r600: make vertex r10g10b10a2_snorm conformant on palm and beyond
The mode r10g10b10a2_snorm processed as vertex on palm at the
hardware level doesn't follow the current standard. Indeed, the .w
component (2-bits) is not calculated as expected. The table below
describes the situation.
This change fixes this issue by adding three gpu instructions at
the vertex fetch shader stage. An equivalent C representation and
a gpu asm dump of the generated sequence are available below.
.w(2-bits) expected palm
0 0.0 0.000000
1 1.0 0.333333
2 -1.0 0.666667
3 -1.0 1.000000
w_out = (4.*w_in > 1. ? 1. : 4.*w_in) - (w_in > 0.5 ? 2. : 0.);
0002 00000008 A0080000 ALU 3 @16
0016 00000C02 A0000CC0 1 y: MOV*4_sat __.y, R2.w
0018 801F8C02 600004A0 w: SETGT*2 __.w, R2.w, 0.5
0020 839FC4FE 60400010 2 w: ADD R2.w, PV.y, -PV.w
Note: The rv770 and cypress don't need this correction. This is
definitely a hardware change between these gpus.
This change was tested on palm, barts and cayman. Here are the tests fixed:
spec/arb_vertex_type_2_10_10_10_rev/arb_vertex_type_2_10_10_10_rev-array_types: fail pass
deqp-gles3/functional/draw/random/124: fail pass
deqp-gles3/functional/vertex_arrays/single_attribute/normalize/int2_10_10_10/components4_quads1: fail pass
deqp-gles3/functional/vertex_arrays/single_attribute/normalize/int2_10_10_10/components4_quads256: fail pass
khr-gl43/vertex_attrib_binding/basic-input-case5: fail pass
khr-gl44/vertex_attrib_binding/basic-input-case5: fail pass
khr-gl45/vertex_attrib_binding/basic-input-case5: fail pass
Cc: mesa-stable
Signed-off-by: Patrick Lerda <patrick9876@free.fr>
Reviewed-by: Gert Wollny <gert.wollny@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/32427>
1 file changed
