[Python-Dev] Re: Re: Re: Prospective Peephole Transformation (original) (raw)

Fredrik Lundh fredrik at pythonware.com
Fri Feb 18 18:12:50 CET 2005

Phillip J. Eby wrote:

here's the disassembly: FYI, that's not a dissassembly of what timeit was actually timing; see 'template' in timeit.py. As a practical matter, the only difference would probably be the use of LOADFAST instead of LOADNAME, as timeit runs the code in a function body.

def f1(a): ... if a in (1, 2, 3): ... pass ... def f2(a): ... if a == 1 or a == 2 or a == 3: ... pass ... dis.dis(f1) 2 0 LOAD_FAST 0 (a) 3 LOAD_CONST 4 ((1, 2, 3)) 6 COMPARE_OP 6 (in) 9 JUMP_IF_FALSE 4 (to 16) 12 POP_TOP 3 13 JUMP_FORWARD 1 (to 17) 16 POP_TOP 17 LOAD_CONST 0 (None) 20 RETURN_VALUE

dis.dis(f2) 2 0 LOAD_FAST 0 (a) 3 LOAD_CONST 1 (1) 6 COMPARE_OP 2 (==) 9 JUMP_IF_TRUE 26 (to 38) 12 POP_TOP 13 LOAD_FAST 0 (a) 16 LOAD_CONST 2 (2) 19 COMPARE_OP 2 (==) 22 JUMP_IF_TRUE 13 (to 38) 25 POP_TOP 26 LOAD_FAST 0 (a) 29 LOAD_CONST 3 (3) 32 COMPARE_OP 2 (==) 35 JUMP_IF_FALSE 4 (to 42) 38 POP_TOP 3 39 JUMP_FORWARD 1 (to 43) 42 POP_TOP 43 LOAD_CONST 0 (None) 46 RETURN_VALUE

Still, it's rather interesting that tuple.contains appears slower than a series of LOADCONST and "==" operations, considering that the tuple should be doing basically the same thing, only without bytecode fetch-and-decode overhead. Maybe it's tuple.contains that needs optimizing here?

wouldn't be the first time...

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