[InstCombine] Fix issue with X udiv (POW2_C1 << N) for non-splat constant vectors

foldUDivShl was assuming that the input was a scalar or a splat constant

llvm-svn: 324613

1 files changed, 6 insertions, 4 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
index 9efc797d464..9bbabd9203b 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
@@ -1081,12 +1081,14 @@ static Instruction *foldUDivShl(Value *Op0, Value *Op1, const BinaryOperator &I,
   if (!match(Op1, m_ZExt(m_Value(ShiftLeft))))
     ShiftLeft = Op1;
 
-  const APInt *CI;
+  Constant *CI;
   Value *N;
-  if (!match(ShiftLeft, m_Shl(m_APInt(CI), m_Value(N))))
+  if (!match(ShiftLeft, m_Shl(m_Constant(CI), m_Value(N))))
     llvm_unreachable("match should never fail here!");
-  if (*CI != 1)
-    N = IC.Builder.CreateAdd(N, ConstantInt::get(N->getType(), CI->logBase2()));
+  Constant *Log2Base = getLogBase2(N->getType(), CI);
+  if (!Log2Base)
+    llvm_unreachable("getLogBase2 should never fail here!");
+  N = IC.Builder.CreateAdd(N, Log2Base);
   if (Op1 != ShiftLeft)
     N = IC.Builder.CreateZExt(N, Op1->getType());
   BinaryOperator *LShr = BinaryOperator::CreateLShr(Op0, N);