[Mesa-dev] [PATCH 1/2] gm107/ir: make use of FADD32I for all immediates

[Samuel Pitoiset]

On 06/28/2016 04:23 PM, Ilia Mirkin wrote:
> On Tue, Jun 28, 2016 at 10:21 AM, Samuel Pitoiset
> <samuel.pitoiset at gmail.com> wrote:
>> On 06/28/2016 04:15 PM, Ilia Mirkin wrote:
>>>
>>> Again, what problem was this patch trying to solve?
>>
>>
>> The problem is that FADD can only emits 19-bits but longIMMD() will return
>> false because it only checks for the high 12-bits.
>>
>> I don't know if you saw my messages on IRC but I found some other issues
>> with longIMMD() and emitIMMD().
>
> Nope, it will emit 19 bits and then the 20th (high aka sign) bit as
> well, just to a different location. [And the bottom 12 bits are
> guaranteed to be 0.]
>
> What's a specific example that you think it doesn't emit correctly?

I don't have any shaders which hit that issue, but I think it's similar 
to the fix I did for IMUL32I. The immediate value was 0xf4240 in that 
specific case, and IMUL emitted 0x74240 instead... because the sign bit 
was used to emit the NEG modifier.

>
>  -ilia
>

-- 
-Samuel