[PATCH] D58560: [AST] Set 'MayAlias' instead of 'MustAlias' in AliasSets for PHI nodes (bugzilla bug#36801)

[Eli Friedman via Phabricator via llvm-commits]

efriedma added a comment.

> What blocked optimizations are you referring to?

This patch blocks store sinking/promotion for any store where the pointer operand is a PHI node, no matter where in the function that PHI node is defined, or when it was created.

> That code in the SSAUpdater seems to not have changed for 7 years, so if that usage causes other bugs, they're very well hidden...

Caching bugs tend to be hard to discover... as shown by the fact nobody found this bug for years either.


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