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Re: i seem to have hit a problem with my new conflict finder.


Andrew MacLeod wrote:
> On Fri, 2007-08-17 at 12:01 -0400, Kenneth Zadeck wrote:
>
>   
>>> In any case IRA can not use UREC because UREC is needed before IRA
>>> calculates reg class info and the reg class info is needed for
>>> calculation of UREC.  If you manage to use LIVE instead of UREC, it
>>> would permit to use LIVE also in IRA instead of LR.  But I can not say
>>> can we use LIVE instead of UREC because I don't know the
>>> df-infrastructure well yet.
>>>
>>>       
>> we should talk.  I am avail today.  i am leaving on vacation tomorrow
>> for a week.
>>
>> Even if this patch does not get in this round, you should consider it as
>> a starting point for building the interference graph for ira.  
>>
>> it does not use urec and a big part of the patch is just getting rid of
>> urec,  It does a backwards scan using the live at bottom set as the
>> starting point for the scan.
>> This is the most accurate you can get so there really is no reason not
>> to use it since it is also no more expensive than any weaker technique. 
>>     
>
> It is the standard way of doing things. Out-Of-SSA has always used live
> range info from the bottom up for its conflict graph. I'm marginally
> suprised it is calculated any other way...
>
> Andrew
>
>   
this is gcc, get a life. 

bottom up is the way i was taught when i was a small child playing with
compilers with training wheels. 

Gcc always seemed weird because you need reg_dead and reg_unused notes. 
Note that my patch does not use reg_dead or unused notes.

kenny


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