[PATCH] D86815: [LangRef] Remove non-overlapping guarantee from memcpy.

[Richard Smith - zygoloid via Phabricator via llvm-commits]

rsmith added a comment.

In D86815#2245467 <https://reviews.llvm.org/D86815#2245467>, @arsenm wrote:

> In D86815#2245466 <https://reviews.llvm.org/D86815#2245466>, @arsenm wrote:
>
>> Why would we change this? What's the point of having separate memcpy and memmove intrinsics?
>
> I'm reading this as clang mis-uses llvm.memcpy when it probably should be using llvm.memmove

There is a longstanding assumption made by ~every compiler that `memcpy(p, p, n)` is safe. That's what we should be encoding here. We should not be removing all overlap restrictions.


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https://reviews.llvm.org/D86815