[modules] When explicitly building a module file, don't include timestamps in

the produced pcm file for stable file creation across distributed build
systems.

llvm-svn: 245199

1 files changed, 20 insertions, 18 deletions

diff --git a/clang/lib/Serialization/ASTWriter.cpp b/clang/lib/Serialization/ASTWriter.cpp
index 566c7d7c9f2..b774abe17e1 100644
--- a/clang/lib/Serialization/ASTWriter.cpp
+++ b/clang/lib/Serialization/ASTWriter.cpp
@@ -1148,6 +1148,7 @@ void ASTWriter::WriteControlBlock(Preprocessor &PP, ASTContext &Context,
   MetadataAbbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 16)); // Clang maj.
   MetadataAbbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 16)); // Clang min.
   MetadataAbbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // Relocatable
+  MetadataAbbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // Timestamps
   MetadataAbbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1)); // Errors
   MetadataAbbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob)); // SVN branch/tag
   unsigned MetadataAbbrevCode = Stream.EmitAbbrev(MetadataAbbrev);
@@ -1159,6 +1160,7 @@ void ASTWriter::WriteControlBlock(Preprocessor &PP, ASTContext &Context,
   assert((!WritingModule || isysroot.empty()) &&
          "writing module as a relocatable PCH?");
   Record.push_back(!isysroot.empty());
+  Record.push_back(IncludeTimestamps);
   Record.push_back(ASTHasCompilerErrors);
   Stream.EmitRecordWithBlob(MetadataAbbrevCode, Record,
                             getClangFullRepositoryVersion());
@@ -1248,7 +1250,7 @@ void ASTWriter::WriteControlBlock(Preprocessor &PP, ASTContext &Context,
       Record.push_back((unsigned)M->Kind); // FIXME: Stable encoding
       AddSourceLocation(M->ImportLoc, Record);
       Record.push_back(M->File->getSize());
-      Record.push_back(M->File->getModificationTime());
+      Record.push_back(getTimestampForOutput(M->File));
       Record.push_back(M->Signature);
       AddPath(M->FileName, Record);
     }
@@ -1512,7 +1514,7 @@ void ASTWriter::WriteInputFiles(SourceManager &SourceMgr,
 
     // Emit size/modification time for this file.
     Record.push_back(Entry.File->getSize());
-    Record.push_back(Entry.File->getModificationTime());
+    Record.push_back(getTimestampForOutput(Entry.File));
 
     // Whether this file was overridden.
     Record.push_back(Entry.BufferOverridden);
@@ -1624,15 +1626,12 @@ namespace {
     typedef unsigned hash_value_type;
     typedef unsigned offset_type;
     
-    static hash_value_type ComputeHash(key_type_ref key) {
+    hash_value_type ComputeHash(key_type_ref key) {
       // The hash is based only on size/time of the file, so that the reader can
       // match even when symlinking or excess path elements ("foo/../", "../")
       // change the form of the name. However, complete path is still the key.
-      //
-      // FIXME: Using the mtime here will cause problems for explicit module
-      // imports.
       return llvm::hash_combine(key.FE->getSize(),
-                                key.FE->getModificationTime());
+                                Writer.getTimestampForOutput(key.FE));
     }
     
     std::pair<unsigned,unsigned>
@@ -1653,7 +1652,7 @@ namespace {
       endian::Writer<little> LE(Out);
       LE.write<uint64_t>(key.FE->getSize());
       KeyLen -= 8;
-      LE.write<uint64_t>(key.FE->getModificationTime());
+      LE.write<uint64_t>(Writer.getTimestampForOutput(key.FE));
       KeyLen -= 8;
       Out.write(key.Filename, KeyLen);
     }
@@ -4058,22 +4057,21 @@ void ASTWriter::SetSelectorOffset(Selector Sel, uint32_t Offset) {
   SelectorOffsets[ID - FirstSelectorID] = Offset;
 }
 
-ASTWriter::ASTWriter(llvm::BitstreamWriter &Stream)
+ASTWriter::ASTWriter(llvm::BitstreamWriter &Stream, bool IncludeTimestamps)
     : Stream(Stream), Context(nullptr), PP(nullptr), Chain(nullptr),
-      WritingModule(nullptr), WritingAST(false),
-      DoneWritingDeclsAndTypes(false), ASTHasCompilerErrors(false),
-      FirstDeclID(NUM_PREDEF_DECL_IDS), NextDeclID(FirstDeclID),
-      FirstTypeID(NUM_PREDEF_TYPE_IDS), NextTypeID(FirstTypeID),
-      FirstIdentID(NUM_PREDEF_IDENT_IDS), NextIdentID(FirstIdentID),
-      FirstMacroID(NUM_PREDEF_MACRO_IDS), NextMacroID(FirstMacroID),
-      FirstSubmoduleID(NUM_PREDEF_SUBMODULE_IDS),
+      WritingModule(nullptr), IncludeTimestamps(IncludeTimestamps),
+      WritingAST(false), DoneWritingDeclsAndTypes(false),
+      ASTHasCompilerErrors(false), FirstDeclID(NUM_PREDEF_DECL_IDS),
+      NextDeclID(FirstDeclID), FirstTypeID(NUM_PREDEF_TYPE_IDS),
+      NextTypeID(FirstTypeID), FirstIdentID(NUM_PREDEF_IDENT_IDS),
+      NextIdentID(FirstIdentID), FirstMacroID(NUM_PREDEF_MACRO_IDS),
+      NextMacroID(FirstMacroID), FirstSubmoduleID(NUM_PREDEF_SUBMODULE_IDS),
       NextSubmoduleID(FirstSubmoduleID),
       FirstSelectorID(NUM_PREDEF_SELECTOR_IDS), NextSelectorID(FirstSelectorID),
       CollectedStmts(&StmtsToEmit), NumStatements(0), NumMacros(0),
       NumLexicalDeclContexts(0), NumVisibleDeclContexts(0),
       NextCXXBaseSpecifiersID(1), NextCXXCtorInitializersID(1),
-      TypeExtQualAbbrev(0),
-      TypeFunctionProtoAbbrev(0), DeclParmVarAbbrev(0),
+      TypeExtQualAbbrev(0), TypeFunctionProtoAbbrev(0), DeclParmVarAbbrev(0),
       DeclContextLexicalAbbrev(0), DeclContextVisibleLookupAbbrev(0),
       UpdateVisibleAbbrev(0), DeclRecordAbbrev(0), DeclTypedefAbbrev(0),
       DeclVarAbbrev(0), DeclFieldAbbrev(0), DeclEnumAbbrev(0),
@@ -4090,6 +4088,10 @@ const LangOptions &ASTWriter::getLangOpts() const {
   return Context->getLangOpts();
 }
 
+time_t ASTWriter::getTimestampForOutput(const FileEntry *E) const {
+  return IncludeTimestamps ? E->getModificationTime() : 0;
+}
+
 void ASTWriter::WriteAST(Sema &SemaRef,
                          const std::string &OutputFile,
                          Module *WritingModule, StringRef isysroot,