSize);
    Address ret = static_cast<Address>(
        DecodeShiftImm(mov_instr) | DecodeShiftImm(orr_instr_1) |
        DecodeShiftImm(orr_instr_2) | DecodeShiftImm(orr_instr_3));
    return ret;
  } else {
    Instruction* branch = Instruction::At(pc);
    int32_t delta = branch->GetBranchOffset();
    return pc + delta + Instruction::kPcLoadDelta;
  }
}

void Assembler::set_target_address_at(Address pc, Address constant_pool,
                                      Address target,
                                      ICacheFlushMode icache_flush_mode) {
  if (is_constant_pool_load(pc)) {
    // This is a constant pool lookup. Update the entry in the constant pool.
    Memory<Address>(constant_pool_entry_address(pc, constant_pool)) = target;
    // Intuitively, we would think it is necessary to always flush the
    // instruction cache after patching a target address in the code as follows:
    //   Assembler::FlushICache(pc, sizeof(target));
    // However, on ARM, no instruction is actually patched in the case
    // of embedded constants of the form:
    // ldr   ip, [pp, #...]
    // since the instruction accessing this address in the constant pool remains
    // unchanged.
  } else if (CpuFeatures::IsSupported(ARMv7) && IsMovW(Memory<int32_t>(pc))) {
    // This is an movw / movt immediate load. Patch the immediate embedded in
    // the instructions.
    DCHECK(IsMovW(Memory<int32_t>(pc)));
    DCHECK(IsMovT(Memory<int32_t>(pc + kInstrSize)));
    uint32_t* instr_ptr = reinterpret_cast<uint32_t*>(pc);
    uint32_t immediate = static_cast<uint32_t>(target);
    instr_ptr[0] = PatchMovwImmediate(instr_ptr[0], immediate & 0xFFFF);
    instr_ptr[1] = PatchMovwImmediate(instr_ptr[1], immediate >> 16);
    DCHECK(IsMovW(Memory<int32_t>(pc)));
    DCHECK(IsMovT(Memory<int32_t>(pc + kInstrSize)));
    if (icache_flush_mode != SKIP_ICACHE_FLUSH) {
      Assembler::FlushICache(pc, 2 * kInstrSize);
    }
  } else if (IsMovImmed(Memory<int32_t>(pc))) {
    // This is an mov / orr immediate load. Patch the immediate embedded in
    // the instructions.
    DCHECK(IsMovImmed(Memory<int32_t>(pc)) &&
           IsOrrImmed(Memory<int32_t>(pc + kInstrSize)) &&
           IsOrrImmed(Memory<int32_t>(pc + 2 * kInstrSize)) &&
           IsOrrImmed(Memory<int32_t>(pc + 3 * kInstrSize)));
    uint32_t* instr_ptr = reinterpret_cast<uint32_t*>(pc);
    uint32_t immediate = static_cast<uint32_t>(target);
    instr_ptr[0] = PatchShiftImm(instr_ptr[0], immediate & kImm8Mask);
    instr_ptr[1] = PatchShiftImm(instr_ptr[1], immediate & (kImm8Mask << 8));
    instr_ptr[2] = PatchShiftImm(instr_ptr[2], immediate & (kImm8Mask << 16));
    instr_ptr[3] = PatchShiftImm(instr_ptr[3], immediate & (kImm8Mask << 24));
    DCHECK(IsMovImmed(Memory<int32_t>(pc)) &&
           IsOrrImmed(Memory<int32_t>(pc + kInstrSize)) &&
           IsOrrImmed(Memory<int32_t>(pc + 2 * kInstrSize)) &&
           IsOrrImmed(Memory<int32_t>(pc + 3 * kInstrSize)));
    if (icache_flush_mode != SKIP_ICACHE_FLUSH) {
      Assembler::FlushICache(pc, 4 * kInstrSize);
    }
  } else {
    intptr_t branch_offset = target - pc - Instruction::kPcLoadDelta;
    Instruction* branch = Instruction::At(pc);
    branch->SetBranchOffset(branch_offset);
    if (icache_flush_mode != SKIP_ICACHE_FLUSH) {
      Assembler::FlushICache(pc, kInstrSize);
    }
  }
}

EnsureSpace::EnsureSpace(Assembler* assembler) { assembler->CheckBuffer(); }

template <typename T>
bool UseScratchRegisterScope::CanAcquireVfp() const {
  VfpRegList* available = assembler_->GetScratchVfpRegisterList();
  DCHECK_NOT_NULL(available);
  for (int index = 0; index < T::kNumRegisters; index++) {
    T reg = T::from_code(index);
    uint64_t mask = reg.ToVfpRegList();
    if ((*available & mask) == mask) {
      return true;
    }
  }
  return false;
}

template <typename T>
T UseScratchRegisterScope::AcquireVfp() {
  VfpRegList* available = assembler_->GetScratchVfpRegisterList();
  DCHECK_NOT_NULL(available);
  for (int index = 0; index < T::kNumRegisters; index++) {
    T reg = T::from_code(index);
    uint64_t mask = reg.ToVfpRegList();
    if ((*available & mask) == mask) {
      *available &= ~mask;
      return reg;
    }
  }
  UNREACHABLE();
}

}  // namespace internal
}  // namespace v8

#endif  // V8_ARM_ASSEMBLER_ARM_INL_H_