[DWARFv5] Tolerate files not all having an MD5 checksum.

In some cases, for example when compiling a preprocessed file, the
front-end is not able to provide an MD5 checksum for all files. When
that happens, omit the MD5 checksums from the final DWARF, because
DWARF doesn't have a way to indicate that some but not all files have
a checksum.

When assembling a .s file, and some but not all .file directives
provide an MD5 checksum, issue a warning and don't emit MD5 into the
DWARF.

Fixes PR37623.

Differential Revision: https://reviews.llvm.org/D48135

llvm-svn: 334710

1 files changed, 3 insertions, 0 deletions

diff --git a/llvm/lib/MC/MCAsmStreamer.cpp b/llvm/lib/MC/MCAsmStreamer.cpp
index d07f3cac410..681e7e482e7 100644
--- a/llvm/lib/MC/MCAsmStreamer.cpp
+++ b/llvm/lib/MC/MCAsmStreamer.cpp
@@ -1171,6 +1171,9 @@ void MCAsmStreamer::emitDwarfFile0Directive(StringRef Directory,
   // .file 0 is new for DWARF v5.
   if (getContext().getDwarfVersion() < 5)
     return;
+  // Inform MCDwarf about the root file.
+  getContext().setMCLineTableRootFile(CUID, Directory, Filename, Checksum,
+                                      Source);
 
   SmallString<128> Str;
   raw_svector_ostream OS1(Str);