summaryrefslogtreecommitdiff
path: root/src/compiler/nir/nir_lower_io_to_vector.c
blob: 82c4bdf87496ae9ba6c25d0cda314dd8aedb6899 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
/*
 * Copyright © 2019 Intel Corporation
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 */

#include "nir.h"
#include "nir_builder.h"
#include "nir_deref.h"

/** @file nir_lower_io_to_vector.c
 *
 * Merges compatible input/output variables residing in different components
 * of the same location. It's expected that further passes such as
 * nir_lower_io_to_temporaries will combine loads and stores of the merged
 * variables, producing vector nir_load_input/nir_store_output instructions
 * when all is said and done.
 */

/* FRAG_RESULT_MAX+1 instead of just FRAG_RESULT_MAX because of how this pass
 * handles dual source blending */
#define MAX_SLOTS MAX2(VARYING_SLOT_TESS_MAX, FRAG_RESULT_MAX+1)

static unsigned
get_slot(const nir_variable *var)
{
   /* This handling of dual-source blending might not be correct when more than
    * one render target is supported, but it seems no driver supports more than
    * one. */
   return var->data.location + var->data.index;
}

static const struct glsl_type *
get_per_vertex_type(const nir_shader *shader, const nir_variable *var,
                    unsigned *num_vertices)
{
   if (nir_is_per_vertex_io(var, shader->info.stage)) {
      assert(glsl_type_is_array(var->type));
      if (num_vertices)
         *num_vertices = glsl_get_length(var->type);
      return glsl_get_array_element(var->type);
   } else {
      if (num_vertices)
         *num_vertices = 0;
      return var->type;
   }
}

static const struct glsl_type *
resize_array_vec_type(const struct glsl_type *type, unsigned num_components)
{
   if (glsl_type_is_array(type)) {
      const struct glsl_type *arr_elem =
         resize_array_vec_type(glsl_get_array_element(type), num_components);
      return glsl_array_type(arr_elem, glsl_get_length(type), 0);
   } else {
      assert(glsl_type_is_vector_or_scalar(type));
      return glsl_vector_type(glsl_get_base_type(type), num_components);
   }
}

static bool
variables_can_merge(const nir_shader *shader,
                    const nir_variable *a, const nir_variable *b,
                    bool same_array_structure)
{
   if (a->data.compact || b->data.compact)
      return false;

   const struct glsl_type *a_type_tail = a->type;
   const struct glsl_type *b_type_tail = b->type;

   if (nir_is_per_vertex_io(a, shader->info.stage) !=
       nir_is_per_vertex_io(b, shader->info.stage))
      return false;

   /* They must have the same array structure */
   if (same_array_structure) {
      while (glsl_type_is_array(a_type_tail)) {
         if (!glsl_type_is_array(b_type_tail))
            return false;

         if (glsl_get_length(a_type_tail) != glsl_get_length(b_type_tail))
            return false;

         a_type_tail = glsl_get_array_element(a_type_tail);
         b_type_tail = glsl_get_array_element(b_type_tail);
      }
      if (glsl_type_is_array(b_type_tail))
         return false;
   } else {
      a_type_tail = glsl_without_array(a_type_tail);
      b_type_tail = glsl_without_array(b_type_tail);
   }

   if (!glsl_type_is_vector_or_scalar(a_type_tail) ||
       !glsl_type_is_vector_or_scalar(b_type_tail))
      return false;

   if (glsl_get_base_type(a_type_tail) != glsl_get_base_type(b_type_tail))
      return false;

   /* TODO: add 64/16bit support ? */
   if (glsl_get_bit_size(a_type_tail) != 32)
      return false;

   assert(a->data.mode == b->data.mode);
   if (shader->info.stage == MESA_SHADER_FRAGMENT &&
       a->data.mode == nir_var_shader_in &&
       a->data.interpolation != b->data.interpolation)
      return false;

   if (shader->info.stage == MESA_SHADER_FRAGMENT &&
       a->data.mode == nir_var_shader_out &&
       a->data.index != b->data.index)
      return false;

   return true;
}

static const struct glsl_type *
get_flat_type(const nir_shader *shader, nir_variable *old_vars[MAX_SLOTS][4],
              unsigned *loc, nir_variable **first_var, unsigned *num_vertices)
{
   unsigned todo = 1;
   unsigned slots = 0;
   unsigned num_vars = 0;
   enum glsl_base_type base;
   *num_vertices = 0;
   *first_var = NULL;

   while (todo) {
      assert(*loc < MAX_SLOTS);
      for (unsigned frac = 0; frac < 4; frac++) {
         nir_variable *var = old_vars[*loc][frac];
         if (!var)
            continue;
         if ((*first_var &&
              !variables_can_merge(shader, var, *first_var, false)) ||
             var->data.compact) {
            (*loc)++;
            return NULL;
         }

         if (!*first_var) {
            if (!glsl_type_is_vector_or_scalar(glsl_without_array(var->type))) {
               (*loc)++;
               return NULL;
            }
            *first_var = var;
            base = glsl_get_base_type(
               glsl_without_array(get_per_vertex_type(shader, var, NULL)));
         }

         bool vs_in = shader->info.stage == MESA_SHADER_VERTEX &&
                      var->data.mode == nir_var_shader_in;
         unsigned var_slots = glsl_count_attribute_slots(
            get_per_vertex_type(shader, var, num_vertices), vs_in);
         todo = MAX2(todo, var_slots);
         num_vars++;
      }
      todo--;
      slots++;
      (*loc)++;
   }

   if (num_vars <= 1)
      return NULL;

   if (slots == 1)
      return glsl_vector_type(base, 4);
   else
      return glsl_array_type(glsl_vector_type(base, 4), slots, 0);
}

static bool
create_new_io_vars(nir_shader *shader, struct exec_list *io_list,
                   nir_variable *new_vars[MAX_SLOTS][4],
                   bool flat_vars[MAX_SLOTS])
{
   if (exec_list_is_empty(io_list))
      return false;

   nir_variable *old_vars[MAX_SLOTS][4] = {{0}};

   nir_foreach_variable(var, io_list) {
      unsigned frac = var->data.location_frac;
      old_vars[get_slot(var)][frac] = var;
   }

   bool merged_any_vars = false;

   for (unsigned loc = 0; loc < MAX_SLOTS; loc++) {
      unsigned frac = 0;
      while (frac < 4) {
         nir_variable *first_var = old_vars[loc][frac];
         if (!first_var) {
            frac++;
            continue;
         }

         int first = frac;
         bool found_merge = false;

         while (frac < 4) {
            nir_variable *var = old_vars[loc][frac];
            if (!var)
               break;

            if (var != first_var) {
               if (!variables_can_merge(shader, first_var, var, true))
                  break;

               found_merge = true;
            }

            const unsigned num_components =
               glsl_get_components(glsl_without_array(var->type));
            if (!num_components) {
               assert(frac == 0);
               frac++;
               break; /* The type was a struct. */
            }

            /* We had better not have any overlapping vars */
            for (unsigned i = 1; i < num_components; i++)
               assert(old_vars[loc][frac + i] == NULL);

            frac += num_components;
         }

         if (!found_merge)
            continue;

         merged_any_vars = true;

         nir_variable *var = nir_variable_clone(old_vars[loc][first], shader);
         var->data.location_frac = first;
         var->type = resize_array_vec_type(var->type, frac - first);

         nir_shader_add_variable(shader, var);
         for (unsigned i = first; i < frac; i++) {
            new_vars[loc][i] = var;
            old_vars[loc][i] = NULL;
         }

         old_vars[loc][first] = var;
      }
   }

   /* "flat" mode: tries to ensure there is at most one variable per slot by
    * merging variables into vec4s
    */
   for (unsigned loc = 0; loc < MAX_SLOTS;) {
      nir_variable *first_var;
      unsigned num_vertices;
      unsigned new_loc = loc;
      const struct glsl_type *flat_type =
         get_flat_type(shader, old_vars, &new_loc, &first_var, &num_vertices);
      if (flat_type) {
         merged_any_vars = true;

         nir_variable *var = nir_variable_clone(first_var, shader);
         var->data.location_frac = 0;
         if (num_vertices)
            var->type = glsl_array_type(flat_type, num_vertices, 0);
         else
            var->type = flat_type;

         nir_shader_add_variable(shader, var);
         for (unsigned i = 0; i < glsl_get_length(flat_type); i++) {
            for (unsigned j = 0; j < 4; j++)
               new_vars[loc + i][j] = var;
            flat_vars[loc + i] = true;
         }
      }
      loc = new_loc;
   }

   return merged_any_vars;
}

static nir_deref_instr *
build_array_deref_of_new_var(nir_builder *b, nir_variable *new_var,
                             nir_deref_instr *leader)
{
   if (leader->deref_type == nir_deref_type_var)
      return nir_build_deref_var(b, new_var);

   nir_deref_instr *parent =
      build_array_deref_of_new_var(b, new_var, nir_deref_instr_parent(leader));

   return nir_build_deref_follower(b, parent, leader);
}

static nir_ssa_def *
build_array_index(nir_builder *b, nir_deref_instr *deref, nir_ssa_def *base,
                  bool vs_in)
{
   switch (deref->deref_type) {
   case nir_deref_type_var:
      return base;
   case nir_deref_type_array: {
      nir_ssa_def *index = nir_i2i(b, deref->arr.index.ssa,
                                   deref->dest.ssa.bit_size);
      return nir_iadd(
         b, build_array_index(b, nir_deref_instr_parent(deref), base, vs_in),
         nir_amul_imm(b, index, glsl_count_attribute_slots(deref->type, vs_in)));
   }
   default:
      unreachable("Invalid deref instruction type");
   }
}

static nir_deref_instr *
build_array_deref_of_new_var_flat(nir_shader *shader,
                                  nir_builder *b, nir_variable *new_var,
                                  nir_deref_instr *leader, unsigned base)
{
   nir_deref_instr *deref = nir_build_deref_var(b, new_var);

   if (nir_is_per_vertex_io(new_var, shader->info.stage)) {
      assert(leader->deref_type == nir_deref_type_array);
      nir_ssa_def *index = leader->arr.index.ssa;
      leader = nir_deref_instr_parent(leader);
      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(
      b, deref, build_array_index(b, leader, nir_imm_int(b, base), vs_in));
}

static bool
nir_lower_io_to_vector_impl(nir_function_impl *impl, nir_variable_mode modes)
{
   assert(!(modes & ~(nir_var_shader_in | nir_var_shader_out)));

   nir_builder b;
   nir_builder_init(&b, impl);

   nir_metadata_require(impl, nir_metadata_dominance);

   nir_shader *shader = impl->function->shader;
   nir_variable *new_inputs[MAX_SLOTS][4] = {{0}};
   nir_variable *new_outputs[MAX_SLOTS][4] = {{0}};
   bool flat_inputs[MAX_SLOTS] = {0};
   bool flat_outputs[MAX_SLOTS] = {0};

   if (modes & nir_var_shader_in) {
      /* Vertex shaders support overlapping inputs.  We don't do those */
      assert(b.shader->info.stage != MESA_SHADER_VERTEX);

      /* If we don't actually merge any variables, remove that bit from modes
       * so we don't bother doing extra non-work.
       */
      if (!create_new_io_vars(shader, &shader->inputs,
                              new_inputs, flat_inputs))
         modes &= ~nir_var_shader_in;
   }

   if (modes & nir_var_shader_out) {
      /* If we don't actually merge any variables, remove that bit from modes
       * so we don't bother doing extra non-work.
       */
      if (!create_new_io_vars(shader, &shader->outputs,
                              new_outputs, flat_outputs))
         modes &= ~nir_var_shader_out;
   }

   if (!modes)
      return false;

   bool progress = false;

   /* Actually lower all the IO load/store intrinsics.  Load instructions are
    * lowered to a vector load and an ALU instruction to grab the channels we
    * want.  Outputs are lowered to a write-masked store of the vector output.
    * For non-TCS outputs, we then run nir_lower_io_to_temporaries at the end
    * to clean up the partial writes.
    */
   nir_foreach_block(block, impl) {
      nir_foreach_instr_safe(instr, block) {
         if (instr->type != nir_instr_type_intrinsic)
            continue;

         nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);

         switch (intrin->intrinsic) {
         case nir_intrinsic_load_deref:
         case nir_intrinsic_interp_deref_at_centroid:
         case nir_intrinsic_interp_deref_at_sample:
         case nir_intrinsic_interp_deref_at_offset: {
            nir_deref_instr *old_deref = nir_src_as_deref(intrin->src[0]);
            if (!(old_deref->mode & modes))
               break;

            if (old_deref->mode == nir_var_shader_out)
               assert(b.shader->info.stage == MESA_SHADER_TESS_CTRL ||
                      b.shader->info.stage == MESA_SHADER_FRAGMENT);

            nir_variable *old_var = nir_deref_instr_get_variable(old_deref);

            const unsigned loc = get_slot(old_var);
            const unsigned old_frac = old_var->data.location_frac;
            nir_variable *new_var = old_deref->mode == nir_var_shader_in ?
                                    new_inputs[loc][old_frac] :
                                    new_outputs[loc][old_frac];
            bool flat = old_deref->mode == nir_var_shader_in ?
                        flat_inputs[loc] : flat_outputs[loc];
            if (!new_var)
               break;

            const unsigned new_frac = new_var->data.location_frac;

            nir_component_mask_t vec4_comp_mask =
               ((1 << intrin->num_components) - 1) << old_frac;

            b.cursor = nir_before_instr(&intrin->instr);

            /* Rewrite the load to use the new variable and only select a
             * portion of the result.
             */
            nir_deref_instr *new_deref;
            if (flat) {
               new_deref = build_array_deref_of_new_var_flat(
                  shader, &b, new_var, old_deref, loc - get_slot(new_var));
            } else {
               assert(get_slot(new_var) == loc);
               new_deref = build_array_deref_of_new_var(&b, new_var, old_deref);
               assert(glsl_type_is_vector(new_deref->type));
            }
            nir_instr_rewrite_src(&intrin->instr, &intrin->src[0],
                                  nir_src_for_ssa(&new_deref->dest.ssa));

            intrin->num_components =
               glsl_get_components(new_deref->type);
            intrin->dest.ssa.num_components = intrin->num_components;

            b.cursor = nir_after_instr(&intrin->instr);

            nir_ssa_def *new_vec = nir_channels(&b, &intrin->dest.ssa,
                                                vec4_comp_mask >> new_frac);
            nir_ssa_def_rewrite_uses_after(&intrin->dest.ssa,
                                           nir_src_for_ssa(new_vec),
                                           new_vec->parent_instr);

            progress = true;
            break;
         }

         case nir_intrinsic_store_deref: {
            nir_deref_instr *old_deref = nir_src_as_deref(intrin->src[0]);
            if (old_deref->mode != nir_var_shader_out)
               break;

            nir_variable *old_var = nir_deref_instr_get_variable(old_deref);

            const unsigned loc = get_slot(old_var);
            const unsigned old_frac = old_var->data.location_frac;
            nir_variable *new_var = new_outputs[loc][old_frac];
            bool flat = flat_outputs[loc];
            if (!new_var)
               break;

            const unsigned new_frac = new_var->data.location_frac;

            b.cursor = nir_before_instr(&intrin->instr);

            /* Rewrite the store to be a masked store to the new variable */
            nir_deref_instr *new_deref;
            if (flat) {
               new_deref = build_array_deref_of_new_var_flat(
                  shader, &b, new_var, old_deref, loc - get_slot(new_var));
            } else {
               assert(get_slot(new_var) == loc);
               new_deref = build_array_deref_of_new_var(&b, new_var, old_deref);
               assert(glsl_type_is_vector(new_deref->type));
            }
            nir_instr_rewrite_src(&intrin->instr, &intrin->src[0],
                                  nir_src_for_ssa(&new_deref->dest.ssa));

            intrin->num_components =
               glsl_get_components(new_deref->type);

            nir_component_mask_t old_wrmask = nir_intrinsic_write_mask(intrin);

            assert(intrin->src[1].is_ssa);
            nir_ssa_def *old_value = intrin->src[1].ssa;
            nir_ssa_def *comps[4];
            for (unsigned c = 0; c < intrin->num_components; c++) {
               if (new_frac + c >= old_frac &&
                   (old_wrmask & 1 << (new_frac + c - old_frac))) {
                  comps[c] = nir_channel(&b, old_value,
                                         new_frac + c - old_frac);
               } else {
                  comps[c] = nir_ssa_undef(&b, old_value->num_components,
                                               old_value->bit_size);
               }
            }
            nir_ssa_def *new_value = nir_vec(&b, comps, intrin->num_components);
            nir_instr_rewrite_src(&intrin->instr, &intrin->src[1],
                                  nir_src_for_ssa(new_value));

            nir_intrinsic_set_write_mask(intrin,
                                         old_wrmask << (old_frac - new_frac));

            progress = true;
            break;
         }

         default:
            break;
         }
      }
   }

   if (progress) {
      nir_metadata_preserve(impl, nir_metadata_block_index |
                                  nir_metadata_dominance);
   }

   return progress;
}

bool
nir_lower_io_to_vector(nir_shader *shader, nir_variable_mode modes)
{
   bool progress = false;

   nir_foreach_function(function, shader) {
      if (function->impl)
         progress |= nir_lower_io_to_vector_impl(function->impl, modes);
   }

   return progress;
}