[Patch Debug] Emit pubnames for reorder & partition case.

[IainS]

On 20 Dec 2010, at 21:38, Richard Henderson wrote:

> On 12/20/2010 01:20 PM, IainS wrote:
>>
>> On 20 Dec 2010, at 21:15, Richard Henderson wrote:
>>
>>> On 12/20/2010 03:18 AM, IainS wrote:
>>>> +          /* There is no real support in DW2 for this .. so we  
>>>> make
>>>> +             a work-around.  First, emit the pub name for the  
>>>> segment
>>>> +             containing the function label.  Then make and emit a
>>>> +             simplified subprogram DIE for the second segment  
>>>> with the
>>>> +             name post-fixed with _$hot$ or _$cold$.  We use the  
>>>> same
>>>> +             linkage name for the second die so that gdb will  
>>>> find both
>>>> +             sections when given "b foo".  */
>>>
>>> This doesn't work when $ is not allowed, aka NO_DOLLAR_IN_LABEL.
>>> Presumably we need this workaround since Darwin is strict dwarf2?
>>
>> Yes, we need the work-around ..

FWIW, the problem is that we support only a sub-set of DW3 - so if you  
try gcc -gdwarf-3 either the linker or dsymutil dies.
so, we're stuck with DW2/strict.

>> but I'm not massively attached to $ (or even £ ;-))
>>
>> is it OK apart from that?
>
> Yeah, and I suppose you're after matching the symbols here with
> the symbols from that previous patch.
>
> Ok with an extra bit akin to the use in clone_function_name:
>
> #ifndef NO_DOT_IN_LABEL
>  prefix[len] = '.';
> #elif !defined NO_DOLLAR_IN_LABEL
>  prefix[len] = '$';
> #else
>  prefix[len] = '_';
> #endif
>
> though of course you may swap the preferencing of [$.] to match
> what you already have in darwin.c.

what I'm after is
(a) avoiding a name clash.
(b) having a generated  tag which is clearly understandable to the  
person debugging ..

If I prefix (rather than the current post-fix) with  "__hot_" and  
"__cold_"  (or even __hot_partition_) that should be safe and not  
require the extra hoops?

(I"m happy to do what you've suggested above, of course, if that's the  
best solution).

thanks,
Iain