[LLVMdev] x86 unwind support[MESSAGE NOT SCANNED]

Kenneth Uildriks
Mon, 20 Jul 2009 16:48:13 -0000

On Mon, Jul 20, 2009 at 11:18 AM, Duncan Sands<baldrick at free.fr>
wrote:
> Hi Mark,
>
>> You are confusing stopping the unwinding at *some* levels or at *all*
>> levels.
>> Eg.
>> invoke
>>   call
>>    call
>>     invoke
>>      call
>>       call
>>        unwind
>
> the dwarf unwinder only stops and runs user code at the invokes.
> It does restore registers and so forth at every stack frame.
> This is extra work done at unwind time that reduces the cost of
> making invoke calls by avoiding the need to save a bunch of
> context.
>
Is there anything in the current codebase that maps an "unwind"
instruction to a DWARF unnwinder?  Seeing as how (I think) the DWARF
info is already compiled in, this would be a useful thing.