Sampling coeffs with trilinear filtering will output 2x sets of data.
Whether bilinear or trilinear filtering is in use can't be determined
without checking state words, so unconditionally reserve 2x to avoid
clobbering output regs.
Fixes: 7df32ba09d ("pco: initial texture/sampler compiler support")
Signed-off-by: Simon Perretta <simon.perretta@imgtec.com>
Acked-by: Frank Binns <frank.binns@imgtec.com>
Tested-by: Icenowy Zheng <zhengxingda@iscas.ac.cn>
(cherry picked from commit af1669d9e2)
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/41269>