src/ic/x64/ic-x64.cc

// Copyright 2012 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#if V8_TARGET_ARCH_X64

#include "src/codegen.h"
#include "src/ic/ic.h"
#include "src/ic/stub-cache.h"
#include "src/objects-inl.h"

namespace v8 {
namespace internal {


Condition CompareIC::ComputeCondition(Token::Value op) {
  switch (op) {
    case Token::EQ_STRICT:
    case Token::EQ:
      return equal;
    case Token::LT:
      return less;
    case Token::GT:
      return greater;
    case Token::LTE:
      return less_equal;
    case Token::GTE:
      return greater_equal;
    default:
      UNREACHABLE();
      return no_condition;
  }
}


bool CompareIC::HasInlinedSmiCode(Address address) {
  // The address of the instruction following the call.
  Address test_instruction_address =
      address + Assembler::kCallTargetAddressOffset;

  // If the instruction following the call is not a test al, nothing
  // was inlined.
  return *test_instruction_address == Assembler::kTestAlByte;
}


void PatchInlinedSmiCode(Isolate* isolate, Address address,
                         InlinedSmiCheck check) {
  // The address of the instruction following the call.
  Address test_instruction_address =
      address + Assembler::kCallTargetAddressOffset;

  // If the instruction following the call is not a test al, nothing
  // was inlined.
  if (*test_instruction_address != Assembler::kTestAlByte) {
    DCHECK(*test_instruction_address == Assembler::kNopByte);
    return;
  }

  Address delta_address = test_instruction_address + 1;
  // The delta to the start of the map check instruction and the
  // condition code uses at the patched jump.
  uint8_t delta = *reinterpret_cast<uint8_t*>(delta_address);
  if (FLAG_trace_ic) {
    LOG(isolate, PatchIC(address, test_instruction_address, delta));
  }

  // Patch with a short conditional jump. Enabling means switching from a short
  // jump-if-carry/not-carry to jump-if-zero/not-zero, whereas disabling is the
  // reverse operation of that.
  Address jmp_address = test_instruction_address - delta;
  DCHECK((check == ENABLE_INLINED_SMI_CHECK)
             ? (*jmp_address == Assembler::kJncShortOpcode ||
                *jmp_address == Assembler::kJcShortOpcode)
             : (*jmp_address == Assembler::kJnzShortOpcode ||
                *jmp_address == Assembler::kJzShortOpcode));
  Condition cc =
      (check == ENABLE_INLINED_SMI_CHECK)
          ? (*jmp_address == Assembler::kJncShortOpcode ? not_zero : zero)
          : (*jmp_address == Assembler::kJnzShortOpcode ? not_carry : carry);
  *jmp_address = static_cast<byte>(Assembler::kJccShortPrefix | cc);
}
}  // namespace internal
}  // namespace v8

#endif  // V8_TARGET_ARCH_X64