Fix header-search problems with precompiled headers, where the

presence or absence of header map arguments when using the precompiled
header would cause Clang to get confused about which headers had
already been included/imported, along with their controlling
macros. The fundamental problem is that the serialization of the
header search information was relying on the UIDs of FileEntry objects
at PCH generation time and PCH load time to be equivalent, which
effectively means that we had to probe the same files in the same
order. Differing header map arguments caused an extra FileEntry
lookup, but it's easy to imagine other minor command-line arguments
triggering this problem.

Header-search information is now encoded along with the
source-location entry for a file, so that we register information
about a file's properties as a header at the same time we create the
FileEntry for that file.

Fixes <rdar://problem/7743243>.

llvm-svn: 98636

clang/include/clang/Frontend/PCHBitCodes.h

@@ -245,10 +245,7 @@ namespace clang {
       SM_SLOC_INSTANTIATION_ENTRY = 4,
       /// \brief Describes the SourceManager's line table, with
       /// information about #line directives.
-      SM_LINE_TABLE = 5,
-      /// \brief Describes one header file info [isImport, DirInfo, NumIncludes]
-      /// ControllingMacro is optional.
-      SM_HEADER_FILE_INFO = 6
+      SM_LINE_TABLE = 5
     };
 
     /// \brief Record types used within a preprocessor block.

clang/include/clang/Frontend/PCHReader.h

@@ -106,7 +106,7 @@ public:
   }
 
   /// \brief Receives a HeaderFileInfo entry.
-  virtual void ReadHeaderFileInfo(const HeaderFileInfo &HFI) {}
+  virtual void ReadHeaderFileInfo(const HeaderFileInfo &HFI, unsigned ID) {}
 
   /// \brief Receives __COUNTER__ value.
   virtual void ReadCounter(unsigned Value) {}
@@ -130,7 +130,7 @@ public:
                                     FileID PCHBufferID,
                                     llvm::StringRef OriginalFileName,
                                     std::string &SuggestedPredefines);
-  virtual void ReadHeaderFileInfo(const HeaderFileInfo &HFI);
+  virtual void ReadHeaderFileInfo(const HeaderFileInfo &HFI, unsigned ID);
   virtual void ReadCounter(unsigned Value);
 };
 

clang/include/clang/Lex/HeaderSearch.h

@@ -214,9 +214,10 @@ public:
 
   void IncrementFrameworkLookupCount() { ++NumFrameworkLookups; }
 
-  typedef std::vector<HeaderFileInfo>::iterator header_file_iterator;
-  header_file_iterator header_file_begin() { return FileInfo.begin(); }
-  header_file_iterator header_file_end() { return FileInfo.end(); }
+  typedef std::vector<HeaderFileInfo>::const_iterator header_file_iterator;
+  header_file_iterator header_file_begin() const { return FileInfo.begin(); }
+  header_file_iterator header_file_end() const { return FileInfo.end(); }
+  unsigned header_file_size() const { return FileInfo.size(); }
 
   // Used by PCHReader.
   void setHeaderFileInfoForUID(HeaderFileInfo HFI, unsigned UID);

clang/lib/Frontend/PCHReader.cpp

@@ -300,8 +300,10 @@ bool PCHValidator::ReadPredefinesBuffer(llvm::StringRef PCHPredef,
   return false;
 }
 
-void PCHValidator::ReadHeaderFileInfo(const HeaderFileInfo &HFI) {
-  PP.getHeaderSearchInfo().setHeaderFileInfoForUID(HFI, NumHeaderInfos++);
+void PCHValidator::ReadHeaderFileInfo(const HeaderFileInfo &HFI,
+                                      unsigned ID) {
+  PP.getHeaderSearchInfo().setHeaderFileInfoForUID(HFI, ID);
+  ++NumHeaderInfos;
 }
 
 void PCHValidator::ReadCounter(unsigned Value) {
@@ -850,17 +852,6 @@ PCHReader::PCHReadResult PCHReader::ReadSourceManagerBlock() {
         return Failure;
       break;
 
-    case pch::SM_HEADER_FILE_INFO: {
-      HeaderFileInfo HFI;
-      HFI.isImport = Record[0];
-      HFI.DirInfo = Record[1];
-      HFI.NumIncludes = Record[2];
-      HFI.ControllingMacroID = Record[3];
-      if (Listener)
-        Listener->ReadHeaderFileInfo(HFI);
-      break;
-    }
-
     case pch::SM_SLOC_FILE_ENTRY:
     case pch::SM_SLOC_BUFFER_ENTRY:
     case pch::SM_SLOC_INSTANTIATION_ENTRY:
@@ -918,6 +909,14 @@ PCHReader::PCHReadResult PCHReader::ReadSLocEntryRecord(unsigned ID) {
       const_cast<SrcMgr::FileInfo&>(SourceMgr.getSLocEntry(FID).getFile())
         .setHasLineDirectives();
 
+    // Reconstruct header-search information for this file.
+    HeaderFileInfo HFI;
+    HFI.isImport = Record[4];
+    HFI.DirInfo = Record[5];
+    HFI.NumIncludes = Record[6];
+    HFI.ControllingMacroID = Record[7];
+    if (Listener)
+      Listener->ReadHeaderFileInfo(HFI, File->getUID());
     break;
   }
 

clang/lib/Frontend/PCHWriter.cpp

@@ -573,7 +573,6 @@ void PCHWriter::WriteBlockInfoBlock() {
   RECORD(SM_SLOC_BUFFER_BLOB);
   RECORD(SM_SLOC_INSTANTIATION_ENTRY);
   RECORD(SM_LINE_TABLE);
-  RECORD(SM_HEADER_FILE_INFO);
 
   // Preprocessor Block.
   BLOCK(PREPROCESSOR_BLOCK);
@@ -918,6 +917,11 @@ static unsigned CreateSLocFileAbbrev(llvm::BitstreamWriter &Stream) {
   Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // Include location
   Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 2)); // Characteristic
   Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // Line directives
+  // HeaderFileInfo fields.
+  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // isImport
+  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 2)); // DirInfo
+  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // NumIncludes
+  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // ControllingMacro
   Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob)); // File name
   return Stream.EmitAbbrev(Abbrev);
 }
@@ -1019,20 +1023,6 @@ void PCHWriter::WriteSourceManagerBlock(SourceManager &SourceMgr,
     Stream.EmitRecord(pch::SM_LINE_TABLE, Record);
   }
 
-  // Write out entries for all of the header files we know about.
-  HeaderSearch &HS = PP.getHeaderSearchInfo();
-  Record.clear();
-  for (HeaderSearch::header_file_iterator I = HS.header_file_begin(),
-                                          E = HS.header_file_end();
-       I != E; ++I) {
-    Record.push_back(I->isImport);
-    Record.push_back(I->DirInfo);
-    Record.push_back(I->NumIncludes);
-    AddIdentifierRef(I->ControllingMacro, Record);
-    Stream.EmitRecord(pch::SM_HEADER_FILE_INFO, Record);
-    Record.clear();
-  }
-
   // Write out the source location entry table. We skip the first
   // entry, which is always the same dummy entry.
   std::vector<uint32_t> SLocEntryOffsets;
@@ -1069,6 +1059,16 @@ void PCHWriter::WriteSourceManagerBlock(SourceManager &SourceMgr,
         // The source location entry is a file. The blob associated
         // with this entry is the file name.
 
+        // Emit header-search information associated with this file.
+        HeaderFileInfo HFI;
+        HeaderSearch &HS = PP.getHeaderSearchInfo();
+        if (Content->Entry->getUID() < HS.header_file_size())
+          HFI = HS.header_file_begin()[Content->Entry->getUID()];
+        Record.push_back(HFI.isImport);
+        Record.push_back(HFI.DirInfo);
+        Record.push_back(HFI.NumIncludes);
+        AddIdentifierRef(HFI.ControllingMacro, Record);
+
         // Turn the file name into an absolute path, if it isn't already.
         const char *Filename = Content->Entry->getName();
         llvm::sys::Path FilePath(Filename, strlen(Filename));

clang/test/PCH/headermap.h

@@ -0,0 +1,3 @@
+/* Helper for the headermap.m test */
+int x = 17;
+

clang/test/PCH/headermap.m

@@ -0,0 +1,15 @@
+// RUN: touch %t.hmap
+
+// RUN: %clang_cc1 -x objective-c -emit-pch -o %t.h.pch %S/headermap.h
+// RUN: %clang_cc1 -include-pch %t.h.pch %s
+
+// RUN: %clang_cc1 -x objective-c -emit-pch -o %t.h.pch %S/headermap.h
+// RUN: %clang_cc1 -include-pch %t.h.pch -I%t.hmap %s
+
+// RUN: %clang_cc1 -x objective-c -I%t.hmap -emit-pch -o %t.h.pch %S/headermap.h
+// RUN: %clang_cc1 -include-pch %t.h.pch %s
+
+// RUN: %clang_cc1 -x objective-c -I%t.hmap -emit-pch -o %t.h.pch %S/headermap.h
+// RUN: %clang_cc1 -include-pch %t.h.pch -I%t.hmap %s
+#import "headermap.h"
+