[Mesa-dev] [PATCH] gallium/r600: Replace ALIGN_DIVUP with DIV_ROUND_UP

[Krzysztof A. Sobiecki]

Nicolai Hähnle <nhaehnle at gmail.com> writes:

> On 30.12.2015 13:44, Krzysztof A. Sobiecki wrote:
>> Nicolai Hähnle <nhaehnle at gmail.com> writes:
>>
>>> On 30.12.2015 08:42, Krzysztof A. Sobiecki wrote:
>>>> Nicolai Hähnle <nhaehnle at gmail.com> writes:
>>>>
>>>>> On 29.12.2015 14:27, Krzysztof A. Sobiecki wrote:
>>>>>> From: Krzysztof Sobiecki <sobkas at gmail.com>
>>>>>>
>>>>>> ALIGN_DIVUP is a driver specific(r600g) macro that duplicates DIV_ROUND_UP functionality.
>>>>>> Replacing it with DIV_ROUND_UP eliminates this problems.
>>>>>
>>>>> Those macros are actually slightly different, and the assembly
>>>>> generated by the ALIGN_DIVUP looks clearly better to me.
>>>>>
>>>>> I remember seeing a very long thread about this not so long ago - what
>>>>> was the resolution there?
>>>>>
>>>>> Cheers,
>>>>> Nicolai
>>>>>
>>>> I would like to remove ALIGN_DIVUP first and then debate with
>>>> implementation DIV_ROUND_UP should use.
>>>>
>>>> btw. I prefer 1 + ((x - 1) / y)
>>>
>>> That produces an incorrect result when x is an unsigned type and equal
>>> to 0 -- and that is something that existing code definitely relies on.
>>>
>>> Cheers,
>>> Nicolai
>>>
>> Then what about (x / y) + (i % y != 0)
>
> Generates similar assembly to the DIV_ROUND_UP version.
>
> Anyway, now that I look at it again I'd say just go ahead and add my
> R-b. Yes, the assembly looks slightly worse, but only slightly, and
> avoiding surprises with overflows down the line seems like a good
> idea.
>
> Cheers,
> Nicolai
>
I don't have commit access, can you push it, sorry.
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