https://bugs.llvm.org/show_bug.cgi?id=52478
Bug ID: 52478
Summary: [InstCombine] Failure to simplify (A^B)|~A --> ~(A&B)
Product: libraries
Version: trunk
Hardware: PC
OS: Linux
Status: NEW
Severity: enhancement
Priority: P
Component: Scalar Optimizations
Assignee: unassignedb...@nondot.org
Reporter: jay.f...@gmail.com
CC: llvm-bugs@lists.llvm.org
InstCombine should simplify (A^B)|~A --> ~(A&B).
Here's CompilerExplorer showing that (a) the transformation is valid according
to Alive2, and (b) "opt -O3" does not do it:
https://alive2.llvm.org/ce/#z:OYLghAFBqd5QCxAYwPYBMCmBRdBLAF1QCcAaPECAM1QDsCBlZAQwBtMQBGAFlICsupVs1qhWrAG4BbUgGdM7ZATx1KmWugDCqVgFcptQevQAZPLUwA5fQCNMxLrwAOqWYRW1teg4JdvldGYW1lJ2DjxyCphKHgwEzMQEXvqGnJGKAbRxCQRBVrb2jnLxick%2BabIlueb5oYU8AJRyqLrEyBwA5FhUNQDUeNy9AAIEwAQQA70ApABMAKwADKT9g7NznA3TAOwAQlMLAII2NiD7B73T8zPTAMwAIr0i6CuX68trC2cXaze3DwAeJBeaxmywAtJwvr1iJgCMD5jczlMtnczt0%2BpMhrI2hNVvMlvD1ptkXtDsdTodvlc/r1AcRCWlXp9Ka9flN7rSgZMPuDISy1qsOVy8XNQayoTC4dz5twkSizh0mqwQB05h1SIYOgt1agVSYTAA1ACyvQAkgAlXqyFptTCXG6cdUEFXahpNADWIEWQhV3HVmu1pF1HXVshAS2dWsVpDgsBgiBQqCkTjw7DIFAgaGTqcKqCcBFIPVYBHsYYgJyjpBs5gSAE8VY7SFmpOoCAB5WiseuVrBSETAdgu9X4GExCSYMOVzD/aK6EsN9XmEvKyusPA2Yh17RYBekAjEPBSBdNGj0JhsDgRARpYSiEDiaRCddhyBNPOZSdgtszUNRGKqCBjDKVJSGMPIQjCXxXHcOhgKg/wPHAgpwnSaJMmyUodBSQR5AyWIqiQuoUMqHI4IqAiagg%2BommtVp2i4JUVTVDUhyDFV316CBcEIIFZgdZZtGzNN7Q2Xp9WNM1zSdIc3VIBBMGYLAHAgD0vSWFc/VII9vQDHUVVDcM9xkmN4wgJAsxTNNyEoCycwcNg8HHQtUxLYgywrQNq1oOtd2bVsOy7Vje37QcezwUdlHHSdA2nWd5w6RslwUVi1w3LcME6Rt90PY9CzoRgWEHK8QFBW8xEkGRUpfFSg3zDxJ1/PCAKArDylAjRCMgtI/BgzxWpAnrMk6%2BpUP/LIqjI0b0Io4JkJwib%2BvmnJhvCGibXojYfVVf1WODBzxzBAgJE47iiHpPjGUEyz7HtGZNnEk0LWkqNZPkxTChqjT1W0pZdLYkM5EMyNXVU70VxuHbK2DZ6Qa2n8WKh/SjJeppxzcjwQG4IA%3D%3D%3D
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