1 files changed, 10 insertions, 0 deletions
diff --git a/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp b/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
index 35a0bbb..2a7182f 100644
--- a/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
+++ b/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
@@ -462,6 +462,16 @@ Instruction *InstCombiner::visitUDiv(BinaryOperator &I) {
     }
   }
 
+  // (x lshr C1) udiv C2 --> x udiv (C2 << C1)
+  if (ConstantInt *C2 = dyn_cast<ConstantInt>(Op1)) {
+    Value *X;
+    ConstantInt *C1;
+    if (match(Op0, m_LShr(m_Value(X), m_ConstantInt(C1)))) {
+      APInt NC = C2->getValue().shl(C1->getLimitedValue(C1->getBitWidth()-1));
+      return BinaryOperator::CreateUDiv(X, Builder->getInt(NC));
+    }
+  }
+
   // X udiv (C1 << N), where C1 is "1<<C2"  -->  X >> (N+C2)
   { const APInt *CI; Value *N;
     if (match(Op1, m_Shl(m_Power2(CI), m_Value(N))) ||