IRBuilder can return optimized Value which may not be an instruction.

Added if check to make sure we have an instruction.

Author: rajatbajpai

llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp

@@ -3873,14 +3873,16 @@ Instruction *InstCombinerImpl::visitSelectInst(SelectInst &SI) {
       if (match(&SI, m_OrdOrUnordFMax(m_Value(X), m_Value(Y)))) {
         Value *BinIntr =
             Builder.CreateBinaryIntrinsic(Intrinsic::maxnum, X, Y, &SI);
-        cast<Instruction>(BinIntr)->setHasNoNaNs(FCmp->hasNoNaNs());
+        if (auto *BinIntrInst = dyn_cast<Instruction>(BinIntr))
+          BinIntrInst->setHasNoNaNs(FCmp->hasNoNaNs());
         return replaceInstUsesWith(SI, BinIntr);
       }
 
       if (match(&SI, m_OrdOrUnordFMin(m_Value(X), m_Value(Y)))) {
         Value *BinIntr =
             Builder.CreateBinaryIntrinsic(Intrinsic::minnum, X, Y, &SI);
-        cast<Instruction>(BinIntr)->setHasNoNaNs(FCmp->hasNoNaNs());
+        if (auto *BinIntrInst = dyn_cast<Instruction>(BinIntr))
+          BinIntrInst->setHasNoNaNs(FCmp->hasNoNaNs());
         return replaceInstUsesWith(SI, BinIntr);
       }
     }