runtime/arch/x86/jni_frame_x86.h

/*
 * Copyright (C) 2020 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef ART_RUNTIME_ARCH_X86_JNI_FRAME_X86_H_
#define ART_RUNTIME_ARCH_X86_JNI_FRAME_X86_H_

#include <string.h>

#include "arch/instruction_set.h"
#include "base/bit_utils.h"
#include "base/globals.h"
#include "base/logging.h"

namespace art {
namespace x86 {

constexpr size_t kFramePointerSize = static_cast<size_t>(PointerSize::k32);
static_assert(kX86PointerSize == PointerSize::k32, "Unexpected x86 pointer size");

static constexpr size_t kNativeStackAlignment = 16;  // IA-32 cdecl requires 16 byte alignment.
static_assert(kNativeStackAlignment == kStackAlignment);

// Get the size of "out args" for @CriticalNative method stub.
// This must match the size of the frame emitted by the JNI compiler at the native call site.
inline size_t GetCriticalNativeOutArgsSize(const char* shorty, uint32_t shorty_len) {
  DCHECK_EQ(shorty_len, strlen(shorty));

  size_t num_long_or_double_args = 0u;
  for (size_t i = 1; i != shorty_len; ++i) {
    if (shorty[i] == 'J' || shorty[i] == 'D') {
      num_long_or_double_args += 1u;
    }
  }
  size_t num_arg_words = shorty_len - 1u + num_long_or_double_args;

  // The size of outgoing arguments.
  size_t size = num_arg_words * static_cast<size_t>(kX86PointerSize);

  // Add return address size.
  size += kFramePointerSize;
  // We can make a tail call if there are no stack args and the return type is not
  // FP type (needs moving from ST0 to MMX0) and we do not need to extend the result.
  bool return_type_ok = shorty[0] == 'I' || shorty[0] == 'J' || shorty[0] == 'V';
  if (return_type_ok && size == kFramePointerSize) {
    return kFramePointerSize;
  }

  return RoundUp(size, kNativeStackAlignment);
}

}  // namespace x86
}  // namespace art

#endif  // ART_RUNTIME_ARCH_X86_JNI_FRAME_X86_H_