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[InstCombine] Failure to simplify (~A|B)^A --> ~(A&B) #51860

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jayfoad opened this issue Nov 16, 2021 · 1 comment
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[InstCombine] Failure to simplify (~A|B)^A --> ~(A&B) #51860

jayfoad opened this issue Nov 16, 2021 · 1 comment
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bugzilla Issues migrated from bugzilla llvm:optimizations

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@jayfoad
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jayfoad commented Nov 16, 2021

Bugzilla Link 52518
Version trunk
OS Linux
CC @RKSimon,@rotateright

Extended Description

InstCombine should simplify (~A|B)^A --> ~(A&B).

Here's CompilerExplorer showing that (a) the transformation is valid according to Alive2, and (b) "opt -O2" does not do it:
https://alive2.llvm.org/ce/#z:OYLghAFBqd5QCxAYwPYBMCmBRdBLAF1QCcAaPECAM1QDsCBlZAQwBtMQBGAFlICsupVs1qhWrAG4BbUgGdM7ZATx1KmWugDCqVgFcptLgFZS69ABk8tTADl9AI0zEQAdlIAHVLMIra2vQbGHl4%2BdJbWdlKOzm7yisp0DATMxAT%2B%2BoacJnGYSr5JKQThtg5OrnLJqemBWRWFxZHRrgCUcqi6xMgcAORYVFaYANR43IMAAgTABBAjgwCkAExGAAykw6OLRpzNg6yoLKwA%2Brq0tMxSmOiHzOjoxPMLAMzL8y4AQnPLAIL29iCfX0GDyMC3mjwAIoMROh1sDOGtNssAUDNo8wZCAB4kWGbBZrAC0nGRg2ImAIOKWjwBcxc4IBfQGsLGsk6Mw2S1WFK2Oz2B2Op3Ol2ut3ui2erw%2B31%2B/2%2BKKWoLmEMGWPus0RBKJsuBaMVkOxavlCKWmsBwI2SpVXMeRpWxNJ5INRm41NpAO6rVYIG6Rm6pEM3WWvtQXvM5gAagBZQYASQASoNZO1OkMxZxfQQvYHmq0ANYgFZCL3cX3%2BwOkYPdX2yECrDMB92kOCwGCIFCoKTuPDsMgUCBoDtdsqodwEUj9VgEJzViB/eukexWFIATy9adI/Yu9AA8rRWCu51gpCJgOxM778KS8hJMNW55gMbldJPV76rJPPXPWHh7MRl9osC%2BpAEMQeBSC%2BrQ0PQTBsBwPD8IIwiiCA4jSEI37VpArTDgktC3viW4LFWCi5DhagaNUmSmBoDSlM48KeN4OEUYIDGhLQNFRGU8I5HkiSVGkOgZIIPE4QUqQcU03H8cxUn1AMjRca0iYdF0XAel6Pp%2Bme5ZethgwQLghDYqmazaAO3YPI82yDKGkYxrG6ZntmpAIJgNxlBAub5qsH7FqQYEFqWQZelWNZAU5jYthASD9p23bkJQsWDs4bB4NeY5dpOxDTrOZYLmcxD7muG7qAQO57tph7HqeB54JeyjXreZb3o%2Bz7dGub4KNpX4/n%2BGA9GuwGgeBY50IwBywbwAh4ohYiSDIPUYZ55Yjr4t5EfEvhkVogk1FRFjybRLEhExu2UaxOESVxcjEbxtBiQJASUSJ%2BT8VddF1FUZ3CW9h2cXRSlJqp2yFt6JbaRWqXXviBASPphlEKKTzwoMZlxU4lkLDstlRnGjn1s5rnuc4y2%2Bb6AWrEFOmVnIYV1lmXkFh%2Bjzg3OFb4wzoOEVpbMheFBOtNe2VbdwQA%3D%3D%3D
@llvmbot llvmbot transferred this issue from llvm/llvm-bugzilla-archive Dec 11, 2021
@RKSimon
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RKSimon commented Feb 12, 2022

Fixed by D114339 / c572eb1

@RKSimon RKSimon closed this as completed Feb 12, 2022
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@jayfoad @RKSimon @EugeneZelenko