[IR] adjust assert when replacing undef elements in vector constant

As noted in follow-up to:
rGa1e8ad4f2fa7

It's not safe to assume that an element of the constant is always
non-null. It's definitely not an expected case for the current
instcombine user, but that may not hold if this function is
eventually called from arbitrary places.

1 files changed, 1 insertions, 1 deletions

diff --git a/llvm/lib/IR/Constants.cpp b/llvm/lib/IR/Constants.cpp
index eb40b291b00..a6a8eaac2f9 100644
--- a/llvm/lib/IR/Constants.cpp
+++ b/llvm/lib/IR/Constants.cpp
@@ -611,7 +611,7 @@ Constant *Constant::replaceUndefsWith(Constant *C, Constant *Replacement) {
   SmallVector<Constant *, 32> NewC(NumElts);
   for (unsigned i = 0; i != NumElts; ++i) {
     Constant *EltC = C->getAggregateElement(i);
-    assert(EltC->getType() == Replacement->getType() &&
+    assert((!EltC || EltC->getType() == Replacement->getType()) &&
            "Expected matching types");
     NewC[i] = EltC && match(EltC, m_Undef()) ? Replacement : EltC;
   }