New submission from Neal Norwitz:
>>> def fo():
... if a:
... if b:
... if c:
... print
...
>>> dis.dis(fo)
2 0 LOAD_GLOBAL 0 (a)
3 POP_JUMP_IF_FALSE 28
3 6 LOAD_GLOBAL 1 (b)
9 POP_JUMP_IF_FALSE 28
4 12 LOAD_GLOBAL 2 (c)
15 POP_JUMP_IF_FALSE 25
5 18 PRINT_NEWLINE
19 JUMP_ABSOLUTE 25
22 JUMP_ABSOLUTE 28
>> 25 JUMP_FORWARD 0 (to 28)
>> 28 LOAD_CONST 0 (None)
31 RETURN_VALUE
The 2 JUMP_ABSOLUTEs should be optimized away since the code is equivalent to:
if a and b and c: as in:
>>> dis.dis(fo)
2 0 LOAD_GLOBAL 0 (a)
3 POP_JUMP_IF_FALSE 22
6 LOAD_GLOBAL 1 (b)
9 POP_JUMP_IF_FALSE 22
12 LOAD_GLOBAL 2 (c)
15 POP_JUMP_IF_FALSE 22
3 18 PRINT_NEWLINE
19 JUMP_FORWARD 0 (to 22)
>> 22 LOAD_CONST 0 (None)
25 RETURN_VALUE
----------
messages: 184245
nosy: Neal.Norwitz
priority: normal
severity: normal
status: open
title: missed peephole optimization
type: performance
versions: Python 2.7
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Python tracker <[email protected]>
<http://bugs.python.org/issue17430>
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