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Re: [PATCH] x86-64: Add FMA multiarch functions to libm
- From: Joseph Myers <joseph at codesourcery dot com>
- To: "H.J. Lu" <hjl dot tools at gmail dot com>
- Cc: GNU C Library <libc-alpha at sourceware dot org>
- Date: Mon, 7 Aug 2017 14:17:01 +0000
- Subject: Re: [PATCH] x86-64: Add FMA multiarch functions to libm
- Authentication-results: sourceware.org; auth=none
- References: <20170806042544.GA11557@gmail.com> <20170806145012.GA15947@gmail.com>
On Sun, 6 Aug 2017, H.J. Lu wrote:
> +# FMA is disabled due to [BZ #19003].
> +CFLAGS-e_pow-fma.c = -mno-fma -mavx2
That's not correct. You should use -mfma -mavx2 $(config-cflags-nofma),
so that fma is used for code explicitly wanting a fused operation (via
DLA_FMS), but not implicitly via contraction.
--
Joseph S. Myers
joseph@codesourcery.com