[llvm] r204667 - DebugInfo: Don't emit relocations to abbreviations in debug_info.dwo

[David Blaikie]

On Fri, Mar 28, 2014 at 4:37 PM, Eric Christopher <echristo at gmail.com> wrote:
>>    assert(useSplitDwarf() && "No split dwarf debug info?");
>> -  InfoHolder.emitUnits(this, DwarfAbbrevDWOSectionSym);
>> +  InfoHolder.emitUnits(this, nullptr);
>>  }
>>
>>  // Emit the .debug_abbrev.dwo section for separated dwarf. This contains the
>>
>> Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp?rev=204667&r1=204666&r2=204667&view=diff
>> ==============================================================================
>> --- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp (original)
>> +++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp Mon Mar 24 15:53:02 2014
>> @@ -2037,7 +2037,11 @@ void DwarfUnit::emitHeader(const MCSymbo
>>    // We share one abbreviations table across all units so it's always at the
>>    // start of the section. Use a relocatable offset where needed to ensure
>>    // linking doesn't invalidate that offset.
>> -  Asm->EmitSectionOffset(ASectionSym, ASectionSym);
>> +  if (ASectionSym)
>> +    Asm->EmitSectionOffset(ASectionSym, ASectionSym);
>> +  else
>> +    // Use a constant value in the dwo file, to avoid relocations
>> +    Asm->EmitInt32(0);
>>
>
> This comment is probably better up above,

Fair point

> with a separate one of
> "assume a 0 offset if we haven't had a symbol passed in" here.

Not sure how much value that comment adds - it sort of just seems to
describe what the code does (which, in 3 lines or so seems fairly
clear), not why we'd want to do that. Not sure if there's a better
comment to add there...

in any case, added/modified both these comments in r205386.