[PATCH] D77201: [CodeGen][SelectionDAG] Flip Booleans More Often

[Eli Friedman via Phabricator via llvm-commits]

efriedma added a comment.

We have to call getBooleanContents on the vector type, not the vector element type.  On ARM, a boolean in a vector is ZeroOrNegativeOneBooleanContent.  A scalar boolean on its own is ZeroOrOneBooleanContent.  If you choose incorrectly, that's a potential miscompile.  (Not sure why it isn't showing up as a regression test change for other targets; maybe the specific VSELECT pattern in question is rare after legalization.)

Maybe the code should be truncating the APInt before it checks isAllOnesValue(), though.  For a boolean, isOne() and isAllOnesValue() should be equivalent.


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  https://reviews.llvm.org/D77201/new/

https://reviews.llvm.org/D77201