[PATCH] D69272: Restricted variant of '#pragma STDC FENV_ACCESS'

[John McCall via Phabricator via cfe-commits]

rjmccall added a comment.

Okay.  If the optimizer cannot correctly handle a mix of constrained and unconstrained FP operations, then the optimizer should protect itself, either by refusing to inline across such boundaries or by adding constraints as necessary before inlining.  If it does that, I don't think it's particularly appropriate for the frontend to warn about the combination of constrained FP and supposedly inlining-related attributes (which only really seems true of `always_inline`).  We should just mention in the documentation that this isn't particularly performant at the moment.

I feel quite confident that we can solve the engineering problem of efficiently figuring out that there's a constrained scope somewhere in a function and therefore we need constrained intrinsics.


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  https://reviews.llvm.org/D69272/new/

https://reviews.llvm.org/D69272