[llvm-dev] valid BasicAA behavior?

Michael Kruse via llvm-dev llvm-dev at lists.llvm.org
Wed Mar 18 14:42:41 PDT 2020

As far

Am Mi., 18. März 2020 um 11:34 Uhr schrieb Chawla, Pankaj
<pankaj.chawla at intel.com>:
> >> There seems to be a bug in DI, see Felipe's answer.
> Maybe I missed something. There seems to be no resolution to the problem. How can DA fix this without help from alias analysis?

DependenceInfo is not using the AA interface correctly. Either DI has
to be fixed, or another method added to AA that gives additional
guarantees. Please see the bug report for details.

> >> Since aliasPHI looks for any incoming value contradicting the NoAlias assumption, it would be equivalant to always return MayAlias.
> I pasted the code snippet below with some extra comments.

As far as the AA interface specification is concerned, the NoAlias
result is correct. Such a patch would be a pessimization without
giving any additional guarantees.


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