From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugzilla@gcc.gnu.org>
Received: by sourceware.org (Postfix, from userid 48)
	id 0AC453858C31; Mon,  6 May 2024 11:08:43 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 0AC453858C31
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1714993724;
	bh=nHlw9PeOtsYRmSTPEZiEXL7xJvEQJCNIaEdR5+2shkU=;
	h=From:To:Subject:Date:In-Reply-To:References:From;
	b=mtdy+rWw8ZEVYtonnyQVnqNfrehPFwsNDwvootJd4l9AmKS0RpZSUmHkSk630jeb0
	 Dl9JQQ3MI91YeMSdptWA4QabplR+zLC3gzZ09cruH3nuRJj5jNiYj+ywiN4uqOrcNi
	 zzV0ltCRKX5vHCDeBFuAp6izj47n4io2IDjMw52o=
From: "mkretz at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/114958] use __builtin_shufflevector for
 std::experimental::simd split and concat (at least the common cases) to
 enable better optimizations
Date: Mon, 06 May 2024 11:08:43 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: libstdc++
X-Bugzilla-Version: 15.0
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: mkretz at gcc dot gnu.org
X-Bugzilla-Status: ASSIGNED
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: mkretz at gcc dot gnu.org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: 
Message-ID: <bug-114958-4-V27Qgz8EHt@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-114958-4@http.gcc.gnu.org/bugzilla/>
References: <bug-114958-4@http.gcc.gnu.org/bugzilla/>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
MIME-Version: 1.0
List-Id: <gcc-bugs.sourceware.org>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D114958

--- Comment #3 from Matthias Kretz (Vir) <mkretz at gcc dot gnu.org> ---
Hmm, it actually fails on Clang because Clang requires the vector width of =
both
arguments to be equal.

But yes, I guess I should make __vec_shuffle friendlier to non-GCC compiler=
s.
I'm not sure about backporting, maybe GCC 14.2 can get it?

I'd be happy for feedback about my dg-* usage, though. It's the first time I
try to require a certain optimized outcome. I guess it would be better to s=
can
for the shuffle pattern rather than the selected instruction? I'm a noob on
that topic.=