asahi: Submit batches that don't touch RTs

If there is any draw, we should submit in case there are active queries,
fragment shader side effects, etc. Together with previous commit fixes
no_attachment framebuffers.

Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/21267>

src/gallium/drivers/asahi/agx_batch.c

@@ -60,6 +60,7 @@ agx_batch_init(struct agx_context *ctx,
    batch->clear_depth = 0;
    batch->clear_stencil = 0;
    batch->varyings = 0;
+   batch->any_draws = false;
 
    /* We need to emit prim state at the start. Max collides with all. */
    batch->reduced_prim = PIPE_PRIM_MAX;

src/gallium/drivers/asahi/agx_pipe.c

@@ -964,8 +964,8 @@ agx_flush_batch(struct agx_context *ctx, struct agx_batch *batch)
 
    assert(agx_batch_is_active(batch));
 
-   /* Nothing to do */
-   if (!(batch->draw | batch->clear)) {
+   /* Make sure there's something to submit. */
+   if (!batch->clear && !batch->any_draws) {
       agx_batch_cleanup(ctx, batch);
       return;
    }

src/gallium/drivers/asahi/agx_state.c

@@ -2424,6 +2424,8 @@ agx_draw_vbo(struct pipe_context *pctx, const struct pipe_draw_info *info,
       batch->resolve |= ctx->zs->store;
    }
 
+   batch->any_draws = true;
+
    if (agx_update_vs(ctx))
       ctx->dirty |= AGX_DIRTY_VS | AGX_DIRTY_VS_PROG;
    else if (ctx->stage[PIPE_SHADER_VERTEX].dirty)

src/gallium/drivers/asahi/agx_state.h

@@ -162,6 +162,7 @@ struct agx_batch {
 
    /* PIPE_CLEAR_* bitmask */
    uint32_t clear, draw, load, resolve;
+   bool any_draws;
 
    uint64_t uploaded_clear_color[PIPE_MAX_COLOR_BUFS];
    double clear_depth;