On Fri, Apr 24, 2015 at 5:08 PM, Axel Davy <axel.d...@ens.fr> wrote:
> Le 24/04/2015 23:04, Ilia Mirkin a écrit :
>>
>> On Fri, Apr 24, 2015 at 4:09 PM, Axel Davy <axel.d...@ens.fr> wrote:
>>>
>>> Signed-off-by: Axel Davy <axel.d...@ens.fr>
>>> ---
>>> src/gallium/state_trackers/nine/nine_shader.c | 19 ++++++++++++++++++-
>>> 1 file changed, 18 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/src/gallium/state_trackers/nine/nine_shader.c
>>> b/src/gallium/state_trackers/nine/nine_shader.c
>>> index 2ba625e..0fd3d37 100644
>>> --- a/src/gallium/state_trackers/nine/nine_shader.c
>>> +++ b/src/gallium/state_trackers/nine/nine_shader.c
>>> @@ -2040,6 +2040,23 @@ DECL_SPECIAL(LOG)
>>> return D3D_OK;
>>> }
>>>
>>> +DECL_SPECIAL(LIT)
>>> +{
>>> + struct ureg_program *ureg = tx->ureg;
>>> + struct ureg_dst tmp = tx_scratch(tx);
>>> + struct ureg_dst dst = tx_dst_param(tx, &tx->insn.dst[0]);
>>> + struct ureg_src src = tx_src_param(tx, &tx->insn.src[0]);
>>> + ureg_LIT(ureg, tmp, src);
>>> + /* d3d9 LIT is the same than gallium LIT. One difference is that
>>> d3d9
>>> + * states that dst.z is 0 when src.y <= 0. Gallium definition can
>>> assign
>>> + * it 0^0 if src.w=0, which value is driver dependent. */
>>> + ureg_CMP(ureg, ureg_writemask(dst, TGSI_WRITEMASK_Z),
>>> + ureg_negate(ureg_scalar(src, TGSI_SWIZZLE_Y)),
>>> + ureg_src(tmp), ureg_imm1f(ureg, 0.0f));
>>> + ureg_MOV(ureg, ureg_writemask(dst, TGSI_WRITEMASK_XYW),
>>> ureg_src(tmp));
>>
>> Why use a separate temp? Couldn't you just
>>
>> ureg_LIT(ureg, dst, src);
>> ureg_CMP(ureg, writemask(dst, Z), -src.y, ureg_src(dst), ureg_imm1f(0.0))
>> ?
>>
> Isn't there a restriction in the case dst is an output register of the
> shader ? Reading from it would be forbidden.
> Also likely it is easier to optimiser for compilers with the temp version.
Ah yes. Usually that doesn't come in st/mesa, but I guess it can
happen with d3d9. OK.
Reviewed-by: Ilia Mirkin <imir...@alum.mit.edu>
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