rubi

DynASM

簡介

  • DynASM 是一種支援即時編譯(Just-in-time compilation)的動態組譯器
  • 支援c語言以及組合語言混合編譯、亦支援MARCO、define、local與global宣告等

實做：分析使用JIT版本加速

未優化版本

  • 根據教學，輸出碎形

  • 尚未優化前的執行時間

    • 以time指令測量時間
      time ./tutorial mandelbrot.bf
    • 輸出結果：
      real 0m39.753s user 0m39.576s sys 0m0.168s
      大概執行了接近40秒的時間
    • 補充:閱讀time資訊

    Real is wall clock time - time from start to finish of the call. This is all elapsed time
    including time slices used by other processes and time the process spends blocked (for example if
    it is waiting for I/O to complete).

    User is the amount of CPU time spent in user-mode code (outside the kernel) within the process.
    This is only actual CPU time used in executing the process. Other processes and time the process
    spends blocked do not count towards this figure.

    Sys is the amount of CPU time spent in the kernel within the process. This means executing CPU
    time spent in system calls within the kernel, as opposed to library code, which is still running
    in user-space. Like 'user', this is only CPU time used by the process.

優化後版本

  • 使用DynASM優化步驟
    • 引入DynASM header
    

    ​​​​#include "luajit-2.0/dynasm/dasm_proto.h";
​​​​#include "luajit-2.0/dynasm/dasm_x86.h";
    • 把bf_interpret 修改成 bf_compile，並修正輸入參數
    

    ​​​​- static void bf_interpret(const char* program, bf_state_t* state) ;
​​​​+ static void(* bf_compile(const char* program) )(bf_state_t*)
    • 呼叫也要一併更改
    

    ​​​​- bf_interpret(program, &state);
​​​​+ bf_compile(program)(&state);
    • 以time指令測量時間
      time ./tutorial mandelbrot.bf
    • 輸出結果：
      real 0m1.877s user 0m1.868s sys 0m0.000s
      大概只執行了接近2秒的時間…
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