[PATCH] D91415: [InstCombine] add multi-use demanded bits fold for add with low-bit mask
Simon Pilgrim via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Fri Nov 13 09:07:45 PST 2020
RKSimon added inline comments.
================
Comment at: llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp:838
+ // just return the add's variable operand.
+ if ((*C & LowMask).isNullValue())
+ return I->getOperand(0);
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We could technically support non-uniform vectors here by matching m_Constant and using a similar ConstantExpr fold.
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Comment at: llvm/test/Transforms/InstCombine/and.ll:1052
+; Multi-use demanded bits - 'add' doesn't change 'and'
+
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Vector tests?
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D91415/new/
https://reviews.llvm.org/D91415
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