lavapipe: add a zeroed buffer that can be bound in place of an index buffer

technically this is illegal in vulkan semantics, but some extensions have
their own definition of "illegal" when it comes to binding index buffers

Acked-by: Dave Airlie <airlied@redhat.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/23394>

diff --git a/src/gallium/frontends/lavapipe/lvp_device.c b/src/gallium/frontends/lavapipe/lvp_device.c
index 90be3bd..f6f6a1c 100644 (file)
--- a/src/gallium/frontends/lavapipe/lvp_device.c
+++ b/src/gallium/frontends/lavapipe/lvp_device.c
@@ -1530,6 +1530,9 @@ VKAPI_ATTR VkResult VKAPI_CALL lvp_CreateDevice(
    _mesa_hash_table_init(&device->bda, NULL, _mesa_hash_pointer, _mesa_key_pointer_equal);
    simple_mtx_init(&device->bda_lock, mtx_plain);
 
+   uint32_t zero = 0;
+   device->zero_buffer = pipe_buffer_create_with_data(device->queue.ctx, 0, PIPE_USAGE_IMMUTABLE, sizeof(uint32_t), &zero);
+
    *pDevice = lvp_device_to_handle(device);
 
    return VK_SUCCESS;
@@ -1548,6 +1551,7 @@ VKAPI_ATTR void VKAPI_CALL lvp_DestroyDevice(
       device->pscreen->fence_reference(device->pscreen, &device->queue.last_fence, NULL);
    ralloc_free(device->bda.table);
    simple_mtx_destroy(&device->bda_lock);
+   pipe_resource_reference(&device->zero_buffer, NULL);
 
    lvp_queue_finish(&device->queue);
    vk_device_finish(&device->vk);

diff --git a/src/gallium/frontends/lavapipe/lvp_execute.c b/src/gallium/frontends/lavapipe/lvp_execute.c
index 36e4d19..2c0c2a2 100644 (file)
--- a/src/gallium/frontends/lavapipe/lvp_execute.c
+++ b/src/gallium/frontends/lavapipe/lvp_execute.c
@@ -2833,7 +2833,7 @@ static void handle_index_buffer(struct vk_cmd_queue_entry *cmd,
    if (ib->buffer)
       state->index_buffer = lvp_buffer_from_handle(ib->buffer)->bo;
    else
-      state->index_buffer = NULL;
+      state->index_buffer = state->device->zero_buffer;
 
    state->ib_dirty = true;
 }

diff --git a/src/gallium/frontends/lavapipe/lvp_private.h b/src/gallium/frontends/lavapipe/lvp_private.h
index 97da27b..fbbf315 100644 (file)
--- a/src/gallium/frontends/lavapipe/lvp_private.h
+++ b/src/gallium/frontends/lavapipe/lvp_private.h
@@ -193,6 +193,7 @@ struct lvp_device {
    void *noop_fs;
    simple_mtx_t bda_lock;
    struct hash_table bda;
+   struct pipe_resource *zero_buffer; /* for zeroed bda */
    bool poison_mem;
    bool print_cmds;
 };