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From: "rhalbersma at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/113807] New: [performance] bitset::set not using
 memset opportunity
Date: Wed, 07 Feb 2024 12:34:06 +0000
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X-Bugzilla-Product: gcc
X-Bugzilla-Component: libstdc++
X-Bugzilla-Version: 14.0
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D113807

            Bug ID: 113807
           Summary: [performance] bitset::set not using memset opportunity
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: rhalbersma at gmail dot com
  Target Milestone: ---

Conditionally on is_constant_evaluated() being false, bitset::reset delegat=
e to
__builtin_memset(_M_w, 0, _Nw * sizeof(_WordT)) and uses a loop otherwise. =
In
contrast, bitset::set unconditionally has a raw loop.=20

Can't bitset::set also not similarly use __builtin_memset(_M_w, 0xFF, _Nw *
sizeof(_WordT)); when is_constant_evaluated() is false?=