IRBuilder: add an assertion that checks if we try to get a debug loc from ->end();

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185952 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/IR/IRBuilder.h

@@ -90,6 +90,7 @@ public:
   void SetInsertPoint(Instruction *I) {
     BB = I->getParent();
     InsertPt = I;
+    assert(I != BB->end() && "Can't read debug loc from end()");
     SetCurrentDebugLocation(I->getDebugLoc());
   }