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[Bug tree-optimization/32183] Gcc 4.3 revision 125030 miscompiles 482.sphinx3 in SPEC CPU 2006
- From: "rakdver at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 1 Jun 2007 23:13:20 -0000
- Subject: [Bug tree-optimization/32183] Gcc 4.3 revision 125030 miscompiles 482.sphinx3 in SPEC CPU 2006
- References: <bug-32183-682@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #3 from rakdver at gcc dot gnu dot org 2007-06-01 23:13 -------
(In reply to comment #2)
> Is that OK to transform
>
> float sf;
> ...
> sf = 500 * sf;
> for (i = 0; i < ceplen; i++)
> sum[i] *= sf;
>
> to
>
> for (i = 0; i < ceplen; i++)
> sum[i] = (sum[i]* 500)*sf;
>
> You can certainly get the different results when sf is small and sum[i] is
> large.
with -ffast-math, this transformation is ok (although it does not seem to make
sense to do it, it moves a multiplication into a loop).
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32183