This is the mail archive of the
mailing list for the GCC project.
Re: Shouldn't unsafe-math-optimizations (re-)enable fp-contract=fast?
- From: Tim Prince <n8tm at aol dot com>
- To: gcc at gcc dot gnu dot org
- Date: Thu, 06 Mar 2014 13:39:37 -0500
- Subject: Re: Shouldn't unsafe-math-optimizations (re-)enable fp-contract=fast?
- Authentication-results: sourceware.org; auth=none
- References: <000001cf395b$7eab81d0$7c028570$ at email@example.com> <Pine dot LNX dot 4 dot 64 dot 1403061800380 dot 19817 at digraph dot polyomino dot org dot uk>
- Reply-to: tprince at computer dot org
On 3/6/2014 1:01 PM, Joseph S. Myers wrote:
I do see an improvement in several benchmarks by use of fma when I
append -ffp-contract=fast after -std=c99
On Thu, 6 Mar 2014, Ian Bolton wrote:
I see in common.opt that fp-contract=fast is the default for GCC.
But then it gets disabled in c-family/c-opts.c if you are using ISO C
(e.g. with -std=c99).
But surely if you have also specified -funsafe-math-optimizations then
it should flip it back onto fast?
That seems reasonable.