[PATCH] D49837: [SelectionDAG] Handle unary SelectPatternFlavor for ABS case in SelectionDAGBuilder::visitSelect.

[Sanjay Patel via Phabricator via llvm-commits]

spatel added inline comments.


================
Comment at: lib/Analysis/ValueTracking.cpp:4856
       // (-X >s 0) ? -X : X or (-X >s -1) ? -X : X --> ABS(X)
-      if (Pred == ICmpInst::ICMP_SGT && match(CmpRHS, ZeroOrAllOnes))
+      if ((Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SGE) && match(CmpRHS, ZeroOrAllOnes))
         return {SPF_ABS, SPNB_NA, false};
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This is saying that:
X >= -1 ? X : -X 
...is an abs(). But that's not correct:
https://rise4fun.com/Alive/eVzs

This diff should be split into its own patch and include correctness tests. Preferably, the tests can go in:
llvm/unittests/Analysis/ValueTrackingTest.cpp


Repository:
  rL LLVM

https://reviews.llvm.org/D49837