Support -fdebug-prefix-map in llvm-mc. This is useful to omit the

debug compilation dir when compiling assembly files with -g.
Part of PR38050.

Patch by Siddhartha Bagaria!

Differential Revision: https://reviews.llvm.org/D48988

llvm-svn: 336680

1 files changed, 12 insertions, 4 deletions

diff --git a/llvm/lib/MC/MCDwarf.cpp b/llvm/lib/MC/MCDwarf.cpp
index 37e1263be65..1d33d9947be 100644
--- a/llvm/lib/MC/MCDwarf.cpp
+++ b/llvm/lib/MC/MCDwarf.cpp
@@ -250,8 +250,11 @@ void MCDwarfLineTable::Emit(MCObjectStreamer *MCOS,
   MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfLineSection());
 
   // Handle the rest of the Compile Units.
-  for (const auto &CUIDTablePair : LineTables)
-    CUIDTablePair.second.EmitCU(MCOS, Params, LineStr);
+  for (const auto &CUIDTablePair : LineTables) {
+    auto &LineTable = context.getMCDwarfLineTable(CUIDTablePair.first);
+    LineTable.RemapDwarfDirs(MCOS->getContext());
+    LineTable.EmitCU(MCOS, Params, LineStr);
+  }
 
   if (LineStr)
     LineStr->emitSection(MCOS);
@@ -394,13 +397,13 @@ void MCDwarfLineTableHeader::emitV5FileDirTables(
   if (LineStr) {
     // Record path strings, emit references here.
     LineStr->emitRef(MCOS, CompDir);
-    for (auto &Dir : MCDwarfDirs)
+    for (const auto &Dir : MCDwarfDirs)
       LineStr->emitRef(MCOS, Dir);
   } else {
     // The list of directory paths.  Compilation directory comes first.
     MCOS->EmitBytes(CompDir);
     MCOS->EmitBytes(StringRef("\0", 1));
-    for (auto &Dir : MCDwarfDirs) {
+    for (const auto &Dir : MCDwarfDirs) {
       MCOS->EmitBytes(Dir);                // The DirectoryName, and...
       MCOS->EmitBytes(StringRef("\0", 1)); // its null terminator.
     }
@@ -631,6 +634,11 @@ MCDwarfLineTableHeader::tryGetFile(StringRef &Directory,
   return FileNumber;
 }
 
+void MCDwarfLineTable::RemapDwarfDirs(MCContext &Context) {
+  for (auto &Dir : Header.MCDwarfDirs)
+    Context.RemapDebugPath(&Dir);
+}
+
 /// Utility function to emit the encoding to a streamer.
 void MCDwarfLineAddr::Emit(MCStreamer *MCOS, MCDwarfLineTableParams Params,
                            int64_t LineDelta, uint64_t AddrDelta) {