First part of support for generating dwarf for assembly source files with the

-g flag.  In this part we generate the .file for the source being assembled and
the .loc's for the assembled instructions.

The next part will be to generate the dwarf Compile Unit DIE and a dwarf
subprogram DIE for each non-temporary label.

Once the next part is done test cases will be added.  rdar://9275556


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@143509 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/MC/MCContext.h

@@ -98,6 +98,17 @@ namespace llvm {
     MCDwarfLoc CurrentDwarfLoc;
     bool DwarfLocSeen;
 
+    /// Generate dwarf debugging info for assembly source files.
+    bool GenDwarfForAssembly;
+
+    /// The current dwarf file number when generate dwarf debugging info for
+    /// assembly source files.
+    unsigned GenDwarfFileNumber;
+
+    /// The default initial text section that we generate dwarf debugging line
+    /// info for when generating dwarf assembly source files.
+    const MCSection *GenDwarfSection;
+
     /// Honor temporary labels, this is useful for debugging semantic
     /// differences between temporary and non-temporary labels (primarily on
     /// Darwin).
@@ -252,6 +263,13 @@ namespace llvm {
     bool getDwarfLocSeen() { return DwarfLocSeen; }
     const MCDwarfLoc &getCurrentDwarfLoc() { return CurrentDwarfLoc; }
 
+    bool getGenDwarfForAssembly() { return GenDwarfForAssembly; }
+    void setGenDwarfForAssembly(bool Value) { GenDwarfForAssembly = Value; }
+    unsigned getGenDwarfFileNumber() { return GenDwarfFileNumber; }
+    unsigned nextGenDwarfFileNumber() { return ++GenDwarfFileNumber; }
+    const MCSection *getGenDwarfSection() { return GenDwarfSection; }
+    void setGenDwarfSection(const MCSection *Sec) { GenDwarfSection = Sec; }
+
     /// @}
 
     char *getSecureLogFile() { return SecureLogFile; }

lib/MC/MCContext.cpp

@@ -43,6 +43,8 @@ MCContext::MCContext(const MCAsmInfo &mai, const MCRegisterInfo &mri,
   SecureLogUsed = false;
 
   DwarfLocSeen = false;
+  GenDwarfForAssembly = false;
+  GenDwarfFileNumber = 0;
 }
 
 MCContext::~MCContext() {

lib/MC/MCParser/AsmParser.cpp

@@ -464,6 +464,14 @@ bool AsmParser::Run(bool NoInitialTextSection, bool NoFinalize) {
   HadError = false;
   AsmCond StartingCondState = TheCondState;
 
+  // If we are generating dwarf for assembly source files save the initial text
+  // section and generate a .file directive.
+  if (getContext().getGenDwarfForAssembly()) {
+    getContext().setGenDwarfSection(getStreamer().getCurrentSection());
+    getStreamer().EmitDwarfFileDirective(getContext().nextGenDwarfFileNumber(),
+      StringRef(), SrcMgr.getMemoryBuffer(CurBuffer)->getBufferIdentifier());
+  }
+
   // While we have input, parse each statement.
   while (Lexer.isNot(AsmToken::Eof)) {
     if (!ParseStatement()) continue;
@@ -1211,6 +1219,18 @@ bool AsmParser::ParseStatement() {
     PrintMessage(IDLoc, SourceMgr::DK_Note, OS.str());
   }
 
+  // If we are generating dwarf for assembly source files and the current
+  // section is the initial text section then generate a .loc directive for
+  // the instruction.
+  if (!HadError && getContext().getGenDwarfForAssembly() &&
+      getContext().getGenDwarfSection() == getStreamer().getCurrentSection() ) {
+    getStreamer().EmitDwarfLocDirective(getContext().getGenDwarfFileNumber(),
+                                        SrcMgr.FindLineNumber(IDLoc, CurBuffer),
+                                        0, DWARF2_LINE_DEFAULT_IS_STMT ?
+					DWARF2_FLAG_IS_STMT : 0, 0, 0,
+                                        StringRef());
+  }
+
   // If parsing succeeded, match the instruction.
   if (!HadError)
     HadError = getTargetParser().MatchAndEmitInstruction(IDLoc, ParsedOperands,
@@ -2342,6 +2362,10 @@ bool GenericAsmParser::ParseDirectiveFile(StringRef, SMLoc DirectiveLoc) {
   if (getLexer().isNot(AsmToken::EndOfStatement))
     return TokError("unexpected token in '.file' directive");
 
+  if (getContext().getGenDwarfForAssembly() == true)
+    Error(DirectiveLoc, "input can't have .file dwarf directives when -g is "
+                        "used to generate dwarf debug info for assembly code");
+
   if (FileNumber == -1)
     getStreamer().EmitFileDirective(Filename);
   else {

tools/llvm-mc/llvm-mc.cpp

@@ -152,6 +152,10 @@ NoInitialTextSection("n", cl::desc("Don't assume assembly file starts "
 static cl::opt<bool>
 SaveTempLabels("L", cl::desc("Don't discard temporary labels"));
 
+static cl::opt<bool>
+GenDwarfForAssembly("g", cl::desc("Generate dwarf debugging info for assembly "
+                                  "source files"));
+
 enum ActionType {
   AC_AsLex,
   AC_Assemble,
@@ -377,6 +381,8 @@ static int AssembleInput(const char *ProgName) {
   if (SaveTempLabels)
     Ctx.setAllowTemporaryLabels(false);
 
+  Ctx.setGenDwarfForAssembly(GenDwarfForAssembly);
+
   // Package up features to be passed to target/subtarget
   std::string FeaturesStr;
   if (MAttrs.size()) {