1 files changed, 10 insertions, 0 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
index 18a2b2fdbfe..45cacc73d63 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
@@ -325,6 +325,16 @@ Value *InstCombiner::SimplifyDemandedUseBits(Value *V, APInt DemandedMask,
       unsigned CTZ = DemandedMask.countTrailingZeros();
       if (match(RHS, m_APInt(C)) && CTZ >= C->getActiveBits())
         return LHS;
+    } else if (SPF == SPF_UMIN) {
+      // UMin(A, C) == A if ...
+      // The lowest non-zero bit of DemandMask is higher than the highest
+      // non-one bit of C.
+      // This comes from using DeMorgans on the above umax example.
+      const APInt *C;
+      unsigned CTZ = DemandedMask.countTrailingZeros();
+      if (match(RHS, m_APInt(C)) &&
+          CTZ >= C->getBitWidth() - C->countLeadingOnes())
+        return LHS;
     }
 
     // If this is a select as part of any other min/max pattern, don't simplify