We set the maximum at 16 iterations (the GL compiler chooses 32
iterations for the GLSL front-end loop unrolling pass) because we
have observed a bunch of shaders from Sascha Willems that spill
significantly with 32, leading to massive performance degradation,
while 16 avoids spilling and doesn't seem to cause visible
performance degradation compared to cases that unroll 32 without
spilling.
Reviewed-by: Alejandro Piñeiro <apinheiro@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/10647>
Iago Toral Quiroga
db3fa1cc8c