nir/gather_info: implement partial masking of struct and compact I/O

fossil-db (Sienna):
Totals from 138 (0.10% of 138791) affected shaders:
CodeSize: 504060 -> 482136 (-4.35%)
Instrs: 97318 -> 94518 (-2.88%)
Cycles: 389272 -> 378072 (-2.88%)
VMEM: 14397 -> 14614 (+1.51%); split: +1.76%, -0.25%
SMEM: 9088 -> 9024 (-0.70%)
VClause: 2915 -> 2430 (-16.64%)
SClause: 1790 -> 1791 (+0.06%)
PreVGPRs: 5013 -> 4998 (-0.30%)

Signed-off-by: Rhys Perry <pendingchaos02@gmail.com>
Reviewed-by: Timothy Arceri <tarceri@itsqueeze.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/8364>

src/compiler/nir/nir_gather_info.c

@@ -194,7 +194,7 @@ mark_whole_variable(nir_shader *shader, nir_variable *var,
 }
 
 static unsigned
-get_io_offset(nir_deref_instr *deref, bool is_vertex_input, bool per_vertex)
+get_io_offset(nir_deref_instr *deref, bool compact, bool per_vertex)
 {
    unsigned offset = 0;
 
@@ -206,10 +206,18 @@ get_io_offset(nir_deref_instr *deref, bool is_vertex_input, bool per_vertex)
          if (!nir_src_is_const(d->arr.index))
             return -1;
 
-         offset += glsl_count_attribute_slots(d->type, is_vertex_input) *
+         if (compact)
-                   nir_src_as_uint(d->arr.index);
+            offset += nir_src_as_uint(d->arr.index) / 4;
+         else
+            offset += glsl_count_attribute_slots(d->type, false) *
+                      nir_src_as_uint(d->arr.index);
+      } else if (d->deref_type == nir_deref_type_struct) {
+         const struct glsl_type *parent_type = nir_deref_instr_parent(d)->type;
+         for (unsigned i = 0; i < d->strct.index; i++) {
+            const struct glsl_type *field_type = glsl_get_struct_field(parent_type, i);
+            offset += glsl_count_attribute_slots(field_type, false);
+         }
       }
-      /* TODO: we can get the offset for structs here see nir_lower_io() */
    }
 
    return offset;
@@ -238,45 +246,15 @@ try_mask_partial_io(nir_shader *shader, nir_variable *var,
    if (var->data.per_view)
       return false;
 
-   /* The code below only handles:
+   unsigned offset = get_io_offset(deref, var->data.compact, per_vertex);
-    *
-    * - Indexing into matrices
-    * - Indexing into arrays of (arrays, matrices, vectors, or scalars)
-    *
-    * For now, we just give up if we see varying structs and arrays of structs
-    * here marking the entire variable as used.
-    */
-   if (!(glsl_type_is_matrix(type) ||
-         (glsl_type_is_array(type) && !var->data.compact &&
-          (glsl_type_is_numeric(glsl_without_array(type)) ||
-           glsl_type_is_boolean(glsl_without_array(type)))))) {
-
-      /* If we don't know how to handle this case, give up and let the
-       * caller mark the whole variable as used.
-       */
-      return false;
-   }
-
-   unsigned offset = get_io_offset(deref, false, per_vertex);
    if (offset == -1)
       return false;
 
-   unsigned num_elems;
+   const unsigned slots =
-   unsigned elem_width = 1;
+      var->data.compact ? DIV_ROUND_UP(glsl_get_length(type), 4)
-   unsigned mat_cols = 1;
+                        : glsl_count_attribute_slots(type, false);
-   if (glsl_type_is_array(type)) {
-      num_elems = glsl_get_aoa_size(type);
-      if (glsl_type_is_matrix(glsl_without_array(type)))
-         mat_cols = glsl_get_matrix_columns(glsl_without_array(type));
-   } else {
-      num_elems = glsl_get_matrix_columns(type);
-   }
 
-   /* double element width for double types that takes two slots */
+   if (offset >= slots) {
-   if (glsl_type_is_dual_slot(glsl_without_array(type)))
-      elem_width *= 2;
-
-   if (offset >= num_elems * elem_width * mat_cols) {
       /* Constant index outside the bounds of the matrix/array.  This could
        * arise as a result of constant folding of a legal GLSL program.
        *
@@ -289,7 +267,8 @@ try_mask_partial_io(nir_shader *shader, nir_variable *var,
       return false;
    }
 
-   set_io_mask(shader, var, offset, elem_width, deref, is_output_read);
+   unsigned len = glsl_count_attribute_slots(deref->type, false);
+   set_io_mask(shader, var, offset, len, deref, is_output_read);
    return true;
 }