[Object] Replace TimeValue with std::chrono

[labath]

Summary

Most of the changes are very straight-forward. The only choice I had to make was
to use second-precision time points in the Archive classes. I did this because
the archive files use that precision in the on-disk representation anyway.

[• rafael]

LGTM

lib/Object/ArchiveWriter.cpp

99

Will you also change what Status.getLastModificationTime in FileSystem. h returns?

[labath]

lib/Object/ArchiveWriter.cpp

99

I am doing that in D25730, which this change depends on (I am proceeding roughly by subfolders).

If you are referring to the presence of the cast however, that will need to stay, as getLAstModificationTime() returns a nanosecond precision timestamp, and we need to explicitly cast away the extra precision.

include/llvm/Object/Archive.h

 
 #ifndef LLVM_OBJECT_ARCHIVE_H
 #define LLVM_OBJECT_ARCHIVE_H
 
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/iterator_range.h"
 #include "llvm/Object/Binary.h"
+#include "llvm/Support/Chrono.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/MemoryBuffer.h"
-#include "llvm/Support/TimeValue.h"
 
 namespace llvm {
 namespace object {
 
 class Archive;
 
 class ArchiveMemberHeader {
 public:
   friend class Archive;
   ArchiveMemberHeader(Archive const *Parent, const char *RawHeaderPtr,
                       uint64_t Size, Error *Err);
   // ArchiveMemberHeader() = default;
 
   /// Get the name without looking up long names.
   Expected<llvm::StringRef> getRawName() const;
 
   /// Get the name looking up long names.
   Expected<llvm::StringRef> getName(uint64_t Size) const;
 
   /// Members are not larger than 4GB.
   Expected<uint32_t> getSize() const;
 
   Expected<sys::fs::perms> getAccessMode() const;
-  Expected<sys::TimeValue> getLastModified() const;
+  Expected<sys::TimePoint<std::chrono::seconds>> getLastModified() const;
   llvm::StringRef getRawLastModified() const {
     return StringRef(ArMemHdr->LastModified,
                      sizeof(ArMemHdr->LastModified)).rtrim(' ');
   }
   Expected<unsigned> getUID() const;
   Expected<unsigned> getGID() const;
 
   // This returns the size of the private struct ArMemHdrType
public:
     }
 
     const Archive *getParent() const { return Parent; }
     Expected<Child> getNext() const;
 
     Expected<StringRef> getName() const;
     Expected<std::string> getFullName() const;
     Expected<StringRef> getRawName() const { return Header.getRawName(); }
-    Expected<sys::TimeValue> getLastModified() const {
+    Expected<sys::TimePoint<std::chrono::seconds>> getLastModified() const {
       return Header.getLastModified();
     }
     StringRef getRawLastModified() const {
       return Header.getRawLastModified();
     }
     Expected<unsigned> getUID() const { return Header.getUID(); }
     Expected<unsigned> getGID() const { return Header.getGID(); }
     Expected<sys::fs::perms> getAccessMode() const {

include/llvm/Object/ArchiveWriter.h

 #include "llvm/ADT/StringRef.h"
 #include "llvm/Object/Archive.h"
 #include "llvm/Support/FileSystem.h"
 
 namespace llvm {
 
 struct NewArchiveMember {
   std::unique_ptr<MemoryBuffer> Buf;
-  sys::TimeValue ModTime = sys::TimeValue::PosixZeroTime();
+  sys::TimePoint<std::chrono::seconds> ModTime;
   unsigned UID = 0, GID = 0, Perms = 0644;
 
   NewArchiveMember() = default;
   NewArchiveMember(NewArchiveMember &&Other)
       : Buf(std::move(Other.Buf)), ModTime(Other.ModTime), UID(Other.UID),
         GID(Other.GID), Perms(Other.Perms) {}
   NewArchiveMember &operator=(NewArchiveMember &&Other) {
     Buf = std::move(Other.Buf);

lib/Object/Archive.cpp

uint64_t Offset = reinterpret_cast<const char *>(ArMemHdr) -
                       Parent->getData().data();
     return malformedError("characters in AccessMode field in archive header "
                           "are not all decimal numbers: '" + Buf + "' for the "
                           "archive member header at offset " + Twine(Offset));
   }
   return static_cast<sys::fs::perms>(Ret);
 }
 
-Expected<sys::TimeValue> ArchiveMemberHeader::getLastModified() const {
+Expected<sys::TimePoint<std::chrono::seconds>>
+ArchiveMemberHeader::getLastModified() const {
   unsigned Seconds;
   if (StringRef(ArMemHdr->LastModified,
                 sizeof(ArMemHdr->LastModified)).rtrim(' ')
           .getAsInteger(10, Seconds)) {
     std::string Buf;
     raw_string_ostream OS(Buf);
     OS.write_escaped(llvm::StringRef(ArMemHdr->LastModified,
                                    sizeof(ArMemHdr->LastModified)).rtrim(" "));
     OS.flush();
     uint64_t Offset = reinterpret_cast<const char *>(ArMemHdr) -
                       Parent->getData().data();
     return malformedError("characters in LastModified field in archive header "
                           "are not all decimal numbers: '" + Buf + "' for the "
                           "archive member header at offset " + Twine(Offset));
   }
 
-  sys::TimeValue Ret;
-  Ret.fromEpochTime(Seconds);
-  return Ret;
+  return sys::toTimePoint(Seconds);
 }
 
 Expected<unsigned> ArchiveMemberHeader::getUID() const {
   unsigned Ret;
   StringRef User = StringRef(ArMemHdr->UID, sizeof(ArMemHdr->UID)).rtrim(' ');
   if (User.empty())
     return 0;
   if (User.getAsInteger(10, Ret)) {

lib/Object/ArchiveWriter.cpp

NewArchiveMember::getOldMember(const object::Archive::Child &OldMember,
                                bool Deterministic) {
   Expected<llvm::MemoryBufferRef> BufOrErr = OldMember.getMemoryBufferRef();
   if (!BufOrErr)
     return BufOrErr.takeError();
 
   NewArchiveMember M;
   M.Buf = MemoryBuffer::getMemBuffer(*BufOrErr, false);
   if (!Deterministic) {
-    Expected<sys::TimeValue> ModTimeOrErr = OldMember.getLastModified();
+    auto ModTimeOrErr = OldMember.getLastModified();
     if (!ModTimeOrErr)
       return ModTimeOrErr.takeError();
     M.ModTime = ModTimeOrErr.get();
     Expected<unsigned> UIDOrErr = OldMember.getUID();
     if (!UIDOrErr)
       return UIDOrErr.takeError();
     M.UID = UIDOrErr.get();
     Expected<unsigned> GIDOrErr = OldMember.getGID();
if (!MemberBufferOrErr)
     return errorCodeToError(MemberBufferOrErr.getError());
 
   if (close(FD) != 0)
     return errorCodeToError(std::error_code(errno, std::generic_category()));
 
   NewArchiveMember M;
   M.Buf = std::move(*MemberBufferOrErr);
   if (!Deterministic) {
-    M.ModTime = Status.getLastModificationTime();
+    M.ModTime = std::chrono::time_point_cast<std::chrono::seconds>(
+        Status.getLastModificationTime());
     M.UID = Status.getUser();
     M.GID = Status.getGroup();
     M.Perms = Status.permissions();
   }
   return std::move(M);
 }
 
 template <typename T>

 static void print32(raw_ostream &Out, object::Archive::Kind Kind,
                     uint32_t Val) {
   if (Kind == object::Archive::K_GNU)
     support::endian::Writer<support::big>(Out).write(Val);
   else
     support::endian::Writer<support::little>(Out).write(Val);
 }
 
-static void printRestOfMemberHeader(raw_fd_ostream &Out,
-                                    const sys::TimeValue &ModTime, unsigned UID,
-                                    unsigned GID, unsigned Perms,
-                                    unsigned Size) {
-  printWithSpacePadding(Out, ModTime.toEpochTime(), 12);
+static void printRestOfMemberHeader(
+    raw_fd_ostream &Out, const sys::TimePoint<std::chrono::seconds> &ModTime,
+    unsigned UID, unsigned GID, unsigned Perms, unsigned Size) {
+  printWithSpacePadding(Out, sys::toTimeT(ModTime), 12);
   printWithSpacePadding(Out, UID, 6, true);
   printWithSpacePadding(Out, GID, 6, true);
   printWithSpacePadding(Out, format("%o", Perms), 8);
   printWithSpacePadding(Out, Size, 10);
   Out << "`\n";
 }
 
-static void printGNUSmallMemberHeader(raw_fd_ostream &Out, StringRef Name,
-                                      const sys::TimeValue &ModTime,
-                                      unsigned UID, unsigned GID,
-                                      unsigned Perms, unsigned Size) {
+static void
+printGNUSmallMemberHeader(raw_fd_ostream &Out, StringRef Name,
+                          const sys::TimePoint<std::chrono::seconds> &ModTime,
+                          unsigned UID, unsigned GID, unsigned Perms,
+                          unsigned Size) {
   printWithSpacePadding(Out, Twine(Name) + "/", 16);
   printRestOfMemberHeader(Out, ModTime, UID, GID, Perms, Size);
 }
 
-static void printBSDMemberHeader(raw_fd_ostream &Out, StringRef Name,
-                                 const sys::TimeValue &ModTime, unsigned UID,
-                                 unsigned GID, unsigned Perms, unsigned Size) {
+static void
+printBSDMemberHeader(raw_fd_ostream &Out, StringRef Name,
+                     const sys::TimePoint<std::chrono::seconds> &ModTime,
+                     unsigned UID, unsigned GID, unsigned Perms,
+                     unsigned Size) {
   uint64_t PosAfterHeader = Out.tell() + 60 + Name.size();
   // Pad so that even 64 bit object files are aligned.
   unsigned Pad = OffsetToAlignment(PosAfterHeader, 8);
   unsigned NameWithPadding = Name.size() + Pad;
   printWithSpacePadding(Out, Twine("#1/") + Twine(NameWithPadding), 16);
   printRestOfMemberHeader(Out, ModTime, UID, GID, Perms,
                           NameWithPadding + Size);
   Out << Name;
   assert(PosAfterHeader == Out.tell());
   while (Pad--)
     Out.write(uint8_t(0));
 }
 
 static bool useStringTable(bool Thin, StringRef Name) {
   return Thin || Name.size() >= 16;
 }
 
 static void
 printMemberHeader(raw_fd_ostream &Out, object::Archive::Kind Kind, bool Thin,
                   StringRef Name,
                   std::vector<unsigned>::iterator &StringMapIndexIter,
-                  const sys::TimeValue &ModTime, unsigned UID, unsigned GID,
-                  unsigned Perms, unsigned Size) {
+                  const sys::TimePoint<std::chrono::seconds> &ModTime,
+                  unsigned UID, unsigned GID, unsigned Perms, unsigned Size) {
   if (Kind == object::Archive::K_BSD)
     return printBSDMemberHeader(Out, Name, ModTime, UID, GID, Perms, Size);
   if (!useStringTable(Thin, Name))
     return printGNUSmallMemberHeader(Out, Name, ModTime, UID, GID, Perms, Size);
   Out << '/';
   printWithSpacePadding(Out, *StringMapIndexIter++, 15);
   printRestOfMemberHeader(Out, ModTime, UID, GID, Perms, Size);
 }
static void writeStringTable(raw_fd_ostream &Out, StringRef ArcName,
   if (Out.tell() % 2)
     Out << '\n';
   int Pos = Out.tell();
   Out.seek(StartOffset - 12);
   printWithSpacePadding(Out, Pos - StartOffset, 10);
   Out.seek(Pos);
 }
 
-static sys::TimeValue now(bool Deterministic) {
+static sys::TimePoint<std::chrono::seconds> now(bool Deterministic) {
+  using namespace std::chrono;
+
   if (!Deterministic)
-    return sys::TimeValue::now();
-  sys::TimeValue TV;
-  TV.fromEpochTime(0);
-  return TV;
+    return time_point_cast<seconds>(system_clock::now());
+  return sys::TimePoint<seconds>();
 }
 
 // Returns the offset of the first reference to a member offset.
 static ErrorOr<unsigned>
 writeSymbolTable(raw_fd_ostream &Out, object::Archive::Kind Kind,
                  ArrayRef<NewArchiveMember> Members,
                  std::vector<unsigned> &MemberOffsetRefs, bool Deterministic) {
   unsigned HeaderStartOffset = 0;

tools/llvm-ar/llvm-ar.cpp

if (Operation == ReplaceOrInsert) {
     }
 
     // We could try to optimize this to a fstat, but it is not a common
     // operation.
     sys::fs::file_status Status;
     failIfError(sys::fs::status(*MI, Status), *MI);
     auto ModTimeOrErr = Member.getLastModified();
     failIfError(ModTimeOrErr.takeError());
-    if (sys::TimeValue(Status.getLastModificationTime()) < ModTimeOrErr.get()) {
+    if (Status.getLastModificationTime() < ModTimeOrErr.get()) {
       if (PosName.empty())
         return IA_AddOldMember;
       return IA_MoveOldMember;
     }
 
     if (PosName.empty())
       return IA_AddNewMeber;
     return IA_MoveNewMember;