{"push_id":2728296330,"size":1,"distinct_size":1,"ref":"refs/heads/master","head":"1cd41cb270935f71ca45d7d356bffe77dece8dcc","before":"0c246047310c779463c64a7d864d32b5879559ad","commits":[{"sha":"1cd41cb270935f71ca45d7d356bffe77dece8dcc","author":{"name":"Roman Lebedev","email":"c247390a474ba78064f3a5ec8d0ca3a56d88a36b@gmail.com"},"message":"[InstCombine] Re-commit: Fold 'check for [no] signed truncation' pattern\n\nSummary:\n[[ https://bugs.llvm.org/show_bug.cgi?id=38149 | PR38149 ]]\n\nAs discussed in https://reviews.llvm.org/D49179#1158957 and later,\nthe IR for 'check for [no] signed truncation' pattern can be improved:\nhttps://rise4fun.com/Alive/gBf\n^ that pattern will be produced by Implicit Integer Truncation sanitizer,\nhttps://reviews.llvm.org/D48958 https://bugs.llvm.org/show_bug.cgi?id=21530\nin signed case, therefore it is probably a good idea to improve it.\n\nThe DAGCombine will reverse this transform, see\nhttps://reviews.llvm.org/D49266\n\nThis transform is surprisingly frustrating.\nThis does not deal with non-splat shift amounts, or with undef shift amounts.\nI've outlined what i think the solution should be:\n```\n  // Potential handling of non-splats: for each element:\n  //  * if both are undef, replace with constant 0.\n  //    Because (1<<0) is OK and is 1, and ((1<<0)>>1) is also OK and is 0.\n  //  * if both are not undef, and are different, bailout.\n  //  * else, only one is undef, then pick the non-undef one.\n```\n\nThis is a re-commit, as the original patch, committed in rL337190\nwas reverted in rL337344 as it broke chromium build:\nhttps://bugs.llvm.org/show_bug.cgi?id=38204 and\nhttps://crbug.com/864832\nProofs that the fixed folds are ok: https://rise4fun.com/Alive/VYM\n\nDifferential Revision: https://reviews.llvm.org/D49320\n\ngit-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@337376 91177308-0d34-0410-b5e6-96231b3b80d8","distinct":true,"url":"https://api.github.com/repos/llvm-project/llvm/commits/1cd41cb270935f71ca45d7d356bffe77dece8dcc"}]}
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