src/compiler/nir/nir_lower_io_to_scalar.c

   1 /*
   2  * Copyright © 2016 Broadcom
   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 #include "nir_deref.h"
  27
  28 /** @file nir_lower_io_to_scalar.c
  29  *
  30  * Replaces nir_load_input/nir_store_output operations with num_components !=
  31  * 1 with individual per-channel operations.
  32  */
  33
  34 static void
  35 lower_load_input_to_scalar(nir_builder *b, nir_intrinsic_instr *intr)
  36 {
  37    b->cursor = nir_before_instr(&intr->instr);
  38
  39    assert(intr->dest.is_ssa);
  40
  41    nir_ssa_def *loads[4];
  42
  43    for (unsigned i = 0; i < intr->num_components; i++) {
  44       nir_intrinsic_instr *chan_intr =
  45          nir_intrinsic_instr_create(b->shader, intr->intrinsic);
  46       nir_ssa_dest_init(&chan_intr->instr, &chan_intr->dest,
  47                         1, intr->dest.ssa.bit_size, NULL);
  48       chan_intr->num_components = 1;
  49
  50       nir_intrinsic_set_base(chan_intr, nir_intrinsic_base(intr));
  51       nir_intrinsic_set_component(chan_intr, nir_intrinsic_component(intr) + i);
  52       /* offset */
  53       nir_src_copy(&chan_intr->src[0], &intr->src[0], chan_intr);
  54
  55       nir_builder_instr_insert(b, &chan_intr->instr);
  56
  57       loads[i] = &chan_intr->dest.ssa;
  58    }
  59
  60    nir_ssa_def_rewrite_uses(&intr->dest.ssa,
  61                             nir_src_for_ssa(nir_vec(b, loads,
  62                                                     intr->num_components)));
  63    nir_instr_remove(&intr->instr);
  64 }
  65
  66 static void
  67 lower_store_output_to_scalar(nir_builder *b, nir_intrinsic_instr *intr)
  68 {
  69    b->cursor = nir_before_instr(&intr->instr);
  70
  71    nir_ssa_def *value = nir_ssa_for_src(b, intr->src[0], intr->num_components);
  72
  73    for (unsigned i = 0; i < intr->num_components; i++) {
  74       if (!(nir_intrinsic_write_mask(intr) & (1 << i)))
  75          continue;
  76
  77       nir_intrinsic_instr *chan_intr =
  78          nir_intrinsic_instr_create(b->shader, intr->intrinsic);
  79       chan_intr->num_components = 1;
  80
  81       nir_intrinsic_set_base(chan_intr, nir_intrinsic_base(intr));
  82       nir_intrinsic_set_write_mask(chan_intr, 0x1);
  83       nir_intrinsic_set_component(chan_intr, nir_intrinsic_component(intr) + i);
  84
  85       /* value */
  86       chan_intr->src[0] = nir_src_for_ssa(nir_channel(b, value, i));
  87       /* offset */
  88       nir_src_copy(&chan_intr->src[1], &intr->src[1], chan_intr);
  89
  90       nir_builder_instr_insert(b, &chan_intr->instr);
  91    }
  92
  93    nir_instr_remove(&intr->instr);
  94 }
  95
  96 void
  97 nir_lower_io_to_scalar(nir_shader *shader, nir_variable_mode mask)
  98 {
  99    nir_foreach_function(function, shader) {
 100       if (function->impl) {
 101          nir_builder b;
 102          nir_builder_init(&b, function->impl);
 103
 104          nir_foreach_block(block, function->impl) {
 105             nir_foreach_instr_safe(instr, block) {
 106                if (instr->type != nir_instr_type_intrinsic)
 107                   continue;
 108
 109                nir_intrinsic_instr *intr = nir_instr_as_intrinsic(instr);
 110
 111                if (intr->num_components == 1)
 112                   continue;
 113
 114                switch (intr->intrinsic) {
 115                case nir_intrinsic_load_input:
 116                   if (mask & nir_var_shader_in)
 117                      lower_load_input_to_scalar(&b, intr);
 118                   break;
 119                case nir_intrinsic_store_output:
 120                   if (mask & nir_var_shader_out)
 121                      lower_store_output_to_scalar(&b, intr);
 122                   break;
 123                default:
 124                   break;
 125                }
 126             }
 127          }
 128       }
 129    }
 130 }
 131
 132 static nir_variable **
 133 get_channel_variables(struct hash_table *ht, nir_variable *var)
 134 {
 135    nir_variable **chan_vars;
 136    struct hash_entry *entry = _mesa_hash_table_search(ht, var);
 137    if (!entry) {
 138       chan_vars = (nir_variable **) calloc(4, sizeof(nir_variable *));
 139       _mesa_hash_table_insert(ht, var, chan_vars);
 140    } else {
 141       chan_vars = (nir_variable **) entry->data;
 142    }
 143
 144    return chan_vars;
 145 }
 146
 147 /*
 148  * Note that the src deref that we are cloning is the head of the
 149  * chain of deref instructions from the original intrinsic, but
 150  * the dst we are cloning to is the tail (because chains of deref
 151  * instructions are created back to front)
 152  */
 153
 154 static nir_deref_instr *
 155 clone_deref_array(nir_builder *b, nir_deref_instr *dst_tail,
 156                   const nir_deref_instr *src_head)
 157 {
 158    const nir_deref_instr *parent = nir_deref_instr_parent(src_head);
 159
 160    if (!parent)
 161       return dst_tail;
 162
 163    assert(src_head->deref_type == nir_deref_type_array);
 164
 165    dst_tail = clone_deref_array(b, dst_tail, parent);
 166
 167    return nir_build_deref_array(b, dst_tail,
 168                                 nir_ssa_for_src(b, src_head->arr.index, 1));
 169 }
 170
 171 static void
 172 lower_load_to_scalar_early(nir_builder *b, nir_intrinsic_instr *intr,
 173                            nir_variable *var, struct hash_table *split_inputs,
 174                            struct hash_table *split_outputs)
 175 {
 176    b->cursor = nir_before_instr(&intr->instr);
 177
 178    assert(intr->dest.is_ssa);
 179
 180    nir_ssa_def *loads[4];
 181
 182    nir_variable **chan_vars;
 183    if (var->data.mode == nir_var_shader_in) {
 184       chan_vars = get_channel_variables(split_inputs, var);
 185    } else {
 186       chan_vars = get_channel_variables(split_outputs, var);
 187    }
 188
 189    for (unsigned i = 0; i < intr->num_components; i++) {
 190       nir_variable *chan_var = chan_vars[var->data.location_frac + i];
 191       if (!chan_vars[var->data.location_frac + i]) {
 192          chan_var = nir_variable_clone(var, b->shader);
 193          chan_var->data.location_frac =  var->data.location_frac + i;
 194          chan_var->type = glsl_channel_type(chan_var->type);
 195
 196          chan_vars[var->data.location_frac + i] = chan_var;
 197
 198          nir_shader_add_variable(b->shader, chan_var);
 199       }
 200
 201       nir_intrinsic_instr *chan_intr =
 202          nir_intrinsic_instr_create(b->shader, intr->intrinsic);
 203       nir_ssa_dest_init(&chan_intr->instr, &chan_intr->dest,
 204                         1, intr->dest.ssa.bit_size, NULL);
 205       chan_intr->num_components = 1;
 206
 207       nir_deref_instr *deref = nir_build_deref_var(b, chan_var);
 208
 209       deref = clone_deref_array(b, deref, nir_src_as_deref(intr->src[0]));
 210
 211       chan_intr->src[0] = nir_src_for_ssa(&deref->dest.ssa);
 212
 213       if (intr->intrinsic == nir_intrinsic_interp_deref_at_offset ||
 214           intr->intrinsic == nir_intrinsic_interp_deref_at_sample)
 215          nir_src_copy(&chan_intr->src[1], &intr->src[1], &chan_intr->instr);
 216
 217       nir_builder_instr_insert(b, &chan_intr->instr);
 218
 219       loads[i] = &chan_intr->dest.ssa;
 220    }
 221
 222    nir_ssa_def_rewrite_uses(&intr->dest.ssa,
 223                             nir_src_for_ssa(nir_vec(b, loads,
 224                                                     intr->num_components)));
 225
 226    /* Remove the old load intrinsic */
 227    nir_instr_remove(&intr->instr);
 228 }
 229
 230 static void
 231 lower_store_output_to_scalar_early(nir_builder *b, nir_intrinsic_instr *intr,
 232                                    nir_variable *var,
 233                                    struct hash_table *split_outputs)
 234 {
 235    b->cursor = nir_before_instr(&intr->instr);
 236
 237    nir_ssa_def *value = nir_ssa_for_src(b, intr->src[1], intr->num_components);
 238
 239    nir_variable **chan_vars = get_channel_variables(split_outputs, var);
 240    for (unsigned i = 0; i < intr->num_components; i++) {
 241       if (!(nir_intrinsic_write_mask(intr) & (1 << i)))
 242          continue;
 243
 244       nir_variable *chan_var = chan_vars[var->data.location_frac + i];
 245       if (!chan_vars[var->data.location_frac + i]) {
 246          chan_var = nir_variable_clone(var, b->shader);
 247          chan_var->data.location_frac =  var->data.location_frac + i;
 248          chan_var->type = glsl_channel_type(chan_var->type);
 249
 250          chan_vars[var->data.location_frac + i] = chan_var;
 251
 252          nir_shader_add_variable(b->shader, chan_var);
 253       }
 254
 255       nir_intrinsic_instr *chan_intr =
 256          nir_intrinsic_instr_create(b->shader, intr->intrinsic);
 257       chan_intr->num_components = 1;
 258
 259       nir_intrinsic_set_write_mask(chan_intr, 0x1);
 260
 261       nir_deref_instr *deref = nir_build_deref_var(b, chan_var);
 262
 263       deref = clone_deref_array(b, deref, nir_src_as_deref(intr->src[0]));
 264
 265       chan_intr->src[0] = nir_src_for_ssa(&deref->dest.ssa);
 266       chan_intr->src[1] = nir_src_for_ssa(nir_channel(b, value, i));
 267
 268       nir_builder_instr_insert(b, &chan_intr->instr);
 269    }
 270
 271    /* Remove the old store intrinsic */
 272    nir_instr_remove(&intr->instr);
 273 }
 274
 275 /*
 276  * This function is intended to be called earlier than nir_lower_io_to_scalar()
 277  * i.e. before nir_lower_io() is called.
 278  */
 279 void
 280 nir_lower_io_to_scalar_early(nir_shader *shader, nir_variable_mode mask)
 281 {
 282    struct hash_table *split_inputs =
 283       _mesa_hash_table_create(NULL, _mesa_hash_pointer,
 284                               _mesa_key_pointer_equal);
 285    struct hash_table *split_outputs =
 286       _mesa_hash_table_create(NULL, _mesa_hash_pointer,
 287                               _mesa_key_pointer_equal);
 288
 289    nir_assert_unlowered_derefs(shader, nir_lower_load_store_derefs | nir_lower_interp_derefs);
 290
 291    nir_foreach_function(function, shader) {
 292       if (function->impl) {
 293          nir_builder b;
 294          nir_builder_init(&b, function->impl);
 295
 296          nir_foreach_block(block, function->impl) {
 297             nir_foreach_instr_safe(instr, block) {
 298                if (instr->type != nir_instr_type_intrinsic)
 299                   continue;
 300
 301                nir_intrinsic_instr *intr = nir_instr_as_intrinsic(instr);
 302
 303                if (intr->num_components == 1)
 304                   continue;
 305
 306                if (intr->intrinsic != nir_intrinsic_load_deref &&
 307                    intr->intrinsic != nir_intrinsic_store_deref &&
 308                    intr->intrinsic != nir_intrinsic_interp_deref_at_centroid &&
 309                    intr->intrinsic != nir_intrinsic_interp_deref_at_sample &&
 310                    intr->intrinsic != nir_intrinsic_interp_deref_at_offset)
 311                   continue;
 312
 313                nir_variable *var =
 314                   nir_deref_instr_get_variable(nir_src_as_deref(intr->src[0]));
 315                nir_variable_mode mode = var->data.mode;
 316
 317                /* TODO: add patch support */
 318                if (var->data.patch)
 319                   continue;
 320
 321                /* TODO: add doubles support */
 322                if (glsl_type_is_64bit(glsl_without_array(var->type)))
 323                   continue;
 324
 325                if (var->data.location < VARYING_SLOT_VAR0 &&
 326                    var->data.location >= 0)
 327                   continue;
 328
 329                /* Don't bother splitting if we can't opt away any unused
 330                 * components.
 331                 */
 332                if (var->data.always_active_io)
 333                   continue;
 334
 335               /* Skip types we cannot split */
 336               if (glsl_type_is_matrix(glsl_without_array(var->type)) ||
 337                   glsl_type_is_struct(glsl_without_array(var->type)))
 338                  continue;
 339
 340                switch (intr->intrinsic) {
 341                case nir_intrinsic_interp_deref_at_centroid:
 342                case nir_intrinsic_interp_deref_at_sample:
 343                case nir_intrinsic_interp_deref_at_offset:
 344                case nir_intrinsic_load_deref:
 345                   if ((mask & nir_var_shader_in && mode == nir_var_shader_in) ||
 346                       (mask & nir_var_shader_out && mode == nir_var_shader_out))
 347                      lower_load_to_scalar_early(&b, intr, var, split_inputs,
 348                                                 split_outputs);
 349                   break;
 350                case nir_intrinsic_store_deref:
 351                   if (mask & nir_var_shader_out &&
 352                       mode == nir_var_shader_out)
 353                      lower_store_output_to_scalar_early(&b, intr, var,
 354                                                         split_outputs);
 355                   break;
 356                default:
 357                   break;
 358                }
 359             }
 360          }
 361       }
 362    }
 363
 364    /* Remove old input from the shaders inputs list */
 365    struct hash_entry *entry;
 366    hash_table_foreach(split_inputs, entry) {
 367       nir_variable *var = (nir_variable *) entry->key;
 368       exec_node_remove(&var->node);
 369
 370       free(entry->data);
 371    }
 372
 373    /* Remove old output from the shaders outputs list */
 374    hash_table_foreach(split_outputs, entry) {
 375       nir_variable *var = (nir_variable *) entry->key;
 376       exec_node_remove(&var->node);
 377
 378       free(entry->data);
 379    }
 380
 381    _mesa_hash_table_destroy(split_inputs, NULL);
 382    _mesa_hash_table_destroy(split_outputs, NULL);
 383
 384    nir_remove_dead_derefs(shader);
 385 }