Line data    Source code

       1             : // Copyright 2019 the V8 project authors. All rights reserved.
       2             : // Use of this source code is governed by a BSD-style license that can be
       3             : // found in the LICENSE file.
       4             : 
       5             : #ifndef V8_CODE_DESC_H_
       6             : #define V8_CODE_DESC_H_
       7             : 
       8             : #include "src/globals.h"
       9             : 
      10             : namespace v8 {
      11             : namespace internal {
      12             : 
      13             : // A CodeDesc describes a buffer holding instructions and relocation
      14             : // information. The instructions start at the beginning of the buffer
      15             : // and grow forward, the relocation information starts at the end of
      16             : // the buffer and grows backward. Inlined metadata sections may exist
      17             : // at the end of the instructions.
      18             : //
      19             : //  │<--------------- buffer_size ----------------------------------->│
      20             : //  │<---------------- instr_size ------------->│      │<-reloc_size->│
      21             : //  ├───────────────────────────────────────────┼──────┼──────────────┤
      22             : //  │ instructions │         data               │ free │  reloc info  │
      23             : //  ├───────────────────────────────────────────┴──────┴──────────────┘
      24             : 
      25             : // TODO(jgruber): Add a single chokepoint for specifying the instruction area
      26             : // layout (i.e. the order of inlined metadata fields).
      27             : // TODO(jgruber): Systematically maintain inlined metadata offsets and sizes
      28             : // to simplify CodeDesc initialization.
      29             : 
      30     2515379 : class CodeDesc {
      31             :  public:
      32             :   static void Initialize(CodeDesc* desc, Assembler* assembler,
      33             :                          int safepoint_table_offset, int handler_table_offset,
      34             :                          int constant_pool_offset, int code_comments_offset,
      35             :                          int reloc_info_offset);
      36             : 
      37             : #ifdef DEBUG
      38             :   static void Verify(const CodeDesc* desc);
      39             : #else
      40             :   inline static void Verify(const CodeDesc* desc) {}
      41             : #endif
      42             : 
      43             :  public:
      44             :   byte* buffer = nullptr;
      45             :   int buffer_size = 0;
      46             : 
      47             :   // The instruction area contains executable code plus inlined metadata.
      48             : 
      49             :   int instr_size = 0;
      50             : 
      51             :   // Metadata packed into the instructions area.
      52             : 
      53             :   int safepoint_table_offset = 0;
      54             :   int safepoint_table_size = 0;
      55             : 
      56             :   int handler_table_offset = 0;
      57             :   int handler_table_size = 0;
      58             : 
      59             :   int constant_pool_offset = 0;
      60             :   int constant_pool_size = 0;
      61             : 
      62             :   int code_comments_offset = 0;
      63             :   int code_comments_size = 0;
      64             : 
      65             :   // Relocation info is located at the end of the buffer and not part of the
      66             :   // instructions area.
      67             : 
      68             :   int reloc_offset = 0;
      69             :   int reloc_size = 0;
      70             : 
      71             :   // Unwinding information.
      72             :   // TODO(jgruber,mstarzinger): Pack this into the inlined metadata section.
      73             : 
      74             :   byte* unwinding_info = nullptr;
      75             :   int unwinding_info_size = 0;
      76             : 
      77             :   Assembler* origin = nullptr;
      78             : };
      79             : 
      80             : }  // namespace internal
      81             : }  // namespace v8
      82             : 
      83             : #endif  // V8_CODE_DESC_H_