[Mesa-dev] [PATCH v2 3/4] ra: consider all spillable nodes for spilling

Eric Anholt eric at anholt.net
Fri Aug 1 11:51:02 PDT 2014


Connor Abbott <cwabbott0 at gmail.com> writes:

> On Thu, Jul 31, 2014 at 1:05 PM, Eric Anholt <eric at anholt.net> wrote:
>> Connor Abbott <cwabbott0 at gmail.com> writes:
>>> That's not necessarily true - you could want to spill a trivially
>>> colored register that interferes with a non trivially colored
>>> register, especially if the spill cost of the non trivially colored
>>> register is higher than that of the trivially colored register because
>>> e.g. the non trivially colored register is used in a loop. Especially,
>>> I ran into trouble with the varying packing tests in piglit which
>>> after a few rounds of spilling looked something like:
>>
>> If it's trivially colorable, then when you're trying to get a
>> non-conflicting color for a difficult neighbor (an optimistic-coloring
>> one near the top of the stack that's triggering the need for spilling),
>> it's out consideration because it's deeper in the stack.
>
> Right... so in that case, can't we just ignore everything on the stack
> below the node that couldn't be colored in ra_select()?

Yep, that's what the code's doing currently.
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