[llvm] [ConstraintElim] Handle (X | Y) >=s 0 as X >=s 0 && Y >=s 0. (PR #209743)

[Nikita Popov via llvm-commits]

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@@ -1980,6 +1980,30 @@ static bool eliminateConstraints(Function &F, DominatorTree &DT, LoopInfo &LI,
                                      DFSInStack);
       }
 
+      // (X | Y) >=s 0 implies X >=s 0 and Y >=s 0, because the sign bit of an
+      // OR is the OR of the operand sign bits. Look through this
+      // canonicalization by InstCombine. disjunct so it is available to the
+      // solver.
+      if ((Pred == CmpInst::ICMP_SGE && match(B, m_Zero())) ||
+          (Pred == CmpInst::ICMP_SGT && match(B, m_AllOnes()))) {
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nikic wrote:

sge 0 is non-canonical, do we need to handle it here?

https://github.com/llvm/llvm-project/pull/209743