[PATCH] D67839: [FPEnv] Document requirement of function attributes with constrained floating point

[Eli Friedman via Phabricator via llvm-commits]

efriedma added a comment.

> Are we certain that there is no architecture important to LLVM that will ever trap when simply doing a move of arbitrary bytes using FP instructions?

strictfp should be enough to imply that the compiler shouldn't implicitly insert FP operations that can raise an exception, on any target.  As it happens, there is one reasonably popular target that can raise an exception on an FP load: x86 without SSE, using x87 floating-point.  But noimplicitfloat shouldn't be necessary there... strictfp should be enough to imply that can't insert x87 loads that aren't immediately used by an arithmetic operation.  (This is probably broken, currently, and probably nobody will ever fix it, but that isn't really relevant.)  No other modern target has similar behavior.


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https://reviews.llvm.org/D67839