The prog_to_nir->NIR-to-TGSI change ended up causing regressions on r300,
and svga against r300-class hardware, because nir_lower_uniforms_to_ubo()
introduced shifts that nir_lower_ubo_vec4() tried to reverse, but that NIR
couldn't prove are no-ops (since shifting up and back down may drop bits),
and the hardware can't do the integer ops.
Instead, make it so that nir_lower_uniforms_to_ubo can generate
nir_intrinsic_load_ubo_vec4 directly for !INTEGER hardware.
Fixes: cf3fc79cd0 ("st/mesa: Replace mesa_to_tgsi() with prog_to_nir() and nir_to_tgsi().")
Closes: #4602
Reviewed-By: Mike Blumenkrantz <michael.blumenkrantz@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/10194>
5de3cbbb2e