[Mesa-dev] [PATCH] r600g: fix and optimize tgsi_cmp when using ABS and NEG modifier

[Ian Romanick]

On 04/02/2016 02:45 AM, Patrick Rudolph wrote:
> Are there optimizations done on TGSI ?
> I can't find any file in src/gallium/auxiliary/tgsi that does so.

What I meant was, at some point the driver translates TGSI into its own
representation.  When that translation occurs, generate the smarter code.

> Kind Regards,
> Patrick
> 
> On 2016-03-30 06:59 PM, Ian Romanick wrote:
>> I'd recommend doing this at a higher level.  We've been doing this in
>> NIR (in nir_opt_algebraic.py) for quite some time, and we've found that
>> having x==0 instead of -abs(x)>=0 in higher-level IR helps other
>> optimizations make progress.  Maybe do this when translating out of TGSI?
>>
>> On 03/30/2016 03:30 AM, Patrick Rudolph wrote:
>>> It affects the game "RIFT" and fixes slightly wrong colors on
>>> the player model, when using the nine state-tracker.
>>>
>>> Kind Regards,
>>> Patrick
>>>
>>> On 2016-03-29 11:09 PM, Dave Airlie wrote:
>>>> On 28 March 2016 at 19:52,  <siro at das-labor.org> wrote:
>>>>> From: Patrick Rudolph <siro at das-labor.org>
>>>>>
>>>>> Some apps set NEG and ABS on the source param to test for zero.
>>>>> Use ALU_OP3_CNDE insted of ALU_OP3_CNDGE and unset both modifiers.
>>>>>
>>>>> It also removes the need for a MOV instruction, as ABS isn't
>>>>> supported on op3.
>>>>>
>>>>> Tested on AMD CAYMAN and AMD RV770.
>>>>>
>>>>> Signed-off-by: Patrick Rudolph <siro at das-labor.org>
>>>>
>>>> Seems sane to me, does this help in any app in particular?
>>>>
>>>> Reviewed-by: Dave Airlie <airlied at redhat.com>
>>>>
>>>> I just have to remember to push this tomorrow.
>>>>
>>>> Dave.
>>>>
>>>>> ---
>>>>>  src/gallium/drivers/r600/r600_shader.c | 11 ++++++++++-
>>>>>  1 file changed, 10 insertions(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/src/gallium/drivers/r600/r600_shader.c b/src/gallium/drivers/r600/r600_shader.c
>>>>> index 77658f5..e5e2e3f 100644
>>>>> --- a/src/gallium/drivers/r600/r600_shader.c
>>>>> +++ b/src/gallium/drivers/r600/r600_shader.c
>>>>> @@ -7707,6 +7707,15 @@ static int tgsi_cmp(struct r600_shader_ctx *ctx)
>>>>>         int i, r, j;
>>>>>         int lasti = tgsi_last_instruction(inst->Dst[0].Register.WriteMask);
>>>>>         int temp_regs[3];
>>>>> +       unsigned op;
>>>>> +
>>>>> +       if (ctx->src[0].abs && ctx->src[0].neg) {
>>>>> +               op = ALU_OP3_CNDE;
>>>>> +               ctx->src[0].abs = 0;
>>>>> +               ctx->src[0].neg = 0;
>>>>> +       } else {
>>>>> +               op = ALU_OP3_CNDGE;
>>>>> +       }
>>>>>
>>>>>         for (j = 0; j < inst->Instruction.NumSrcRegs; j++) {
>>>>>                 temp_regs[j] = 0;
>>>>> @@ -7719,7 +7728,7 @@ static int tgsi_cmp(struct r600_shader_ctx *ctx)
>>>>>                         continue;
>>>>>
>>>>>                 memset(&alu, 0, sizeof(struct r600_bytecode_alu));
>>>>> -               alu.op = ALU_OP3_CNDGE;
>>>>> +               alu.op = op;
>>>>>                 r = tgsi_make_src_for_op3(ctx, temp_regs[0], i, &alu.src[0], &ctx->src[0]);
>>>>>                 if (r)
>>>>>                         return r;
>>>>> --
>>>>> 2.5.0
>>>>>
>>>>> _______________________________________________
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>>>>> mesa-dev at lists.freedesktop.org
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>