[Mesa-dev] [PATCH 2/3] r600g: replace trans/vector-only instruction lists with ranges

[Alex Deucher]

2012/1/23 Christian König <deathsimple at vodafone.de>:
> On 22.01.2012 17:24, Dave Airlie wrote:
>>
>> 2012/1/22 Christian König<deathsimple at vodafone.de>:
>>>
>>> On 22.01.2012 16:46, Dave Airlie wrote:
>>>>
>>>> 2012/1/22 Christian König<deathsimple at vodafone.de>:
>>>>>
>>>>> Sorry, but that looks really ugly and pretty much unmaintainable, cause
>>>>> you
>>>>> constantly need to lookup the meaning of the values.
>>>>>
>>>>> Also I haven't looked into the docs (but going to do so tomorrow), but
>>>>> I'm
>>>>> pretty sure that those ranges aren't 100% correct.
>>>>
>>>> It was the docs that the ranges came from, and we keep forgetting to
>>>> add things to these lookup functions.
>>>
>>>
>>> Really? Where? I asked around when I coded this in the first place if it
>>> could be simplified by using ranges, but never got an clear answer on
>>> this
>>> topic.
>>>
>>> When I now look into the AMD docs they mostly seems to use tables for
>>> opcode
>>> attributes, so I assumed that they are spread around in the opcode range.
>>>
>>> If this isn't the case then this indeed seems to be an good idea.
>>
>> Its in the Evergreen ISA docs (it might only be evergreen they managed
>> this).
>>
>> ALU_WORD1_OP2
>> ALU_INST
>> [17:7]
>> enum(11)
>> Instruction. The top three bits of this field must be zero. Gaps in
>> opcode values
>> are not marked in the list below. See Chapter 7 for descriptions of each
>> instruction. Opcodes 0..95 can be used in either the Vector or Trans unit.
>> Opcodes 128..159 are Trans only. Opcodes 160..255 are vector only.
>
> Those ranges are even better than the table based documentation! The tables
> contained an quite ugly bug which lead to this comment in the original code:
>
>
> /* Note that FLT_TO_INT_* instructions are vector-only instructions
>  * on Evergreen, despite what the documentation says. FLT_TO_INT
>  * can do both vector and scalar. */
>
> Very interesting, but I couldn't such ranges for R6xx and R7xx. Alex do you
> remember where you got that original documentation from?

I've been talking to the hw guys and referencing the hw specs.

Alex

>
> Anyway I would still suggest to not use magic numbers, let's define the
> beginning and end of ranges in r600_opcode.h instead, and then use those
> defines inside the code.
>
> Christian.