[Modules] Resolve top-headers of modules lazily.

This allows resolving top-header filenames of modules to FileEntries when
we need them, not eagerly.

Note that that this breaks ABI for libclang functions
clang_Module_getTopLevelHeader / clang_Module_getNumTopLevelHeaders
but this is fine because they are experimental and not widely used yet.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@176975 91177308-0d34-0410-b5e6-96231b3b80d8

5 files changed, 23 insertions, 9 deletions

diff --git a/lib/Basic/Module.cpp b/lib/Basic/Module.cpp
index 65deac1b4a..f074391098 100644
--- a/lib/Basic/Module.cpp
+++ b/lib/Basic/Module.cpp
@@ -15,6 +15,7 @@
 #include "clang/Basic/FileManager.h"
 #include "clang/Basic/LangOptions.h"
 #include "clang/Basic/TargetInfo.h"
+#include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringSwitch.h"
 #include "llvm/Support/ErrorHandling.h"
@@ -129,6 +130,19 @@ const DirectoryEntry *Module::getUmbrellaDir() const {
   return Umbrella.dyn_cast<const DirectoryEntry *>();
 }
 
+ArrayRef<const FileEntry *> Module::getTopHeaders(FileManager &FileMgr) {
+  if (!TopHeaderNames.empty()) {
+    for (std::vector<std::string>::iterator
+           I = TopHeaderNames.begin(), E = TopHeaderNames.end(); I != E; ++I) {
+      if (const FileEntry *FE = FileMgr.getFile(*I))
+        TopHeaders.insert(FE);
+    }
+    TopHeaderNames.clear();
+  }
+
+  return llvm::makeArrayRef(TopHeaders.begin(), TopHeaders.end());
+}
+
 void Module::addRequirement(StringRef Feature, const LangOptions &LangOpts,
                             const TargetInfo &Target) {
   Requires.push_back(Feature);
diff --git a/lib/Frontend/FrontendActions.cpp b/lib/Frontend/FrontendActions.cpp
index 965e762d79..f3466f0234 100644
--- a/lib/Frontend/FrontendActions.cpp
+++ b/lib/Frontend/FrontendActions.cpp
@@ -173,12 +173,12 @@ static void collectModuleHeaderIncludes(const LangOptions &LangOpts,
   // Add includes for each of these headers.
   for (unsigned I = 0, N = Module->Headers.size(); I != N; ++I) {
     const FileEntry *Header = Module->Headers[I];
-    Module->TopHeaders.insert(Header);
+    Module->addTopHeader(Header);
     addHeaderInclude(Header, Includes, LangOpts);
   }
 
   if (const FileEntry *UmbrellaHeader = Module->getUmbrellaHeader()) {
-    Module->TopHeaders.insert(UmbrellaHeader);
+    Module->addTopHeader(UmbrellaHeader);
     if (Module->Parent) {
       // Include the umbrella header for submodules.
       addHeaderInclude(UmbrellaHeader, Includes, LangOpts);
@@ -203,7 +203,7 @@ static void collectModuleHeaderIncludes(const LangOptions &LangOpts,
       if (const FileEntry *Header = FileMgr.getFile(Dir->path())) {
         if (ModMap.isHeaderInUnavailableModule(Header))
           continue;
-        Module->TopHeaders.insert(Header);
+        Module->addTopHeader(Header);
       }
       
       // Include this header umbrella header for submodules.
diff --git a/lib/Lex/ModuleMap.cpp b/lib/Lex/ModuleMap.cpp
index 81cb94de51..f9b4e2c947 100644
--- a/lib/Lex/ModuleMap.cpp
+++ b/lib/Lex/ModuleMap.cpp
@@ -202,7 +202,7 @@ Module *ModuleMap::findModuleForHeader(const FileEntry *File) {
                            llvm::sys::path::stem(File->getName()), NameBuf);
         Result = findOrCreateModule(Name, Result, /*IsFramework=*/false,
                                     Explicit).first;
-        Result->TopHeaders.insert(File);
+        Result->addTopHeader(File);
         
         // If inferred submodules export everything they import, add a 
         // wildcard to the set of exports.
diff --git a/lib/Serialization/ASTReader.cpp b/lib/Serialization/ASTReader.cpp
index 93ae6f1c44..54fe424ddf 100644
--- a/lib/Serialization/ASTReader.cpp
+++ b/lib/Serialization/ASTReader.cpp
@@ -3546,9 +3546,7 @@ bool ASTReader::ReadSubmoduleBlock(ModuleFile &F) {
       if (!CurrentModule)
         break;
 
-      // FIXME: Be more lazy about this!
-      if (const FileEntry *File = PP.getFileManager().getFile(Blob))
-        CurrentModule->TopHeaders.insert(File);
+      CurrentModule->addTopHeaderFilename(Blob);
       break;
     }
 
diff --git a/lib/Serialization/ASTWriter.cpp b/lib/Serialization/ASTWriter.cpp
index 815cf12f11..8f48d5870a 100644
--- a/lib/Serialization/ASTWriter.cpp
+++ b/lib/Serialization/ASTWriter.cpp
@@ -2170,11 +2170,13 @@ void ASTWriter::WriteSubmodules(Module *WritingModule) {
       Stream.EmitRecordWithBlob(ExcludedHeaderAbbrev, Record, 
                                 Mod->ExcludedHeaders[I]->getName());
     }
-    for (unsigned I = 0, N = Mod->TopHeaders.size(); I != N; ++I) {
+    ArrayRef<const FileEntry *>
+      TopHeaders = Mod->getTopHeaders(PP->getFileManager());
+    for (unsigned I = 0, N = TopHeaders.size(); I != N; ++I) {
       Record.clear();
       Record.push_back(SUBMODULE_TOPHEADER);
       Stream.EmitRecordWithBlob(TopHeaderAbbrev, Record,
-                                Mod->TopHeaders[I]->getName());
+                                TopHeaders[I]->getName());
     }
 
     // Emit the imports.