It is possible that main input file does not have any symbol with debug info. To handle this edge case, always create main compile unit first.

This fixes PR 4228.

llvm-svn: 73520

2 files changed, 43 insertions, 21 deletions

diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
index 049e716c7c1..1f17692a1d5 100644
--- a/clang/lib/CodeGen/CGDebugInfo.cpp
+++ b/clang/lib/CodeGen/CGDebugInfo.cpp
@@ -50,6 +50,24 @@ void CGDebugInfo::setLocation(SourceLocation Loc) {
 /// getOrCreateCompileUnit - Get the compile unit from the cache or create a new
 /// one if necessary. This returns null for invalid source locations.
 llvm::DICompileUnit CGDebugInfo::getOrCreateCompileUnit(SourceLocation Loc) {
+
+  // Each input file is encoded as a separate compile unit in LLVM
+  // debugging information output. However, many target specific tool chains
+  // prefer to encode only one compile unit in an object file. In this 
+  // situation, the LLVM code generator will include  debugging information
+  // entities in the compile unit that is marked as main compile unit. The 
+  // code generator accepts maximum one main compile unit per module. If a
+  // module does not contain any main compile unit then the code generator 
+  // will emit multiple compile units in the output object file. Create main
+  // compile unit if there is not one available.
+  const LangOptions &LO = M->getLangOptions();
+  if (isMainCompileUnitCreated == false) {
+    if (LO.getMainFileName()) {
+      createCompileUnit(LO.getMainFileName(), true /* isMain */);
+      isMainCompileUnitCreated = true;
+    }
+  }
+
   // Get source file information.
   const char *FileName =  "<unknown>";
   SourceManager &SM = M->getContext().getSourceManager();
@@ -72,25 +90,26 @@ llvm::DICompileUnit CGDebugInfo::getOrCreateCompileUnit(SourceLocation Loc) {
     AbsFileName = tmp;
   }
 
-  // See if thie compile unit is representing main source file. Each source
-  // file has corresponding compile unit. There is only one main source
-  // file at a time.
-  bool isMain = false;
-  const LangOptions &LO = M->getLangOptions();
-  const char *MainFileName = LO.getMainFileName();
-  if (isMainCompileUnitCreated == false) {
-    if (MainFileName) {
-      if (!strcmp(AbsFileName.getLast().c_str(), MainFileName))
-        isMain = true;
-    } else {
-      if (Loc.isValid() && SM.isFromMainFile(Loc))
-        isMain = true;
-    }
-    if (isMain)
-      isMainCompileUnitCreated = true;
+  // There is only one main source file at a time whose compile unit
+  // is already created.
+  Unit = createCompileUnit(FileName, false /* isMain */);
+  return Unit;
+}
+
+/// createCompileUnit - Create a new unit for the given file.
+llvm::DICompileUnit CGDebugInfo::createCompileUnit(const char *FileName,
+                                                   bool isMain) {
+
+  // Get absolute path name.
+  llvm::sys::Path AbsFileName(FileName);
+  if (!AbsFileName.isAbsolute()) {
+    llvm::sys::Path tmp = llvm::sys::Path::GetCurrentDirectory();
+    tmp.appendComponent(FileName);
+    AbsFileName = tmp;
   }
 
   unsigned LangTag;
+  const LangOptions &LO = M->getLangOptions();
   if (LO.CPlusPlus) {
     if (LO.ObjC1)
       LangTag = llvm::dwarf::DW_LANG_ObjC_plus_plus;
@@ -114,12 +133,13 @@ llvm::DICompileUnit CGDebugInfo::getOrCreateCompileUnit(SourceLocation Loc) {
     RuntimeVers = LO.ObjCNonFragileABI ? 2 : 1;
   
   // Create new compile unit.
-  return Unit = DebugFactory.CreateCompileUnit(LangTag, AbsFileName.getLast(),
-                                               AbsFileName.getDirname(), 
-                                               Producer, isMain, isOptimized,
-                                               Flags, RuntimeVers);
+  return DebugFactory.CreateCompileUnit(LangTag, AbsFileName.getLast(),
+                                        AbsFileName.getDirname(), 
+                                        Producer, isMain, isOptimized,
+                                        Flags, RuntimeVers);
 }
 
+
 /// CreateType - Get the Basic type from the cache or create a new
 /// one if necessary.
 llvm::DIType CGDebugInfo::CreateType(const BuiltinType *BT,
diff --git a/clang/lib/CodeGen/CGDebugInfo.h b/clang/lib/CodeGen/CGDebugInfo.h
index de655800fa0..8f3368e4ebf 100644
--- a/clang/lib/CodeGen/CGDebugInfo.h
+++ b/clang/lib/CodeGen/CGDebugInfo.h
@@ -111,7 +111,9 @@ private:
   void EmitDeclare(const VarDecl *decl, unsigned Tag, llvm::Value *AI,
                    CGBuilderTy &Builder);
   
-  
+  /// createCompileUnit - Create a new unit for the given file.
+  llvm::DICompileUnit createCompileUnit(const char *FileName, bool isMain);
+
   /// getOrCreateCompileUnit - Get the compile unit from the cache or create a
   /// new one if necessary.
   llvm::DICompileUnit getOrCreateCompileUnit(SourceLocation Loc);