This is the mail archive of the
gcc-bugs@gcc.gnu.org
mailing list for the GCC project.
[Bug middle-end/69845] [4.9/5/6 Regression] Expression getting incorrectly optimized after being rewritten by compiler
- From: "pinskia at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Tue, 16 Feb 2016 21:55:19 +0000
- Subject: [Bug middle-end/69845] [4.9/5/6 Regression] Expression getting incorrectly optimized after being rewritten by compiler
- Auto-submitted: auto-generated
- References: <bug-69845-4 at http dot gcc dot gnu dot org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69845
--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Jakub Jelinek from comment #4)
> regressed at -O2 with r204454.
That just points to the -O2 regression, -O1 would have happened at a different
point as VRP is enabled at -O2 and above.
I suspect doing distribution of 1207142401 * ... is the original cause of the
problem. The main reason is because (((8 * B) + 9483541) - 230968044) is 1
without any overflow but with distribution, B * 1067204616 overflows right
away.