Index: llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
===================================================================
--- llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
+++ llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
@@ -2499,7 +2499,11 @@
            "trying to erase instruction with users.");
     Pair.getFirst()->eraseFromParent();
   }
-  LLVM_DEBUG(verifyFunction(*F));
+#ifdef EXPENSIVE_CHECKS
+  // If we could guarantee that this call is not extremely slow, we could
+  // remove the ifdef limitation (see PR47712).
+  assert(!verifyFunction(*F, %dbgs()));
+#endif
 }
 
 void BoUpSLP::eraseInstructions(ArrayRef<Value *> AV) {