Debug Info: store the files and directories for each compile unit.

We now emit a line table for each compile unit. To reduce the prologue size
of each line table, the files and directories used by each compile unit are
stored in std::map<unsigned, std::vector< > > instead of std::vector< >.

The prologue for a lto'ed image can be as big as 93K. Duplicating 93K for each
compile unit causes a huge increase of debug info. With this patch, each
prologue will only emit the files required by the compile unit.

rdar://problem/13342023


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@176605 91177308-0d34-0410-b5e6-96231b3b80d8

lib/MC/MCAsmStreamer.cpp

@@ -215,7 +215,7 @@ public:
 
   virtual void EmitFileDirective(StringRef Filename);
   virtual bool EmitDwarfFileDirective(unsigned FileNo, StringRef Directory,
-                                      StringRef Filename);
+                                      StringRef Filename, unsigned CUID = 0);
   virtual void EmitDwarfLocDirective(unsigned FileNo, unsigned Line,
                                      unsigned Column, unsigned Flags,
                                      unsigned Isa, unsigned Discriminator,
@@ -828,14 +828,14 @@ void MCAsmStreamer::EmitFileDirective(StringRef Filename) {
 }
 
 bool MCAsmStreamer::EmitDwarfFileDirective(unsigned FileNo, StringRef Directory,
-                                           StringRef Filename) {
+                                           StringRef Filename, unsigned CUID) {
   if (!UseDwarfDirectory && !Directory.empty()) {
     if (sys::path::is_absolute(Filename))
-      return EmitDwarfFileDirective(FileNo, "", Filename);
+      return EmitDwarfFileDirective(FileNo, "", Filename, CUID);
 
     SmallString<128> FullPathName = Directory;
     sys::path::append(FullPathName, Filename);
-    return EmitDwarfFileDirective(FileNo, "", FullPathName);
+    return EmitDwarfFileDirective(FileNo, "", FullPathName, CUID);
   }
 
   if (UseLoc) {
@@ -846,8 +846,11 @@ bool MCAsmStreamer::EmitDwarfFileDirective(unsigned FileNo, StringRef Directory,
     }
     PrintQuotedString(Filename, OS);
     EmitEOL();
+    // All .file will belong to a single CUID.
+    CUID = 0;
   }
-  return this->MCStreamer::EmitDwarfFileDirective(FileNo, Directory, Filename);
+  return this->MCStreamer::EmitDwarfFileDirective(FileNo, Directory, Filename,
+                                                  CUID);
 }
 
 void MCAsmStreamer::EmitDwarfLocDirective(unsigned FileNo, unsigned Line,

lib/MC/MCContext.cpp

@@ -77,8 +77,8 @@ void MCContext::reset() {
   Symbols.clear();
   Allocator.Reset();
   Instances.clear();
-  MCDwarfFiles.clear();
-  MCDwarfDirs.clear();
+  MCDwarfFilesCUMap.clear();
+  MCDwarfDirsCUMap.clear();
   MCGenDwarfLabelEntries.clear();
   DwarfDebugFlags = StringRef();
   MCLineSections.clear();
@@ -299,11 +299,13 @@ const MCSection *MCContext::getCOFFSection(StringRef Section,
 /// error and zero is returned and the client reports the error, else the
 /// allocated file number is returned.  The file numbers may be in any order.
 unsigned MCContext::GetDwarfFile(StringRef Directory, StringRef FileName,
-                                 unsigned FileNumber) {
+                                 unsigned FileNumber, unsigned CUID) {
   // TODO: a FileNumber of zero says to use the next available file number.
   // Note: in GenericAsmParser::ParseDirectiveFile() FileNumber was checked
   // to not be less than one.  This needs to be change to be not less than zero.
 
+  std::vector<MCDwarfFile *>& MCDwarfFiles = MCDwarfFilesCUMap[CUID];
+  std::vector<StringRef>& MCDwarfDirs = MCDwarfDirsCUMap[CUID];
   // Make space for this FileNumber in the MCDwarfFiles vector if needed.
   if (FileNumber >= MCDwarfFiles.size()) {
     MCDwarfFiles.resize(FileNumber + 1);
@@ -363,7 +365,8 @@ unsigned MCContext::GetDwarfFile(StringRef Directory, StringRef FileName,
 
 /// isValidDwarfFileNumber - takes a dwarf file number and returns true if it
 /// currently is assigned and false otherwise.
-bool MCContext::isValidDwarfFileNumber(unsigned FileNumber) {
+bool MCContext::isValidDwarfFileNumber(unsigned FileNumber, unsigned CUID) {
+  std::vector<MCDwarfFile *>& MCDwarfFiles = MCDwarfFilesCUMap[CUID];
   if(FileNumber == 0 || FileNumber >= MCDwarfFiles.size())
     return false;
 

lib/MC/MCDwarf.cpp

@@ -299,7 +299,7 @@ const MCSymbol *MCDwarfFileTable::EmitCU(MCStreamer *MCOS, unsigned CUID) {
 
   // First the directory table.
   const std::vector<StringRef> &MCDwarfDirs =
-    context.getMCDwarfDirs();
+    context.getMCDwarfDirs(CUID);
   for (unsigned i = 0; i < MCDwarfDirs.size(); i++) {
     MCOS->EmitBytes(MCDwarfDirs[i]); // the DirectoryName
     MCOS->EmitBytes(StringRef("\0", 1)); // the null term. of the string
@@ -308,7 +308,7 @@ const MCSymbol *MCDwarfFileTable::EmitCU(MCStreamer *MCOS, unsigned CUID) {
 
   // Second the file table.
   const std::vector<MCDwarfFile *> &MCDwarfFiles =
-    MCOS->getContext().getMCDwarfFiles();
+    MCOS->getContext().getMCDwarfFiles(CUID);
   for (unsigned i = 1; i < MCDwarfFiles.size(); i++) {
     MCOS->EmitBytes(MCDwarfFiles[i]->getName()); // FileName
     MCOS->EmitBytes(StringRef("\0", 1)); // the null term. of the string

lib/MC/MCNullStreamer.cpp

@@ -89,7 +89,7 @@ namespace {
 
     virtual void EmitFileDirective(StringRef Filename) {}
     virtual bool EmitDwarfFileDirective(unsigned FileNo, StringRef Directory,
-                                        StringRef Filename) {
+                                        StringRef Filename, unsigned CUID = 0) {
       return false;
     }
     virtual void EmitDwarfLocDirective(unsigned FileNo, unsigned Line,

lib/MC/MCPureStreamer.cpp

@@ -95,7 +95,7 @@ public:
     report_fatal_error("unsupported directive in pure streamer");
   }
   virtual bool EmitDwarfFileDirective(unsigned FileNo, StringRef Directory,
-                                      StringRef Filename) {
+                                      StringRef Filename, unsigned CUID = 0) {
     report_fatal_error("unsupported directive in pure streamer");
   }
 

lib/MC/MCStreamer.cpp

@@ -157,8 +157,8 @@ void MCStreamer::EmitFill(uint64_t NumBytes, uint8_t FillValue,
 
 bool MCStreamer::EmitDwarfFileDirective(unsigned FileNo,
                                         StringRef Directory,
-                                        StringRef Filename) {
-  return getContext().GetDwarfFile(Directory, Filename, FileNo) == 0;
+                                        StringRef Filename, unsigned CUID) {
+  return getContext().GetDwarfFile(Directory, Filename, FileNo, CUID) == 0;
 }
 
 void MCStreamer::EmitDwarfLocDirective(unsigned FileNo, unsigned Line,