[issue6690] BUILD_SET followed by COMPARE_OP (in) can be optimized if all items are consts
Dave Malcolm
report at bugs.python.org
Tue Jan 12 20:36:22 CET 2010
Dave Malcolm <dmalcolm at redhat.com> added the comment:
Attaching a probably over-simplistic attempt at this patch, against the py3k branch.
This patch attempts to extend the replacement of
LOAD_CONST, ...., LOAD_CONST, BUILD_LIST, COMPARE_OP(in)
with
LOAD_CONST(tuple), COMPAREOP(in)
so that it also replaces:
LOAD_CONST, ...., LOAD_CONST, BUILD_SET, COMPARE_OP(in)
with
LOAD_CONST(tuple), COMPAREOP(in)
i.e. using a tuple, not a frozenset (on the grounds that the "in" conditions should at least still work); caveat: I'm relatively new to the innards of this code.
With this patch:
>>> dis.dis(lambda o: o in {1,2,3})
1 0 LOAD_FAST 0 (o)
3 LOAD_CONST 3 ((1, 2, 3))
6 COMPARE_OP 6 (in)
9 RETURN_VALUE
but:
>>> dis.dis(lambda o: o in {1,2,3,3,2,1})
1 0 LOAD_FAST 0 (o)
3 LOAD_CONST 3 ((1, 2, 3, 3, 2, 1))
6 COMPARE_OP 6 (in)
9 RETURN_VALUE
Is it worth me working on a rewrite to use a frozenset.
Hope this is helpful
Dave
----------
keywords: +patch
nosy: +dmalcolm
Added file: http://bugs.python.org/file15840/simple-optimization-of-BUILD_SET-COMPARE_OP(IN)-to-LOAD_CONST(tuple)_COMPARE_OP(IN)-py3k.patch
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