tamarin中interpter的一点分析

最新推荐文章于 2025-05-30 09:40:46 发布

haihaiger

最新推荐文章于 2025-05-30 09:40:46 发布

阅读量976

点赞数

CC 4.0 BY-SA版权

本文链接：https://blog.youkuaiyun.com/haihaiger/article/details/8995740

本文深入解析了AVMPLUS字节码指令的优化策略，包括线程化处理、不同编译器环境下的指令标签定义、以及针对不同场景的指令执行方式。通过分析AVMPLUS在不同条件下的指令实现细节，揭示了其如何在提高代码执行效率的同时，保持代码的清晰性和可维护性。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

#ifdef AVMPLUS_WORD_CODE

# if defined AVMPLUS_DIRECT_THREADED //可以直接线程化
#    if defined GNUC_THREADING // linux下的宏
#      define INSTR(op)       L_##op: VERBOSE;    放置虚拟指令标签
#      define NEXT            goto *(*pc++)
#    elif defined MSVC_X86_REWRITE_THREADING //switch和标签相结合
#      define INSTR(op)       case WOP_##op: L_ ## op: VERBOSE;
#      define NEXT            continue
#    elif defined MSVC_X86_ASM_THREADING //直接分发，要对abc码预处理
#      define INSTR(op)       L_ ## op: VERBOSE;
#      define NEXT __asm { \
               __asm mov ebx, pc \ //pc指向的是指令的地址
               __asm mov eax, [ebx] \
               __asm add ebx, 4 \
               __asm mov pc, ebx \
               __asm jmp eax \
           }
#    endif // threading discipline
# else // AVMPLUS_DIRECT_THREADED
#    define INSTR(op)       case WOP_##op: VERBOSE;
#    define NEXT            continue
# endif

# define U30ARG            (*pc++)
# define U8ARG             (*pc++)
# define S24ARG            (intptr_t)(*pc++)
# ifdef DEBUGGER
   // expc is visible outside this function, so make sure it's correct.
   // It's probably possible to adjust it on demand outside the function too,
   // because code that accesses it will have access to "info" and can
   // perform the adjustment.
#    define SAVE_EXPC         expc = pc-1-info->word_code_start()
#    define SAVE_EXPC_S24     expc = pc-2-info->word_code_start()
# else
   // Adjusted on demand in the CATCH clause. Reduces size of interpreter function
   // by 2.5KB of object code (x86 / gcc4.0 / -O3).
#    define SAVE_EXPC         expc = (intptr_t)pc
#    define SAVE_EXPC_S24     expc = (intptr_t)(pc-1)
# endif

#else // !AVMPLUS_WORD_CODE

# define INSTR(op) case OP_##op: VERBOSE;

# define NEXT              continue
# define U30ARG            (tmp_pc=pc, tmp_u30 = uint32_t(readU30(tmp_pc)), pc = tmp_pc, tmp_u30)
# define U8ARG             (*pc++)
# define S24ARG            (pc+=3, readS24(pc-3))
# define SAVE_EXPC            expc = pc-1-codeStart
# define SAVE_EXPC_S24     expc = pc-4-codeStart

#endif // AVMPLUS_WORD_CODE