[Bug tree-optimization/19224] [4.0 regression] Endless loop compiling simple file: Bug in tree-scalar-evolution.c (instantiate_parameters_1)?
sebastian dot pop at cri dot ensmp dot fr
gcc-bugzilla@gcc.gnu.org
Sun Jan 2 21:46:00 GMT 2005
------- Additional Comments From sebastian dot pop at cri dot ensmp dot fr 2005-01-02 21:46 -------
(In reply to comment #7)
> Subject: Re: [4.0 regression] Endless loop compiling simple file: Bug in
tree-scalar-evolution.c (instantiate_parameters_1)?
>
> not really (well, maybe in this particular case, but not in general).
> Your patch definitely helps (and you should submit it anyway), but
> yhe problem is that even with your patch it may happen that
> instantiate_parameters is called recursively several times for one
> ssa name if the expression contains it several times, and if this
> happens for several expressions in a row, you get the exponential
> complexity. I am just testing the patch below that caches the results
> to avoid this problem.
>
Richtig. I'm just speeding the chrec_dont_know case, whereas your patch
solves the more general problem of huge expressions that have to be
instantiated and that don't necessarily lead to unknown evolutions.
Thanks.
PS: I'll test my patch separately and will post it to gcc-patches.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19224
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