Don't try to call getFileCharacteristic if the function declaration has an invalid source location (as is the case for the global allocation functions.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@72671 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/Mangle.cpp b/lib/CodeGen/Mangle.cpp
index c09a13a..6ee1223 100644
--- a/lib/CodeGen/Mangle.cpp
+++ b/lib/CodeGen/Mangle.cpp
@@ -93,8 +93,9 @@
              !Context.getLangOptions().CPlusPlus ||
              // "main" is not mangled in C++
              FD->isMain() ||
-             // No mangling in an "implicit extern C" header.
-             Context.getSourceManager().getFileCharacteristic(FD->getLocation())
+             // No mangling in an "implicit extern C" header. 
+             (FD->getLocation().isValid() && 
+              Context.getSourceManager().getFileCharacteristic(FD->getLocation()))
                == SrcMgr::C_ExternCSystem ||
              // No name mangling in a C linkage specification.
              isInCLinkageSpecification(FD))