Accessing the TG4 component via immediates in the llvmpipe backend is quite messy (like really messy). Roland suggested we change the instruction encoding, so introduce a cap to allow the component to be selected to be store in the sampler swizzle, which should be otherwise unused.
I could probably switch all drivers over, but virgl would need some work that I'd prefer not to rush it.
0c09df52e10 gallium: add a a new cap for changing the TGSI TG4 instruction encoding
src/gallium/auxiliary/util/u_screen.c | 1 +
src/gallium/docs/source/screen.rst | 1 +
src/gallium/docs/source/tgsi.rst | 8 ++++++++
src/gallium/include/pipe/p_defines.h | 1 +
4 files changed, 11 insertions(+)