lua 1.0 源码分析 -- 1 lua 的虚拟指令

曾经终败给现在 2023-08-17 15:48 149阅读 0赞

lua的解释器拿到 lua 编写的源码，首先进行解析，就是进行词法分析和语法分析，将源码转换成 lua 的指令集，然后执行这个指令集。

lua 源码：

function f(val)
        return val;
    end
    
    function main()
        local i = 1;
        local j = 2;
        local b = i + f(2);
        --local b = i + j;
    
        print("retval = "..b);
    
        return b;
    end

调用 main 的指令集分析：

in while  opcode = [CALLFUNC]. -- main
     in while  opcode = [NOP].
     in while  opcode = [SETFUNCTION].
     in while  opcode = [ADJUST].
     in while  opcode = [NOP].
     in while  opcode = [SETLINE].
     in while  opcode = [PUSH1].  -- i 
     in while  opcode = [SETLINE].
     in while  opcode = [PUSH2].  -- j
     in while  opcode = [SETLINE].  -- local b = i + f(2)
     in while  opcode = [PUSHLOCAL0]. -- i
     in while  opcode = [PUSHGLOBAL]. -- f
     in while  opcode = [PUSHMARK].
     in while  opcode = [PUSH2].    -- val
     in while  opcode = [CALLFUNC]. -- f()
     in while  opcode = [NOP].
     in while  opcode = [SETFUNCTION].
     in while  opcode = [ADJUST].
     in while  opcode = [NOP].
     in while  opcode = [SETLINE].
     in while  opcode = [PUSHLOCAL0]. -- val 
     in while  opcode = [RESET].
     in while  opcode = [RETCODE].
     in while  opcode = [SETLINE].
     in while  opcode = [ADJUST].
     in while  opcode = [ADDOP].  -- local b = i + f(2)
     in while  opcode = [SETLINE].
     in while  opcode = [NOP].
     in while  opcode = [PUSHGLOBAL]. --  print
     in while  opcode = [PUSHMARK].
     in while  opcode = [PUSHSTRING]. -- retval =
     in while  opcode = [PUSHLOCAL2]. -- b
     in while  opcode = [CONCOP].
     in while  opcode = [CALLFUNC]. -- print()
    retval = 3
     in while  opcode = [ADJUST].
     in while  opcode = [SETLINE].
     in while  opcode = [PUSHLOCAL2].
     in while  opcode = [RESET].
     in while  opcode = [RETCODE].
     in while  opcode = [HALT].

PS:

函数就是一个入口地址，入口是通向将要执行的指令集。想下 汇编 中的 call，ret。lua 中的虚拟指令类似，只不过入口中的指令集是 lua 自己的虚拟指令，不是像 c 那样的机器指令。

转载于:https://www.cnblogs.com/ashen/p/11547044.html