nir/lower_io_to_vector: don't create arrays when not needed

Some backends require that there are no array varyings.

If there were no arrays in the input shader, the pass shouldn't have to
create new ones.

Closes: https://gitlab.freedesktop.org/mesa/mesa/issues/2103
Fixes: bcd14756eec ('nir/lower_io_to_vector: add flat mode')
Signed-off-by: Rhys Perry <pendingchaos02@gmail.com>
Reviewed-by: Connor Abbott <cwabbott0@gmail.com>

diff --git a/src/compiler/nir/nir_lower_io_to_vector.c b/src/compiler/nir/nir_lower_io_to_vector.c
index 0ef40216da6817916d7fc8116390b3018869d739..82c4bdf87496ae9ba6c25d0cda314dd8aedb6899 100644 (file)
--- a/src/compiler/nir/nir_lower_io_to_vector.c
+++ b/src/compiler/nir/nir_lower_io_to_vector.c
@@ -184,7 +184,10 @@ get_flat_type(const nir_shader *shader, nir_variable *old_vars[MAX_SLOTS][4],
    if (num_vars <= 1)
       return NULL;
 
-   return glsl_array_type(glsl_vector_type(base, 4), slots, 0);
+   if (slots == 1)
+      return glsl_vector_type(base, 4);
+   else
+      return glsl_array_type(glsl_vector_type(base, 4), slots, 0);
 }
 
 static bool
@@ -340,6 +343,9 @@ build_array_deref_of_new_var_flat(nir_shader *shader,
       deref = nir_build_deref_array(b, deref, index);
    }
 
+   if (!glsl_type_is_array(deref->type))
+      return deref;
+
    bool vs_in = shader->info.stage == MESA_SHADER_VERTEX &&
                 new_var->data.mode == nir_var_shader_in;
    return nir_build_deref_array(