If SI->size() is 0, we are not allowed to dereference ->begin().

This fixed PR3078.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@59416 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/IPO/ArgumentPromotion.cpp

@@ -565,9 +565,11 @@ Function *ArgPromotion::DoPromotion(Function *F,
       // Add a parameter to the function for each element passed in.
       for (ScalarizeTable::iterator SI = ArgIndices.begin(),
              E = ArgIndices.end(); SI != E; ++SI) {
+        unsigned num = SI->size();
+        // not allowed to dereference ->begin() if size() is 0
         Params.push_back(GetElementPtrInst::getIndexedType(I->getType(),
-                                                           &*SI->begin(),
-                                                           SI->size()));
+                                                           num ? &*SI->begin(): 0,
+                                                           num));
         assert(Params.back());
       }