Debug Info: Modified DIBuilder::createCompileUnit() to take DIFile instead of FileName and Directory. (Clang part)

[aaboud]

Summary

Changed DIBuilder::createCompileUnit() to take DIFile instead of FileName and Directory.
This way it will be easier to expand DIFile (e.g., to contain checksum) without the need to modify the createCompileUnit() API.

lib/CodeGen/CGDebugInfo.cpp

void CGDebugInfo::CreateCompileUnit() {
   case codegenoptions::FullDebugInfo:
     EmissionKind = llvm::DICompileUnit::FullDebug;
     break;
   }
 
   // Create new compile unit.
   // FIXME - Eliminate TheCU.
   TheCU = DBuilder.createCompileUnit(
-      LangTag, remapDIPath(MainFileName), remapDIPath(getCurrentDirname()),
+      LangTag, DBuilder.createFile(remapDIPath(MainFileName),
+                                    remapDIPath(getCurrentDirname())),
       Producer, LO.Optimize, CGM.getCodeGenOpts().DwarfDebugFlags, RuntimeVers,
       CGM.getCodeGenOpts().SplitDwarfFile, EmissionKind, 0 /* DWOid */,
       CGM.getCodeGenOpts().SplitDwarfInlining);
 }
 
 llvm::DIType *CGDebugInfo::CreateType(const BuiltinType *BT) {
   llvm::dwarf::TypeKind Encoding;
   StringRef BTName;
CGDebugInfo::getOrCreateModuleRef(ExternalASTSource::ASTSourceDescriptor Mod,
   }
 
   bool IsRootModule = M ? !M->Parent : true;
   if (CreateSkeletonCU && IsRootModule) {
     // PCH files don't have a signature field in the control block,
     // but LLVM detects skeleton CUs by looking for a non-zero DWO id.
     uint64_t Signature = Mod.getSignature() ? Mod.getSignature() : ~1ULL;
     llvm::DIBuilder DIB(CGM.getModule());
-    DIB.createCompileUnit(TheCU->getSourceLanguage(), Mod.getModuleName(),
-                          Mod.getPath(), TheCU->getProducer(), true,
-                          StringRef(), 0, Mod.getASTFile(),
-                          llvm::DICompileUnit::FullDebug, Signature);
+    DIB.createCompileUnit(TheCU->getSourceLanguage(),
+                          DIB.createFile(Mod.getModuleName(), Mod.getPath()),
+                          TheCU->getProducer(), true, StringRef(), 0,
+                          Mod.getASTFile(), llvm::DICompileUnit::FullDebug,
+                          Signature);
     DIB.finalize();
   }
   llvm::DIModule *Parent =
       IsRootModule ? nullptr
                    : getOrCreateModuleRef(
                          ExternalASTSource::ASTSourceDescriptor(*M->Parent),
                          CreateSkeletonCU);
   llvm::DIModule *DIMod =