[PATCH] D91576: [MemCpyOpt] Bail on call slot optimization if it merges alias scopes

[Jeroen Dobbelaere via Phabricator via llvm-commits]

jeroen.dobbelaere added a comment.

Hi Modi,

Following line in your input example is wrong and explains why the resulting alias info is corrupt:

> call void @llvm.memcpy.p0i8.p0i8.i64(i8* align 8 %tmp, i8* align 8 %src, i64 1, i1 false), !alias.scope !1

It should be !alias.scope !0

Given that, it does not change the result of the alias analysis which indeed seems to be wrong. It seems the 'union' should only be allowed if the domains match (and maybe not just for this case ?)

I would propose as solution to not 'merge' the !alias.scope in this case, but to:

- keep it if it is identical on both memcpy
- throw it away if it is not identical

Note to self: check why this should not be a problem with the full restrict patches (which does not use !alias.scope).


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https://reviews.llvm.org/D91576