[clang][modules] NFCI: Scaffolding for serialization of adjusted SourceManager offsets

[jansvoboda11]

Summary

This patch is a NFC prep for D136624, where we start adjusting offsets into SourceManager.

Depends on D137213.

[dexonsmith]

LGTM.

clang/include/clang/Serialization/ASTWriter.h

private:
 
   /// A list of the module file extension writers.
   std::vector<std::unique_ptr<ModuleFileExtensionWriter>>
       ModuleFileExtensionWriters;
 
   /// User ModuleMaps skipped when writing control block.
   std::set<const FileEntry *> SkippedModuleMaps;
 
+  /// Returns an adjusted \c FileID, accounting for any non-affecting input
+  /// files.
+  FileID getAdjustedFileID(FileID FID) const;
+  /// Returns an adjusted number of \c FileIDs created within the specified \c
+  /// FileID, accounting for any non-affecting input files.
+  unsigned getAdjustedNumCreatedFIDs(FileID FID) const;
+  /// Returns an adjusted \c SourceLocation, accounting for any non-affecting
+  /// input files.
+  SourceLocation getAdjustedLocation(SourceLocation Loc) const;
+  /// Returns an adjusted \c SourceRange, accounting for any non-affecting input
+  /// files.
+  SourceRange getAdjustedRange(SourceRange Range) const;
+  /// Returns an adjusted \c SourceLocation offset, accounting for any
+  /// non-affecting input files.
+  SourceLocation::UIntTy getAdjustedOffset(SourceLocation::UIntTy Offset) const;
+
   /// Retrieve or create a submodule ID for this module.
   unsigned getSubmoduleID(Module *Mod);
 
   /// Write the given subexpression to the bitstream.
   void WriteSubStmt(Stmt *S);
 
   void WriteBlockInfoBlock();
   void WriteControlBlock(Preprocessor &PP, ASTContext &Context,

clang/lib/Serialization/ASTWriter.cpp

if (SLoc->isFile()) {
       } else
         Code = SM_SLOC_BUFFER_ENTRY;
     } else
       Code = SM_SLOC_EXPANSION_ENTRY;
     Record.clear();
     Record.push_back(Code);
 
     // Starting offset of this entry within this module, so skip the dummy.
-    Record.push_back(SLoc->getOffset() - 2);
+    Record.push_back(getAdjustedOffset(SLoc->getOffset()) - 2);
     if (SLoc->isFile()) {
       const SrcMgr::FileInfo &File = SLoc->getFile();
       const SrcMgr::ContentCache *Content = &File.getContentCache();
       if (Content->OrigEntry && !SkippedModuleMaps.empty() &&
           SkippedModuleMaps.find(Content->OrigEntry) !=
               SkippedModuleMaps.end()) {
         // Do not emit files that were not listed as inputs.
         continue;
       }
       AddSourceLocation(File.getIncludeLoc(), Record);
       Record.push_back(File.getFileCharacteristic()); // FIXME: stable encoding
       Record.push_back(File.hasLineDirectives());
 
       bool EmitBlob = false;
       if (Content->OrigEntry) {
         assert(Content->OrigEntry == Content->ContentsEntry &&
                "Writing to AST an overridden file is not supported");
 
         // The source location entry is a file. Emit input file ID.
         assert(InputFileIDs[Content->OrigEntry] != 0 && "Missed file entry");
         Record.push_back(InputFileIDs[Content->OrigEntry]);
 
-        Record.push_back(File.NumCreatedFIDs);
+        Record.push_back(getAdjustedNumCreatedFIDs(FID));
 
         FileDeclIDsTy::iterator FDI = FileDeclIDs.find(FID);
         if (FDI != FileDeclIDs.end()) {
           Record.push_back(FDI->second->FirstDeclIndex);
           Record.push_back(FDI->second->DeclIDs.size());
         } else {
           Record.push_back(0);
           Record.push_back(0);
if (SLoc->isFile()) {
                             : Expansion.getExpansionLocEnd(),
                         Record, Seq);
       Record.push_back(Expansion.isExpansionTokenRange());
 
       // Compute the token length for this macro expansion.
       SourceLocation::UIntTy NextOffset = SourceMgr.getNextLocalOffset();
       if (I + 1 != N)
         NextOffset = SourceMgr.getLocalSLocEntry(I + 1).getOffset();
-      Record.push_back(NextOffset - SLoc->getOffset() - 1);
+      Record.push_back(getAdjustedOffset(NextOffset - SLoc->getOffset()) - 1);
       Stream.EmitRecordWithAbbrev(SLocExpansionAbbrv, Record);
     }
   }
 
   Stream.ExitBlock();
 
   if (SLocEntryOffsets.empty())
     return;
 
   // Write the source-location offsets table into the AST block. This
   // table is used for lazily loading source-location information.
   using namespace llvm;
 
   auto Abbrev = std::make_shared<BitCodeAbbrev>();
   Abbrev->Add(BitCodeAbbrevOp(SOURCE_LOCATION_OFFSETS));
   Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 16)); // # of slocs
   Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 16)); // total size
   Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 32)); // base offset
   Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob)); // offsets
   unsigned SLocOffsetsAbbrev = Stream.EmitAbbrev(std::move(Abbrev));
   {
     RecordData::value_type Record[] = {
         SOURCE_LOCATION_OFFSETS, SLocEntryOffsets.size(),
-        SourceMgr.getNextLocalOffset() - 1 /* skip dummy */,
+        getAdjustedOffset(SourceMgr.getNextLocalOffset()) - 1 /* skip dummy */,
         SLocEntryOffsetsBase - SourceManagerBlockOffset};
     Stream.EmitRecordWithBlob(SLocOffsetsAbbrev, Record,
                               bytes(SLocEntryOffsets));
   }
   // Write the source location entry preloads array, telling the AST
   // reader which source locations entries it should load eagerly.
   Stream.EmitRecord(SOURCE_LOCATION_PRELOADS, PreloadSLocs);
 
for (PreprocessingRecord::iterator E = PPRec.local_begin(),
                                   EEnd = PPRec.local_end();
        E != EEnd;
        (void)++E, ++NumPreprocessingRecords, ++NextPreprocessorEntityID) {
     Record.clear();
 
     uint64_t Offset = Stream.GetCurrentBitNo() - MacroOffsetsBase;
     assert((Offset >> 32) == 0 && "Preprocessed entity offset too large");
     PreprocessedEntityOffsets.push_back(
-        PPEntityOffset((*E)->getSourceRange(), Offset));
+        PPEntityOffset(getAdjustedRange((*E)->getSourceRange()), Offset));
 
     if (auto *MD = dyn_cast<MacroDefinitionRecord>(*E)) {
       // Record this macro definition's ID.
       MacroDefinitions[MD] = NextPreprocessorEntityID;
 
       AddIdentifierRef(MD->getName(), Record);
       Stream.EmitRecord(PPD_MACRO_DEFINITION, Record);
       continue;
if (!FileIDAndFile.first.isValid() ||
         !FileIDAndFile.second.HasLocalTransitions)
       continue;
     ++NumLocations;
 
     AddFileID(FileIDAndFile.first, Record);
 
     Record.push_back(FileIDAndFile.second.StateTransitions.size());
     for (auto &StatePoint : FileIDAndFile.second.StateTransitions) {
-      Record.push_back(StatePoint.Offset);
+      Record.push_back(getAdjustedOffset(StatePoint.Offset));
       AddDiagState(StatePoint.State, false);
     }
   }
 
   // Backpatch the number of locations.
   Record[NumLocationsIdx] = NumLocations;
 
   // Emit CurDiagStateLoc.  Do it last in order to match source order.

 }
 
 void ASTWriter::AddAlignPackInfo(const Sema::AlignPackInfo &Info,
                                  RecordDataImpl &Record) {
   uint32_t Raw = Sema::AlignPackInfo::getRawEncoding(Info);
   Record.push_back(Raw);
 }
 
+FileID ASTWriter::getAdjustedFileID(FileID FID) const {
+  // TODO: Actually adjust this.
+  return FID;
+}
+
+unsigned ASTWriter::getAdjustedNumCreatedFIDs(FileID FID) const {
+  // TODO: Actually adjust this.
+  return PP->getSourceManager()
+      .getLocalSLocEntry(FID.ID)
+      .getFile()
+      .NumCreatedFIDs;
+}
+
+SourceLocation ASTWriter::getAdjustedLocation(SourceLocation Loc) const {
+  // TODO: Actually adjust this.
+  return Loc;
+}
+
+SourceRange ASTWriter::getAdjustedRange(SourceRange Range) const {
+  // TODO: Actually adjust this.
+  return Range;
+}
+
+SourceLocation::UIntTy
+ASTWriter::getAdjustedOffset(SourceLocation::UIntTy Offset) const {
+  // TODO: Actually adjust this.
+  return Offset;
+}
+
 void ASTWriter::AddFileID(FileID FID, RecordDataImpl &Record) {
-  Record.push_back(FID.getOpaqueValue());
+  Record.push_back(getAdjustedFileID(FID).getOpaqueValue());
 }
 
 void ASTWriter::AddSourceLocation(SourceLocation Loc, RecordDataImpl &Record,
                                   SourceLocationSequence *Seq) {
+  Loc = getAdjustedLocation(Loc);
   Record.push_back(SourceLocationEncoding::encode(Loc, Seq));
 }
 
 void ASTWriter::AddSourceRange(SourceRange Range, RecordDataImpl &Record,
                                SourceLocationSequence *Seq) {
   AddSourceLocation(Range.getBegin(), Record, Seq);
   AddSourceLocation(Range.getEnd(), Record, Seq);
 }

clang/lib/Serialization/ASTWriterDecl.cpp

void ASTWriter::WriteDecl(ASTContext &Context, Decl *D) {
 
   // Emit this declaration to the bitstream.
   uint64_t Offset = W.Emit(D);
 
   // Record the offset for this declaration
   SourceLocation Loc = D->getLocation();
   unsigned Index = ID - FirstDeclID;
   if (DeclOffsets.size() == Index)
-    DeclOffsets.emplace_back(Loc, Offset, DeclTypesBlockStartOffset);
+    DeclOffsets.emplace_back(getAdjustedLocation(Loc), Offset,
+                             DeclTypesBlockStartOffset);
   else if (DeclOffsets.size() < Index) {
     // FIXME: Can/should this happen?
     DeclOffsets.resize(Index+1);
-    DeclOffsets[Index].setLocation(Loc);
+    DeclOffsets[Index].setLocation(getAdjustedLocation(Loc));
     DeclOffsets[Index].setBitOffset(Offset, DeclTypesBlockStartOffset);
   } else {
     llvm_unreachable("declarations should be emitted in ID order");
   }
 
   SourceManager &SM = Context.getSourceManager();
   if (Loc.isValid() && SM.isLocalSourceLocation(Loc))
     associateDeclWithFile(D, ID);