https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88713
--- Comment #38 from H.J. Lu <hjl.tools at gmail dot com> --- (In reply to rguent...@suse.de from comment #37) > On Wed, 23 Jan 2019, hjl.tools at gmail dot com wrote: > > > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88713 > > > > --- Comment #36 from H.J. Lu <hjl.tools at gmail dot com> --- > > (In reply to Richard Biener from comment #34) > > > GCC definitely fails to see the FMA use as opportunity in > > > ix86_emit_swsqrtsf, the a == 0 checking is because of the missing > > > expander w/o avx512er where we could still use the NR sequence > > > with the other instruction. HJ? > > > > Like this? > > Yes. The lack of an expander for the rqsrt operation is probably > more severe though (causing sqrt + approx recip to appear) > Can we use UNSPEC_RSQRT14 here if UNSPEC_RSQRT28 isn't available?
