[llvm] b556ce3 - [IR] adjust assert when replacing undef elements in vector constant

[Sanjay Patel via llvm-commits]

Author: Sanjay Patel
Date: 2019-11-04T10:05:24-05:00
New Revision: b556ce3992709e1f6302ca1d4c296f57e83cd6a7

URL: https://github.com/llvm/llvm-project/commit/b556ce3992709e1f6302ca1d4c296f57e83cd6a7
DIFF: https://github.com/llvm/llvm-project/commit/b556ce3992709e1f6302ca1d4c296f57e83cd6a7.diff

LOG: [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.

Added: 
    

Modified: 
    llvm/lib/IR/Constants.cpp

Removed: 
    


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diff  --git a/llvm/lib/IR/Constants.cpp b/llvm/lib/IR/Constants.cpp
index eb40b291b005..a6a8eaac2f94 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;
   }