vc4: Allow user index buffers, to avoid slow readback for shadow IBs.

Improves low-settings openarena performance by 31.9975% +/- 0.659931%
(n=7).

1 files changed, 12 insertions, 6 deletions

diff --git a/src/gallium/drivers/vc4/vc4_resource.c b/src/gallium/drivers/vc4/vc4_resource.c
index 5d5166fd818..122bda0bac6 100644
--- a/src/gallium/drivers/vc4/vc4_resource.c
+++ b/src/gallium/drivers/vc4/vc4_resource.c
@@ -667,11 +667,16 @@ vc4_get_shadow_index_buffer(struct pipe_context *pctx,
                        shadow_offset, &shadow_rsc, &data);
         uint16_t *dst = data;
 
-        struct pipe_transfer *src_transfer;
-        uint32_t *src = pipe_buffer_map_range(pctx, &orig->base.b,
-                                              ib->offset,
-                                              count * 4,
-                                              PIPE_TRANSFER_READ, &src_transfer);
+        struct pipe_transfer *src_transfer = NULL;
+        uint32_t *src;
+        if (ib->user_buffer) {
+                src = ib->user_buffer;
+        } else {
+                src = pipe_buffer_map_range(pctx, &orig->base.b,
+                                            ib->offset,
+                                            count * 4,
+                                            PIPE_TRANSFER_READ, &src_transfer);
+        }
 
         for (int i = 0; i < count; i++) {
                 uint32_t src_index = src[i];
@@ -679,7 +684,8 @@ vc4_get_shadow_index_buffer(struct pipe_context *pctx,
                 dst[i] = src_index;
         }
 
-        pctx->transfer_unmap(pctx, src_transfer);
+        if (src_transfer)
+                pctx->transfer_unmap(pctx, src_transfer);
 
         return shadow_rsc;
 }