[Constant] add undef element query for vector constants; NFC

This is likely to be used in D48987 and similar patches, 
so adding it as an NFC preliminary step.

llvm-svn: 336442

1 files changed, 10 insertions, 0 deletions

diff --git a/llvm/lib/IR/Constants.cpp b/llvm/lib/IR/Constants.cpp
index 3ea7598c11e..032793effed 100644
--- a/llvm/lib/IR/Constants.cpp
+++ b/llvm/lib/IR/Constants.cpp
@@ -254,6 +254,16 @@ bool Constant::isNaN() const {
   return true;
 }
 
+bool Constant::containsUndefElement() const {
+  if (!getType()->isVectorTy())
+    return false;
+  for (unsigned i = 0, e = getType()->getVectorNumElements(); i != e; ++i)
+    if (isa<UndefValue>(getAggregateElement(i)))
+      return true;
+
+  return false;
+}
+
 /// Constructor to create a '0' constant of arbitrary type.
 Constant *Constant::getNullValue(Type *Ty) {
   switch (Ty->getTypeID()) {