[PATCH] D63782: [FPEnv] Add fptosi and fptoui constrained intrinsics

[Eli Friedman via Phabricator via llvm-commits]

efriedma added a comment.

> Is this a general comment or referring to a change in Kevin's patch?

It's a question about the semantics of the proposed llvm.experimental.constrained.fptosi/llvm.experimental.constrained.fptoui.  Specifically, what does it do when the result is larger than the largest integer representable in the destination format?  LangRef for fptoui/fptosi says "If the value cannot fit in ty2, the result is a poison value."

> Unless I'm misunderstanding, we should be leaving the constrained converts alone until a hardware instruction is produced.

We have to define the semantics; I mean, I guess we could say "If the value cannot fit in the destination type, the result is computed in a target-specific way", but we'd have to state it explicitly.  And it's sort of awkward.


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  rL LLVM

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  https://reviews.llvm.org/D63782/new/

https://reviews.llvm.org/D63782