[Mesa-dev] [PATCH 03/10] i965: Don't implicitly set predicate default state in brw_CMP.

[Kenneth Graunke]

On 05/25/2014 01:02 PM, Matt Turner wrote:
> On Sun, May 25, 2014 at 1:08 AM, Kenneth Graunke <kenneth at whitecape.org> wrote:
>> diff --git a/src/mesa/drivers/dri/i965/brw_clip_tri.c b/src/mesa/drivers/dri/i965/brw_clip_tri.c
>> index fdab260..5894b80 100644
>> --- a/src/mesa/drivers/dri/i965/brw_clip_tri.c
>> +++ b/src/mesa/drivers/dri/i965/brw_clip_tri.c
>> @@ -433,6 +434,7 @@ void brw_clip_tri( struct brw_clip_compile *c )
>>               BRW_CONDITIONAL_GE,
>>               c->reg.nr_verts,
>>               brw_imm_ud(3));
>> +      brw_set_predicate_control(p, BRW_PREDICATE_NORMAL);
> 
> I think the following instructions are predicated on the flag value
> set by this compare instruction -- a couple of shifts, and add, and
> then a while instruction. I don't see a break or another way out of
> the loop, so I'm guessing that the while is predicated on this
> compare.

Yes, I agree...and that's what the code should be doing.

brw_set_predicate_control(p, BRW_PREDICATE_NORMAL) sets the default
state for all future instructions to be predicated.  brw_WHILE will
reset that to BRW_PREDICATE_NONE after emitting the WHILE instruction.

Killing that implicit magic is on my to do list as well, but for now,
this at least gets the rubbish out of brw_CMP.  One bit at a time... :)

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