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

[Ian Romanick]

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
>>>
>>> _______________________________________________
>>> mesa-dev mailing list
>>> mesa-dev at lists.freedesktop.org
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