From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 2181) id 65511386480A; Thu, 15 Feb 2024 11:44:28 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 65511386480A DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1707997468; bh=FN5orTzhh9+0xupvzBxjE8XPQcSdkrhxPP2cM/p1/JQ=; h=From:To:Subject:Date:From; b=lL8ikqWVHBAGK3TkTL4IhMKVt8f4IloqTlhcJsbBHc3qLZbpboja72AzZFLPeX/Xt GEEjIds9AVJGAxLDHot60lE6tIPpLMQLYWJi9l4i7Ye5r6BW2RWLcxB9wqIUxsBDFR 3vfENe44Ww/yiKxgEYuYO1fUMHTn+DXD8IY2eX8M= MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="utf-8" From: Jonathan Wakely To: gcc-cvs@gcc.gnu.org, libstdc++-cvs@gcc.gnu.org Subject: [gcc r14-9002] libstdc++: Use memset to optimize std::bitset::set() [PR113807] X-Act-Checkin: gcc X-Git-Author: Jonathan Wakely X-Git-Refname: refs/heads/master X-Git-Oldrev: 4d819db7f229a23cb15ef68f310e0bb51d201c45 X-Git-Newrev: e7ae13a858f36031b8fd3aa07362752ff2b19b2e Message-Id: <20240215114428.65511386480A@sourceware.org> Date: Thu, 15 Feb 2024 11:44:28 +0000 (GMT) List-Id: https://gcc.gnu.org/g:e7ae13a858f36031b8fd3aa07362752ff2b19b2e commit r14-9002-ge7ae13a858f36031b8fd3aa07362752ff2b19b2e Author: Jonathan Wakely Date: Thu Feb 8 15:46:08 2024 +0000 libstdc++: Use memset to optimize std::bitset::set() [PR113807] As pointed out in the PR we already do this for reset(). libstdc++-v3/ChangeLog: PR libstdc++/113807 * include/std/bitset (bitset::set()): Use memset instead of a loop over the individual words. Diff: --- libstdc++-v3/include/std/bitset | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/libstdc++-v3/include/std/bitset b/libstdc++-v3/include/std/bitset index 3243c6497314..16c4040f532f 100644 --- a/libstdc++-v3/include/std/bitset +++ b/libstdc++-v3/include/std/bitset @@ -177,8 +177,15 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER _GLIBCXX14_CONSTEXPR void _M_do_set() _GLIBCXX_NOEXCEPT { - for (size_t __i = 0; __i < _Nw; __i++) - _M_w[__i] = ~static_cast<_WordT>(0); +#if __cplusplus >= 201402L + if (__builtin_is_constant_evaluated()) + { + for (_WordT& __w : _M_w) + __w = ~static_cast<_WordT>(0);; + return; + } +#endif + __builtin_memset(_M_w, 0xFF, _Nw * sizeof(_WordT)); } _GLIBCXX14_CONSTEXPR void