https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89071
--- Comment #22 from Peter Cordes <peter at cordes dot ca> --- Nice, that's exactly the kind of thing I suggested in bug 80571. If this covers * vsqrtss/sd (mem),%merge_into, %xmm * vpcmpeqd %same,%same, %dest # false dep on KNL / Silvermont * vcmptrueps %same,%same, %ymm # splat -1 without AVX2. false dep on all known uarches as well as int->FP conversions, then we could probably close that as fixed by this as well. bug 80571 does suggest that we could look for any cold reg, like a non-zero constant, instead of requiring an xor-zeroed vector, so it might go slightly beyond what this patch does. And looking for known-to-be-ready dead regs from earlier in the same dep chain could certainly be useful for non-AVX code-gen, allowing us to copy-and-sqrt without introducing a dependency on anything that's not already ready. (In reply to h...@gcc.gnu.org from comment #21) > Author: hjl > Date: Fri Feb 22 15:54:08 2019 > New Revision: 269119
