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From: "amker at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/100499] Different results with -fpeel-loops
 -ftree-loop-vectorize options
Date: Mon, 17 May 2021 02:17:23 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D100499

--- Comment #9 from bin cheng <amker at gcc dot gnu.org> ---
Seems we have a long standing bug in fold-const.c:multiple_of_p in case of
wrapping types.  Take unsigned int as an example:
  (0xfffffffc * 0x3) % 0x3 =3D 0x1
But multiple_of_p returns true here.

The same issue also stands for MINUS_EXPR and PLUS_EXPR.  Given multiple_of=
_p
is used elsewhere, the fix might break existing optimizations.  Especially,
number of loop iterations is computed in unsigned types=