path: root/deps/v8/src/codegen/riscv/assembler-riscv.cc

// Copyright (c) 1994-2006 Sun Microsystems Inc.
// All Rights Reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// - Redistributions of source code must retain the above copyright notice,
// this list of conditions and the following disclaimer.
//
// - Redistribution in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
//
// - Neither the name of Sun Microsystems or the names of contributors may
// be used to endorse or promote products derived from this software without
// specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
// IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
// THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
// PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

// The original source code covered by the above license above has been
// modified significantly by Google Inc.
// Copyright 2021 the V8 project authors. All rights reserved.

#include "src/codegen/riscv/assembler-riscv.h"

#include "src/base/cpu.h"
#include "src/codegen/assembler-inl.h"
#include "src/codegen/safepoint-table.h"
#include "src/codegen/string-constants.h"
#include "src/deoptimizer/deoptimizer.h"
#include "src/diagnostics/disasm.h"
#include "src/diagnostics/disassembler.h"
#include "src/objects/heap-number-inl.h"

namespace v8 {
namespace internal {
// Get the CPU features enabled by the build. For cross compilation the
// preprocessor symbols CAN_USE_FPU_INSTRUCTIONS
// can be defined to enable FPU instructions when building the
// snapshot.
static unsigned CpuFeaturesImpliedByCompiler() {
  unsigned answer = 0;
#ifdef CAN_USE_FPU_INSTRUCTIONS
  answer |= 1u << FPU;
#endif  // def CAN_USE_FPU_INSTRUCTIONS

#if (defined CAN_USE_RVV_INSTRUCTIONS)
  answer |= 1u << RISCV_SIMD;
#endif  // def CAN_USE_RVV_INSTRUCTIONS
  return answer;
}

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

void CpuFeatures::ProbeImpl(bool cross_compile) {
  supported_ |= CpuFeaturesImpliedByCompiler();
  // Only use statically determined features for cross compile (snapshot).
  if (cross_compile) return;
  // Probe for additional features at runtime.
  base::CPU cpu;
  if (cpu.has_fpu()) supported_ |= 1u << FPU;
  if (cpu.has_rvv()) supported_ |= 1u << RISCV_SIMD;
  // Set a static value on whether SIMD is supported.
  // This variable is only used for certain archs to query SupportWasmSimd128()
  // at runtime in builtins using an extern ref. Other callers should use
  // CpuFeatures::SupportWasmSimd128().
  CpuFeatures::supports_wasm_simd_128_ = CpuFeatures::SupportsWasmSimd128();
}

void CpuFeatures::PrintTarget() {}
void CpuFeatures::PrintFeatures() {}
int ToNumber(Register reg) {
  DCHECK(reg.is_valid());
  const int kNumbers[] = {
      0,   // zero_reg
      1,   // ra
      2,   // sp
      3,   // gp
      4,   // tp
      5,   // t0
      6,   // t1
      7,   // t2
      8,   // s0/fp
      9,   // s1
      10,  // a0
      11,  // a1
      12,  // a2
      13,  // a3
      14,  // a4
      15,  // a5
      16,  // a6
      17,  // a7
      18,  // s2
      19,  // s3
      20,  // s4
      21,  // s5
      22,  // s6
      23,  // s7
      24,  // s8
      25,  // s9
      26,  // s10
      27,  // s11
      28,  // t3
      29,  // t4
      30,  // t5
      31,  // t6
  };
  return kNumbers[reg.code()];
}

Register ToRegister(int num) {
  DCHECK(num >= 0 && num < kNumRegisters);
  const Register kRegisters[] = {
      zero_reg, ra, sp, gp, tp, t0, t1, t2, fp, s1, a0,  a1,  a2, a3, a4, a5,
      a6,       a7, s2, s3, s4, s5, s6, s7, s8, s9, s10, s11, t3, t4, t5, t6};
  return kRegisters[num];
}

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

const int RelocInfo::kApplyMask =
    RelocInfo::ModeMask(RelocInfo::INTERNAL_REFERENCE) |
    RelocInfo::ModeMask(RelocInfo::NEAR_BUILTIN_ENTRY) |
    RelocInfo::ModeMask(RelocInfo::INTERNAL_REFERENCE_ENCODED) |
    RelocInfo::ModeMask(RelocInfo::RELATIVE_CODE_TARGET) |
    RelocInfo::ModeMask(RelocInfo::CODE_TARGET);

bool RelocInfo::IsCodedSpecially() {
  // The deserializer needs to know whether a pointer is specially coded.  Being
  // specially coded on RISC-V means that it is a lui/addi instruction, and that
  // is always the case inside code objects.
  return true;
}

bool RelocInfo::IsInConstantPool() { return false; }

uint32_t RelocInfo::wasm_call_tag() const {
  DCHECK(rmode_ == WASM_CALL || rmode_ == WASM_STUB_CALL);
  return static_cast<uint32_t>(
      Assembler::target_address_at(pc_, constant_pool_));
}

// -----------------------------------------------------------------------------
// Implementation of Operand and MemOperand.
// See assembler-riscv-inl.h for inlined constructors.

Operand::Operand(Handle<HeapObject> handle)
    : rm_(no_reg), rmode_(RelocInfo::FULL_EMBEDDED_OBJECT) {
  value_.immediate = static_cast<intptr_t>(handle.address());
}

Operand Operand::EmbeddedNumber(double value) {
  int32_t smi;
  if (DoubleToSmiInteger(value, &smi)) return Operand(Smi::FromInt(smi));
  Operand result(0, RelocInfo::FULL_EMBEDDED_OBJECT);
  result.is_heap_number_request_ = true;
  result.value_.heap_number_request = HeapNumberRequest(value);
  return result;
}

MemOperand::MemOperand(Register rm, int32_t offset) : Operand(rm) {
  offset_ = offset;
}

MemOperand::MemOperand(Register rm, int32_t unit, int32_t multiplier,
                       OffsetAddend offset_addend)
    : Operand(rm) {
  offset_ = unit * multiplier + offset_addend;
}

void Assembler::AllocateAndInstallRequestedHeapNumbers(Isolate* isolate) {
  DCHECK_IMPLIES(isolate == nullptr, heap_number_requests_.empty());
  for (auto& request : heap_number_requests_) {
    Handle<HeapObject> object =
        isolate->factory()->NewHeapNumber<AllocationType::kOld>(
            request.heap_number());
    Address pc = reinterpret_cast<Address>(buffer_start_) + request.offset();
    set_target_value_at(pc, reinterpret_cast<uintptr_t>(object.location()));
  }
}

// -----------------------------------------------------------------------------
// Specific instructions, constants, and masks.

Assembler::Assembler(const AssemblerOptions& options,
                     std::unique_ptr<AssemblerBuffer> buffer)
    : AssemblerBase(options, std::move(buffer)),
      VU(this),
      scratch_register_list_({t3, t5}),
      constpool_(this) {
  reloc_info_writer.Reposition(buffer_start_ + buffer_->size(), pc_);

  last_trampoline_pool_end_ = 0;
  no_trampoline_pool_before_ = 0;
  trampoline_pool_blocked_nesting_ = 0;
  // We leave space (16 * kTrampolineSlotsSize)
  // for BlockTrampolinePoolScope buffer.
  next_buffer_check_ = v8_flags.force_long_branches
                           ? kMaxInt
                           : kMaxBranchOffset - kTrampolineSlotsSize * 16;
  internal_trampoline_exception_ = false;
  last_bound_pos_ = 0;

  trampoline_emitted_ = v8_flags.force_long_branches;
  unbound_labels_count_ = 0;
  block_buffer_growth_ = false;
}

void Assembler::AbortedCodeGeneration() { constpool_.Clear(); }
Assembler::~Assembler() { CHECK(constpool_.IsEmpty()); }

void Assembler::GetCode(Isolate* isolate, CodeDesc* desc,
                        SafepointTableBuilder* safepoint_table_builder,
                        int handler_table_offset) {
  // As a crutch to avoid having to add manual Align calls wherever we use a
  // raw workflow to create Code objects (mostly in tests), add another Align
  // call here. It does no harm - the end of the Code object is aligned to the
  // (larger) kCodeAlignment anyways.
  // TODO(jgruber): Consider moving responsibility for proper alignment to
  // metadata table builders (safepoint, handler, constant pool, code
  // comments).
  DataAlign(Code::kMetadataAlignment);

  ForceConstantPoolEmissionWithoutJump();

  int code_comments_size = WriteCodeComments();

  DCHECK(pc_ <= reloc_info_writer.pos());  // No overlap.

  AllocateAndInstallRequestedHeapNumbers(isolate);

  // Set up code descriptor.
  // TODO(jgruber): Reconsider how these offsets and sizes are maintained up to
  // this point to make CodeDesc initialization less fiddly.

  static constexpr int kConstantPoolSize = 0;
  const int instruction_size = pc_offset();
  const int code_comments_offset = instruction_size - code_comments_size;
  const int constant_pool_offset = code_comments_offset - kConstantPoolSize;
  const int handler_table_offset2 = (handler_table_offset == kNoHandlerTable)
                                        ? constant_pool_offset
                                        : handler_table_offset;
  const int safepoint_table_offset =
      (safepoint_table_builder == kNoSafepointTable)
          ? handler_table_offset2
          : safepoint_table_builder->safepoint_table_offset();
  const int reloc_info_offset =
      static_cast<int>(reloc_info_writer.pos() - buffer_->start());
  CodeDesc::Initialize(desc, this, safepoint_table_offset,
                       handler_table_offset2, constant_pool_offset,
                       code_comments_offset, reloc_info_offset);
}

void Assembler::Align(int m) {
  DCHECK(m >= 4 && base::bits::IsPowerOfTwo(m));
  while ((pc_offset() & (m - 1)) != 0) {
    NOP();
  }
}

void Assembler::CodeTargetAlign() {
  // No advantage to aligning branch/call targets to more than
  // single instruction, that I am aware of.
  Align(4);
}

// Labels refer to positions in the (to be) generated code.
// There are bound, linked, and unused labels.
//
// Bound labels refer to known positions in the already
// generated code. pos() is the position the label refers to.
//
// Linked labels refer to unknown positions in the code
// to be generated; pos() is the position of the last
// instruction using the label.

// The link chain is terminated by a value in the instruction of 0,
// which is an otherwise illegal value (branch 0 is inf loop). When this case
// is detected, return an position of -1, an otherwise illegal position.
const int kEndOfChain = -1;
const int kEndOfJumpChain = 0;

int Assembler::target_at(int pos, bool is_internal) {
  if (is_internal) {
    uintptr_t* p = reinterpret_cast<uintptr_t*>(buffer_start_ + pos);
    uintptr_t address = *p;
    if (address == kEndOfJumpChain) {
      return kEndOfChain;
    } else {
      uintptr_t instr_address = reinterpret_cast<uintptr_t>(p);
      DCHECK(instr_address - address < INT_MAX);
      int delta = static_cast<int>(instr_address - address);
      DCHECK(pos > delta);
      return pos - delta;
    }
  }
  Instruction* instruction = Instruction::At(buffer_start_ + pos);
  DEBUG_PRINTF("target_at: %p (%d)\n\t",
               reinterpret_cast<Instr*>(buffer_start_ + pos), pos);
  Instr instr = instruction->InstructionBits();
  disassembleInstr(instruction->InstructionBits());

  switch (instruction->InstructionOpcodeType()) {
    case BRANCH: {
      int32_t imm13 = BranchOffset(instr);
      if (imm13 == kEndOfJumpChain) {
        // EndOfChain sentinel is returned directly, not relative to pc or pos.
        return kEndOfChain;
      } else {
        return pos + imm13;
      }
    }
    case JAL: {
      int32_t imm21 = JumpOffset(instr);
      if (imm21 == kEndOfJumpChain) {
        // EndOfChain sentinel is returned directly, not relative to pc or pos.
        return kEndOfChain;
      } else {
        return pos + imm21;
      }
    }
    case JALR: {
      int32_t imm12 = instr >> 20;
      if (imm12 == kEndOfJumpChain) {
        // EndOfChain sentinel is returned directly, not relative to pc or pos.
        return kEndOfChain;
      } else {
        return pos + imm12;
      }
    }
    case LUI: {
      Address pc = reinterpret_cast<Address>(buffer_start_ + pos);
      pc = target_address_at(pc);
      uintptr_t instr_address =
          reinterpret_cast<uintptr_t>(buffer_start_ + pos);
      uintptr_t imm = reinterpret_cast<uintptr_t>(pc);
      if (imm == kEndOfJumpChain) {
        return kEndOfChain;
      } else {
        DCHECK(instr_address - imm < INT_MAX);
        int32_t delta = static_cast<int32_t>(instr_address - imm);
        DCHECK(pos > delta);
        return pos - delta;
      }
    }
    case AUIPC: {
      Instr instr_auipc = instr;
      Instr instr_I = instr_at(pos + 4);
      DCHECK(IsJalr(instr_I) || IsAddi(instr_I));
      int32_t offset = BrachlongOffset(instr_auipc, instr_I);
      if (offset == kEndOfJumpChain) return kEndOfChain;
      return offset + pos;
    }
    case RO_C_J: {
      int32_t offset = instruction->RvcImm11CJValue();
      if (offset == kEndOfJumpChain) return kEndOfChain;
      return offset + pos;
    }
    case RO_C_BNEZ:
    case RO_C_BEQZ: {
      int32_t offset = instruction->RvcImm8BValue();
      if (offset == kEndOfJumpChain) return kEndOfChain;
      return pos + offset;
    }
    default: {
      if (instr == kEndOfJumpChain) {
        return kEndOfChain;
      } else {
        int32_t imm18 =
            ((instr & static_cast<int32_t>(kImm16Mask)) << 16) >> 14;
        return (imm18 + pos);
      }
    }
  }
}

static inline Instr SetBranchOffset(int32_t pos, int32_t target_pos,
                                    Instr instr) {
  int32_t imm = target_pos - pos;
  DCHECK_EQ(imm & 1, 0);
  DCHECK(is_intn(imm, Assembler::kBranchOffsetBits));

  instr &= ~kBImm12Mask;
  int32_t imm12 = ((imm & 0x800) >> 4) |   // bit  11
                  ((imm & 0x1e) << 7) |    // bits 4-1
                  ((imm & 0x7e0) << 20) |  // bits 10-5
                  ((imm & 0x1000) << 19);  // bit 12

  return instr | (imm12 & kBImm12Mask);
}

static inline Instr SetLoadOffset(int32_t offset, Instr instr) {
#if V8_TARGET_ARCH_RISCV64
  DCHECK(Assembler::IsLd(instr));
#elif V8_TARGET_ARCH_RISCV32
  DCHECK(Assembler::IsLw(instr));
#endif
  DCHECK(is_int12(offset));
  instr &= ~kImm12Mask;
  int32_t imm12 = offset << kImm12Shift;
  return instr | (imm12 & kImm12Mask);
}

static inline Instr SetAuipcOffset(int32_t offset, Instr instr) {
  DCHECK(Assembler::IsAuipc(instr));
  DCHECK(is_int20(offset));
  instr = (instr & ~kImm31_12Mask) | ((offset & kImm19_0Mask) << 12);
  return instr;
}

static inline Instr SetJalrOffset(int32_t offset, Instr instr) {
  DCHECK(Assembler::IsJalr(instr));
  DCHECK(is_int12(offset));
  instr &= ~kImm12Mask;
  int32_t imm12 = offset << kImm12Shift;
  DCHECK(Assembler::IsJalr(instr | (imm12 & kImm12Mask)));
  DCHECK_EQ(Assembler::JalrOffset(instr | (imm12 & kImm12Mask)), offset);
  return instr | (imm12 & kImm12Mask);
}

static inline Instr SetJalOffset(int32_t pos, int32_t target_pos, Instr instr) {
  DCHECK(Assembler::IsJal(instr));
  int32_t imm = target_pos - pos;
  DCHECK_EQ(imm & 1, 0);
  DCHECK(is_intn(imm, Assembler::kJumpOffsetBits));

  instr &= ~kImm20Mask;
  int32_t imm20 = (imm & 0xff000) |          // bits 19-12
                  ((imm & 0x800) << 9) |     // bit  11
                  ((imm & 0x7fe) << 20) |    // bits 10-1
                  ((imm & 0x100000) << 11);  // bit  20

  return instr | (imm20 & kImm20Mask);
}

static inline ShortInstr SetCJalOffset(int32_t pos, int32_t target_pos,
                                       Instr instr) {
  DCHECK(Assembler::IsCJal(instr));
  int32_t imm = target_pos - pos;
  DCHECK_EQ(imm & 1, 0);
  DCHECK(is_intn(imm, Assembler::kCJalOffsetBits));
  instr &= ~kImm11Mask;
  int16_t imm11 = ((imm & 0x800) >> 1) | ((imm & 0x400) >> 4) |
                  ((imm & 0x300) >> 1) | ((imm & 0x80) >> 3) |
                  ((imm & 0x40) >> 1) | ((imm & 0x20) >> 5) |
                  ((imm & 0x10) << 5) | (imm & 0xe);
  imm11 = imm11 << kImm11Shift;
  DCHECK(Assembler::IsCJal(instr | (imm11 & kImm11Mask)));
  return instr | (imm11 & kImm11Mask);
}
static inline Instr SetCBranchOffset(int32_t pos, int32_t target_pos,
                                     Instr instr) {
  DCHECK(Assembler::IsCBranch(instr));
  int32_t imm = target_pos - pos;
  DCHECK_EQ(imm & 1, 0);
  DCHECK(is_intn(imm, Assembler::kCBranchOffsetBits));

  instr &= ~kRvcBImm8Mask;
  int32_t imm8 = ((imm & 0x20) >> 5) | ((imm & 0x6)) | ((imm & 0xc0) >> 3) |
                 ((imm & 0x18) << 2) | ((imm & 0x100) >> 1);
  imm8 = ((imm8 & 0x1f) << 2) | ((imm8 & 0xe0) << 5);
  DCHECK(Assembler::IsCBranch(instr | imm8 & kRvcBImm8Mask));

  return instr | (imm8 & kRvcBImm8Mask);
}

// We have to use a temporary register for things that can be relocated even
// if they can be encoded in RISC-V's 12 bits of immediate-offset instruction
// space.  There is no guarantee that the relocated location can be similarly
// encoded.
bool Assembler::MustUseReg(RelocInfo::Mode rmode) {
  return !RelocInfo::IsNoInfo(rmode);
}

void Assembler::disassembleInstr(Instr instr) {
  if (!v8_flags.riscv_debug) return;
  disasm::NameConverter converter;
  disasm::Disassembler disasm(converter);
  base::EmbeddedVector<char, 128> disasm_buffer;

  disasm.InstructionDecode(disasm_buffer, reinterpret_cast<byte*>(&instr));
  DEBUG_PRINTF("%s\n", disasm_buffer.begin());
}

void Assembler::target_at_put(int pos, int target_pos, bool is_internal,
                              bool trampoline) {
  if (is_internal) {
    uintptr_t imm = reinterpret_cast<uintptr_t>(buffer_start_) + target_pos;
    *reinterpret_cast<uintptr_t*>(buffer_start_ + pos) = imm;
    return;
  }
  DEBUG_PRINTF("\ttarget_at_put: %p (%d) to %p (%d)\n",
               reinterpret_cast<Instr*>(buffer_start_ + pos), pos,
               reinterpret_cast<Instr*>(buffer_start_ + target_pos),
               target_pos);
  Instruction* instruction = Instruction::At(buffer_start_ + pos);
  Instr instr = instruction->InstructionBits();

  switch (instruction->InstructionOpcodeType()) {
    case BRANCH: {
      instr = SetBranchOffset(pos, target_pos, instr);
      instr_at_put(pos, instr);
    } break;
    case JAL: {
      DCHECK(IsJal(instr));
      instr = SetJalOffset(pos, target_pos, instr);
      instr_at_put(pos, instr);
    } break;
    case LUI: {
      Address pc = reinterpret_cast<Address>(buffer_start_ + pos);
      set_target_value_at(
          pc, reinterpret_cast<uintptr_t>(buffer_start_ + target_pos));
    } break;
    case AUIPC: {
      Instr instr_auipc = instr;
      Instr instr_I = instr_at(pos + 4);
      DCHECK(IsJalr(instr_I) || IsAddi(instr_I));

      intptr_t offset = target_pos - pos;
      if (is_int21(offset) && IsJalr(instr_I) && trampoline) {
        DCHECK(is_int21(offset) && ((offset & 1) == 0));
        Instr instr = JAL;
        instr = SetJalOffset(pos, target_pos, instr);
        DCHECK(IsJal(instr));
        DCHECK(JumpOffset(instr) == offset);
        instr_at_put(pos, instr);
        instr_at_put(pos + 4, kNopByte);
      } else {
        CHECK(is_int32(offset + 0x800));

        int32_t Hi20 = (((int32_t)offset + 0x800) >> 12);
        int32_t Lo12 = (int32_t)offset << 20 >> 20;

        instr_auipc =
            (instr_auipc & ~kImm31_12Mask) | ((Hi20 & kImm19_0Mask) << 12);
        instr_at_put(pos, instr_auipc);

        const int kImm31_20Mask = ((1 << 12) - 1) << 20;
        const int kImm11_0Mask = ((1 << 12) - 1);
        instr_I = (instr_I & ~kImm31_20Mask) | ((Lo12 & kImm11_0Mask) << 20);
        instr_at_put(pos + 4, instr_I);
      }
    } break;
    case RO_C_J: {
      ShortInstr short_instr = SetCJalOffset(pos, target_pos, instr);
      instr_at_put(pos, short_instr);
    } break;
    case RO_C_BNEZ:
    case RO_C_BEQZ: {
      instr = SetCBranchOffset(pos, target_pos, instr);
      instr_at_put(pos, instr);
    } break;
    default: {
      // Emitted label constant, not part of a branch.
      // Make label relative to Code pointer of generated Code object.
      instr_at_put(pos, target_pos + (Code::kHeaderSize - kHeapObjectTag));
    } break;
  }
  disassembleInstr(instr);
}

void Assembler::print(const Label* L) {
  if (L->is_unused()) {
    PrintF("unused label\n");
  } else if (L->is_bound()) {
    PrintF("bound label to %d\n", L->pos());
  } else if (L->is_linked()) {
    Label l;
    l.link_to(L->pos());
    PrintF("unbound label");
    while (l.is_linked()) {
      PrintF("@ %d ", l.pos());
      Instr instr = instr_at(l.pos());
      if ((instr & ~kImm16Mask) == 0) {
        PrintF("value\n");
      } else {
        PrintF("%d\n", instr);
      }
      next(&l, is_internal_reference(&l));
    }
  } else {
    PrintF("label in inconsistent state (pos = %d)\n", L->pos_);
  }
}

void Assembler::bind_to(Label* L, int pos) {
  DCHECK(0 <= pos && pos <= pc_offset());  // Must have valid binding position.
  DEBUG_PRINTF("\tbinding %d to label %p\n", pos, L);
  int trampoline_pos = kInvalidSlotPos;
  bool is_internal = false;
  if (L->is_linked() && !trampoline_emitted_) {
    unbound_labels_count_--;
    if (!is_internal_reference(L)) {
      next_buffer_check_ += kTrampolineSlotsSize;
    }
  }

  while (L->is_linked()) {
    int fixup_pos = L->pos();
    int dist = pos - fixup_pos;
    is_internal = is_internal_reference(L);
    next(L, is_internal);  // Call next before overwriting link with target
                           // at fixup_pos.
    Instr instr = instr_at(fixup_pos);
    DEBUG_PRINTF("\tfixup: %d to %d\n", fixup_pos, dist);
    if (is_internal) {
      target_at_put(fixup_pos, pos, is_internal);
    } else {
      if (IsBranch(instr)) {
        if (dist > kMaxBranchOffset) {
          if (trampoline_pos == kInvalidSlotPos) {
            trampoline_pos = get_trampoline_entry(fixup_pos);
            CHECK_NE(trampoline_pos, kInvalidSlotPos);
          }
          CHECK((trampoline_pos - fixup_pos) <= kMaxBranchOffset);
          DEBUG_PRINTF("\t\ttrampolining: %d\n", trampoline_pos);
          target_at_put(fixup_pos, trampoline_pos, false, true);
          fixup_pos = trampoline_pos;
        }
        target_at_put(fixup_pos, pos, false);
      } else if (IsJal(instr)) {
        if (dist > kMaxJumpOffset) {
          if (trampoline_pos == kInvalidSlotPos) {
            trampoline_pos = get_trampoline_entry(fixup_pos);
            CHECK_NE(trampoline_pos, kInvalidSlotPos);
          }
          CHECK((trampoline_pos - fixup_pos) <= kMaxJumpOffset);
          DEBUG_PRINTF("\t\ttrampolining: %d\n", trampoline_pos);
          target_at_put(fixup_pos, trampoline_pos, false, true);
          fixup_pos = trampoline_pos;
        }
        target_at_put(fixup_pos, pos, false);
      } else {
        target_at_put(fixup_pos, pos, false);
      }
    }
  }
  L->bind_to(pos);

  // Keep track of the last bound label so we don't eliminate any instructions
  // before a bound label.
  if (pos > last_bound_pos_) last_bound_pos_ = pos;
}

void Assembler::bind(Label* L) {
  DCHECK(!L->is_bound());  // Label can only be bound once.
  bind_to(L, pc_offset());
}

void Assembler::next(Label* L, bool is_internal) {
  DCHECK(L->is_linked());
  int link = target_at(L->pos(), is_internal);
  if (link == kEndOfChain) {
    L->Unuse();
  } else {
    DCHECK_GE(link, 0);
    DEBUG_PRINTF("\tnext: %p to %p (%d)\n", L,
                 reinterpret_cast<Instr*>(buffer_start_ + link), link);
    L->link_to(link);
  }
}

bool Assembler::is_near(Label* L) {
  DCHECK(L->is_bound());
  return is_intn((pc_offset() - L->pos()), kJumpOffsetBits);
}

bool Assembler::is_near(Label* L, OffsetSize bits) {
  if (L == nullptr || !L->is_bound()) return true;
  return is_intn((pc_offset() - L->pos()), bits);
}

bool Assembler::is_near_branch(Label* L) {
  DCHECK(L->is_bound());
  return is_intn((pc_offset() - L->pos()), kBranchOffsetBits);
}

int Assembler::BranchOffset(Instr instr) {
  // | imm[12] | imm[10:5] | rs2 | rs1 | funct3 | imm[4:1|11] | opcode |
  //  31          25                      11          7
  int32_t imm13 = ((instr & 0xf00) >> 7) | ((instr & 0x7e000000) >> 20) |
                  ((instr & 0x80) << 4) | ((instr & 0x80000000) >> 19);
  imm13 = imm13 << 19 >> 19;
  return imm13;
}

int Assembler::BrachlongOffset(Instr auipc, Instr instr_I) {
  DCHECK(reinterpret_cast<Instruction*>(&instr_I)->InstructionType() ==
         InstructionBase::kIType);
  DCHECK(IsAuipc(auipc));
  DCHECK_EQ((auipc & kRdFieldMask) >> kRdShift,
            (instr_I & kRs1FieldMask) >> kRs1Shift);
  int32_t imm_auipc = AuipcOffset(auipc);
  int32_t imm12 = static_cast<int32_t>(instr_I & kImm12Mask) >> 20;
  int32_t offset = imm12 + imm_auipc;
  return offset;
}

int Assembler::PatchBranchlongOffset(Address pc, Instr instr_auipc,
                                     Instr instr_jalr, int32_t offset) {
  DCHECK(IsAuipc(instr_auipc));
  DCHECK(IsJalr(instr_jalr));
  CHECK(is_int32(offset + 0x800));
  int32_t Hi20 = (((int32_t)offset + 0x800) >> 12);
  int32_t Lo12 = (int32_t)offset << 20 >> 20;
  instr_at_put(pc, SetAuipcOffset(Hi20, instr_auipc));
  instr_at_put(pc + 4, SetJalrOffset(Lo12, instr_jalr));
  DCHECK(offset ==
         BrachlongOffset(Assembler::instr_at(pc), Assembler::instr_at(pc + 4)));
  return 2;
}

// Returns the next free trampoline entry.
int32_t Assembler::get_trampoline_entry(int32_t pos) {
  int32_t trampoline_entry = kInvalidSlotPos;
  if (!internal_trampoline_exception_) {
    DEBUG_PRINTF("\tstart: %d,pos: %d\n", trampoline_.start(), pos);
    if (trampoline_.start() > pos) {
      trampoline_entry = trampoline_.take_slot();
    }

    if (kInvalidSlotPos == trampoline_entry) {
      internal_trampoline_exception_ = true;
    }
  }
  return trampoline_entry;
}

uintptr_t Assembler::jump_address(Label* L) {
  intptr_t target_pos;
  DEBUG_PRINTF("\tjump_address: %p to %p (%d)\n", L,
               reinterpret_cast<Instr*>(buffer_start_ + pc_offset()),
               pc_offset());
  if (L->is_bound()) {
    target_pos = L->pos();
  } else {
    if (L->is_linked()) {
      target_pos = L->pos();  // L's link.
      L->link_to(pc_offset());
    } else {
      L->link_to(pc_offset());
      if (!trampoline_emitted_) {
        unbound_labels_count_++;
        next_buffer_check_ -= kTrampolineSlotsSize;
      }
      DEBUG_PRINTF("\tstarted link\n");
      return kEndOfJumpChain;
    }
  }
  uintptr_t imm = reinterpret_cast<uintptr_t>(buffer_start_) + target_pos;
  if (v8_flags.riscv_c_extension)
    DCHECK_EQ(imm & 1, 0);
  else
    DCHECK_EQ(imm & 3, 0);

  return imm;
}

int32_t Assembler::branch_long_offset(Label* L) {
  intptr_t target_pos;

  DEBUG_PRINTF("\tbranch_long_offset: %p to %p (%d)\n", L,
               reinterpret_cast<Instr*>(buffer_start_ + pc_offset()),
               pc_offset());
  if (L->is_bound()) {
    target_pos = L->pos();
  } else {
    if (L->is_linked()) {
      target_pos = L->pos();  // L's link.
      L->link_to(pc_offset());
    } else {
      L->link_to(pc_offset());
      if (!trampoline_emitted_) {
        unbound_labels_count_++;
        next_buffer_check_ -= kTrampolineSlotsSize;
      }
      DEBUG_PRINTF("\tstarted link\n");
      return kEndOfJumpChain;
    }
  }
  intptr_t offset = target_pos - pc_offset();
  if (v8_flags.riscv_c_extension)
    DCHECK_EQ(offset & 1, 0);
  else
    DCHECK_EQ(offset & 3, 0);
  DCHECK(is_int32(offset));
  VU.clear();
  return static_cast<int32_t>(offset);
}

int32_t Assembler::branch_offset_helper(Label* L, OffsetSize bits) {
  int32_t target_pos;

  DEBUG_PRINTF("\tbranch_offset_helper: %p to %p (%d)\n", L,
               reinterpret_cast<Instr*>(buffer_start_ + pc_offset()),
               pc_offset());
  if (L->is_bound()) {
    target_pos = L->pos();
    DEBUG_PRINTF("\tbound: %d", target_pos);
  } else {
    if (L->is_linked()) {
      target_pos = L->pos();
      L->link_to(pc_offset());
      DEBUG_PRINTF("\tadded to link: %d\n", target_pos);
    } else {
      L->link_to(pc_offset());
      if (!trampoline_emitted_) {
        unbound_labels_count_++;
        next_buffer_check_ -= kTrampolineSlotsSize;
      }
      DEBUG_PRINTF("\tstarted link\n");
      return kEndOfJumpChain;
    }
  }

  int32_t offset = target_pos - pc_offset();
  DCHECK(is_intn(offset, bits));
  DCHECK_EQ(offset & 1, 0);
  DEBUG_PRINTF("\toffset = %d\n", offset);
  VU.clear();
  return offset;
}

void Assembler::label_at_put(Label* L, int at_offset) {
  int target_pos;
  DEBUG_PRINTF("\tlabel_at_put: %p @ %p (%d)\n", L,
               reinterpret_cast<Instr*>(buffer_start_ + at_offset), at_offset);
  if (L->is_bound()) {
    target_pos = L->pos();
    instr_at_put(at_offset, target_pos + (Code::kHeaderSize - kHeapObjectTag));
  } else {
    if (L->is_linked()) {
      target_pos = L->pos();  // L's link.
      int32_t imm18 = target_pos - at_offset;
      DCHECK_EQ(imm18 & 3, 0);
      int32_t imm16 = imm18 >> 2;
      DCHECK(is_int16(imm16));
      instr_at_put(at_offset, (int32_t)(imm16 & kImm16Mask));
    } else {
      target_pos = kEndOfJumpChain;
      instr_at_put(at_offset, target_pos);
      if (!trampoline_emitted_) {
        unbound_labels_count_++;
        next_buffer_check_ -= kTrampolineSlotsSize;
      }
    }
    L->link_to(at_offset);
  }
}

//===----------------------------------------------------------------------===//
// Instructions
//===----------------------------------------------------------------------===//

// Definitions for using compressed vs non compressed

void Assembler::NOP() {
  if (v8_flags.riscv_c_extension)
    c_nop();
  else
    nop();
}

void Assembler::EBREAK() {
  if (v8_flags.riscv_c_extension)
    c_ebreak();
  else
    ebreak();
}

// Assembler Pseudo Instructions (Tables 25.2 and 25.3, RISC-V Unprivileged ISA)

void Assembler::nop() { addi(ToRegister(0), ToRegister(0), 0); }

#if V8_TARGET_ARCH_RISCV64
void Assembler::RV_li(Register rd, int64_t imm) {
  // 64-bit imm is put in the register rd.
  // In most cases the imm is 32 bit and 2 instructions are generated. If a
  // temporary register is available, in the worst case, 6 instructions are
  // generated for a full 64-bit immediate. If temporay register is not
  // available the maximum will be 8 instructions. If imm is more than 32 bits
  // and a temp register is available, imm is divided into two 32-bit parts,
  // low_32 and up_32. Each part is built in a separate register. low_32 is
  // built before up_32. If low_32 is negative (upper 32 bits are 1), 0xffffffff
  // is subtracted from up_32 before up_32 is built. This compensates for 32
  // bits of 1's in the lower when the two registers are added. If no temp is
  // available, the upper 32 bit is built in rd, and the lower 32 bits are
  // devided to 3 parts (11, 11, and 10 bits). The parts are shifted and added
  // to the upper part built in rd.
  if (is_int32(imm + 0x800)) {
    // 32-bit case. Maximum of 2 instructions generated
    int64_t high_20 = ((imm + 0x800) >> 12);
    int64_t low_12 = imm << 52 >> 52;
    if (high_20) {
      lui(rd, (int32_t)high_20);
      if (low_12) {
        addi(rd, rd, low_12);
      }
    } else {
      addi(rd, zero_reg, low_12);
    }
    return;
  } else {
    // 64-bit case: divide imm into two 32-bit parts, upper and lower
    int64_t up_32 = imm >> 32;
    int64_t low_32 = imm & 0xffffffffull;
    Register temp_reg = rd;
    // Check if a temporary register is available
    if (up_32 == 0 || low_32 == 0) {
      // No temp register is needed
    } else {
      UseScratchRegisterScope temps(this);
      BlockTrampolinePoolScope block_trampoline_pool(this);
      temp_reg = temps.hasAvailable() ? temps.Acquire() : no_reg;
    }
    if (temp_reg != no_reg) {
      // keep track of hardware behavior for lower part in sim_low
      int64_t sim_low = 0;
      // Build lower part
      if (low_32 != 0) {
        int64_t high_20 = ((low_32 + 0x800) >> 12);
        int64_t low_12 = low_32 & 0xfff;
        if (high_20) {
          // Adjust to 20 bits for the case of overflow
          high_20 &= 0xfffff;
          sim_low = ((high_20 << 12) << 32) >> 32;
          lui(rd, (int32_t)high_20);
          if (low_12) {
            sim_low += (low_12 << 52 >> 52) | low_12;
            addi(rd, rd, low_12);
          }
        } else {
          sim_low = low_12;
          ori(rd, zero_reg, low_12);
        }
      }
      if (sim_low & 0x100000000) {
        // Bit 31 is 1. Either an overflow or a negative 64 bit
        if (up_32 == 0) {
          // Positive number, but overflow because of the add 0x800
          slli(rd, rd, 32);
          srli(rd, rd, 32);
          return;
        }
        // low_32 is a negative 64 bit after the build
        up_32 = (up_32 - 0xffffffff) & 0xffffffff;
      }
      if (up_32 == 0) {
        return;
      }
      // Build upper part in a temporary register
      if (low_32 == 0) {
        // Build upper part in rd
        temp_reg = rd;
      }
      int64_t high_20 = (up_32 + 0x800) >> 12;
      int64_t low_12 = up_32 & 0xfff;
      if (high_20) {
        // Adjust to 20 bits for the case of overflow
        high_20 &= 0xfffff;
        lui(temp_reg, (int32_t)high_20);
        if (low_12) {
          addi(temp_reg, temp_reg, low_12);
        }
      } else {
        ori(temp_reg, zero_reg, low_12);
      }
      // Put it at the bgining of register
      slli(temp_reg, temp_reg, 32);
      if (low_32 != 0) {
        add(rd, rd, temp_reg);
      }
      return;
    }
    // No temp register. Build imm in rd.
    // Build upper 32 bits first in rd. Divide lower 32 bits parts and add
    // parts to the upper part by doing shift and add.
    // First build upper part in rd.
    int64_t high_20 = (up_32 + 0x800) >> 12;
    int64_t low_12 = up_32 & 0xfff;
    if (high_20) {
      // Adjust to 20 bits for the case of overflow
      high_20 &= 0xfffff;
      lui(rd, (int32_t)high_20);
      if (low_12) {
        addi(rd, rd, low_12);
      }
    } else {
      ori(rd, zero_reg, low_12);
    }
    // upper part already in rd. Each part to be added to rd, has maximum of 11
    // bits, and always starts with a 1. rd is shifted by the size of the part
    // plus the number of zeros between the parts. Each part is added after the
    // left shift.
    uint32_t mask = 0x80000000;
    int32_t shift_val = 0;
    int32_t i;
    for (i = 0; i < 32; i++) {
      if ((low_32 & mask) == 0) {
        mask >>= 1;
        shift_val++;
        if (i == 31) {
          // rest is zero
          slli(rd, rd, shift_val);
        }
        continue;
      }
      // The first 1 seen
      int32_t part;
      if ((i + 11) < 32) {
        // Pick 11 bits
        part = ((uint32_t)(low_32 << i) >> i) >> (32 - (i + 11));
        slli(rd, rd, shift_val + 11);
        ori(rd, rd, part);
        i += 10;
        mask >>= 11;
      } else {
        part = (uint32_t)(low_32 << i) >> i;
        slli(rd, rd, shift_val + (32 - i));
        ori(rd, rd, part);
        break;
      }
      shift_val = 0;
    }
  }
}

int Assembler::li_estimate(int64_t imm, bool is_get_temp_reg) {
  int count = 0;
  // imitate Assembler::RV_li
  if (is_int32(imm + 0x800)) {
    // 32-bit case. Maximum of 2 instructions generated
    int64_t high_20 = ((imm + 0x800) >> 12);
    int64_t low_12 = imm << 52 >> 52;
    if (high_20) {
      count++;
      if (low_12) {
        count++;
      }
    } else {
      count++;
    }
    return count;
  } else {
    // 64-bit case: divide imm into two 32-bit parts, upper and lower
    int64_t up_32 = imm >> 32;
    int64_t low_32 = imm & 0xffffffffull;
    // Check if a temporary register is available
    if (is_get_temp_reg) {
      // keep track of hardware behavior for lower part in sim_low
      int64_t sim_low = 0;
      // Build lower part
      if (low_32 != 0) {
        int64_t high_20 = ((low_32 + 0x800) >> 12);
        int64_t low_12 = low_32 & 0xfff;
        if (high_20) {
          // Adjust to 20 bits for the case of overflow
          high_20 &= 0xfffff;
          sim_low = ((high_20 << 12) << 32) >> 32;
          count++;
          if (low_12) {
            sim_low += (low_12 << 52 >> 52) | low_12;
            count++;
          }
        } else {
          sim_low = low_12;
          count++;
        }
      }
      if (sim_low & 0x100000000) {
        // Bit 31 is 1. Either an overflow or a negative 64 bit
        if (up_32 == 0) {
          // Positive number, but overflow because of the add 0x800
          count++;
          count++;
          return count;
        }
        // low_32 is a negative 64 bit after the build
        up_32 = (up_32 - 0xffffffff) & 0xffffffff;
      }
      if (up_32 == 0) {
        return count;
      }
      int64_t high_20 = (up_32 + 0x800) >> 12;
      int64_t low_12 = up_32 & 0xfff;
      if (high_20) {
        // Adjust to 20 bits for the case of overflow
        high_20 &= 0xfffff;
        count++;
        if (low_12) {
          count++;
        }
      } else {
        count++;
      }
      // Put it at the bgining of register
      count++;
      if (low_32 != 0) {
        count++;
      }
      return count;
    }
    // No temp register. Build imm in rd.
    // Build upper 32 bits first in rd. Divide lower 32 bits parts and add
    // parts to the upper part by doing shift and add.
    // First build upper part in rd.
    int64_t high_20 = (up_32 + 0x800) >> 12;
    int64_t low_12 = up_32 & 0xfff;
    if (high_20) {
      // Adjust to 20 bits for the case of overflow
      high_20 &= 0xfffff;
      count++;
      if (low_12) {
        count++;
      }
    } else {
      count++;
    }
    // upper part already in rd. Each part to be added to rd, has maximum of 11
    // bits, and always starts with a 1. rd is shifted by the size of the part
    // plus the number of zeros between the parts. Each part is added after the
    // left shift.
    uint32_t mask = 0x80000000;
    int32_t i;
    for (i = 0; i < 32; i++) {
      if ((low_32 & mask) == 0) {
        mask >>= 1;
        if (i == 31) {
          // rest is zero
          count++;
        }
        continue;
      }
      // The first 1 seen
      if ((i + 11) < 32) {
        // Pick 11 bits
        count++;
        count++;
        i += 10;
        mask >>= 11;
      } else {
        count++;
        count++;
        break;
      }
    }
  }
  return count;
}

void Assembler::li_ptr(Register rd, int64_t imm) {
  // Initialize rd with an address
  // Pointers are 48 bits
  // 6 fixed instructions are generated
  DCHECK_EQ((imm & 0xfff0000000000000ll), 0);
  int64_t a6 = imm & 0x3f;                      // bits 0:5. 6 bits
  int64_t b11 = (imm >> 6) & 0x7ff;             // bits 6:11. 11 bits
  int64_t high_31 = (imm >> 17) & 0x7fffffff;   // 31 bits
  int64_t high_20 = ((high_31 + 0x800) >> 12);  // 19 bits
  int64_t low_12 = high_31 & 0xfff;             // 12 bits
  lui(rd, (int32_t)high_20);
  addi(rd, rd, low_12);  // 31 bits in rd.
  slli(rd, rd, 11);      // Space for next 11 bis
  ori(rd, rd, b11);      // 11 bits are put in. 42 bit in rd
  slli(rd, rd, 6);       // Space for next 6 bits
  ori(rd, rd, a6);       // 6 bits are put in. 48 bis in rd
}

void Assembler::li_constant(Register rd, int64_t imm) {
  DEBUG_PRINTF("\tli_constant(%d, %lx <%ld>)\n", ToNumber(rd), imm, imm);
  lui(rd, (imm + (1LL << 47) + (1LL << 35) + (1LL << 23) + (1LL << 11)) >>
              48);  // Bits 63:48
  addiw(rd, rd,
        (imm + (1LL << 35) + (1LL << 23) + (1LL << 11)) << 16 >>
            52);  // Bits 47:36
  slli(rd, rd, 12);
  addi(rd, rd, (imm + (1LL << 23) + (1LL << 11)) << 28 >> 52);  // Bits 35:24
  slli(rd, rd, 12);
  addi(rd, rd, (imm + (1LL << 11)) << 40 >> 52);  // Bits 23:12
  slli(rd, rd, 12);
  addi(rd, rd, imm << 52 >> 52);  // Bits 11:0
}

#elif V8_TARGET_ARCH_RISCV32
void Assembler::RV_li(Register rd, int32_t imm) {
  int32_t high_20 = ((imm + 0x800) >> 12);
  int32_t low_12 = imm & 0xfff;
  if (high_20) {
    lui(rd, high_20);
    if (low_12) {
      addi(rd, rd, low_12);
    }
  } else {
    addi(rd, zero_reg, low_12);
  }
}

int Assembler::li_estimate(int32_t imm, bool is_get_temp_reg) {
  int count = 0;
  // imitate Assembler::RV_li
  int32_t high_20 = ((imm + 0x800) >> 12);
  int32_t low_12 = imm & 0xfff;
  if (high_20) {
    count++;
    if (low_12) {
      count++;
    }
  } else {
    // if high_20 is 0, always need one instruction to load the low_12 bit
    count++;
  }

  return count;
}

void Assembler::li_ptr(Register rd, int32_t imm) {
  // Initialize rd with an address
  // Pointers are 32 bits
  // 2 fixed instructions are generated
  int32_t high_20 = ((imm + 0x800) >> 12);  // bits31:12
  int32_t low_12 = imm & 0xfff;             // bits11:0
  lui(rd, high_20);
  addi(rd, rd, low_12);
}

void Assembler::li_constant(Register rd, int32_t imm) {
  DEBUG_PRINTF("\tli_constant(%d, %x <%d>)\n", ToNumber(rd), imm, imm);
  int32_t high_20 = ((imm + 0x800) >> 12);  // bits31:12
  int32_t low_12 = imm & 0xfff;             // bits11:0
  lui(rd, high_20);
  addi(rd, rd, low_12);
}
#endif

// Break / Trap instructions.
void Assembler::break_(uint32_t code, bool break_as_stop) {
  // We need to invalidate breaks that could be stops as well because the
  // simulator expects a char pointer after the stop instruction.
  // See constants-mips.h for explanation.
  DCHECK(
      (break_as_stop && code <= kMaxStopCode && code > kMaxWatchpointCode) ||
      (!break_as_stop && (code > kMaxStopCode || code <= kMaxWatchpointCode)));

  // since ebreak does not allow additional immediate field, we use the
  // immediate field of lui instruction immediately following the ebreak to
  // encode the "code" info
  ebreak();
  DCHECK(is_uint20(code));
  lui(zero_reg, code);
}

void Assembler::stop(uint32_t code) {
  DCHECK_GT(code, kMaxWatchpointCode);
  DCHECK_LE(code, kMaxStopCode);
#if defined(V8_HOST_ARCH_RISCV64) || defined(V8_HOST_ARCH_RISCV32)
  break_(0x54321);
#else  // V8_HOST_ARCH_RISCV64 || V8_HOST_ARCH_RISCV32
  break_(code, true);
#endif
}

// Original MIPS Instructions

// ------------Memory-instructions-------------

bool Assembler::NeedAdjustBaseAndOffset(const MemOperand& src,
                                        OffsetAccessType access_type,
                                        int second_access_add_to_offset) {
  bool two_accesses = static_cast<bool>(access_type);
  DCHECK_LE(second_access_add_to_offset, 7);  // Must be <= 7.

  // is_int12 must be passed a signed value, hence the static cast below.
  if (is_int12(src.offset()) &&
      (!two_accesses || is_int12(static_cast<int32_t>(
                            src.offset() + second_access_add_to_offset)))) {
    // Nothing to do: 'offset' (and, if needed, 'offset + 4', or other specified
    // value) fits into int12.
    return false;
  }
  return true;
}

void Assembler::AdjustBaseAndOffset(MemOperand* src, Register scratch,
                                    OffsetAccessType access_type,
                                    int second_Access_add_to_offset) {
  // This method is used to adjust the base register and offset pair
  // for a load/store when the offset doesn't fit into int12.

  // Must not overwrite the register 'base' while loading 'offset'.
  constexpr int32_t kMinOffsetForSimpleAdjustment = 0x7F8;
  constexpr int32_t kMaxOffsetForSimpleAdjustment =
      2 * kMinOffsetForSimpleAdjustment;
  if (0 <= src->offset() && src->offset() <= kMaxOffsetForSimpleAdjustment) {
    addi(scratch, src->rm(), kMinOffsetForSimpleAdjustment);
    src->offset_ -= kMinOffsetForSimpleAdjustment;
  } else if (-kMaxOffsetForSimpleAdjustment <= src->offset() &&
             src->offset() < 0) {
    addi(scratch, src->rm(), -kMinOffsetForSimpleAdjustment);
    src->offset_ += kMinOffsetForSimpleAdjustment;
  } else if (access_type == OffsetAccessType::SINGLE_ACCESS) {
    RV_li(scratch, (static_cast<intptr_t>(src->offset()) + 0x800) >> 12 << 12);
    add(scratch, scratch, src->rm());
    src->offset_ = src->offset() << 20 >> 20;
  } else {
    RV_li(scratch, src->offset());
    add(scratch, scratch, src->rm());
    src->offset_ = 0;
  }
  src->rm_ = scratch;
}

int Assembler::RelocateInternalReference(RelocInfo::Mode rmode, Address pc,
                                         intptr_t pc_delta) {
  if (RelocInfo::IsInternalReference(rmode)) {
    intptr_t* p = reinterpret_cast<intptr_t*>(pc);
    if (*p == kEndOfJumpChain) {
      return 0;  // Number of instructions patched.
    }
    *p += pc_delta;
    return 2;  // Number of instructions patched.
  }
  Instr instr = instr_at(pc);
  DCHECK(RelocInfo::IsInternalReferenceEncoded(rmode));
  if (IsLui(instr)) {
    uintptr_t target_address = target_address_at(pc) + pc_delta;
    DEBUG_PRINTF("\ttarget_address 0x%" PRIxPTR "\n", target_address);
    set_target_value_at(pc, target_address);
#if V8_TARGET_ARCH_RISCV64
    return 8;  // Number of instructions patched.
#elif V8_TARGET_ARCH_RISCV32
    return 2;  // Number of instructions patched.
#endif
  } else {
    UNIMPLEMENTED();
  }
}

void Assembler::RelocateRelativeReference(RelocInfo::Mode rmode, Address pc,
                                          intptr_t pc_delta) {
  Instr instr = instr_at(pc);
  Instr instr1 = instr_at(pc + 1 * kInstrSize);
  DCHECK(RelocInfo::IsRelativeCodeTarget(rmode));
  if (IsAuipc(instr) && IsJalr(instr1)) {
    int32_t imm;
    imm = BrachlongOffset(instr, instr1);
    imm -= pc_delta;
    PatchBranchlongOffset(pc, instr, instr1, imm);
    return;
  } else {
    UNREACHABLE();
  }
}

void Assembler::GrowBuffer() {
  DEBUG_PRINTF("GrowBuffer: %p -> ", buffer_start_);
  // Compute new buffer size.
  int old_size = buffer_->size();
  int new_size = std::min(2 * old_size, old_size + 1 * MB);

  // Some internal data structures overflow for very large buffers,
  // they must ensure that kMaximalBufferSize is not too large.
  if (new_size > kMaximalBufferSize) {
    V8::FatalProcessOutOfMemory(nullptr, "Assembler::GrowBuffer");
  }

  // Set up new buffer.
  std::unique_ptr<AssemblerBuffer> new_buffer = buffer_->Grow(new_size);
  DCHECK_EQ(new_size, new_buffer->size());
  byte* new_start = new_buffer->start();

  // Copy the data.
  intptr_t pc_delta = new_start - buffer_start_;
  intptr_t rc_delta = (new_start + new_size) - (buffer_start_ + old_size);
  size_t reloc_size = (buffer_start_ + old_size) - reloc_info_writer.pos();
  MemMove(new_start, buffer_start_, pc_offset());
  MemMove(reloc_info_writer.pos() + rc_delta, reloc_info_writer.pos(),
          reloc_size);

  // Switch buffers.
  buffer_ = std::move(new_buffer);
  buffer_start_ = new_start;
  DEBUG_PRINTF("%p\n", buffer_start_);
  pc_ += pc_delta;
  reloc_info_writer.Reposition(reloc_info_writer.pos() + rc_delta,
                               reloc_info_writer.last_pc() + pc_delta);

  // Relocate runtime entries.
  base::Vector<byte> instructions{buffer_start_,
                                  static_cast<size_t>(pc_offset())};
  base::Vector<const byte> reloc_info{reloc_info_writer.pos(), reloc_size};
  for (RelocIterator it(instructions, reloc_info, 0); !it.done(); it.next()) {
    RelocInfo::Mode rmode = it.rinfo()->rmode();
    if (rmode == RelocInfo::INTERNAL_REFERENCE) {
      RelocateInternalReference(rmode, it.rinfo()->pc(), pc_delta);
    }
  }

  DCHECK(!overflow());
}

void Assembler::db(uint8_t data) {
  if (!is_buffer_growth_blocked()) CheckBuffer();
  DEBUG_PRINTF("%p(%x): constant 0x%x\n", pc_, pc_offset(), data);
  EmitHelper(data);
}

void Assembler::dd(uint32_t data, RelocInfo::Mode rmode) {
  if (!RelocInfo::IsNoInfo(rmode)) {
    DCHECK(RelocInfo::IsLiteralConstant(rmode));
    RecordRelocInfo(rmode);
  }
  if (!is_buffer_growth_blocked()) CheckBuffer();
  DEBUG_PRINTF("%p(%x): constant 0x%x\n", pc_, pc_offset(), data);
  EmitHelper(data);
}

void Assembler::dq(uint64_t data, RelocInfo::Mode rmode) {
  if (!RelocInfo::IsNoInfo(rmode)) {
    DCHECK(RelocInfo::IsLiteralConstant(rmode));
    RecordRelocInfo(rmode);
  }
  if (!is_buffer_growth_blocked()) CheckBuffer();
  EmitHelper(data);
}

void Assembler::dd(Label* label) {
  uintptr_t data;
  if (!is_buffer_growth_blocked()) CheckBuffer();
  if (label->is_bound()) {
    data = reinterpret_cast<uintptr_t>(buffer_start_ + label->pos());
  } else {
    data = jump_address(label);
    internal_reference_positions_.insert(label->pos());
  }
  RecordRelocInfo(RelocInfo::INTERNAL_REFERENCE);
  EmitHelper(data);
}

void Assembler::RecordRelocInfo(RelocInfo::Mode rmode, intptr_t data) {
  if (!ShouldRecordRelocInfo(rmode)) return;
  // We do not try to reuse pool constants.
  RelocInfo rinfo(reinterpret_cast<Address>(pc_), rmode, data, Code());
  DCHECK_GE(buffer_space(), kMaxRelocSize);  // Too late to grow buffer here.
  reloc_info_writer.Write(&rinfo);
}

void Assembler::BlockTrampolinePoolFor(int instructions) {
  DEBUG_PRINTF("\tBlockTrampolinePoolFor %d", instructions);
  CheckTrampolinePoolQuick(instructions);
  DEBUG_PRINTF("\tpc_offset %d,BlockTrampolinePoolBefore %d\n", pc_offset(),
               pc_offset() + instructions * kInstrSize);
  BlockTrampolinePoolBefore(pc_offset() + instructions * kInstrSize);
}

void Assembler::CheckTrampolinePool() {
  // Some small sequences of instructions must not be broken up by the
  // insertion of a trampoline pool; such sequences are protected by setting
  // either trampoline_pool_blocked_nesting_ or no_trampoline_pool_before_,
  // which are both checked here. Also, recursive calls to CheckTrampolinePool
  // are blocked by trampoline_pool_blocked_nesting_.
  DEBUG_PRINTF("\tpc_offset %d no_trampoline_pool_before:%d\n", pc_offset(),
               no_trampoline_pool_before_);
  DEBUG_PRINTF("\ttrampoline_pool_blocked_nesting:%d\n",
               trampoline_pool_blocked_nesting_);
  if ((trampoline_pool_blocked_nesting_ > 0) ||
      (pc_offset() < no_trampoline_pool_before_)) {
    // Emission is currently blocked; make sure we try again as soon as
    // possible.
    if (trampoline_pool_blocked_nesting_ > 0) {
      next_buffer_check_ = pc_offset() + kInstrSize;
    } else {
      next_buffer_check_ = no_trampoline_pool_before_;
    }
    return;
  }

  DCHECK(!trampoline_emitted_);
  DCHECK_GE(unbound_labels_count_, 0);
  if (unbound_labels_count_ > 0) {
    // First we emit jump, then we emit trampoline pool.
    {
      DEBUG_PRINTF("inserting trampoline pool at %p (%d)\n",
                   reinterpret_cast<Instr*>(buffer_start_ + pc_offset()),
                   pc_offset());
      BlockTrampolinePoolScope block_trampoline_pool(this);
      Label after_pool;
      j(&after_pool);

      int pool_start = pc_offset();
      for (int i = 0; i < unbound_labels_count_; i++) {
        int32_t imm;
        imm = branch_long_offset(&after_pool);
        CHECK(is_int32(imm + 0x800));
        int32_t Hi20 = (((int32_t)imm + 0x800) >> 12);
        int32_t Lo12 = (int32_t)imm << 20 >> 20;
        auipc(t6, Hi20);  // Read PC + Hi20 into t6
        jr(t6, Lo12);     // jump PC + Hi20 + Lo12
      }
      // If unbound_labels_count_ is big enough, label after_pool will
      // need a trampoline too, so we must create the trampoline before
      // the bind operation to make sure function 'bind' can get this
      // information.
      trampoline_ = Trampoline(pool_start, unbound_labels_count_);
      bind(&after_pool);

      trampoline_emitted_ = true;
      // As we are only going to emit trampoline once, we need to prevent any
      // further emission.
      next_buffer_check_ = kMaxInt;
    }
  } else {
    // Number of branches to unbound label at this point is zero, so we can
    // move next buffer check to maximum.
    next_buffer_check_ =
        pc_offset() + kMaxBranchOffset - kTrampolineSlotsSize * 16;
  }
  return;
}

void Assembler::set_target_address_at(Address pc, Address constant_pool,
                                      Address target,
                                      ICacheFlushMode icache_flush_mode) {
  Instr* instr = reinterpret_cast<Instr*>(pc);
  if (IsAuipc(*instr)) {
#if V8_TARGET_ARCH_RISCV64
    if (IsLd(*reinterpret_cast<Instr*>(pc + 4))) {
#elif V8_TARGET_ARCH_RISCV32
    if (IsLw(*reinterpret_cast<Instr*>(pc + 4))) {
#endif
      int32_t Hi20 = AuipcOffset(*instr);
      int32_t Lo12 = LoadOffset(*reinterpret_cast<Instr*>(pc + 4));
      Memory<Address>(pc + Hi20 + Lo12) = target;
      if (icache_flush_mode != SKIP_ICACHE_FLUSH) {
        FlushInstructionCache(pc + Hi20 + Lo12, 2 * kInstrSize);
      }
    } else {
      DCHECK(IsJalr(*reinterpret_cast<Instr*>(pc + 4)));
      intptr_t imm = (intptr_t)target - (intptr_t)pc;
      Instr instr = instr_at(pc);
      Instr instr1 = instr_at(pc + 1 * kInstrSize);
      DCHECK(is_int32(imm + 0x800));
      int num = PatchBranchlongOffset(pc, instr, instr1, (int32_t)imm);
      if (icache_flush_mode != SKIP_ICACHE_FLUSH) {
        FlushInstructionCache(pc, num * kInstrSize);
      }
    }
  } else {
    set_target_address_at(pc, target, icache_flush_mode);
  }
}

Address Assembler::target_address_at(Address pc, Address constant_pool) {
  Instr* instr = reinterpret_cast<Instr*>(pc);
  if (IsAuipc(*instr)) {
#if V8_TARGET_ARCH_RISCV64
    if (IsLd(*reinterpret_cast<Instr*>(pc + 4))) {
#elif V8_TARGET_ARCH_RISCV32
    if (IsLw(*reinterpret_cast<Instr*>(pc + 4))) {
#endif
      int32_t Hi20 = AuipcOffset(*instr);
      int32_t Lo12 = LoadOffset(*reinterpret_cast<Instr*>(pc + 4));
      return Memory<Address>(pc + Hi20 + Lo12);
    } else {
      DCHECK(IsJalr(*reinterpret_cast<Instr*>(pc + 4)));
      int32_t Hi20 = AuipcOffset(*instr);
      int32_t Lo12 = JalrOffset(*reinterpret_cast<Instr*>(pc + 4));
      return pc + Hi20 + Lo12;
    }

  } else {
    return target_address_at(pc);
  }
}

#if V8_TARGET_ARCH_RISCV64
Address Assembler::target_address_at(Address pc) {
  DEBUG_PRINTF("target_address_at: pc: %lx\t", pc);
  Instruction* instr0 = Instruction::At((unsigned char*)pc);
  Instruction* instr1 = Instruction::At((unsigned char*)(pc + 1 * kInstrSize));
  Instruction* instr2 = Instruction::At((unsigned char*)(pc + 2 * kInstrSize));
  Instruction* instr3 = Instruction::At((unsigned char*)(pc + 3 * kInstrSize));
  Instruction* instr4 = Instruction::At((unsigned char*)(pc + 4 * kInstrSize));
  Instruction* instr5 = Instruction::At((unsigned char*)(pc + 5 * kInstrSize));

  // Interpret instructions for address generated by li: See listing in
  // Assembler::set_target_address_at() just below.
  if (IsLui(*reinterpret_cast<Instr*>(instr0)) &&
      IsAddi(*reinterpret_cast<Instr*>(instr1)) &&
      IsSlli(*reinterpret_cast<Instr*>(instr2)) &&
      IsOri(*reinterpret_cast<Instr*>(instr3)) &&
      IsSlli(*reinterpret_cast<Instr*>(instr4)) &&
      IsOri(*reinterpret_cast<Instr*>(instr5))) {
    // Assemble the 64 bit value.
    int64_t addr = (int64_t)(instr0->Imm20UValue() << kImm20Shift) +
                   (int64_t)instr1->Imm12Value();
    addr <<= 11;
    addr |= (int64_t)instr3->Imm12Value();
    addr <<= 6;
    addr |= (int64_t)instr5->Imm12Value();

    DEBUG_PRINTF("addr: %lx\n", addr);
    return static_cast<Address>(addr);
  }
  // We should never get here, force a bad address if we do.
  UNREACHABLE();
}
// On RISC-V, a 48-bit target address is stored in an 6-instruction sequence:
//  lui(reg, (int32_t)high_20); // 19 high bits
//  addi(reg, reg, low_12); // 12 following bits. total is 31 high bits in reg.
//  slli(reg, reg, 11); // Space for next 11 bits
//  ori(reg, reg, b11); // 11 bits are put in. 42 bit in reg
//  slli(reg, reg, 6); // Space for next 6 bits
//  ori(reg, reg, a6); // 6 bits are put in. all 48 bis in reg
//
// Patching the address must replace all instructions, and flush the i-cache.
// Note that this assumes the use of SV48, the 48-bit virtual memory system.
void Assembler::set_target_value_at(Address pc, uint64_t target,
                                    ICacheFlushMode icache_flush_mode) {
  DEBUG_PRINTF("set_target_value_at: pc: %lx\ttarget: %lx\n", pc, target);
  uint32_t* p = reinterpret_cast<uint32_t*>(pc);
  DCHECK_EQ((target & 0xffff000000000000ll), 0);
#ifdef DEBUG
  // Check we have the result from a li macro-instruction.
  Instruction* instr0 = Instruction::At((unsigned char*)pc);
  Instruction* instr1 = Instruction::At((unsigned char*)(pc + 1 * kInstrSize));
  Instruction* instr3 = Instruction::At((unsigned char*)(pc + 3 * kInstrSize));
  Instruction* instr5 = Instruction::At((unsigned char*)(pc + 5 * kInstrSize));
  DCHECK(IsLui(*reinterpret_cast<Instr*>(instr0)) &&
         IsAddi(*reinterpret_cast<Instr*>(instr1)) &&
         IsOri(*reinterpret_cast<Instr*>(instr3)) &&
         IsOri(*reinterpret_cast<Instr*>(instr5)));
#endif
  int64_t a6 = target & 0x3f;                     // bits 0:6. 6 bits
  int64_t b11 = (target >> 6) & 0x7ff;            // bits 6:11. 11 bits
  int64_t high_31 = (target >> 17) & 0x7fffffff;  // 31 bits
  int64_t high_20 = ((high_31 + 0x800) >> 12);    // 19 bits
  int64_t low_12 = high_31 & 0xfff;               // 12 bits
  *p = *p & 0xfff;
  *p = *p | ((int32_t)high_20 << 12);
  *(p + 1) = *(p + 1) & 0xfffff;
  *(p + 1) = *(p + 1) | ((int32_t)low_12 << 20);
  *(p + 2) = *(p + 2) & 0xfffff;
  *(p + 2) = *(p + 2) | (11 << 20);
  *(p + 3) = *(p + 3) & 0xfffff;
  *(p + 3) = *(p + 3) | ((int32_t)b11 << 20);
  *(p + 4) = *(p + 4) & 0xfffff;
  *(p + 4) = *(p + 4) | (6 << 20);
  *(p + 5) = *(p + 5) & 0xfffff;
  *(p + 5) = *(p + 5) | ((int32_t)a6 << 20);
  if (icache_flush_mode != SKIP_ICACHE_FLUSH) {
    FlushInstructionCache(pc, 8 * kInstrSize);
  }
  DCHECK_EQ(target_address_at(pc), target);
}
#elif V8_TARGET_ARCH_RISCV32
Address Assembler::target_address_at(Address pc) {
  DEBUG_PRINTF("target_address_at: pc: %x\t", pc);
  Instruction* instr0 = Instruction::At((unsigned char*)pc);
  Instruction* instr1 = Instruction::At((unsigned char*)(pc + 1 * kInstrSize));

  // Interpret instructions for address generated by li: See listing in
  // Assembler::set_target_address_at() just below.
  if (IsLui(*reinterpret_cast<Instr*>(instr0)) &&
      IsAddi(*reinterpret_cast<Instr*>(instr1))) {
    // Assemble the 32bit value.
    int32_t addr = (int32_t)(instr0->Imm20UValue() << kImm20Shift) +
                   (int32_t)instr1->Imm12Value();
    DEBUG_PRINTF("addr: %x\n", addr);
    return static_cast<Address>(addr);
  }
  // We should never get here, force a bad address if we do.
  UNREACHABLE();
}
// On RISC-V, a 32-bit target address is stored in an 2-instruction sequence:
//  lui(reg, high_20); // 20 high bits
//  addi(reg, reg, low_12); // 12 following bits. total is 31 high bits in reg.
//
// Patching the address must replace all instructions, and flush the i-cache.
void Assembler::set_target_value_at(Address pc, uint32_t target,
                                    ICacheFlushMode icache_flush_mode) {
  DEBUG_PRINTF("set_target_value_at: pc: %x\ttarget: %x\n", pc, target);
  uint32_t* p = reinterpret_cast<uint32_t*>(pc);
#ifdef DEBUG
  // Check we have the result from a li macro-instruction.
  Instruction* instr0 = Instruction::At((unsigned char*)pc);
  Instruction* instr1 = Instruction::At((unsigned char*)(pc + 1 * kInstrSize));
  DCHECK(IsLui(*reinterpret_cast<Instr*>(instr0)) &&
         IsAddi(*reinterpret_cast<Instr*>(instr1)));
#endif
  int32_t high_20 = ((target + 0x800) >> 12);  // 20 bits
  int32_t low_12 = target & 0xfff;             // 12 bits
  *p = *p & 0xfff;
  *p = *p | ((int32_t)high_20 << 12);
  *(p + 1) = *(p + 1) & 0xfffff;
  *(p + 1) = *(p + 1) | ((int32_t)low_12 << 20);
  if (icache_flush_mode != SKIP_ICACHE_FLUSH) {
    FlushInstructionCache(pc, 2 * kInstrSize);
  }
  DCHECK_EQ(target_address_at(pc), target);
}
#endif

UseScratchRegisterScope::UseScratchRegisterScope(Assembler* assembler)
    : available_(assembler->GetScratchRegisterList()),
      old_available_(*available_) {}

UseScratchRegisterScope::~UseScratchRegisterScope() {
  *available_ = old_available_;
}

Register UseScratchRegisterScope::Acquire() {
  DCHECK_NOT_NULL(available_);
  DCHECK(!available_->is_empty());
  int index =
      static_cast<int>(base::bits::CountTrailingZeros32(available_->bits()));
  *available_ &= RegList::FromBits(~(1U << index));

  return Register::from_code(index);
}

bool UseScratchRegisterScope::hasAvailable() const {
  return !available_->is_empty();
}

bool Assembler::IsConstantPoolAt(Instruction* instr) {
  // The constant pool marker is made of two instructions. These instructions
  // will never be emitted by the JIT, so checking for the first one is enough:
  // 0: ld x0, x0, #offset
  Instr instr_value = *reinterpret_cast<Instr*>(instr);
#if V8_TARGET_ARCH_RISCV64
  bool result = IsLd(instr_value) && (instr->Rs1Value() == kRegCode_zero_reg) &&
                (instr->RdValue() == kRegCode_zero_reg);
#elif V8_TARGET_ARCH_RISCV32
  bool result = IsLw(instr_value) && (instr->Rs1Value() == kRegCode_zero_reg) &&
                (instr->RdValue() == kRegCode_zero_reg);
#endif
#ifdef DEBUG
  // It is still worth asserting the marker is complete.
  // 1: j 0x0
  Instruction* instr_following = instr + kInstrSize;
  DCHECK(!result || (IsJal(*reinterpret_cast<Instr*>(instr_following)) &&
                     instr_following->Imm20JValue() == 0 &&
                     instr_following->RdValue() == kRegCode_zero_reg));
#endif
  return result;
}

int Assembler::ConstantPoolSizeAt(Instruction* instr) {
  if (IsConstantPoolAt(instr)) {
    return instr->Imm12Value();
  } else {
    return -1;
  }
}

void Assembler::RecordConstPool(int size) {
  // We only need this for debugger support, to correctly compute offsets in the
  // code.
  Assembler::BlockPoolsScope block_pools(this);
  RecordRelocInfo(RelocInfo::CONST_POOL, static_cast<intptr_t>(size));
}

void Assembler::EmitPoolGuard() {
  // We must generate only one instruction as this is used in scopes that
  // control the size of the code generated.
  j(0);
}

// -----------------------------------------------------------------------------
// Assembler.
template <typename T>
void Assembler::EmitHelper(T x) {
  *reinterpret_cast<T*>(pc_) = x;
  pc_ += sizeof(x);
}

void Assembler::emit(Instr x) {
  if (!is_buffer_growth_blocked()) {
    CheckBuffer();
  }
  DEBUG_PRINTF("%p(%x): ", pc_, pc_offset());
  disassembleInstr(x);
  EmitHelper(x);
  CheckTrampolinePoolQuick();
}

void Assembler::emit(ShortInstr x) {
  if (!is_buffer_growth_blocked()) {
    CheckBuffer();
  }
  DEBUG_PRINTF("%p(%x): ", pc_, pc_offset());
  disassembleInstr(x);
  EmitHelper(x);
  CheckTrampolinePoolQuick();
}

void Assembler::emit(uint64_t data) {
  if (!is_buffer_growth_blocked()) CheckBuffer();
  EmitHelper(data);
}

// Constant Pool

void ConstantPool::EmitPrologue(Alignment require_alignment) {
  // Recorded constant pool size is expressed in number of 32-bits words,
  // and includes prologue and alignment, but not the jump around the pool
  // and the size of the marker itself.
  const int marker_size = 1;
  int word_count =
      ComputeSize(Jump::kOmitted, require_alignment) / kInt32Size - marker_size;
#if V8_TARGET_ARCH_RISCV64
  assm_->ld(zero_reg, zero_reg, word_count);
#elif V8_TARGET_ARCH_RISCV32
  assm_->lw(zero_reg, zero_reg, word_count);
#endif
  assm_->EmitPoolGuard();
}

int ConstantPool::PrologueSize(Jump require_jump) const {
  // Prologue is:
  //   j over  ;; if require_jump
  //   ld x0, x0, #pool_size
  //   j 0x0
  int prologue_size = require_jump == Jump::kRequired ? kInstrSize : 0;
  prologue_size += 2 * kInstrSize;
  return prologue_size;
}

void ConstantPool::SetLoadOffsetToConstPoolEntry(int load_offset,
                                                 Instruction* entry_offset,
                                                 const ConstantPoolKey& key) {
  Instr instr_auipc = assm_->instr_at(load_offset);
  Instr instr_load = assm_->instr_at(load_offset + 4);
  // Instruction to patch must be 'ld/lw rd, offset(rd)' with 'offset == 0'.
  DCHECK(assm_->IsAuipc(instr_auipc));
#if V8_TARGET_ARCH_RISCV64
  DCHECK(assm_->IsLd(instr_load));
#elif V8_TARGET_ARCH_RISCV32
  DCHECK(assm_->IsLw(instr_load));
#endif
  DCHECK_EQ(assm_->LoadOffset(instr_load), 0);
  DCHECK_EQ(assm_->AuipcOffset(instr_auipc), 0);
  int32_t distance = static_cast<int32_t>(
      reinterpret_cast<Address>(entry_offset) -
      reinterpret_cast<Address>(assm_->toAddress(load_offset)));
  CHECK(is_int32(distance + 0x800));
  int32_t Hi20 = (((int32_t)distance + 0x800) >> 12);
  int32_t Lo12 = (int32_t)distance << 20 >> 20;
  assm_->instr_at_put(load_offset, SetAuipcOffset(Hi20, instr_auipc));
  assm_->instr_at_put(load_offset + 4, SetLoadOffset(Lo12, instr_load));
}

void ConstantPool::Check(Emission force_emit, Jump require_jump,
                         size_t margin) {
  // Some short sequence of instruction must not be broken up by constant pool
  // emission, such sequences are protected by a ConstPool::BlockScope.
  if (IsBlocked()) {
    // Something is wrong if emission is forced and blocked at the same time.
    DCHECK_EQ(force_emit, Emission::kIfNeeded);
    return;
  }

  // We emit a constant pool only if :
  //  * it is not empty
  //  * emission is forced by parameter force_emit (e.g. at function end).
  //  * emission is mandatory or opportune according to {ShouldEmitNow}.
  if (!IsEmpty() && (force_emit == Emission::kForced ||
                     ShouldEmitNow(require_jump, margin))) {
    // Emit veneers for branches that would go out of range during emission of
    // the constant pool.
    int worst_case_size = ComputeSize(Jump::kRequired, Alignment::kRequired);

    // Check that the code buffer is large enough before emitting the constant
    // pool (this includes the gap to the relocation information).
    int needed_space = worst_case_size + assm_->kGap;
    while (assm_->buffer_space() <= needed_space) {
      assm_->GrowBuffer();
    }

    EmitAndClear(require_jump);
  }
  // Since a constant pool is (now) empty, move the check offset forward by
  // the standard interval.
  SetNextCheckIn(ConstantPool::kCheckInterval);
}

// Pool entries are accessed with pc relative load therefore this cannot be more
// than 1 * MB. Since constant pool emission checks are interval based, and we
// want to keep entries close to the code, we try to emit every 64KB.
const size_t ConstantPool::kMaxDistToPool32 = 1 * MB;
const size_t ConstantPool::kMaxDistToPool64 = 1 * MB;
const size_t ConstantPool::kCheckInterval = 128 * kInstrSize;
const size_t ConstantPool::kApproxDistToPool32 = 64 * KB;
const size_t ConstantPool::kApproxDistToPool64 = kApproxDistToPool32;

const size_t ConstantPool::kOpportunityDistToPool32 = 64 * KB;
const size_t ConstantPool::kOpportunityDistToPool64 = 64 * KB;
const size_t ConstantPool::kApproxMaxEntryCount = 512;

}  // namespace internal
}  // namespace v8