Don't segfault in EmitCXXGlobalInitFunc when main file is a membuf

Summary: When the main file is created from a membuffer, there is no file entry that can be retrieved. This uses "__GLOBAL_I_a" in that case which is what was always used before r208128.

Reviewers: majnemer, thakis

Reviewed By: thakis

Subscribers: yaron.keren, rsmith, cfe-commits

Differential Revision: http://reviews.llvm.org/D5043

llvm-svn: 216495

1 files changed, 12 insertions, 6 deletions

diff --git a/clang/lib/CodeGen/CGDeclCXX.cpp b/clang/lib/CodeGen/CGDeclCXX.cpp
index 94cfe211601..af5919c157f 100644
--- a/clang/lib/CodeGen/CGDeclCXX.cpp
+++ b/clang/lib/CodeGen/CGDeclCXX.cpp
@@ -409,19 +409,25 @@ CodeGenModule::EmitCXXGlobalInitFunc() {
       AddGlobalCtor(Fn, Priority);
     }
   }
-  
-  // Include the filename in the symbol name. Including "sub_" matches gcc and
-  // makes sure these symbols appear lexicographically behind the symbols with
-  // priority emitted above.
+
+  SmallString<128> FileName;
   SourceManager &SM = Context.getSourceManager();
-  SmallString<128> FileName(llvm::sys::path::filename(
-      SM.getFileEntryForID(SM.getMainFileID())->getName()));
+  if (const FileEntry *MainFile = SM.getFileEntryForID(SM.getMainFileID())) {
+    // Include the filename in the symbol name. Including "sub_" matches gcc and
+    // makes sure these symbols appear lexicographically behind the symbols with
+    // priority emitted above.
+    FileName = llvm::sys::path::filename(MainFile->getName());
+  } else {
+    FileName = SmallString<128>("<null>");
+  }
+
   for (size_t i = 0; i < FileName.size(); ++i) {
     // Replace everything that's not [a-zA-Z0-9._] with a _. This set happens
     // to be the set of C preprocessing numbers.
     if (!isPreprocessingNumberBody(FileName[i]))
       FileName[i] = '_';
   }
+
   llvm::Function *Fn = CreateGlobalInitOrDestructFunction(
       *this, FTy, llvm::Twine("_GLOBAL__sub_I_", FileName));