[LLVMdev] Extra padding on DWARF debug info?

[Ken Dyck]

DwarfDebug::emitDebugInfo() always appends four zero bytes to the tail
of the debug info section:

    emitDIE(Die);
    // FIXME - extra padding for gdb bug.
    Asm->OutStreamer.AddComment("4 extra padding bytes for GDB");
    Asm->EmitInt8(0);
    Asm->EmitInt8(0);
    Asm->EmitInt8(0);
    Asm->EmitInt8(0);
    Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("info_end", TheCU->getID()));

Does anybody know what the bug is in GDB that this works around? The
workaround was added as part of r103439[1], which added support for
multiple compilation units in one module. Does the bug ever affect
modules with only a single compilation unit?

-Ken

[1] http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20100510/101040.html