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Re: [PATCH] x86-64: Compile branred.c with -mprefer-vector-width=128 [BZ #24603]
- From: Florian Weimer <fweimer at redhat dot com>
- To: "H.J. Lu" <hjl dot tools at gmail dot com>
- Cc: Joseph Myers <joseph at codesourcery dot com>, GNU C Library <libc-alpha at sourceware dot org>
- Date: Tue, 11 Jun 2019 18:02:30 +0200
- Subject: Re: [PATCH] x86-64: Compile branred.c with -mprefer-vector-width=128 [BZ #24603]
- References: <CAMe9rOoP_293SM=sYpuqx5Yg9K1a-F9GtN6g0DDFjHTZM5OkcA@mail.gmail.com> <alpine.DEB.2.21.1906101545000.29610@digraph.polyomino.org.uk> <CAMe9rOoyj_b=zWkUgcSKLxPLEuBA0Y9-75v+xqg0yT4HDXy56Q@mail.gmail.com>
* H. J. Lu:
> Fixed. I also added check for -mprefer-vector-width=128 which is new in GCC 8.
> GCC 7 doesn't have this problem since it doesn't vectorize the second loop.
>
> Here is the updated patch.
>
> OK for master?
I still don't understand why we need a workaround for a GCC performance
bug in glibc. Is there any precedent for this?
Thanks,
Florian