Add a function to ExternalASTSource that returns a descriptor that

abstracts the commonalities between modules and PCH files that are
needed to emit debug info for a module or precompiled header.

llvm-svn: 241083

3 files changed, 43 insertions, 1 deletions

diff --git a/clang/lib/AST/ExternalASTSource.cpp b/clang/lib/AST/ExternalASTSource.cpp
index 730842a28f6..1c82c355134 100644
--- a/clang/lib/AST/ExternalASTSource.cpp
+++ b/clang/lib/AST/ExternalASTSource.cpp
@@ -22,6 +22,16 @@ using namespace clang;
 
 ExternalASTSource::~ExternalASTSource() { }
 
+llvm::Optional<ExternalASTSource::ASTSourceDescriptor>
+ExternalASTSource::getSourceDescriptor(unsigned ID) {
+  return None;
+}
+
+ExternalASTSource::ASTSourceDescriptor
+ExternalASTSource::getSourceDescriptor(const Module &M) {
+  return ASTSourceDescriptor();
+}
+
 void ExternalASTSource::FindFileRegionDecls(FileID File, unsigned Offset,
                                             unsigned Length,
                                             SmallVectorImpl<Decl *> &Decls) {}
diff --git a/clang/lib/Basic/Module.cpp b/clang/lib/Basic/Module.cpp
index 7308665bd2d..1a48a6c6a8d 100644
--- a/clang/lib/Basic/Module.cpp
+++ b/clang/lib/Basic/Module.cpp
@@ -27,7 +27,7 @@ using namespace clang;
 Module::Module(StringRef Name, SourceLocation DefinitionLoc, Module *Parent,
                bool IsFramework, bool IsExplicit, unsigned VisibilityID)
     : Name(Name), DefinitionLoc(DefinitionLoc), Parent(Parent), Directory(),
-      Umbrella(), ASTFile(nullptr), VisibilityID(VisibilityID),
+      Umbrella(), Signature(0), ASTFile(nullptr), VisibilityID(VisibilityID),
       IsMissingRequirement(false), IsAvailable(true), IsFromModuleFile(false),
       IsFramework(IsFramework), IsExplicit(IsExplicit), IsSystem(false),
       IsExternC(false), IsInferred(false), InferSubmodules(false),
diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index 5e5999d5bf9..48a898cb30d 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -4269,6 +4269,7 @@ ASTReader::ReadSubmoduleBlock(ModuleFile &F, unsigned ClientLoadCapabilities) {
         CurrentModule->setASTFile(F.File);
       }
 
+      CurrentModule->Signature = F.Signature;
       CurrentModule->IsFromModuleFile = true;
       CurrentModule->IsSystem = IsSystem || CurrentModule->IsSystem;
       CurrentModule->IsExternC = IsExternC;
@@ -7366,6 +7367,37 @@ Module *ASTReader::getModule(unsigned ID) {
   return getSubmodule(ID);
 }
 
+ExternalASTSource::ASTSourceDescriptor
+ASTReader::getSourceDescriptor(const Module &M) {
+  StringRef Dir, Filename;
+  if (M.Directory)
+    Dir = M.Directory->getName();
+  if (auto *File = M.getASTFile())
+    Filename = File->getName();
+  return ASTReader::ASTSourceDescriptor{
+             M.getFullModuleName(), Dir, Filename,
+             M.Signature
+         };
+}
+
+llvm::Optional<ExternalASTSource::ASTSourceDescriptor>
+ASTReader::getSourceDescriptor(unsigned ID) {
+  if (const Module *M = getSubmodule(ID))
+    return getSourceDescriptor(*M);
+
+  // If there is only a single PCH, return it instead.
+  // Chained PCH are not suported.
+  if (ModuleMgr.size() == 1) {
+    ModuleFile &MF = ModuleMgr.getPrimaryModule();
+    return ASTReader::ASTSourceDescriptor{
+      MF.OriginalSourceFileName, MF.OriginalDir,
+      MF.FileName,
+      MF.Signature
+    };
+  }
+  return None;
+}
+
 Selector ASTReader::getLocalSelector(ModuleFile &M, unsigned LocalID) {
   return DecodeSelector(getGlobalSelectorID(M, LocalID));
 }