Only computeRelativePath() on new members

Summary:
When using thin archives, and processing the same archive multiple times, we were mangling existing entries.  The root cause is that we were calling computeRelativePath() more than once.   Here, we only call it when adding new members to an archive.

Note that D27218 changes the way thin archives are printed, and will break the new unit test included here.  Depending on which one lands first, the other will need to be slightly modified.

Reviewers: rafael, davide

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D27217

llvm-svn: 288280

3 files changed, 23 insertions, 3 deletions

diff --git a/llvm/include/llvm/Object/ArchiveWriter.h b/llvm/include/llvm/Object/ArchiveWriter.h
index 6b4084351dd..3e84a5814d7 100644
--- a/llvm/include/llvm/Object/ArchiveWriter.h
+++ b/llvm/include/llvm/Object/ArchiveWriter.h
@@ -25,6 +25,7 @@ struct NewArchiveMember {
   sys::TimePoint<std::chrono::seconds> ModTime;
   unsigned UID = 0, GID = 0, Perms = 0644;
 
+  bool IsNew = false;
   NewArchiveMember() = default;
   NewArchiveMember(MemoryBufferRef BufRef);
 
diff --git a/llvm/lib/Object/ArchiveWriter.cpp b/llvm/lib/Object/ArchiveWriter.cpp
index 64d04a0c729..f8e3c5a0a03 100644
--- a/llvm/lib/Object/ArchiveWriter.cpp
+++ b/llvm/lib/Object/ArchiveWriter.cpp
@@ -45,6 +45,7 @@ NewArchiveMember::getOldMember(const object::Archive::Child &OldMember,
     return BufOrErr.takeError();
 
   NewArchiveMember M;
+  assert(M.IsNew == false);
   M.Buf = MemoryBuffer::getMemBuffer(*BufOrErr, false);
   if (!Deterministic) {
     auto ModTimeOrErr = OldMember.getLastModified();
@@ -93,6 +94,7 @@ Expected<NewArchiveMember> NewArchiveMember::getFile(StringRef FileName,
     return errorCodeToError(std::error_code(errno, std::generic_category()));
 
   NewArchiveMember M;
+  M.IsNew = true;
   M.Buf = std::move(*MemberBufferOrErr);
   if (!Deterministic) {
     M.ModTime = std::chrono::time_point_cast<std::chrono::seconds>(
@@ -231,9 +233,12 @@ static void writeStringTable(raw_fd_ostream &Out, StringRef ArcName,
     }
     StringMapIndexes.push_back(Out.tell() - StartOffset);
 
-    if (Thin)
-      Out << computeRelativePath(ArcName, Path);
-    else
+    if (Thin) {
+      if (M.IsNew)
+        Out << computeRelativePath(ArcName, Path);
+      else
+        Out << M.Buf->getBufferIdentifier();
+    } else
       Out << Name;
 
     Out << "/\n";
diff --git a/llvm/test/Object/archive-thin-create.test b/llvm/test/Object/archive-thin-create.test
new file mode 100644
index 00000000000..d9ee518bc2d
--- /dev/null
+++ b/llvm/test/Object/archive-thin-create.test
@@ -0,0 +1,14 @@
+RUN: mkdir -p %t
+RUN: cd %t
+RUN: mkdir -p foo
+RUN: touch foo/test1.o
+RUN: touch foo/test2.o
+RUN: llvm-ar qcT foo/libtest.a foo/test1.o
+RUN: llvm-ar qcT foo/libtest.a foo/test1.o
+RUN: llvm-ar qcT foo/libtest.a foo/test2.o
+RUN: llvm-ar t foo/libtest.a | FileCheck %s
+
+CHECK: test1.o
+CHECK: test1.o
+CHECK: test2.o
+