Mesa (main): i965: Emit a NULL surface for buffer textures with no buffer

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Module: Mesa
Branch: main
Commit: 393fda2d341f65cba6e160d4704983370ae041f9
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=393fda2d341f65cba6e160d4704983370ae041f9

Author: Jason Ekstrand <jason at jlekstrand.net>
Date:   Wed Oct 13 16:31:57 2021 -0500

i965: Emit a NULL surface for buffer textures with no buffer

This is a preexisting bug but it was uncovered by 231653ea3506
("intel/isl: Add a max_buffer_size limit to isl_device") which added an
assert(num_elements > 0) for typed buffers.

Cc: mesa-stable at lists.freedesktop.org
Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/13351>

---

 src/mesa/drivers/dri/i965/brw_wm_surface_state.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/src/mesa/drivers/dri/i965/brw_wm_surface_state.c b/src/mesa/drivers/dri/i965/brw_wm_surface_state.c
index 5caeda5239a..c750bc71936 100644
--- a/src/mesa/drivers/dri/i965/brw_wm_surface_state.c
+++ b/src/mesa/drivers/dri/i965/brw_wm_surface_state.c
@@ -680,6 +680,11 @@ buffer_texture_range_size(struct brw_context *brw,
                brw->ctx.Const.MaxTextureBufferSize * texel_size);
 }
 
+static void
+emit_null_surface_state(struct brw_context *brw,
+                        const struct gl_framebuffer *fb,
+                        uint32_t *out_offset);
+
 void
 brw_update_buffer_texture_surface(struct gl_context *ctx,
                                   unsigned unit,
@@ -695,6 +700,11 @@ brw_update_buffer_texture_surface(struct gl_context *ctx,
    const enum isl_format isl_format = brw_isl_format_for_mesa_format(format);
    int texel_size = _mesa_get_format_bytes(format);
 
+   if (tObj->BufferObject == NULL) {
+      emit_null_surface_state(brw, NULL, surf_offset);
+      return;
+   }
+
    if (intel_obj)
       bo = brw_bufferobj_buffer(brw, intel_obj, tObj->BufferOffset, size,
                                 false);