Tcl/Tk Insight: Tcl中的字节码（ByteCode）

风行水上 @ 2014-11-06 12:32:34

标签： tcltk

为了加速脚本的执行，Tcl引入了字节码（ByteCode）。

ByteCode实际上像是一种汇编指令。通过把Tcl脚本源代码转换为字节码，Tcl解释器不再需要频繁调用命令对应的函数，而是执行一条条的指令。

tcl::unsupported::disassemble

Tcl 8.5开始引入了命令tcl::unsupported::disassemble可以用来观察代码编译成字节码之后的结果。

下面的例子可以大致说明其用法和输出结果。

proc t-append {s} {
  append s "abc" 
  append s2 "def$s" 
  append [set s2] "hij"
}

tcl::unsupported::disassemble proc t-append

ByteCode 0x02E58658, refCt 1, epoch 3, interp 0x009B40F8 (epoch 3)
  Source "\n  append s \"abc\" \n  append s2 \"def$s\" \n  append [set s"
  Cmds 4, src 64, inst 38, litObjs 3, aux 0, stkDepth 2, code/src 0.00
  Proc 0x02E76898, refCt 1, args 1, compiled locals 2
      slot 0, scalar, arg, "s"
      slot 1, scalar, "s2"
  Commands 4:
      1: pc 0-4, src 3-17   	   2: pc 5-22, src 21-38
      3: pc 23-36, src 42-62   	   4: pc 32-33, src 50-55
  Command 1: "append s \"abc\" "
    (0) push1 0 	# "abc"
    (2) appendScalar1 %v0 	# var "s"
    (4) pop 
  Command 2: "append s2 \"def$s\" "
    (5) startCommand +17 1 	# next cmd at pc 22
    (14) push1 1 	# "def"
    (16) loadScalar1 %v0 	# var "s"
    (18) concat1 2 
    (20) appendScalar1 %v1 	# var "s2"
    (22) pop 
  Command 3: "append [set s2] \"hij\""
    (23) startCommand +14 2 	# next cmd at pc 37, 2 cmds start here
  Command 4: "set s2"
    (32) loadScalar1 %v1 	# var "s2"
    (34) push1 2 	# "hij"
    (36) appendStk 
    (37) done

tcl::unsupported::assemble

TODO

标签： tcltk