3 files changed, 27 insertions, 15 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);
diff --git a/llvm/lib/MC/MCDwarf.cpp b/llvm/lib/MC/MCDwarf.cpp
index 9dbe211cd8e..e7c805da9a9 100644
--- a/llvm/lib/MC/MCDwarf.cpp
+++ b/llvm/lib/MC/MCDwarf.cpp
@@ -350,7 +350,7 @@ void MCDwarfLineTableHeader::emitV2FileDirTables(MCStreamer *MCOS) const {
 }
 
 static void emitOneV5FileEntry(MCStreamer *MCOS, const MCDwarfFile &DwarfFile,
-                               bool HasMD5, bool HasSource,
+                               bool EmitMD5, bool HasSource,
                                Optional<MCDwarfLineStr> &LineStr) {
   assert(!DwarfFile.Name.empty());
   if (LineStr)
@@ -360,7 +360,7 @@ static void emitOneV5FileEntry(MCStreamer *MCOS, const MCDwarfFile &DwarfFile,
     MCOS->EmitBytes(StringRef("\0", 1)); // its null terminator.
   }
   MCOS->EmitULEB128IntValue(DwarfFile.DirIndex); // Directory number.
-  if (HasMD5) {
+  if (EmitMD5) {
     MD5::MD5Result *Cksum = DwarfFile.Checksum;
     MCOS->EmitBinaryData(
         StringRef(reinterpret_cast<const char *>(Cksum->Bytes.data()),
@@ -410,7 +410,7 @@ void MCDwarfLineTableHeader::emitV5FileDirTables(
   // directory index.  We don't track file size/timestamp so don't emit them
   // in the v5 table.  Emit MD5 checksums and source if we have them.
   uint64_t Entries = 2;
-  if (HasMD5)
+  if (HasAllMD5)
     Entries += 1;
   if (HasSource)
     Entries += 1;
@@ -420,7 +420,7 @@ void MCDwarfLineTableHeader::emitV5FileDirTables(
                                     : dwarf::DW_FORM_string);
   MCOS->EmitULEB128IntValue(dwarf::DW_LNCT_directory_index);
   MCOS->EmitULEB128IntValue(dwarf::DW_FORM_udata);
-  if (HasMD5) {
+  if (HasAllMD5) {
     MCOS->EmitULEB128IntValue(dwarf::DW_LNCT_MD5);
     MCOS->EmitULEB128IntValue(dwarf::DW_FORM_data16);
   }
@@ -435,9 +435,9 @@ void MCDwarfLineTableHeader::emitV5FileDirTables(
   // explicitly, replicate file #1.
   MCOS->EmitULEB128IntValue(MCDwarfFiles.size());
   emitOneV5FileEntry(MCOS, RootFile.Name.empty() ? MCDwarfFiles[1] : RootFile,
-                     HasMD5, HasSource, LineStr);
+                     HasAllMD5, HasSource, LineStr);
   for (unsigned i = 1; i < MCDwarfFiles.size(); ++i)
-    emitOneV5FileEntry(MCOS, MCDwarfFiles[i], HasMD5, HasSource, LineStr);
+    emitOneV5FileEntry(MCOS, MCDwarfFiles[i], HasAllMD5, HasSource, LineStr);
 }
 
 std::pair<MCSymbol *, MCSymbol *>
@@ -554,9 +554,10 @@ MCDwarfLineTableHeader::tryGetFile(StringRef &Directory,
     Directory = "";
   }
   assert(!FileName.empty());
-  // If any files have an MD5 checksum or embedded source, they all must.
+  // Keep track of whether any or all files have an MD5 checksum.
+  // If any files have embedded source, they all must.
   if (MCDwarfFiles.empty()) {
-    HasMD5 = (Checksum != nullptr);
+    trackMD5Usage(Checksum);
     HasSource = (Source != None);
   }
   if (FileNumber == 0) {
@@ -582,10 +583,6 @@ MCDwarfLineTableHeader::tryGetFile(StringRef &Directory,
     return make_error<StringError>("file number already allocated",
                                    inconvertibleErrorCode());
 
-  // If any files have an MD5 checksum, they all must.
-  if (HasMD5 != (Checksum != nullptr))
-    return make_error<StringError>("inconsistent use of MD5 checksums",
-                                   inconvertibleErrorCode());
   // If any files have embedded source, they all must.
   if (HasSource != (Source != None))
     return make_error<StringError>("inconsistent use of embedded source",
@@ -625,8 +622,7 @@ MCDwarfLineTableHeader::tryGetFile(StringRef &Directory,
   File.Name = FileName;
   File.DirIndex = DirIndex;
   File.Checksum = Checksum;
-  if (Checksum)
-    HasMD5 = true;
+  trackMD5Usage(Checksum);
   File.Source = Source;
   if (Source)
     HasSource = true;
diff --git a/llvm/lib/MC/MCParser/AsmParser.cpp b/llvm/lib/MC/MCParser/AsmParser.cpp
index 5c8946b286b..39922611e0e 100644
--- a/llvm/lib/MC/MCParser/AsmParser.cpp
+++ b/llvm/lib/MC/MCParser/AsmParser.cpp
@@ -177,6 +177,9 @@ private:
   /// Are we parsing ms-style inline assembly?
   bool ParsingInlineAsm = false;
 
+  /// Did we already inform the user about inconsistent MD5 usage?
+  bool ReportedInconsistentMD5 = false;
+
 public:
   AsmParser(SourceMgr &SM, MCContext &Ctx, MCStreamer &Out,
             const MCAsmInfo &MAI, unsigned CB);
@@ -3337,7 +3340,11 @@ bool AsmParser::parseDirectiveFile(SMLoc DirectiveLoc) {
 
   // In case there is a -g option as well as debug info from directive .file,
   // we turn off the -g option, directly use the existing debug info instead.
-  getContext().setGenDwarfForAssembly(false);
+  // Also reset any implicit ".file 0" for the assembler source.
+  if (Ctx.getGenDwarfForAssembly()) {
+    Ctx.getMCDwarfLineTable(0).resetRootFile();
+    Ctx.setGenDwarfForAssembly(false);
+  }
 
   if (FileNumber == -1)
     getStreamer().EmitFileDirective(Filename);
@@ -3364,6 +3371,12 @@ bool AsmParser::parseDirectiveFile(SMLoc DirectiveLoc) {
         return Error(DirectiveLoc, toString(FileNumOrErr.takeError()));
       FileNumber = FileNumOrErr.get();
     }
+    // Alert the user if there are some .file directives with MD5 and some not.
+    // But only do that once.
+    if (!ReportedInconsistentMD5 && !Ctx.isDwarfMD5UsageConsistent(0)) {
+      ReportedInconsistentMD5 = true;
+      return Warning(DirectiveLoc, "inconsistent use of MD5 checksums");
+    }
   }
 
   return false;