[PATCH] D45616: [X86] Lower _mm[256|512]_cmp[.]_mask intrinsics to native llvm IR
Eli Friedman via Phabricator via cfe-commits
cfe-commits at lists.llvm.org
Thu Nov 8 14:38:11 PST 2018
efriedma added a comment.
Yes, in constrained-fp mode we might need intrinsics, at least short-term. I assume you'll probably add target-independent constrained masked fp vector operations at some point, but that's probably not a priority. But that still leaves two problems. One, clang doesn't currently have any flag that actually makes sense to control this. (I assume it will be added soon, but it doesn't exist yet.) I mean, it's technically possible to gate it under one of the fast-math flags, like @nastafev suggested, but that's not semantically correct. And two, the removed intrinsics didn't have the right semantics for constrained-fp mode anyway: they were marked readnone. So we need new intrinsics anyway.
So yes, it's possible we could revert this patch, and that might fix @nastafev's code for the next few months, but it doesn't help us at all in terms of making constrained fp work correctly in general.
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