[Mesa-dev] [PATCH 3/7] nir: fix output offset compute for dvec3/4

[Alejandro Piñeiro]

The offset compute was working fine for the case of attrib_slots=1,
and updating the offset for the following varying.

But in the case of attrib_slots=2 (so dvec3/4), we are basically
splitting the comp_slots needed in two outputs. In that case we can't
add to the offset the full size of the type.
---
 src/compiler/nir/nir_gather_xfb_info.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/compiler/nir/nir_gather_xfb_info.c b/src/compiler/nir/nir_gather_xfb_info.c
index f5d831c6567..01fc2b26624 100644
--- a/src/compiler/nir/nir_gather_xfb_info.c
+++ b/src/compiler/nir/nir_gather_xfb_info.c
@@ -81,7 +81,11 @@ add_var_xfb_outputs(nir_xfb_info *xfb,
          output->component_mask = (comp_mask >> (s * 4)) & 0xf;
 
          (*location)++;
-         *offset += comp_slots * 4;
+         /* attrib_slots would be only > 1 for doubles. On that case
+          * comp_slots will be a multiple of 2, so the following doesn't need
+          * to use DIV_ROUND_UP or similar
+          */
+         *offset += comp_slots / attrib_slots * 4;
       }
    }
 }
-- 
2.14.1