[Mesa-dev] [PATCH] i965: skip varyings without slot

[Juan A. Suarez Romero]

Commit 00620782c9 (i965: use nir_shader_gather_info() over
do_set_program_inouts()) changed how we compute the outputs written.

In the previous version it was using the IR declared outputs, while in
the new one it uses NIR to parse the instructions that write outputs.

Thus, if the shader has declared some output that is not written later
in the code, like this:

~~~
struct S {
    vec4 a;
    vec4 b;
    vec4 c;
};

layout (xfb_offset = sizeof_type) out S s;

void main()
{

    s.a = vec4(1.0, 0.0, 0.0, 1.0);
    s.c = vec4(0.0, 1.0, 0.0, 1.0);
}
~~~

The former version computing 3 outputs written (s.a, s.b and s.c), while
the new version only counts 2 (s.a and s.c).

This means that with the new version, then could be varyings in the VUE
map that do not have an slot assigned (s.b), that must be skipped.

This fixes KHR-GL45.enhanced_layouts.xfb_capture_struct.
---
 src/mesa/drivers/dri/i965/genX_state_upload.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/genX_state_upload.c b/src/mesa/drivers/dri/i965/genX_state_upload.c
index a5ad2ca..573f0e3 100644
--- a/src/mesa/drivers/dri/i965/genX_state_upload.c
+++ b/src/mesa/drivers/dri/i965/genX_state_upload.c
@@ -3102,9 +3102,10 @@ genX(upload_3dstate_so_decl_list)(struct brw_context *brw,
       const unsigned stream_id = output->StreamId;
       assert(stream_id < MAX_VERTEX_STREAMS);
 
-      buffer_mask[stream_id] |= 1 << buffer;
+      if (vue_map->varying_to_slot[varying] == -1)
+	      continue;
 
-      assert(vue_map->varying_to_slot[varying] >= 0);
+      buffer_mask[stream_id] |= 1 << buffer;
 
       /* Mesa doesn't store entries for gl_SkipComponents in the Outputs[]
        * array.  Instead, it simply increments DstOffset for the following
-- 
2.9.4