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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/112312] -O3 produces worse code than -O2 for
 std::ranges::lower_bound in some cases, not marking a loop as finite
Date: Tue, 31 Oct 2023 19:23:13 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D112312

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2023-10-31
     Ever confirmed|0                           |1
            Summary|-O3 produces worse code     |-O3 produces worse code
                   |than -O2 for                |than -O2 for
                   |std::ranges::lower_bound in |std::ranges::lower_bound in
                   |some cases, not removing an |some cases, not marking a
                   |empty loop                  |loop as finite
             Status|UNCONFIRMED                 |NEW

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed.

So further difference is the loop seems not to be marked as finite while wi=
th
-O2 (or the non-lamdba version) is.

Someone will need to figure out if and where we lose the idea of the finite
loopness.=