Revert "Reapply "[DWARFv5] Emit file 0 to the line table.""

This reverts commit r328676.

Commit r328676 broke the -no-integrated-as flag necessary to build Linux kernel with Clang:

$ cat t.c
void foo() {}
$ clang -no-integrated-as   -c  t.c -g
/tmp/t-dcdec5.s: Assembler messages:
/tmp/t-dcdec5.s:8: Error: file number less than one
clang-7.0: error: assembler command failed with exit code 1 (use -v to see invocation)

llvm-svn: 328699

20 files changed, 133 insertions, 256 deletions

diff --git a/llvm/include/llvm/MC/MCContext.h b/llvm/include/llvm/MC/MCContext.h
index c110ffd3a77..c4abef1a9b4 100644
--- a/llvm/include/llvm/MC/MCContext.h
+++ b/llvm/include/llvm/MC/MCContext.h
@@ -537,13 +537,8 @@ namespace llvm {
       DwarfCompileUnitID = CUIndex;
     }
 
-    /// Specifies the "root" file and directory of the compilation unit.
-    /// These are "file 0" and "directory 0" in DWARF v5.
-    void setMCLineTableRootFile(unsigned CUID, StringRef CompilationDir,
-                                StringRef Filename, MD5::MD5Result *Checksum,
-                                Optional<StringRef> Source) {
-      getMCDwarfLineTable(CUID).setRootFile(CompilationDir, Filename, Checksum,
-                                            Source);
+    void setMCLineTableCompilationDir(unsigned CUID, StringRef CompilationDir) {
+      getMCDwarfLineTable(CUID).setCompilationDir(CompilationDir);
     }
 
     /// Saves the information from the currently parsed dwarf .loc directive
diff --git a/llvm/include/llvm/MC/MCDwarf.h b/llvm/include/llvm/MC/MCDwarf.h
index 5cdb176e8e2..999e3235936 100644
--- a/llvm/include/llvm/MC/MCDwarf.h
+++ b/llvm/include/llvm/MC/MCDwarf.h
@@ -214,7 +214,6 @@ struct MCDwarfLineTableHeader {
   SmallVector<MCDwarfFile, 3> MCDwarfFiles;
   StringMap<unsigned> SourceIdMap;
   StringRef CompilationDir;
-  MCDwarfFile RootFile;
   bool HasMD5 = false;
   bool HasSource = false;
 
@@ -242,17 +241,8 @@ class MCDwarfDwoLineTable {
   MCDwarfLineTableHeader Header;
 
 public:
-  void maybeSetRootFile(StringRef Directory, StringRef FileName,
-                        MD5::MD5Result *Checksum, Optional<StringRef> Source) {
-    if (!Header.RootFile.Name.empty())
-      return;
-    Header.CompilationDir = Directory;
-    Header.RootFile.Name = FileName;
-    Header.RootFile.DirIndex = 0;
-    Header.RootFile.Checksum = Checksum;
-    Header.RootFile.Source = Source;
-    Header.HasMD5 = (Checksum != nullptr);
-    Header.HasSource = Source.hasValue();
+  void setCompilationDir(StringRef CompilationDir) {
+    Header.CompilationDir = CompilationDir;
   }
 
   unsigned getFile(StringRef Directory, StringRef FileName,
@@ -287,17 +277,6 @@ public:
                                FileNumber));
   }
 
-  void setRootFile(StringRef Directory, StringRef FileName,
-                   MD5::MD5Result *Checksum, Optional<StringRef> Source) {
-    Header.CompilationDir = Directory;
-    Header.RootFile.Name = FileName;
-    Header.RootFile.DirIndex = 0;
-    Header.RootFile.Checksum = Checksum;
-    Header.RootFile.Source = Source;
-    Header.HasMD5 = (Checksum != nullptr);
-    Header.HasSource = Source.hasValue();
-  }
-
   MCSymbol *getLabel() const {
     return Header.Label;
   }
@@ -306,6 +285,10 @@ public:
     Header.Label = Label;
   }
 
+  void setCompilationDir(StringRef CompilationDir) {
+    Header.CompilationDir = CompilationDir;
+  }
+
   const SmallVectorImpl<std::string> &getMCDwarfDirs() const {
     return Header.MCDwarfDirs;
   }
diff --git a/llvm/include/llvm/MC/MCStreamer.h b/llvm/include/llvm/MC/MCStreamer.h
index 582a836023b..288bcbabc21 100644
--- a/llvm/include/llvm/MC/MCStreamer.h
+++ b/llvm/include/llvm/MC/MCStreamer.h
@@ -775,12 +775,6 @@ public:
       MD5::MD5Result *Checksum = nullptr, Optional<StringRef> Source = None,
       unsigned CUID = 0);
 
-  /// Specify the "root" file of the compilation, using the ".file 0" extension.
-  virtual void emitDwarfFile0Directive(StringRef Directory, StringRef Filename,
-                                       MD5::MD5Result *Checksum,
-                                       Optional<StringRef> Source,
-                                       unsigned CUID = 0);
-
   /// \brief This implements the DWARF2 '.loc fileno lineno ...' assembler
   /// directive.
   virtual void EmitDwarfLocDirective(unsigned FileNo, unsigned Line,
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index 0398d0f4c97..024472db87c 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -499,9 +499,8 @@ DwarfDebug::getOrCreateDwarfCompileUnit(const DICompileUnit *DIUnit) {
   // explicitly describe the directory of all files, never relying on the
   // compilation directory.
   if (!Asm->OutStreamer->hasRawTextSupport() || SingleCU)
-    Asm->OutStreamer->emitDwarfFile0Directive(
-        CompilationDir, FN, NewCU.getMD5AsBytes(DIUnit->getFile()),
-        DIUnit->getSource(), NewCU.getUniqueID());
+    Asm->OutStreamer->getContext().setMCLineTableCompilationDir(
+        NewCU.getUniqueID(), CompilationDir);
 
   StringRef Producer = DIUnit->getProducer();
   StringRef Flags = DIUnit->getFlags();
@@ -2149,10 +2148,8 @@ void DwarfDebug::emitDebugStrDWO() {
 MCDwarfDwoLineTable *DwarfDebug::getDwoLineTable(const DwarfCompileUnit &CU) {
   if (!useSplitDwarf())
     return nullptr;
-  const DICompileUnit *DIUnit = CU.getCUNode();
-  SplitTypeUnitFileTable.maybeSetRootFile(
-      DIUnit->getDirectory(), DIUnit->getFilename(),
-      CU.getMD5AsBytes(DIUnit->getFile()), DIUnit->getSource());
+  if (SingleCU)
+    SplitTypeUnitFileTable.setCompilationDir(CU.getCUNode()->getDirectory());
   return &SplitTypeUnitFileTable;
 }
 
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
index a0cd34ea76f..811112a0430 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
@@ -282,7 +282,7 @@ void DwarfUnit::addSectionOffset(DIE &Die, dwarf::Attribute Attribute,
     addUInt(Die, Attribute, dwarf::DW_FORM_data4, Integer);
 }
 
-MD5::MD5Result *DwarfUnit::getMD5AsBytes(const DIFile *File) const {
+MD5::MD5Result *DwarfUnit::getMD5AsBytes(const DIFile *File) {
   assert(File);
   Optional<DIFile::ChecksumInfo<StringRef>> Checksum = File->getChecksum();
   if (!Checksum || Checksum->Kind != DIFile::CSK_MD5)
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h
index c1d46173567..328e3549e05 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h
@@ -306,10 +306,6 @@ public:
                                       const MCSymbol *Label,
                                       const MCSymbol *Sec);
 
-  /// If the \p File has an MD5 checksum, return it as an MD5Result
-  /// allocated in the MCContext.
-  MD5::MD5Result *getMD5AsBytes(const DIFile *File) const;
-
 protected:
   ~DwarfUnit();
 
@@ -320,6 +316,10 @@ protected:
   /// create a new ID and insert it in the line table.
   virtual unsigned getOrCreateSourceID(const DIFile *File) = 0;
 
+  /// If the \p File has an MD5 checksum, return it as an MD5Result
+  /// allocated in the MCContext.
+  MD5::MD5Result *getMD5AsBytes(const DIFile *File);
+
   /// Look in the DwarfDebug map for the MDNode that corresponds to the
   /// reference.
   template <typename T> T *resolve(TypedDINodeRef<T> Ref) const {
diff --git a/llvm/lib/MC/MCAsmStreamer.cpp b/llvm/lib/MC/MCAsmStreamer.cpp
index 225dc757c36..f30dd3eadbd 100644
--- a/llvm/lib/MC/MCAsmStreamer.cpp
+++ b/llvm/lib/MC/MCAsmStreamer.cpp
@@ -219,10 +219,6 @@ public:
                                                MD5::MD5Result *Checksum = 0,
                                                Optional<StringRef> Source = None,
                                                unsigned CUID = 0) override;
-  void emitDwarfFile0Directive(StringRef Directory, StringRef Filename,
-                               MD5::MD5Result *Checksum,
-                               Optional<StringRef> Source,
-                               unsigned CUID = 0) override;
   void EmitDwarfLocDirective(unsigned FileNo, unsigned Line,
                              unsigned Column, unsigned Flags,
                              unsigned Isa, unsigned Discriminator,
@@ -1081,10 +1077,21 @@ void MCAsmStreamer::EmitFileDirective(StringRef Filename) {
   EmitEOL();
 }
 
-void printDwarfFileDirective(unsigned FileNo, StringRef Directory,
-                             StringRef Filename, MD5::MD5Result *Checksum,
-                             Optional<StringRef> Source, bool UseDwarfDirectory,
-                             raw_svector_ostream &OS) {
+Expected<unsigned> MCAsmStreamer::tryEmitDwarfFileDirective(
+    unsigned FileNo, StringRef Directory, StringRef Filename,
+    MD5::MD5Result *Checksum, Optional<StringRef> Source, unsigned CUID) {
+  assert(CUID == 0);
+
+  MCDwarfLineTable &Table = getContext().getMCDwarfLineTable(CUID);
+  unsigned NumFiles = Table.getMCDwarfFiles().size();
+  Expected<unsigned> FileNoOrErr =
+      Table.tryGetFile(Directory, Filename, Checksum, Source, FileNo);
+  if (!FileNoOrErr)
+    return FileNoOrErr.takeError();
+  FileNo = FileNoOrErr.get();
+  if (NumFiles == Table.getMCDwarfFiles().size())
+    return FileNo;
+
   SmallString<128> FullPathName;
 
   if (!UseDwarfDirectory && !Directory.empty()) {
@@ -1098,68 +1105,31 @@ void printDwarfFileDirective(unsigned FileNo, StringRef Directory,
     }
   }
 
-  OS << "\t.file\t" << FileNo << ' ';
+  SmallString<128> Str;
+  raw_svector_ostream OS1(Str);
+  OS1 << "\t.file\t" << FileNo << ' ';
   if (!Directory.empty()) {
-    PrintQuotedString(Directory, OS);
-    OS << ' ';
+    PrintQuotedString(Directory, OS1);
+    OS1 << ' ';
   }
-  PrintQuotedString(Filename, OS);
+  PrintQuotedString(Filename, OS1);
   if (Checksum) {
-    OS << " md5 ";
-    PrintQuotedString(Checksum->digest(), OS);
+    OS1 << " md5 ";
+    PrintQuotedString(Checksum->digest(), OS1);
   }
   if (Source) {
-    OS << " source ";
-    PrintQuotedString(*Source, OS);
+    OS1 << " source ";
+    PrintQuotedString(*Source, OS1);
   }
-}
-
-Expected<unsigned> MCAsmStreamer::tryEmitDwarfFileDirective(
-    unsigned FileNo, StringRef Directory, StringRef Filename,
-    MD5::MD5Result *Checksum, Optional<StringRef> Source, unsigned CUID) {
-  assert(CUID == 0 && "multiple CUs not supported by MCAsmStreamer");
-
-  MCDwarfLineTable &Table = getContext().getMCDwarfLineTable(CUID);
-  unsigned NumFiles = Table.getMCDwarfFiles().size();
-  Expected<unsigned> FileNoOrErr =
-      Table.tryGetFile(Directory, Filename, Checksum, Source, FileNo);
-  if (!FileNoOrErr)
-    return FileNoOrErr.takeError();
-  FileNo = FileNoOrErr.get();
-  if (NumFiles == Table.getMCDwarfFiles().size())
-    return FileNo;
-
-  SmallString<128> Str;
-  raw_svector_ostream OS1(Str);
-  printDwarfFileDirective(FileNo, Directory, Filename, Checksum, Source,
-                          UseDwarfDirectory, OS1);
-
-  if (MCTargetStreamer *TS = getTargetStreamer())
+  if (MCTargetStreamer *TS = getTargetStreamer()) {
     TS->emitDwarfFileDirective(OS1.str());
-  else
+  } else {
     EmitRawText(OS1.str());
+  }
 
   return FileNo;
 }
 
-void MCAsmStreamer::emitDwarfFile0Directive(StringRef Directory,
-                                            StringRef Filename,
-                                            MD5::MD5Result *Checksum,
-                                            Optional<StringRef> Source,
-                                            unsigned CUID) {
-  assert(CUID == 0);
-
-  SmallString<128> Str;
-  raw_svector_ostream OS1(Str);
-  printDwarfFileDirective(0, Directory, Filename, Checksum, Source,
-                          UseDwarfDirectory, OS1);
-
-  if (MCTargetStreamer *TS = getTargetStreamer())
-    TS->emitDwarfFileDirective(OS1.str());
-  else
-    EmitRawText(OS1.str());
-}
-
 void MCAsmStreamer::EmitDwarfLocDirective(unsigned FileNo, unsigned Line,
                                           unsigned Column, unsigned Flags,
                                           unsigned Isa,
diff --git a/llvm/lib/MC/MCDwarf.cpp b/llvm/lib/MC/MCDwarf.cpp
index 0e0ea965d14..2da69fe1e4e 100644
--- a/llvm/lib/MC/MCDwarf.cpp
+++ b/llvm/lib/MC/MCDwarf.cpp
@@ -349,34 +349,6 @@ void MCDwarfLineTableHeader::emitV2FileDirTables(MCStreamer *MCOS) const {
   MCOS->EmitIntValue(0, 1); // Terminate the file list.
 }
 
-static void emitOneV5FileEntry(MCStreamer *MCOS, const MCDwarfFile &DwarfFile,
-                               bool HasMD5, bool HasSource,
-                               Optional<MCDwarfLineStr> &LineStr) {
-  assert(!DwarfFile.Name.empty());
-  if (LineStr)
-    LineStr->emitRef(MCOS, DwarfFile.Name);
-  else {
-    MCOS->EmitBytes(DwarfFile.Name);     // FileName and...
-    MCOS->EmitBytes(StringRef("\0", 1)); // its null terminator.
-  }
-  MCOS->EmitULEB128IntValue(DwarfFile.DirIndex); // Directory number.
-  if (HasMD5) {
-    MD5::MD5Result *Cksum = DwarfFile.Checksum;
-    MCOS->EmitBinaryData(
-        StringRef(reinterpret_cast<const char *>(Cksum->Bytes.data()),
-                  Cksum->Bytes.size()));
-  }
-  if (HasSource) {
-    if (LineStr)
-      LineStr->emitRef(MCOS, DwarfFile.Source.getValueOr(StringRef()));
-    else {
-      MCOS->EmitBytes(
-          DwarfFile.Source.getValueOr(StringRef())); // Source and...
-      MCOS->EmitBytes(StringRef("\0", 1));           // its null terminator.
-    }
-  }
-}
-
 void MCDwarfLineTableHeader::emitV5FileDirTables(
     MCStreamer *MCOS, Optional<MCDwarfLineStr> &LineStr) const {
   // The directory format, which is just a list of the directory paths.  In a
@@ -425,12 +397,33 @@ void MCDwarfLineTableHeader::emitV5FileDirTables(
     MCOS->EmitULEB128IntValue(LineStr ? dwarf::DW_FORM_line_strp
                                       : dwarf::DW_FORM_string);
   }
-  // Then the counted list of files. The root file is file #0, then emit the
-  // files as provide by .file directives.
-  MCOS->EmitULEB128IntValue(MCDwarfFiles.size());
-  emitOneV5FileEntry(MCOS, RootFile, HasMD5, HasSource, LineStr);
-  for (unsigned i = 1; i < MCDwarfFiles.size(); ++i)
-    emitOneV5FileEntry(MCOS, MCDwarfFiles[i], HasMD5, HasSource, LineStr);
+  // Then the list of file names. These start at 1.
+  MCOS->EmitULEB128IntValue(MCDwarfFiles.size() - 1);
+  for (unsigned i = 1; i < MCDwarfFiles.size(); ++i) {
+    assert(!MCDwarfFiles[i].Name.empty());
+    if (LineStr)
+      LineStr->emitRef(MCOS, MCDwarfFiles[i].Name);
+    else {
+      MCOS->EmitBytes(MCDwarfFiles[i].Name); // FileName and...
+      MCOS->EmitBytes(StringRef("\0", 1));   // its null terminator.
+    }
+    MCOS->EmitULEB128IntValue(MCDwarfFiles[i].DirIndex); // Directory number.
+    if (HasMD5) {
+      MD5::MD5Result *Cksum = MCDwarfFiles[i].Checksum;
+      MCOS->EmitBinaryData(
+          StringRef(reinterpret_cast<const char *>(Cksum->Bytes.data()),
+                    Cksum->Bytes.size()));
+    }
+    if (HasSource) {
+      if (LineStr)
+        LineStr->emitRef(MCOS, MCDwarfFiles[i].Source.getValueOr(StringRef()));
+      else {
+        MCOS->EmitBytes(
+            MCDwarfFiles[i].Source.getValueOr(StringRef())); // Source and...
+        MCOS->EmitBytes(StringRef("\0", 1)); // its null terminator.
+      }
+    }
+  }
 }
 
 std::pair<MCSymbol *, MCSymbol *>
diff --git a/llvm/lib/MC/MCParser/AsmParser.cpp b/llvm/lib/MC/MCParser/AsmParser.cpp
index 8de6579fe3f..3042f9964ff 100644
--- a/llvm/lib/MC/MCParser/AsmParser.cpp
+++ b/llvm/lib/MC/MCParser/AsmParser.cpp
@@ -3276,8 +3276,8 @@ bool AsmParser::parseDirectiveFile(SMLoc DirectiveLoc) {
     FileNumber = getTok().getIntVal();
     Lex();
 
-    if (FileNumber < 0)
-      return TokError("negative file number");
+    if (FileNumber < 1)
+      return TokError("file number less than one");
   }
 
   std::string Path = getTok().getString();
@@ -3356,15 +3356,11 @@ bool AsmParser::parseDirectiveFile(SMLoc DirectiveLoc) {
       memcpy(SourceBuf, SourceString.data(), SourceString.size());
       Source = StringRef(SourceBuf, SourceString.size());
     }
-    if (FileNumber == 0)
-      getStreamer().emitDwarfFile0Directive(Directory, Filename, CKMem, Source);
-    else {
-      Expected<unsigned> FileNumOrErr = getStreamer().tryEmitDwarfFileDirective(
-          FileNumber, Directory, Filename, CKMem, Source);
-      if (!FileNumOrErr)
-        return Error(DirectiveLoc, toString(FileNumOrErr.takeError()));
-      FileNumber = FileNumOrErr.get();
-    }
+    Expected<unsigned> FileNumOrErr = getStreamer().tryEmitDwarfFileDirective(
+        FileNumber, Directory, Filename, CKMem, Source);
+    if (!FileNumOrErr)
+      return Error(DirectiveLoc, toString(FileNumOrErr.takeError()));
+    FileNumber = FileNumOrErr.get();
   }
 
   return false;
diff --git a/llvm/lib/MC/MCStreamer.cpp b/llvm/lib/MC/MCStreamer.cpp
index 776569894a5..7d847c67605 100644
--- a/llvm/lib/MC/MCStreamer.cpp
+++ b/llvm/lib/MC/MCStreamer.cpp
@@ -199,15 +199,6 @@ MCStreamer::tryEmitDwarfFileDirective(unsigned FileNo, StringRef Directory,
                                    Source, CUID);
 }
 
-void MCStreamer::emitDwarfFile0Directive(StringRef Directory,
-                                         StringRef Filename,
-                                         MD5::MD5Result *Checksum,
-                                         Optional<StringRef> Source,
-                                         unsigned CUID) {
-  getContext().setMCLineTableRootFile(CUID, Directory, Filename, Checksum,
-                                      Source);
-}
-
 void MCStreamer::EmitDwarfLocDirective(unsigned FileNo, unsigned Line,
                                        unsigned Column, unsigned Flags,
                                        unsigned Isa,
diff --git a/llvm/test/CodeGen/Generic/dwarf-md5.ll b/llvm/test/CodeGen/Generic/dwarf-md5.ll
index 09b901efaf7..b9977200de1 100644
--- a/llvm/test/CodeGen/Generic/dwarf-md5.ll
+++ b/llvm/test/CodeGen/Generic/dwarf-md5.ll
@@ -8,25 +8,28 @@
 ; RUN: %llc_dwarf -dwarf-version 4 -filetype=asm -o - %s | FileCheck %s --check-prefix=ASM
 ; RUN: %llc_dwarf -dwarf-version 5 -filetype=asm -o - %s | FileCheck %s --check-prefix=ASM
 ; RUN: %llc_dwarf -dwarf-version 4 -filetype=obj -o %t4.o %s
-; RUN: llvm-dwarfdump -debug-line %t4.o | FileCheck %s --check-prefix=OBJ
+; RUN: llvm-dwarfdump -debug-line %t4.o | FileCheck %s --check-prefix=OBJ-4
 ; RUN: %llc_dwarf -dwarf-version 5 -filetype=obj -o %t5.o %s
-; RUN: llvm-dwarfdump -debug-line %t5.o | FileCheck %s --check-prefixes=OBJ,OBJ-5
+; RUN: llvm-dwarfdump -debug-line %t5.o | FileCheck %s --check-prefix=OBJ-5
 
-; ASM: .file 0 "[[COMPDIR:.*]]{{[/\\]}}t.c" md5 "00000000000000000000000000000000"
-; ASM: .file 1 "[[COMPDIR]]{{[/\\]}}t1.h" md5 "11111111111111111111111111111111"
-; ASM: .file 2 "[[COMPDIR]]{{[/\\]}}t2.h" md5 "22222222222222222222222222222222"
+; FIXME: Need to convey the MD5 for the primary source file.
+; ASM: .file 1 ".{{/|\\\\}}t1.h" md5 "11111111111111111111111111111111"
+; ASM: .file 2 ".{{/|\\\\}}t2.h" md5 "22222222222222222222222222222222"
+
+; OBJ-4: file_names[ 1]:
+; OBJ-4-NEXT: name: "t1.h"
+; OBJ-4-NEXT: dir_index: 1
+; OBJ-4: file_names[ 2]:
+; OBJ-4-NEXT: name: "t2.h"
+; OBJ-4-NEXT: dir_index: 1
 
 ; OBJ-5: file_names[ 0]:
-; OBJ-5-NEXT: name: "t.c"
-; OBJ-5-NEXT: dir_index: 0
-; OBJ-5-NEXT: md5_checksum: 00000000000000000000000000000000
-; OBJ: file_names[ 1]:
-; OBJ-NEXT: name: "t1.h"
-; OBJ-NEXT: dir_index: 0
+; OBJ-5-NEXT: name: "t1.h"
+; OBJ-5-NEXT: dir_index: 1
 ; OBJ-5-NEXT: md5_checksum: 11111111111111111111111111111111
-; OBJ: file_names[ 2]:
-; OBJ-NEXT: name: "t2.h"
-; OBJ-NEXT: dir_index: 0
+; OBJ-5: file_names[ 1]:
+; OBJ-5-NEXT: name: "t2.h"
+; OBJ-5-NEXT: dir_index: 1
 ; OBJ-5-NEXT: md5_checksum: 22222222222222222222222222222222
 
 ; ModuleID = 't.c'
@@ -47,9 +50,9 @@ source_filename = "t.c"
 !5 = !{!0, !6}
 !6 = !DIGlobalVariableExpression(var: !7, expr: !DIExpression())
 !7 = distinct !DIGlobalVariable(name: "t2", scope: !2, file: !8, line: 1, type: !9, isLocal: false, isDefinition: true)
-!8 = !DIFile(filename: "t2.h", directory: "/home/probinson/projects/scratch", checksumkind: CSK_MD5, checksum: "22222222222222222222222222222222")
+!8 = !DIFile(filename: "./t2.h", directory: "/home/probinson/projects/scratch", checksumkind: CSK_MD5, checksum: "22222222222222222222222222222222")
 !9 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
-!10 = !DIFile(filename: "t1.h", directory: "/home/probinson/projects/scratch", checksumkind: CSK_MD5, checksum: "11111111111111111111111111111111")
+!10 = !DIFile(filename: "./t1.h", directory: "/home/probinson/projects/scratch", checksumkind: CSK_MD5, checksum: "11111111111111111111111111111111")
 !11 = !{i32 2, !"Dwarf Version", i32 4}
 !12 = !{i32 2, !"Debug Info Version", i32 3}
 !13 = !{i32 1, !"wchar_size", i32 4}
diff --git a/llvm/test/CodeGen/Generic/dwarf-source.ll b/llvm/test/CodeGen/Generic/dwarf-source.ll
index e59193d0d8a..9c34fc5285b 100644
--- a/llvm/test/CodeGen/Generic/dwarf-source.ll
+++ b/llvm/test/CodeGen/Generic/dwarf-source.ll
@@ -8,27 +8,30 @@
 ; RUN: %llc_dwarf -dwarf-version 4 -filetype=asm -o - %s | FileCheck %s --check-prefix=ASM
 ; RUN: %llc_dwarf -dwarf-version 5 -filetype=asm -o - %s | FileCheck %s --check-prefix=ASM
 ; RUN: %llc_dwarf -dwarf-version 4 -filetype=obj -o %t4.o %s
-; RUN: llvm-dwarfdump -debug-line %t4.o | FileCheck %s --check-prefixes=OBJ,OBJ-4
+; RUN: llvm-dwarfdump -debug-line %t4.o | FileCheck %s --check-prefix=OBJ-4
 ; RUN: %llc_dwarf -dwarf-version 5 -filetype=obj -o %t5.o %s
-; RUN: llvm-dwarfdump -debug-line %t5.o | FileCheck %s --check-prefixes=OBJ,OBJ-5
+; RUN: llvm-dwarfdump -debug-line %t5.o | FileCheck %s --check-prefix=OBJ-5
 
-; ASM: .file 0 "[[COMPDIR:.*]]{{[/\\]}}t.c" source "00000000000000000000000000000000"
-; ASM: .file 1 "[[COMPDIR]]{{[/\\]}}t1.h" source "11111111111111111111111111111111"
-; ASM: .file 2 "[[COMPDIR]]{{[/\\]}}t2.h" source "22222222222222222222222222222222"
+; FIXME: Need to convey the source for the primary source file.
+; ASM: .file 1 ".{{/|\\\\}}t1.h" source "11111111111111111111111111111111"
+; ASM: .file 2 ".{{/|\\\\}}t2.h" source "22222222222222222222222222222222"
 
-; OBJ-5: file_names[ 0]:
-; OBJ-5-NEXT: name: "t.c"
-; OBJ-5-NEXT: dir_index: 0
-; OBJ-5-NEXT: source: "00000000000000000000000000000000"
-; OBJ: file_names[ 1]:
-; OBJ-NEXT: name: "t1.h"
-; OBJ-NEXT: dir_index: 0
+; OBJ-4: file_names[ 1]:
+; OBJ-4-NEXT: name: "t1.h"
+; OBJ-4-NEXT: dir_index: 1
 ; OBJ-4-NOT: 11111111111111111111111111111111
-; OBJ-5-NEXT: source: "11111111111111111111111111111111"
-; OBJ: file_names[ 2]:
-; OBJ-NEXT: name: "t2.h"
-; OBJ-NEXT: dir_index: 0
+; OBJ-4: file_names[ 2]:
+; OBJ-4-NEXT: name: "t2.h"
+; OBJ-4-NEXT: dir_index: 1
 ; OBJ-4-NOT: 22222222222222222222222222222222
+
+; OBJ-5: file_names[ 0]:
+; OBJ-5-NEXT: name: "t1.h"
+; OBJ-5-NEXT: dir_index: 1
+; OBJ-5-NEXT: source: "11111111111111111111111111111111"
+; OBJ-5: file_names[ 1]:
+; OBJ-5-NEXT: name: "t2.h"
+; OBJ-5-NEXT: dir_index: 1
 ; OBJ-5-NEXT: source: "22222222222222222222222222222222"
 
 ; ModuleID = 't.c'
@@ -49,9 +52,9 @@ source_filename = "t.c"
 !5 = !{!0, !6}
 !6 = !DIGlobalVariableExpression(var: !7, expr: !DIExpression())
 !7 = distinct !DIGlobalVariable(name: "t2", scope: !2, file: !8, line: 1, type: !9, isLocal: false, isDefinition: true)
-!8 = !DIFile(filename: "t2.h", directory: "/test", source: "22222222222222222222222222222222")
+!8 = !DIFile(filename: "./t2.h", directory: "/test", source: "22222222222222222222222222222222")
 !9 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
-!10 = !DIFile(filename: "t1.h", directory: "/test", source: "11111111111111111111111111111111")
+!10 = !DIFile(filename: "./t1.h", directory: "/test", source: "11111111111111111111111111111111")
 !11 = !{i32 2, !"Dwarf Version", i32 4}
 !12 = !{i32 2, !"Debug Info Version", i32 3}
 !13 = !{i32 1, !"wchar_size", i32 4}
diff --git a/llvm/test/DebugInfo/X86/dbg-file-name.ll b/llvm/test/DebugInfo/X86/dbg-file-name.ll
index 633b9c069c5..251952df191 100644
--- a/llvm/test/DebugInfo/X86/dbg-file-name.ll
+++ b/llvm/test/DebugInfo/X86/dbg-file-name.ll
@@ -2,7 +2,7 @@
 
 ; Verify that the file name is relative to the directory.
 ; rdar://problem/8884898
-; CHECK: file	1 "/Users/manav/one/two" "simple.c"
+; CHECK: file	1 "simple.c"
 
 declare i32 @printf(i8*, ...) nounwind
 
diff --git a/llvm/test/DebugInfo/X86/inline-asm-locs.ll b/llvm/test/DebugInfo/X86/inline-asm-locs.ll
index 5412c7f4133..632aa0be623 100644
--- a/llvm/test/DebugInfo/X86/inline-asm-locs.ll
+++ b/llvm/test/DebugInfo/X86/inline-asm-locs.ll
@@ -22,7 +22,7 @@
 ; CHECK: .file 2 "B.asm"
 ; CHECK: .loc  1 111
 ; CHECK: .loc  2 222
-; CHECK: .file 3 "{{.*[/\\]}}test.c"
+; CHECK: .file 3 "test.c"
 ; CHECK: .loc  3 14 0  
 
 target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
diff --git a/llvm/test/MC/ARM/dwarf-asm-multiple-sections.s b/llvm/test/MC/ARM/dwarf-asm-multiple-sections.s
index cff8f000731..4c099acccd5 100644
--- a/llvm/test/MC/ARM/dwarf-asm-multiple-sections.s
+++ b/llvm/test/MC/ARM/dwarf-asm-multiple-sections.s
@@ -54,9 +54,9 @@ b:
 // DWARF-DL: .debug_line contents:
 // DWARF-DL: version: [[DWVER]]
 // DWARF-DL-5:    address_size: 4
-// DWARF-DL-5:    include_directories[  0] = "/tmp"
+// DWARF-DL-5:    include_directories[  0] = ""
 // DWARF-DL:      file_names[  [[DWFILE]]]:
-// DWARF-DL:      name: "{{(<stdin>|-)}}"
+// DWARF-DL:      name: "<stdin>"
 // DWARF-DL:      0x0000000000000000     17      0      1   0   0  is_stmt
 // DWARF-DL-NEXT: 0x0000000000000004     17      0      1   0   0  is_stmt end_sequence
 // DWARF-DL-NEXT: 0x0000000000000000     21      0      1   0   0  is_stmt
diff --git a/llvm/test/MC/ELF/debug-file-options.s b/llvm/test/MC/ELF/debug-file-options.s
index 5c77a48ab72..3bcd131cc38 100644
--- a/llvm/test/MC/ELF/debug-file-options.s
+++ b/llvm/test/MC/ELF/debug-file-options.s
@@ -11,32 +11,25 @@
 
 # CHECK: debug_line[0x00000000]
 # CHECK: version: 5
-# CHECK: include_directories[ 0] = .debug_line_str[0x[[DIR0:[0-9a-f]+]]] = "{{.+}}"
+# CHECK: include_directories[ 0] = .debug_line_str[0x[[DIR0:[0-9a-f]+]]] = ""
 # CHECK: include_directories[ 1] = .debug_line_str[0x[[DIR1:[0-9a-f]+]]] = "dir1"
 # CHECK: include_directories[ 2] = .debug_line_str[0x[[DIR2:[0-9a-f]+]]] = "dir2"
 # CHECK-NOT: include_directories
 # CHECK: file_names[ 0]:
-# CHECK-NEXT: name: .debug_line_str[0x[[FILE0:[0-9a-f]+]]] = "{{.+}}"
-# CHECK-NEXT: dir_index: 0
-# CHECK-NEXT: md5_checksum:
-# CHECK-NEXT: source: .debug_line_str[0x[[FILE0SRC:[0-9a-f]+]]] = ""
-# CHECK: file_names[ 1]:
 # CHECK-NEXT: name: .debug_line_str[0x[[FILE1:[0-9a-f]+]]] = "foo"
 # CHECK-NEXT: dir_index: 1
 # CHECK-NEXT: md5_checksum: ee87e05688663173cd6043a3a15bba6e
 # CHECK-NEXT: source: .debug_line_str[0x[[FILE1SRC:[0-9a-f]+]]] = "void foo() {}"
-# CHECK: file_names[ 2]:
+# CHECK: file_names[ 1]:
 # CHECK-NEXT: name: .debug_line_str[0x[[FILE2:[0-9a-f]+]]] = "bar"
 # CHECK-NEXT: dir_index: 2
 # CHECK-NEXT: md5_checksum: 816225a0c90ca8948b70eb58be4d522f
 # CHECK-NEXT: source: .debug_line_str[0x[[FILE2SRC:[0-9a-f]+]]] = "void bar() {}"
 
 # CHECK: .debug_line_str contents:
-# CHECK-NEXT: 0x[[DIR0]]: "{{.+}}"
+# CHECK-NEXT: 0x[[DIR0]]: ""
 # CHECK-NEXT: 0x[[DIR1]]: "dir1"
 # CHECK-NEXT: 0x[[DIR2]]: "dir2"
-# CHECK-NEXT: 0x[[FILE0]]: "{{.+}}"
-# CHECK-NEXT: 0x[[FILE0SRC]]: ""
 # CHECK-NEXT: 0x[[FILE1]]: "foo"
 # CHECK-NEXT: 0x[[FILE1SRC]]: "void foo() {}"
 # CHECK-NEXT: 0x[[FILE2]]: "bar"
diff --git a/llvm/test/MC/ELF/debug-md5.s b/llvm/test/MC/ELF/debug-md5.s
index 658e02e5917..f8f3bc1a362 100644
--- a/llvm/test/MC/ELF/debug-md5.s
+++ b/llvm/test/MC/ELF/debug-md5.s
@@ -1,4 +1,4 @@
-// RUN: llvm-mc -triple x86_64-unknown-unknown -dwarf-version 5 -fdebug-compilation-dir=/tmp -filetype=obj %s -o - | llvm-dwarfdump --debug-line --debug-line-str -v - | FileCheck %s
+// RUN: llvm-mc -triple x86_64-unknown-unknown -dwarf-version 5 -filetype=obj %s -o - | llvm-dwarfdump --debug-line --debug-line-str -v - | FileCheck %s
 
         .file 1 "dir1/foo"   md5 "00112233445566778899aabbccddeeff"
         .file 2 "dir2" "bar" md5 "ffeeddccbbaa99887766554433221100"
@@ -9,26 +9,22 @@
 
 # CHECK: debug_line[0x00000000]
 # CHECK: version: 5
-# CHECK: include_directories[ 0] = .debug_line_str[0x[[DIR0:[0-9a-f]+]]] = "/tmp"
+# CHECK: include_directories[ 0] = .debug_line_str[0x[[DIR0:[0-9a-f]+]]] = ""
 # CHECK: include_directories[ 1] = .debug_line_str[0x[[DIR1:[0-9a-f]+]]] = "dir1"
 # CHECK: include_directories[ 2] = .debug_line_str[0x[[DIR2:[0-9a-f]+]]] = "dir2"
 # CHECK-NOT: include_directories
 # CHECK: file_names[ 0]:
-# CHECK-NEXT: name: .debug_line_str[0x[[FILE0:[0-9a-f]+]]] = "{{.+}}"
-# CHECK-NEXT: dir_index: 0
-# CHECK: file_names[ 1]:
 # CHECK-NEXT: name: .debug_line_str[0x[[FILE1:[0-9a-f]+]]] = "foo"
 # CHECK-NEXT: dir_index: 1
 # CHECK-NEXT: md5_checksum: 00112233445566778899aabbccddeeff
-# CHECK: file_names[ 2]:
+# CHECK: file_names[ 1]:
 # CHECK-NEXT: name: .debug_line_str[0x[[FILE2:[0-9a-f]+]]] = "bar"
 # CHECK-NEXT: dir_index: 2
 # CHECK-NEXT: md5_checksum: ffeeddccbbaa99887766554433221100
 
 # CHECK: .debug_line_str contents:
-# CHECK-NEXT: 0x[[DIR0]]: "/tmp"
+# CHECK-NEXT: 0x[[DIR0]]: ""
 # CHECK-NEXT: 0x[[DIR1]]: "dir1"
 # CHECK-NEXT: 0x[[DIR2]]: "dir2"
-# CHECK-NEXT: 0x[[FILE0]]: "{{.+}}"
 # CHECK-NEXT: 0x[[FILE1]]: "foo"
 # CHECK-NEXT: 0x[[FILE2]]: "bar"
diff --git a/llvm/test/MC/ELF/debug-source.s b/llvm/test/MC/ELF/debug-source.s
index 1cf39c7a9d2..0b919e15ddb 100644
--- a/llvm/test/MC/ELF/debug-source.s
+++ b/llvm/test/MC/ELF/debug-source.s
@@ -9,29 +9,23 @@
 
 # CHECK: debug_line[0x00000000]
 # CHECK: version: 5
-# CHECK: include_directories[ 0] = .debug_line_str[0x[[DIR0:[0-9a-f]+]]] = "{{.+}}"
+# CHECK: include_directories[ 0] = .debug_line_str[0x[[DIR0:[0-9a-f]+]]] = ""
 # CHECK: include_directories[ 1] = .debug_line_str[0x[[DIR1:[0-9a-f]+]]] = "dir1"
 # CHECK: include_directories[ 2] = .debug_line_str[0x[[DIR2:[0-9a-f]+]]] = "dir2"
 # CHECK-NOT: include_directories
 # CHECK: file_names[ 0]:
-# CHECK-NEXT: name: .debug_line_str[0x[[FILE0:[0-9a-f]+]]] = "{{.+}}"
-# CHECK-NEXT: dir_index: 0
-# CHECK-NEXT: source: .debug_line_str[0x[[FILE0SRC:[0-9a-f]+]]] = ""
-# CHECK: file_names[ 1]:
 # CHECK-NEXT: name: .debug_line_str[0x[[FILE1:[0-9a-f]+]]] = "foo"
 # CHECK-NEXT: dir_index: 1
 # CHECK-NEXT: source: .debug_line_str[0x[[FILE1SRC:[0-9a-f]+]]] = "void foo() {}"
-# CHECK: file_names[ 2]:
+# CHECK: file_names[ 1]:
 # CHECK-NEXT: name: .debug_line_str[0x[[FILE2:[0-9a-f]+]]] = "bar"
 # CHECK-NEXT: dir_index: 2
 # CHECK-NEXT: source: .debug_line_str[0x[[FILE2SRC:[0-9a-f]+]]] = "void bar()\n{\n}"
 
 # CHECK: .debug_line_str contents:
-# CHECK-NEXT: 0x[[DIR0]]: "{{.+}}"
+# CHECK-NEXT: 0x[[DIR0]]: ""
 # CHECK-NEXT: 0x[[DIR1]]: "dir1"
 # CHECK-NEXT: 0x[[DIR2]]: "dir2"
-# CHECK-NEXT: 0x[[FILE0]]: "{{.+}}"
-# CHECK-NEXT: 0x[[FILE0SRC]]: ""
 # CHECK-NEXT: 0x[[FILE1]]: "foo"
 # CHECK-NEXT: 0x[[FILE1SRC]]: "void foo() {}"
 # CHECK-NEXT: 0x[[FILE2]]: "bar"
diff --git a/llvm/test/MC/ELF/dwarf-file0.s b/llvm/test/MC/ELF/dwarf-file0.s
deleted file mode 100644
index ae87df2a3f0..00000000000
--- a/llvm/test/MC/ELF/dwarf-file0.s
+++ /dev/null
@@ -1,19 +0,0 @@
-# RUN: llvm-mc -dwarf-version 4 %s -filetype=obj -o - | llvm-dwarfdump -debug-line - | FileCheck %s --check-prefixes=CHECK,CHECK-4
-# RUN: llvm-mc -dwarf-version 5 %s -filetype=obj -o - | llvm-dwarfdump -debug-line - | FileCheck %s --check-prefixes=CHECK,CHECK-5
-# Darwin is stuck on DWARF v2.
-# XFAIL: darwin
-        .file 0 "root.cpp"
-        .file 1 "header.h"
-        .file 2 "root.cpp"
-# CHECK-5:     include_directories[ 0] = ""
-# CHECK-4-NOT: include_directories
-# CHECK-4-NOT: file_names[ 0]
-# CHECK-5:     file_names[ 0]:
-# CHECK-5-NEXT: name: "root.cpp"
-# CHECK-5-NEXT: dir_index: 0
-# CHECK:       file_names[ 1]:
-# CHECK-NEXT:  name: "header.h"
-# CHECK-NEXT:  dir_index: 0
-# CHECK:       file_names[ 2]:
-# CHECK-NEXT:  name: "root.cpp"
-# CHECK-NEXT:  dir_index: 0
diff --git a/llvm/tools/llvm-mc/llvm-mc.cpp b/llvm/tools/llvm-mc/llvm-mc.cpp
index 5d9c060dc21..933aecce696 100644
--- a/llvm/tools/llvm-mc/llvm-mc.cpp
+++ b/llvm/tools/llvm-mc/llvm-mc.cpp
@@ -390,18 +390,6 @@ int main(int argc, char **argv) {
   }
   if (!MainFileName.empty())
     Ctx.setMainFileName(MainFileName);
-  if (DwarfVersion >= 5) {
-    // DWARF v5 needs the root file as well as the compilation directory.
-    // If we find a '.file 0' directive that will supersede these values.
-    MD5 Hash;
-    MD5::MD5Result *Cksum =
-        (MD5::MD5Result *)Ctx.allocate(sizeof(MD5::MD5Result), 1);
-    Hash.update(Buffer->getBuffer());
-    Hash.final(*Cksum);
-    Ctx.setMCLineTableRootFile(
-        /*CUID=*/0, Ctx.getCompilationDir(),
-        !MainFileName.empty() ? MainFileName : InputFilename, Cksum, None);
-  }
 
   // Package up features to be passed to target/subtarget
   std::string FeaturesStr;