Bytecode disassemby command, introduced in Tcl 8.5.
Disassembles the bytecode of a procedure, lambda/apply term, general script, etc. and returns the disassembly. The format is formally undefined, but is really an exposure of the disassembler built in since 8.0 when compiling with the correct options and can probably be read by anyone who has ever read any assembly code without much difficulty. Understanding the bytecodes requires reading tclCompile.c and (possibly) tclExecute.c. Will not disassemble anything created by tbcload.
It's unfortunately not at all compatible with the assemble command; the formats are quite different (though the opcodes themselves are the same).
Not present in safe interpreters. This command was developed during the Fourteenth Annual Tcl/Tk Conference (2007).
% proc foo {x} {
for {set y 0} {$y < $x} {incr y} {
puts $x,$y
}
}
% tcl::unsupported::disassemble proc foo
ByteCode 0x0x9a2ec58, refCt 1, epoch 1, interp 0x0x9a377d8 (epoch 1)
Source "\n for {set y 0} {$y < $x} {incr y} {\n puts $x,$y"
Cmds 4, src 61, inst 43, litObjs 4, aux 0, stkDepth 4, code/src 0.00
Proc 0x0x9a48f70, refCt 1, args 1, compiled locals 2
slot 0, scalar, arg, "x"
slot 1, scalar, "y"
Exception ranges 2, depth 1:
0: level 0, loop, pc 7-18, continue 20, break 40
1: level 0, loop, pc 20-31, continue -1, break 40
Commands 4:
1: pc 0-41, src 4-59 2: pc 0-3, src 9-15
3: pc 7-18, src 45-54 4: pc 20-31, src 29-34
Command 1: "for {set y 0} {$y < $x} {incr y} {\n puts $x,$y\n "
Command 2: "set y 0"
(0) push1 0 # "0"
(2) storeScalar1 %v1 # var "y"
(4) pop
(5) jump1 +28 # pc 33
Command 3: "puts $x,$y"
(7) push1 1 # "puts"
(9) loadScalar1 %v0 # var "x"
(11) push1 2 # ","
(13) loadScalar1 %v1 # var "y"
(15) concat1 3
(17) invokeStk1 2
(19) pop
Command 4: "incr y"
(20) startCommand +12 1 # next cmd at pc 32
(29) incrScalar1Imm %v1 +1 # var "y"
(32) pop
(33) loadScalar1 %v1 # var "y"
(35) loadScalar1 %v0 # var "x"
(37) lt
(38) jumpTrue1 -31 # pc 7
(40) push1 3 # ""
(42) done