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// Copyright 2019 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_CODE_DESC_H_
#define V8_CODE_DESC_H_
#include "src/globals.h"
namespace v8 {
namespace internal {
// A CodeDesc describes a buffer holding instructions and relocation
// information. The instructions start at the beginning of the buffer
// and grow forward, the relocation information starts at the end of
// the buffer and grows backward. Inlined metadata sections may exist
// at the end of the instructions.
//
// │<--------------- buffer_size ----------------------------------->│
// │<---------------- instr_size ------------->│ │<-reloc_size->│
// ├───────────────────────────────────────────┼──────┼──────────────┤
// │ instructions │ data │ free │ reloc info │
// ├───────────────────────────────────────────┴──────┴──────────────┘
// TODO(jgruber): Change Code::safepoint_table_offset() semantics to always
// contain a real offset, and add has_safepoint_table() and
// safepoint_table_size() helpers. Likewise for other inlined metadata.
// TODO(jgruber): Update documentation about inlined metadata in code.h.
// TODO(jgruber): Add a single chokepoint for specifying the instruction area
// layout (i.e. the order of inlined metadata fields).
// TODO(jgruber): Systematically maintain inlined metadata offsets and sizes
// to simplify CodeDesc initialization.
class CodeDesc {
public:
static void Initialize(CodeDesc* desc, Assembler* assembler,
int safepoint_table_offset, int handler_table_offset,
int constant_pool_offset, int code_comments_offset,
int reloc_info_offset);
#ifdef DEBUG
static void Verify(const CodeDesc* desc);
#else
inline static void Verify(const CodeDesc* desc) {}
#endif
public:
byte* buffer = nullptr;
int buffer_size = 0;
// The instruction area contains executable code plus inlined metadata.
int instr_size = 0;
// Metadata packed into the instructions area.
int safepoint_table_offset = 0;
int safepoint_table_size = 0;
int handler_table_offset = 0;
int handler_table_size = 0;
int constant_pool_offset = 0;
int constant_pool_size = 0;
int code_comments_offset = 0;
int code_comments_size = 0;
// Relocation info is located at the end of the buffer and not part of the
// instructions area.
int reloc_offset = 0;
int reloc_size = 0;
// Unwinding information.
// TODO(jgruber,mstarzinger): Pack this into the inlined metadata section.
byte* unwinding_info = nullptr;
int unwinding_info_size = 0;
Assembler* origin = nullptr;
};
} // namespace internal
} // namespace v8
#endif // V8_CODE_DESC_H_