1 /*
2 * Copyright © 2015 Intel Corporation
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining a
5 * copy of this software and associated documentation files (the "Software"),
6 * to deal in the Software without restriction, including without limitation
7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8 * and/or sell copies of the Software, and to permit persons to whom the
9 * Software is furnished to do so, subject to the following conditions:
10 *
11 * The above copyright notice and this permission notice (including the next
12 * paragraph) shall be included in all copies or substantial portions of the
13 * Software.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
18 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
20 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
21 * IN THE SOFTWARE.
22 */
23
24 #include "nir.h"
25 #include "nir_builder.h"
26
27 /**
28 * @file
29 *
30 * This pass combines separate clip and cull distance arrays into a
31 * single array that contains both. Clip distances come first, then
32 * cull distances. It also populates nir_shader_info with the size
33 * of the original arrays so the driver knows which are which.
34 */
35
36 /**
37 * Get the length of the clip/cull distance array, looking past
38 * any interface block arrays.
39 */
40 static unsigned
get_unwrapped_array_length(nir_shader * nir,nir_variable * var)41 get_unwrapped_array_length(nir_shader *nir, nir_variable *var)
42 {
43 if (!var)
44 return 0;
45
46 /* Unwrap GS input and TCS input/output interfaces. We want the
47 * underlying clip/cull distance array length, not the per-vertex
48 * array length.
49 */
50 const struct glsl_type *type = var->type;
51 if (nir_is_per_vertex_io(var, nir->stage))
52 type = glsl_get_array_element(type);
53
54 assert(glsl_type_is_array(type));
55
56 return glsl_get_length(type);
57 }
58
59 /**
60 * Update the type of the combined array (including interface block nesting).
61 */
62 static void
update_type(nir_variable * var,gl_shader_stage stage,unsigned length)63 update_type(nir_variable *var, gl_shader_stage stage, unsigned length)
64 {
65 const struct glsl_type *type = glsl_array_type(glsl_float_type(), length);
66
67 if (nir_is_per_vertex_io(var, stage))
68 type = glsl_array_type(type, glsl_get_length(var->type));
69
70 var->type = type;
71 }
72
73 /**
74 * Rewrite any clip/cull distances to refer to the new combined array.
75 */
76 static void
rewrite_references(nir_instr * instr,nir_variable * combined,unsigned cull_offset)77 rewrite_references(nir_instr *instr,
78 nir_variable *combined,
79 unsigned cull_offset)
80 {
81 if (instr->type != nir_instr_type_intrinsic)
82 return;
83
84 nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);
85
86 /* copy_var needs to be lowered to load/store before calling this pass */
87 assert(intrin->intrinsic != nir_intrinsic_copy_var);
88
89 if (intrin->intrinsic != nir_intrinsic_load_var &&
90 intrin->intrinsic != nir_intrinsic_store_var)
91 return;
92
93 nir_deref_var *var_ref = intrin->variables[0];
94 if (var_ref->var->data.mode != combined->data.mode)
95 return;
96
97 if (var_ref->var->data.location != VARYING_SLOT_CLIP_DIST0 &&
98 var_ref->var->data.location != VARYING_SLOT_CULL_DIST0)
99 return;
100
101 /* Update types along the deref chain */
102 const struct glsl_type *type = combined->type;
103 nir_deref *deref = &var_ref->deref;
104 while (deref) {
105 deref->type = type;
106 deref = deref->child;
107 type = glsl_get_array_element(type);
108 }
109
110 /* For cull distances, add an offset to the array index */
111 if (var_ref->var->data.location == VARYING_SLOT_CULL_DIST0) {
112 nir_deref *tail = nir_deref_tail(&intrin->variables[0]->deref);
113 nir_deref_array *array_ref = nir_deref_as_array(tail);
114
115 array_ref->base_offset += cull_offset;
116 }
117
118 /* Point the deref at the combined array */
119 var_ref->var = combined;
120
121 /* There's no need to update writemasks; it's a scalar array. */
122 }
123
124 static void
combine_clip_cull(nir_shader * nir,struct exec_list * vars,bool store_info)125 combine_clip_cull(nir_shader *nir,
126 struct exec_list *vars,
127 bool store_info)
128 {
129 nir_variable *cull = NULL;
130 nir_variable *clip = NULL;
131
132 nir_foreach_variable(var, vars) {
133 if (var->data.location == VARYING_SLOT_CLIP_DIST0)
134 clip = var;
135
136 if (var->data.location == VARYING_SLOT_CULL_DIST0)
137 cull = var;
138 }
139
140 const unsigned clip_array_size = get_unwrapped_array_length(nir, clip);
141 const unsigned cull_array_size = get_unwrapped_array_length(nir, cull);
142
143 if (store_info) {
144 nir->info->clip_distance_array_size = clip_array_size;
145 nir->info->cull_distance_array_size = cull_array_size;
146 }
147
148 if (clip)
149 clip->data.compact = true;
150
151 if (cull)
152 cull->data.compact = true;
153
154 if (cull_array_size > 0) {
155 if (clip_array_size == 0) {
156 /* No clip distances, just change the cull distance location */
157 cull->data.location = VARYING_SLOT_CLIP_DIST0;
158 } else {
159 /* Turn the ClipDistance array into a combined one */
160 update_type(clip, nir->stage, clip_array_size + cull_array_size);
161
162 /* Rewrite CullDistance to reference the combined array */
163 nir_foreach_function(function, nir) {
164 if (function->impl) {
165 nir_foreach_block(block, function->impl) {
166 nir_foreach_instr(instr, block) {
167 rewrite_references(instr, clip, clip_array_size);
168 }
169 }
170 }
171 }
172
173 /* Delete the old CullDistance variable */
174 exec_node_remove(&cull->node);
175 ralloc_free(cull);
176 }
177 }
178 }
179
180 void
nir_lower_clip_cull_distance_arrays(nir_shader * nir)181 nir_lower_clip_cull_distance_arrays(nir_shader *nir)
182 {
183 if (nir->stage <= MESA_SHADER_GEOMETRY)
184 combine_clip_cull(nir, &nir->outputs, true);
185
186 if (nir->stage > MESA_SHADER_VERTEX)
187 combine_clip_cull(nir, &nir->inputs, false);
188 }
189