BBVectorize: Correctly merge SubclassOptionalData

When two instructions are combined into a vector instruction,
the resulting instruction must have the most-conservative flags.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@168765 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/Vectorize/BBVectorize.cpp

@@ -2903,6 +2903,7 @@ namespace {
         K->mutateType(getVecTypeForPair(L->getType(), H->getType()));
 
       combineMetadata(K, H);
+      K->intersectOptionalDataWith(H);
 
       for (unsigned o = 0; o < NumOperands; ++o)
         K->setOperand(o, ReplacedOperands[o]);