vc4: Speed up glGenerateMipmaps by avoiding shadow baselevel.

To support general GL_TEXTURE_BASE_LEVEL we have to copy to a temporary
miptree.  However, if a single level is being selected, we can use the
existing miptree and force all the sampling to be from that particular
level.

This avoids a ton of software fallbacks in glGenerateMipmaps(), which uses
base levels in the blit implementation in gallium.  Improves "glmark2 -b
terrain" from 2 fps to 3 (perhaps some more precision would be useful?),
and cuts its CPU usage during the benchmarking from ~30% to ~10% (total
CPU time from 8.8s to 7.6s).

1 files changed, 1 insertions, 0 deletions

diff --git a/src/gallium/drivers/vc4/vc4_qir.h b/src/gallium/drivers/vc4/vc4_qir.h
index 88eda225d80..81b55651cec 100644
--- a/src/gallium/drivers/vc4/vc4_qir.h
+++ b/src/gallium/drivers/vc4/vc4_qir.h
@@ -314,6 +314,7 @@ struct vc4_key {
                                 unsigned compare_func:3;
                                 unsigned wrap_s:3;
                                 unsigned wrap_t:3;
+                                unsigned forced_first_level:8;
                         };
                         struct {
                                 uint16_t msaa_width, msaa_height;