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3c78215a1c
The status quo is quite the mess:
1. tgsi_exec will do a per-channel computation, and store the dst[0]
result (significand) correctly for each channel. The dst[1] result
(exponent) will be written to the first bit set in the writemask.
So per-component calculation only works partially.
2. r600 will only do a single computation. It will replicate the
exponent but not the significand.
3. The docs pretend that there's per-component calculation, but even
get dst[0] and dst[1] confused.
4. Luckily, st_glsl_to_tgsi only ever emits single-component instructions,
and kind-of assumes that everything is replicated, generating this for
the dvec4 case:
DFRACEXP TEMP[0].xy, TEMP[1].x, CONST[0][0].xyxy
DFRACEXP TEMP[0].zw, TEMP[1].y, CONST[0][0].zwzw
DFRACEXP TEMP[2].xy, TEMP[1].z, CONST[0][1].xyxy
DFRACEXP TEMP[2].zw, TEMP[1].w, CONST[0][1].zwzw
Settle on the simplest behavior, which is single-component calculation
with replication, document it, and adjust tgsi_exec and r600.
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Tested-by: Dieter Nützel <Dieter@nuetzel-hh.de>
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| .. | ||
| cso | ||
| drivers | ||
| exts | ||
| conf.py | ||
| context.rst | ||
| cso.rst | ||
| debugging.rst | ||
| distro.rst | ||
| drivers.rst | ||
| format.rst | ||
| glossary.rst | ||
| index.rst | ||
| intro.rst | ||
| pipeline.txt | ||
| resources.rst | ||
| screen.rst | ||
| tgsi.rst | ||