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

1 files changed, 8 insertions, 5 deletions

diff --git a/lib/MC/MCAsmStreamer.cpp b/lib/MC/MCAsmStreamer.cpp
index 7eb7202332..35613b411c 100644
--- a/lib/MC/MCAsmStreamer.cpp
+++ b/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,