1/*
2 * Copyright © 2014 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 * Authors:
24 *    Connor Abbott (cwabbott0@gmail.com)
25 *
26 */
27
28#include "nir.h"
29#include "nir_builder.h"
30#include "util/u_math.h"
31#include "util/set.h"
32
33struct lower_sysval_state {
34   const nir_lower_compute_system_values_options *options;
35
36   /* List of intrinsics that have already been lowered and shouldn't be
37    * lowered again.
38    */
39   struct set *lower_once_list;
40};
41
42static nir_ssa_def *
43sanitize_32bit_sysval(nir_builder *b, nir_intrinsic_instr *intrin)
44{
45   assert(intrin->dest.is_ssa);
46   const unsigned bit_size = intrin->dest.ssa.bit_size;
47   if (bit_size == 32)
48      return NULL;
49
50   intrin->dest.ssa.bit_size = 32;
51   return nir_u2u(b, &intrin->dest.ssa, bit_size);
52}
53
54static nir_ssa_def*
55build_global_group_size(nir_builder *b, unsigned bit_size)
56{
57   nir_ssa_def *group_size = nir_load_workgroup_size(b);
58   nir_ssa_def *num_workgroups = nir_load_num_workgroups(b, bit_size);
59   return nir_imul(b, nir_u2u(b, group_size, bit_size),
60                      num_workgroups);
61}
62
63static bool
64lower_system_value_filter(const nir_instr *instr, const void *_state)
65{
66   return instr->type == nir_instr_type_intrinsic;
67}
68
69static nir_ssa_def *
70lower_system_value_instr(nir_builder *b, nir_instr *instr, void *_state)
71{
72   nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);
73
74   /* All the intrinsics we care about are loads */
75   if (!nir_intrinsic_infos[intrin->intrinsic].has_dest)
76      return NULL;
77
78   assert(intrin->dest.is_ssa);
79   const unsigned bit_size = intrin->dest.ssa.bit_size;
80
81   switch (intrin->intrinsic) {
82   case nir_intrinsic_load_vertex_id:
83      if (b->shader->options->vertex_id_zero_based) {
84         return nir_iadd(b, nir_load_vertex_id_zero_base(b),
85                            nir_load_first_vertex(b));
86      } else {
87         return NULL;
88      }
89
90   case nir_intrinsic_load_base_vertex:
91      /**
92       * From the OpenGL 4.6 (11.1.3.9 Shader Inputs) specification:
93       *
94       * "gl_BaseVertex holds the integer value passed to the baseVertex
95       * parameter to the command that resulted in the current shader
96       * invocation. In the case where the command has no baseVertex
97       * parameter, the value of gl_BaseVertex is zero."
98       */
99      if (b->shader->options->lower_base_vertex) {
100         return nir_iand(b, nir_load_is_indexed_draw(b),
101                            nir_load_first_vertex(b));
102      } else {
103         return NULL;
104      }
105
106   case nir_intrinsic_load_helper_invocation:
107      if (b->shader->options->lower_helper_invocation) {
108         nir_ssa_def *tmp;
109         tmp = nir_ishl(b, nir_imm_int(b, 1),
110                           nir_load_sample_id_no_per_sample(b));
111         tmp = nir_iand(b, nir_load_sample_mask_in(b), tmp);
112         return nir_inot(b, nir_i2b(b, tmp));
113      } else {
114         return NULL;
115      }
116
117   case nir_intrinsic_load_local_invocation_id:
118   case nir_intrinsic_load_local_invocation_index:
119   case nir_intrinsic_load_workgroup_size:
120      return sanitize_32bit_sysval(b, intrin);
121
122   case nir_intrinsic_load_deref: {
123      nir_deref_instr *deref = nir_src_as_deref(intrin->src[0]);
124      if (!nir_deref_mode_is(deref, nir_var_system_value))
125         return NULL;
126
127      nir_ssa_def *column = NULL;
128      if (deref->deref_type != nir_deref_type_var) {
129         /* The only one system values that aren't plane variables are
130          * gl_SampleMask which is always an array of one element and a
131          * couple of ray-tracing intrinsics which are matrices.
132          */
133         assert(deref->deref_type == nir_deref_type_array);
134         assert(deref->arr.index.is_ssa);
135         column = deref->arr.index.ssa;
136         deref = nir_deref_instr_parent(deref);
137         assert(deref->deref_type == nir_deref_type_var);
138         assert(deref->var->data.location == SYSTEM_VALUE_SAMPLE_MASK_IN ||
139                deref->var->data.location == SYSTEM_VALUE_RAY_OBJECT_TO_WORLD ||
140                deref->var->data.location == SYSTEM_VALUE_RAY_WORLD_TO_OBJECT ||
141                deref->var->data.location == SYSTEM_VALUE_MESH_VIEW_INDICES);
142      }
143      nir_variable *var = deref->var;
144
145      switch (var->data.location) {
146      case SYSTEM_VALUE_INSTANCE_INDEX:
147         return nir_iadd(b, nir_load_instance_id(b),
148                            nir_load_base_instance(b));
149
150      case SYSTEM_VALUE_SUBGROUP_EQ_MASK:
151      case SYSTEM_VALUE_SUBGROUP_GE_MASK:
152      case SYSTEM_VALUE_SUBGROUP_GT_MASK:
153      case SYSTEM_VALUE_SUBGROUP_LE_MASK:
154      case SYSTEM_VALUE_SUBGROUP_LT_MASK: {
155         nir_intrinsic_op op =
156            nir_intrinsic_from_system_value(var->data.location);
157         nir_intrinsic_instr *load = nir_intrinsic_instr_create(b->shader, op);
158         nir_ssa_dest_init_for_type(&load->instr, &load->dest,
159                                    var->type, NULL);
160         load->num_components = load->dest.ssa.num_components;
161         nir_builder_instr_insert(b, &load->instr);
162         return &load->dest.ssa;
163      }
164
165      case SYSTEM_VALUE_DEVICE_INDEX:
166         if (b->shader->options->lower_device_index_to_zero)
167            return nir_imm_int(b, 0);
168         break;
169
170      case SYSTEM_VALUE_GLOBAL_GROUP_SIZE:
171         return build_global_group_size(b, bit_size);
172
173      case SYSTEM_VALUE_BARYCENTRIC_LINEAR_PIXEL:
174         return nir_load_barycentric(b, nir_intrinsic_load_barycentric_pixel,
175                                     INTERP_MODE_NOPERSPECTIVE);
176
177      case SYSTEM_VALUE_BARYCENTRIC_LINEAR_CENTROID:
178         return nir_load_barycentric(b, nir_intrinsic_load_barycentric_centroid,
179                                     INTERP_MODE_NOPERSPECTIVE);
180
181      case SYSTEM_VALUE_BARYCENTRIC_LINEAR_SAMPLE:
182         return nir_load_barycentric(b, nir_intrinsic_load_barycentric_sample,
183                                     INTERP_MODE_NOPERSPECTIVE);
184
185      case SYSTEM_VALUE_BARYCENTRIC_PERSP_PIXEL:
186         return nir_load_barycentric(b, nir_intrinsic_load_barycentric_pixel,
187                                     INTERP_MODE_SMOOTH);
188
189      case SYSTEM_VALUE_BARYCENTRIC_PERSP_CENTROID:
190         return nir_load_barycentric(b, nir_intrinsic_load_barycentric_centroid,
191                                     INTERP_MODE_SMOOTH);
192
193      case SYSTEM_VALUE_BARYCENTRIC_PERSP_SAMPLE:
194         return nir_load_barycentric(b, nir_intrinsic_load_barycentric_sample,
195                                     INTERP_MODE_SMOOTH);
196
197      case SYSTEM_VALUE_BARYCENTRIC_PULL_MODEL:
198         return nir_load_barycentric(b, nir_intrinsic_load_barycentric_model,
199                                     INTERP_MODE_NONE);
200
201      case SYSTEM_VALUE_HELPER_INVOCATION: {
202         /* When demote operation is used, reading the HelperInvocation
203          * needs to use Volatile memory access semantics to provide the
204          * correct (dynamic) value.  See OpDemoteToHelperInvocation.
205          */
206         if (nir_intrinsic_access(intrin) & ACCESS_VOLATILE)
207            return nir_is_helper_invocation(b, 1);
208         break;
209      }
210
211      case SYSTEM_VALUE_MESH_VIEW_INDICES:
212         return nir_load_mesh_view_indices(b, intrin->dest.ssa.num_components,
213               bit_size, column, .base = 0,
214               .range = intrin->dest.ssa.num_components * bit_size / 8);
215
216      default:
217         break;
218      }
219
220      nir_intrinsic_op sysval_op =
221         nir_intrinsic_from_system_value(var->data.location);
222      if (glsl_type_is_matrix(var->type)) {
223         assert(nir_intrinsic_infos[sysval_op].index_map[NIR_INTRINSIC_COLUMN] > 0);
224         unsigned num_cols = glsl_get_matrix_columns(var->type);
225         ASSERTED unsigned num_rows = glsl_get_vector_elements(var->type);
226         assert(num_rows == intrin->dest.ssa.num_components);
227
228         nir_ssa_def *cols[4];
229         for (unsigned i = 0; i < num_cols; i++) {
230            cols[i] = nir_load_system_value(b, sysval_op, i,
231                                            intrin->dest.ssa.num_components,
232                                            intrin->dest.ssa.bit_size);
233            assert(cols[i]->num_components == num_rows);
234         }
235         return nir_select_from_ssa_def_array(b, cols, num_cols, column);
236      } else {
237         return nir_load_system_value(b, sysval_op, 0,
238                                      intrin->dest.ssa.num_components,
239                                      intrin->dest.ssa.bit_size);
240      }
241   }
242
243   default:
244      return NULL;
245   }
246}
247
248bool
249nir_lower_system_values(nir_shader *shader)
250{
251   bool progress = nir_shader_lower_instructions(shader,
252                                                 lower_system_value_filter,
253                                                 lower_system_value_instr,
254                                                 NULL);
255
256   /* We're going to delete the variables so we need to clean up all those
257    * derefs we left lying around.
258    */
259   if (progress)
260      nir_remove_dead_derefs(shader);
261
262   nir_foreach_variable_with_modes_safe(var, shader, nir_var_system_value)
263      exec_node_remove(&var->node);
264
265   return progress;
266}
267
268static nir_ssa_def *
269lower_id_to_index_no_umod(nir_builder *b, nir_ssa_def *index,
270                          nir_ssa_def *size, unsigned bit_size)
271{
272   /* We lower ID to Index with the following formula:
273    *
274    *    id.z = index / (size.x * size.y)
275    *    id.y = (index - (id.z * (size.x * size.y))) / size.x
276    *    id.x = index - ((id.z * (size.x * size.y)) + (id.y * size.x))
277    *
278    * This is more efficient on HW that doesn't have a
279    * modulo division instruction and when the size is either
280    * not compile time known or not a power of two.
281    */
282
283   nir_ssa_def *size_x = nir_channel(b, size, 0);
284   nir_ssa_def *size_y = nir_channel(b, size, 1);
285   nir_ssa_def *size_x_y = nir_imul(b, size_x, size_y);
286
287   nir_ssa_def *id_z = nir_udiv(b, index, size_x_y);
288   nir_ssa_def *z_portion = nir_imul(b, id_z, size_x_y);
289   nir_ssa_def *id_y = nir_udiv(b, nir_isub(b, index, z_portion), size_x);
290   nir_ssa_def *y_portion = nir_imul(b, id_y, size_x);
291   nir_ssa_def *id_x = nir_isub(b, index, nir_iadd(b, z_portion, y_portion));
292
293   return nir_u2u(b, nir_vec3(b, id_x, id_y, id_z), bit_size);
294}
295
296
297static nir_ssa_def *
298lower_id_to_index(nir_builder *b, nir_ssa_def *index, nir_ssa_def *size,
299                  unsigned bit_size)
300{
301   /* We lower gl_LocalInvocationID to gl_LocalInvocationIndex based
302    * on this formula:
303    *
304    *    id.x = index % size.x;
305    *    id.y = (index / size.x) % gl_WorkGroupSize.y;
306    *    id.z = (index / (size.x * size.y)) % size.z;
307    *
308    * However, the final % size.z does nothing unless we
309    * accidentally end up with an index that is too
310    * large so it can safely be omitted.
311    *
312    * Because no hardware supports a local workgroup size greater than
313    * about 1K, this calculation can be done in 32-bit and can save some
314    * 64-bit arithmetic.
315    */
316
317   nir_ssa_def *size_x = nir_channel(b, size, 0);
318   nir_ssa_def *size_y = nir_channel(b, size, 1);
319
320   nir_ssa_def *id_x = nir_umod(b, index, size_x);
321   nir_ssa_def *id_y = nir_umod(b, nir_udiv(b, index, size_x), size_y);
322   nir_ssa_def *id_z = nir_udiv(b, index, nir_imul(b, size_x, size_y));
323
324   return nir_u2u(b, nir_vec3(b, id_x, id_y, id_z), bit_size);
325}
326
327static bool
328lower_compute_system_value_filter(const nir_instr *instr, const void *_state)
329{
330   return instr->type == nir_instr_type_intrinsic;
331}
332
333static nir_ssa_def *
334lower_compute_system_value_instr(nir_builder *b,
335                                 nir_instr *instr, void *_state)
336{
337   nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);
338   struct lower_sysval_state *state = (struct lower_sysval_state *)_state;
339   const nir_lower_compute_system_values_options *options = state->options;
340
341   /* All the intrinsics we care about are loads */
342   if (!nir_intrinsic_infos[intrin->intrinsic].has_dest)
343      return NULL;
344
345   assert(intrin->dest.is_ssa);
346   const unsigned bit_size = intrin->dest.ssa.bit_size;
347
348   switch (intrin->intrinsic) {
349   case nir_intrinsic_load_local_invocation_id:
350      /* If lower_cs_local_id_to_index is true, then we replace
351       * local_invocation_id with a formula based on local_invocation_index.
352       */
353      if (b->shader->options->lower_cs_local_id_to_index ||
354          (options && options->lower_cs_local_id_to_index)) {
355         nir_ssa_def *local_index = nir_load_local_invocation_index(b);
356         nir_ssa_def *local_size = nir_load_workgroup_size(b);
357         return lower_id_to_index(b, local_index, local_size, bit_size);
358      }
359      if (options && options->shuffle_local_ids_for_quad_derivatives &&
360          b->shader->info.cs.derivative_group == DERIVATIVE_GROUP_QUADS &&
361          _mesa_set_search(state->lower_once_list, instr) == NULL) {
362         nir_ssa_def *ids = nir_load_local_invocation_id(b);
363         _mesa_set_add(state->lower_once_list, ids->parent_instr);
364
365         nir_ssa_def *x = nir_channel(b, ids, 0);
366         nir_ssa_def *y = nir_channel(b, ids, 1);
367         nir_ssa_def *z = nir_channel(b, ids, 2);
368         unsigned size_x = b->shader->info.workgroup_size[0];
369         nir_ssa_def *size_x_imm;
370
371         if (b->shader->info.workgroup_size_variable)
372            size_x_imm = nir_channel(b, nir_load_workgroup_size(b), 0);
373         else
374            size_x_imm = nir_imm_int(b, size_x);
375
376         /* Remap indices from:
377          *    | 0| 1| 2| 3|
378          *    | 4| 5| 6| 7|
379          *    | 8| 9|10|11|
380          *    |12|13|14|15|
381          * to:
382          *    | 0| 1| 4| 5|
383          *    | 2| 3| 6| 7|
384          *    | 8| 9|12|13|
385          *    |10|11|14|15|
386          *
387          * That's the layout required by AMD hardware for derivatives to
388          * work. Other hardware may work differently.
389          *
390          * It's a classic tiling pattern that can be implemented by inserting
391          * bit y[0] between bits x[0] and x[1] like this:
392          *
393          *    x[0],y[0],x[1],...x[last],y[1],...,y[last]
394          *
395          * If the width is a power of two, use:
396          *    i = ((x & 1) | ((y & 1) << 1) | ((x & ~1) << 1)) | ((y & ~1) << logbase2(size_x))
397          *
398          * If the width is not a power of two or the local size is variable, use:
399          *    i = ((x & 1) | ((y & 1) << 1) | ((x & ~1) << 1)) + ((y & ~1) * size_x)
400          *
401          * GL_NV_compute_shader_derivatives requires that the width and height
402          * are a multiple of two, which is also a requirement for the second
403          * expression to work.
404          *
405          * The 2D result is: (x,y) = (i % w, i / w)
406          */
407
408         nir_ssa_def *one = nir_imm_int(b, 1);
409         nir_ssa_def *inv_one = nir_imm_int(b, ~1);
410         nir_ssa_def *x_bit0 = nir_iand(b, x, one);
411         nir_ssa_def *y_bit0 = nir_iand(b, y, one);
412         nir_ssa_def *x_bits_1n = nir_iand(b, x, inv_one);
413         nir_ssa_def *y_bits_1n = nir_iand(b, y, inv_one);
414         nir_ssa_def *bits_01 = nir_ior(b, x_bit0, nir_ishl(b, y_bit0, one));
415         nir_ssa_def *bits_01x = nir_ior(b, bits_01,
416                                         nir_ishl(b, x_bits_1n, one));
417         nir_ssa_def *i;
418
419         if (!b->shader->info.workgroup_size_variable &&
420             util_is_power_of_two_nonzero(size_x)) {
421            nir_ssa_def *log2_size_x = nir_imm_int(b, util_logbase2(size_x));
422            i = nir_ior(b, bits_01x, nir_ishl(b, y_bits_1n, log2_size_x));
423         } else {
424            i = nir_iadd(b, bits_01x, nir_imul(b, y_bits_1n, size_x_imm));
425         }
426
427         /* This should be fast if size_x is an immediate or even a power
428          * of two.
429          */
430         x = nir_umod(b, i, size_x_imm);
431         y = nir_udiv(b, i, size_x_imm);
432
433         return nir_vec3(b, x, y, z);
434      }
435
436      /* If a workgroup size dimension is 1, then the local invocation id must be zero. */
437      nir_component_mask_t is_zero = 0;
438      is_zero |= b->shader->info.workgroup_size[0] == 1 ? 0x1 : 0x0;
439      is_zero |= b->shader->info.workgroup_size[1] == 1 ? 0x2 : 0x0;
440      is_zero |= b->shader->info.workgroup_size[2] == 1 ? 0x4 : 0x0;
441      if (!b->shader->info.workgroup_size_variable && is_zero) {
442         nir_ssa_scalar defs[3];
443         for (unsigned i = 0; i < 3; i++) {
444            defs[i] = is_zero & (1 << i) ? nir_get_ssa_scalar(nir_imm_zero(b, 1, 32), 0) :
445                                           nir_get_ssa_scalar(&intrin->dest.ssa, i);
446         }
447         return nir_vec_scalars(b, defs, 3);
448      }
449
450      return NULL;
451
452   case nir_intrinsic_load_local_invocation_index:
453      /* If lower_cs_local_index_to_id is true, then we replace
454       * local_invocation_index with a formula based on local_invocation_id.
455       */
456      if (b->shader->options->lower_cs_local_index_to_id ||
457          (options && options->lower_local_invocation_index)) {
458         /* From the GLSL man page for gl_LocalInvocationIndex:
459          *
460          *    "The value of gl_LocalInvocationIndex is equal to
461          *    gl_LocalInvocationID.z * gl_WorkGroupSize.x *
462          *    gl_WorkGroupSize.y + gl_LocalInvocationID.y *
463          *    gl_WorkGroupSize.x + gl_LocalInvocationID.x"
464          */
465         nir_ssa_def *local_id = nir_load_local_invocation_id(b);
466         nir_ssa_def *local_size = nir_load_workgroup_size(b);
467         nir_ssa_def *size_x = nir_channel(b, local_size, 0);
468         nir_ssa_def *size_y = nir_channel(b, local_size, 1);
469
470         /* Because no hardware supports a local workgroup size greater than
471          * about 1K, this calculation can be done in 32-bit and can save some
472          * 64-bit arithmetic.
473          */
474         nir_ssa_def *index;
475         index = nir_imul(b, nir_channel(b, local_id, 2),
476                             nir_imul(b, size_x, size_y));
477         index = nir_iadd(b, index,
478                             nir_imul(b, nir_channel(b, local_id, 1), size_x));
479         index = nir_iadd(b, index, nir_channel(b, local_id, 0));
480         return nir_u2u(b, index, bit_size);
481      } else {
482         return NULL;
483      }
484
485   case nir_intrinsic_load_workgroup_size:
486      if (b->shader->info.workgroup_size_variable) {
487         /* If the local work group size is variable it can't be lowered at
488          * this point.  We do, however, have to make sure that the intrinsic
489          * is only 32-bit.
490          */
491         return NULL;
492      } else {
493         /* using a 32 bit constant is safe here as no device/driver needs more
494          * than 32 bits for the local size */
495         nir_const_value workgroup_size_const[3];
496         memset(workgroup_size_const, 0, sizeof(workgroup_size_const));
497         workgroup_size_const[0].u32 = b->shader->info.workgroup_size[0];
498         workgroup_size_const[1].u32 = b->shader->info.workgroup_size[1];
499         workgroup_size_const[2].u32 = b->shader->info.workgroup_size[2];
500         return nir_u2u(b, nir_build_imm(b, 3, 32, workgroup_size_const), bit_size);
501      }
502
503   case nir_intrinsic_load_global_invocation_id_zero_base: {
504      if ((options && options->has_base_workgroup_id) ||
505          !b->shader->options->has_cs_global_id) {
506         nir_ssa_def *group_size = nir_load_workgroup_size(b);
507         nir_ssa_def *group_id = nir_load_workgroup_id(b, bit_size);
508         nir_ssa_def *local_id = nir_load_local_invocation_id(b);
509
510         return nir_iadd(b, nir_imul(b, group_id,
511                                        nir_u2u(b, group_size, bit_size)),
512                            nir_u2u(b, local_id, bit_size));
513      } else {
514         return NULL;
515      }
516   }
517
518   case nir_intrinsic_load_global_invocation_id: {
519      if (options && options->has_base_global_invocation_id)
520         return nir_iadd(b, nir_load_global_invocation_id_zero_base(b, bit_size),
521                            nir_load_base_global_invocation_id(b, bit_size));
522      else if ((options && options->has_base_workgroup_id) ||
523               !b->shader->options->has_cs_global_id)
524         return nir_load_global_invocation_id_zero_base(b, bit_size);
525      else
526         return NULL;
527   }
528
529   case nir_intrinsic_load_global_invocation_index: {
530      /* OpenCL's global_linear_id explicitly removes the global offset before computing this */
531      assert(b->shader->info.stage == MESA_SHADER_KERNEL);
532      nir_ssa_def *global_base_id = nir_load_base_global_invocation_id(b, bit_size);
533      nir_ssa_def *global_id = nir_isub(b, nir_load_global_invocation_id(b, bit_size), global_base_id);
534      nir_ssa_def *global_size = build_global_group_size(b, bit_size);
535
536      /* index = id.x + ((id.y + (id.z * size.y)) * size.x) */
537      nir_ssa_def *index;
538      index = nir_imul(b, nir_channel(b, global_id, 2),
539                          nir_channel(b, global_size, 1));
540      index = nir_iadd(b, nir_channel(b, global_id, 1), index);
541      index = nir_imul(b, nir_channel(b, global_size, 0), index);
542      index = nir_iadd(b, nir_channel(b, global_id, 0), index);
543      return index;
544   }
545
546   case nir_intrinsic_load_workgroup_id: {
547      if (options && options->has_base_workgroup_id)
548         return nir_iadd(b, nir_u2u(b, nir_load_workgroup_id_zero_base(b), bit_size),
549                            nir_load_base_workgroup_id(b, bit_size));
550      else if (options && options->lower_workgroup_id_to_index)
551         return lower_id_to_index_no_umod(b, nir_load_workgroup_index(b),
552                                          nir_load_num_workgroups(b, bit_size),
553                                          bit_size);
554
555      return NULL;
556
557   }
558
559   default:
560      return NULL;
561   }
562}
563
564bool
565nir_lower_compute_system_values(nir_shader *shader,
566                                const nir_lower_compute_system_values_options *options)
567{
568   if (!gl_shader_stage_uses_workgroup(shader->info.stage))
569      return false;
570
571   struct lower_sysval_state state;
572   state.options = options;
573   state.lower_once_list = _mesa_pointer_set_create(NULL);
574
575   bool progress =
576      nir_shader_lower_instructions(shader,
577                                    lower_compute_system_value_filter,
578                                    lower_compute_system_value_instr,
579                                    (void*)&state);
580   ralloc_free(state.lower_once_list);
581
582   /* Update this so as not to lower it again. */
583   if (options && options->shuffle_local_ids_for_quad_derivatives &&
584       shader->info.cs.derivative_group == DERIVATIVE_GROUP_QUADS)
585      shader->info.cs.derivative_group = DERIVATIVE_GROUP_LINEAR;
586
587   return progress;
588}
589