OPTIONAL: iris: Perform BLORP buffer barriers outside of iris_blorp_exec() hook.

The iris_blorp_exec() hook needs to be executed under a single
indivisible sync region, which means that in cases where we need to
emit a PIPE_CONTROL for a buffer barrier we won't be able to track the
subsequent commands separately from the previous commands, which will
prevent us from optimizing out subsequent PIPE_CONTROLs if we
encounter the same buffers again.  In particular I've encountered this
situation in some SynMark test-cases which perform lots of BLORP
operations with the same buffer bound as both source and destination
(in order to generate mipmaps): In such a scenario if the source
requires flushing we'd also end up flushing for the destination
redundantly, even though a single PIPE_CONTROL would have been
sufficient.

This avoids a 4.5% FPS regression in SynMark OglHdrBloom and a 3.5%
FPS regression in SynMark OglMultithread.

Reviewed-by: Kenneth Graunke <[email protected]>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/3875>

1 files changed, 1 insertions, 0 deletions

diff --git a/src/gallium/drivers/iris/iris_resolve.c b/src/gallium/drivers/iris/iris_resolve.c
index 71530f4b311..0350e58a225 100644
--- a/src/gallium/drivers/iris/iris_resolve.c
+++ b/src/gallium/drivers/iris/iris_resolve.c
@@ -450,6 +450,7 @@ iris_mcs_partial_resolve(struct iris_context *ice,
    struct blorp_surf surf;
    iris_blorp_surf_for_resource(&batch->screen->isl_dev, &surf,
                                 &res->base, res->aux.usage, 0, true);
+   iris_emit_buffer_barrier_for(batch, res->bo, IRIS_DOMAIN_RENDER_WRITE);
 
    struct blorp_batch blorp_batch;
    iris_batch_sync_region_start(batch);