Cherry-picks from upstream llvm.org that make PCH files output path independent

clang/include/clang/Serialization/ASTBitCodes.h

@@ -343,9 +343,6 @@ enum ControlRecordTypes {
   /// name.
   ORIGINAL_FILE,
 
-  /// The directory that the PCH was originally created in.
-  ORIGINAL_PCH_DIR,
-
   /// Record code for file ID of the file or buffer that was used to
   /// generate the AST file.
   ORIGINAL_FILE_ID,

clang/include/clang/Serialization/ASTWriter.h

@@ -452,7 +452,7 @@ class ASTWriter : public ASTDeserializationListener,
 
   void WriteBlockInfoBlock();
   void WriteControlBlock(Preprocessor &PP, ASTContext &Context,
-                         StringRef isysroot, const std::string &OutputFile);
+                         StringRef isysroot);
 
   /// Write out the signature and diagnostic options, and return the signature.
   ASTFileSignature writeUnhashedControlBlock(Preprocessor &PP,
@@ -531,7 +531,6 @@ class ASTWriter : public ASTDeserializationListener,
   void WriteDecl(ASTContext &Context, Decl *D);
 
   ASTFileSignature WriteASTCore(Sema &SemaRef, StringRef isysroot,
-                                const std::string &OutputFile,
                                 Module *WritingModule);
 
 public:
@@ -569,7 +568,7 @@ class ASTWriter : public ASTDeserializationListener,
   ///
   /// \return the module signature, which eventually will be a hash of
   /// the module but currently is merely a random 32-bit number.
-  ASTFileSignature WriteAST(Sema &SemaRef, const std::string &OutputFile,
+  ASTFileSignature WriteAST(Sema &SemaRef, StringRef OutputFile,
                             Module *WritingModule, StringRef isysroot,
                             bool hasErrors = false,
                             bool ShouldCacheASTInMemory = false);

clang/include/clang/Serialization/ModuleFile.h

@@ -148,10 +148,6 @@ class ModuleFile {
   /// build this AST file.
   FileID OriginalSourceFileID;
 
-  /// The directory that the PCH was originally created in. Used to
-  /// allow resolving headers even after headers+PCH was moved to a new path.
-  std::string OriginalDir;
-
   std::string ModuleMapPath;
 
   /// Whether this precompiled header is a relocatable PCH file.

clang/lib/Serialization/ASTReader.cpp

@@ -1395,41 +1395,6 @@ llvm::Error ASTReader::ReadSourceManagerBlock(ModuleFile &F) {
   }
 }
 
-/// If a header file is not found at the path that we expect it to be
-/// and the PCH file was moved from its original location, try to resolve the
-/// file by assuming that header+PCH were moved together and the header is in
-/// the same place relative to the PCH.
-static std::string
-resolveFileRelativeToOriginalDir(const std::string &Filename,
-                                 const std::string &OriginalDir,
-                                 const std::string &CurrDir) {
-  assert(OriginalDir != CurrDir &&
-         "No point trying to resolve the file if the PCH dir didn't change");
-
-  using namespace llvm::sys;
-
-  SmallString<128> filePath(Filename);
-  fs::make_absolute(filePath);
-  assert(path::is_absolute(OriginalDir));
-  SmallString<128> currPCHPath(CurrDir);
-
-  path::const_iterator fileDirI = path::begin(path::parent_path(filePath)),
-                       fileDirE = path::end(path::parent_path(filePath));
-  path::const_iterator origDirI = path::begin(OriginalDir),
-                       origDirE = path::end(OriginalDir);
-  // Skip the common path components from filePath and OriginalDir.
-  while (fileDirI != fileDirE && origDirI != origDirE &&
-         *fileDirI == *origDirI) {
-    ++fileDirI;
-    ++origDirI;
-  }
-  for (; origDirI != origDirE; ++origDirI)
-    path::append(currPCHPath, "..");
-  path::append(currPCHPath, fileDirI, fileDirE);
-  path::append(currPCHPath, path::filename(Filename));
-  return std::string(currPCHPath.str());
-}
-
 bool ASTReader::ReadSLocEntry(int ID) {
   if (ID == 0)
     return false;
@@ -2332,16 +2297,6 @@ InputFile ASTReader::getInputFile(ModuleFile &F, unsigned ID, bool Complain) {
   OptionalFileEntryRefDegradesToFileEntryPtr File =
       expectedToOptional(FileMgr.getFileRef(Filename, /*OpenFile=*/false));
 
-  // If we didn't find the file, resolve it relative to the
-  // original directory from which this AST file was created.
-  if (!File && !F.OriginalDir.empty() && !F.BaseDirectory.empty() &&
-      F.OriginalDir != F.BaseDirectory) {
-    std::string Resolved = resolveFileRelativeToOriginalDir(
-        std::string(Filename), F.OriginalDir, F.BaseDirectory);
-    if (!Resolved.empty())
-      File = expectedToOptional(FileMgr.getFileRef(Resolved));
-  }
-
   // For an overridden file, create a virtual file with the stored
   // size/timestamp.
   if ((Overridden || Transient) && !File)
@@ -2892,10 +2847,6 @@ ASTReader::ReadControlBlock(ModuleFile &F,
       F.OriginalSourceFileID = FileID::get(Record[0]);
       break;
 
-    case ORIGINAL_PCH_DIR:
-      F.OriginalDir = std::string(Blob);
-      break;
-
     case MODULE_NAME:
       F.ModuleName = std::string(Blob);
       Diag(diag::remark_module_import)
@@ -8701,8 +8652,9 @@ ASTReader::getSourceDescriptor(unsigned ID) {
     ModuleFile &MF = ModuleMgr.getPrimaryModule();
     StringRef ModuleName = llvm::sys::path::filename(MF.OriginalSourceFileName);
     StringRef FileName = llvm::sys::path::filename(MF.FileName);
-    return ASTSourceDescriptor(ModuleName, MF.OriginalDir, FileName,
-                               MF.Signature);
+    return ASTSourceDescriptor(ModuleName,
+                               llvm::sys::path::parent_path(MF.FileName),
+                               FileName, MF.Signature);
   }
   return None;
 }

clang/lib/Serialization/ASTWriter.cpp

@@ -801,7 +801,6 @@ void ASTWriter::WriteBlockInfoBlock() {
   RECORD(MODULE_MAP_FILE);
   RECORD(IMPORTS);
   RECORD(ORIGINAL_FILE);
-  RECORD(ORIGINAL_PCH_DIR);
   RECORD(ORIGINAL_FILE_ID);
   RECORD(INPUT_FILE_OFFSETS);
 
@@ -1232,8 +1231,7 @@ ASTFileSignature ASTWriter::writeUnhashedControlBlock(Preprocessor &PP,
 
 /// Write the control block.
 void ASTWriter::WriteControlBlock(Preprocessor &PP, ASTContext &Context,
-                                  StringRef isysroot,
-                                  const std::string &OutputFile) {
+                                  StringRef isysroot) {
   using namespace llvm;
 
   Stream.EnterSubblock(CONTROL_BLOCK_ID, 5);
@@ -1483,22 +1481,6 @@ void ASTWriter::WriteControlBlock(Preprocessor &PP, ASTContext &Context,
   Record.push_back(SM.getMainFileID().getOpaqueValue());
   Stream.EmitRecord(ORIGINAL_FILE_ID, Record);
 
-  // Original PCH directory
-  if (!OutputFile.empty() && OutputFile != "-") {
-    auto Abbrev = std::make_shared<BitCodeAbbrev>();
-    Abbrev->Add(BitCodeAbbrevOp(ORIGINAL_PCH_DIR));
-    Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob)); // File name
-    unsigned AbbrevCode = Stream.EmitAbbrev(std::move(Abbrev));
-
-    SmallString<128> OutputPath(OutputFile);
-
-    SM.getFileManager().makeAbsolutePath(OutputPath);
-    StringRef origDir = llvm::sys::path::parent_path(OutputPath);
-
-    RecordData::value_type Record[] = {ORIGINAL_PCH_DIR};
-    Stream.EmitRecordWithBlob(AbbrevCode, Record, origDir);
-  }
-
   std::set<const FileEntry *> AffectingModuleMaps;
   if (WritingModule) {
     AffectingModuleMaps =
@@ -4471,8 +4453,7 @@ time_t ASTWriter::getTimestampForOutput(const FileEntry *E) const {
   return IncludeTimestamps ? E->getModificationTime() : 0;
 }
 
-ASTFileSignature ASTWriter::WriteAST(Sema &SemaRef,
-                                     const std::string &OutputFile,
+ASTFileSignature ASTWriter::WriteAST(Sema &SemaRef, StringRef OutputFile,
                                      Module *WritingModule, StringRef isysroot,
                                      bool hasErrors,
                                      bool ShouldCacheASTInMemory) {
@@ -4491,8 +4472,7 @@ ASTFileSignature ASTWriter::WriteAST(Sema &SemaRef,
   Context = &SemaRef.Context;
   PP = &SemaRef.PP;
   this->WritingModule = WritingModule;
-  ASTFileSignature Signature =
-      WriteASTCore(SemaRef, isysroot, OutputFile, WritingModule);
+  ASTFileSignature Signature = WriteASTCore(SemaRef, isysroot, WritingModule);
   Context = nullptr;
   PP = nullptr;
   this->WritingModule = nullptr;
@@ -4518,7 +4498,6 @@ static void AddLazyVectorDecls(ASTWriter &Writer, Vector &Vec,
 }
 
 ASTFileSignature ASTWriter::WriteASTCore(Sema &SemaRef, StringRef isysroot,
-                                         const std::string &OutputFile,
                                          Module *WritingModule) {
   using namespace llvm;
 
@@ -4672,7 +4651,7 @@ ASTFileSignature ASTWriter::WriteASTCore(Sema &SemaRef, StringRef isysroot,
   }
 
   // Write the control block
-  WriteControlBlock(PP, Context, isysroot, OutputFile);
+  WriteControlBlock(PP, Context, isysroot);
 
   // Write the remaining AST contents.
   Stream.FlushToWord();

clang/test/Modules/cxx20-export-import.cpp

@@ -1,3 +1,4 @@
 
+// RUN: rm -rf %t
 // RUN: %clang_cc1 -std=c++20 -fmodules -fmodules-cache-path=%t -fimplicit-module-maps -I%S/Inputs -verify %s
 export import dummy; // expected-error {{export declaration can only be used within a module interface unit after the module declaration}}

clang/test/PCH/pch-output-path-independent.c

@@ -0,0 +1,6 @@
+// RUN: rm -rf %t && mkdir -p %t/a %t/b
+
+// RUN: %clang_cc1 -triple x86_64-apple-macos11 -emit-pch %s -o %t/a/t1.pch
+// RUN: %clang_cc1 -triple x86_64-apple-macos11 -emit-pch %s -o %t/b/t2.pch
+
+// RUN: diff %t/a/t1.pch %t/b/t2.pch