[PATCH] D91415: [InstCombine] add multi-use demanded bits fold for add with low-bit mask

[Sanjay Patel via Phabricator via llvm-commits]

spatel marked an inline comment as done.
spatel added inline comments.


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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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RKSimon wrote:
> We could technically support non-uniform vectors here by matching m_Constant and using a similar ConstantExpr fold.
Ok - I didn't see any signs that we had tried non-uniform in this file yet. Do you think we should do that in this patch or as a TODO/follow-up?


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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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RKSimon wrote:
> Vector tests?
Basic splat is the last (positive) test.


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  https://reviews.llvm.org/D91415/new/

https://reviews.llvm.org/D91415