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[NIR_MAX_VEC_COMPONENTS];
  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       nir_intrinsic_set_type(chan_intr, nir_intrinsic_type(intr));
  53       /* offset */
  54       nir_src_copy(&chan_intr->src[0], &intr->src[0], chan_intr);
  55
  56       nir_builder_instr_insert(b, &chan_intr->instr);
  57
  58       loads[i] = &chan_intr->dest.ssa;
  59    }
  60
  61    nir_ssa_def_rewrite_uses(&intr->dest.ssa,
  62                             nir_src_for_ssa(nir_vec(b, loads,
  63                                                     intr->num_components)));
  64    nir_instr_remove(&intr->instr);
  65 }
  66
  67 static void
  68 lower_store_output_to_scalar(nir_builder *b, nir_intrinsic_instr *intr)
  69 {
  70    b->cursor = nir_before_instr(&intr->instr);
  71
  72    nir_ssa_def *value = nir_ssa_for_src(b, intr->src[0], intr->num_components);
  73
  74    for (unsigned i = 0; i < intr->num_components; i++) {
  75       if (!(nir_intrinsic_write_mask(intr) & (1 << i)))
  76          continue;
  77
  78       nir_intrinsic_instr *chan_intr =
  79          nir_intrinsic_instr_create(b->shader, intr->intrinsic);
  80       chan_intr->num_components = 1;
  81
  82       nir_intrinsic_set_base(chan_intr, nir_intrinsic_base(intr));
  83       nir_intrinsic_set_write_mask(chan_intr, 0x1);
  84       nir_intrinsic_set_component(chan_intr, nir_intrinsic_component(intr) + i);
  85       nir_intrinsic_set_type(chan_intr, nir_intrinsic_type(intr));
  86
  87       /* value */
  88       chan_intr->src[0] = nir_src_for_ssa(nir_channel(b, value, i));
  89       /* offset */
  90       nir_src_copy(&chan_intr->src[1], &intr->src[1], chan_intr);
  91
  92       nir_builder_instr_insert(b, &chan_intr->instr);
  93    }
  94
  95    nir_instr_remove(&intr->instr);
  96 }
  97
  98 static bool
  99 nir_lower_io_to_scalar_instr(nir_builder *b, nir_instr *instr, void *data)
 100 {
 101    nir_variable_mode mask = *(nir_variable_mode *)data;
 102
 103    if (instr->type != nir_instr_type_intrinsic)
 104       return false;
 105
 106    nir_intrinsic_instr *intr = nir_instr_as_intrinsic(instr);
 107
 108    if (intr->num_components == 1)
 109       return false;
 110
 111    if (intr->intrinsic == nir_intrinsic_load_input &&
 112        (mask & nir_var_shader_in)) {
 113       lower_load_input_to_scalar(b, intr);
 114       return true;
 115    }
 116
 117    if (intr->intrinsic == nir_intrinsic_store_output &&
 118        mask & nir_var_shader_out) {
 119       lower_store_output_to_scalar(b, intr);
 120       return true;
 121    }
 122
 123    return false;
 124 }
 125
 126 void
 127 nir_lower_io_to_scalar(nir_shader *shader, nir_variable_mode mask)
 128 {
 129    nir_shader_instructions_pass(shader,
 130                                 nir_lower_io_to_scalar_instr,
 131                                 nir_metadata_block_index |
 132                                 nir_metadata_dominance,
 133                                 &mask);
 134 }
 135
 136 static nir_variable **
 137 get_channel_variables(struct hash_table *ht, nir_variable *var)
 138 {
 139    nir_variable **chan_vars;
 140    struct hash_entry *entry = _mesa_hash_table_search(ht, var);
 141    if (!entry) {
 142       chan_vars = (nir_variable **) calloc(4, sizeof(nir_variable *));
 143       _mesa_hash_table_insert(ht, var, chan_vars);
 144    } else {
 145       chan_vars = (nir_variable **) entry->data;
 146    }
 147
 148    return chan_vars;
 149 }
 150
 151 /*
 152  * Note that the src deref that we are cloning is the head of the
 153  * chain of deref instructions from the original intrinsic, but
 154  * the dst we are cloning to is the tail (because chains of deref
 155  * instructions are created back to front)
 156  */
 157
 158 static nir_deref_instr *
 159 clone_deref_array(nir_builder *b, nir_deref_instr *dst_tail,
 160                   const nir_deref_instr *src_head)
 161 {
 162    const nir_deref_instr *parent = nir_deref_instr_parent(src_head);
 163
 164    if (!parent)
 165       return dst_tail;
 166
 167    assert(src_head->deref_type == nir_deref_type_array);
 168
 169    dst_tail = clone_deref_array(b, dst_tail, parent);
 170
 171    return nir_build_deref_array(b, dst_tail,
 172                                 nir_ssa_for_src(b, src_head->arr.index, 1));
 173 }
 174
 175 static void
 176 lower_load_to_scalar_early(nir_builder *b, nir_intrinsic_instr *intr,
 177                            nir_variable *var, struct hash_table *split_inputs,
 178                            struct hash_table *split_outputs)
 179 {
 180    b->cursor = nir_before_instr(&intr->instr);
 181
 182    assert(intr->dest.is_ssa);
 183
 184    nir_ssa_def *loads[NIR_MAX_VEC_COMPONENTS];
 185
 186    nir_variable **chan_vars;
 187    if (var->data.mode == nir_var_shader_in) {
 188       chan_vars = get_channel_variables(split_inputs, var);
 189    } else {
 190       chan_vars = get_channel_variables(split_outputs, var);
 191    }
 192
 193    for (unsigned i = 0; i < intr->num_components; i++) {
 194       nir_variable *chan_var = chan_vars[var->data.location_frac + i];
 195       if (!chan_vars[var->data.location_frac + i]) {
 196          chan_var = nir_variable_clone(var, b->shader);
 197          chan_var->data.location_frac =  var->data.location_frac + i;
 198          chan_var->type = glsl_channel_type(chan_var->type);
 199          if (var->data.explicit_offset) {
 200             unsigned comp_size = glsl_get_bit_size(chan_var->type) / 8;
 201             chan_var->data.offset = var->data.offset + i * comp_size;
 202          }
 203
 204          chan_vars[var->data.location_frac + i] = chan_var;
 205
 206          nir_shader_add_variable(b->shader, chan_var);
 207       }
 208
 209       nir_intrinsic_instr *chan_intr =
 210          nir_intrinsic_instr_create(b->shader, intr->intrinsic);
 211       nir_ssa_dest_init(&chan_intr->instr, &chan_intr->dest,
 212                         1, intr->dest.ssa.bit_size, NULL);
 213       chan_intr->num_components = 1;
 214
 215       nir_deref_instr *deref = nir_build_deref_var(b, chan_var);
 216
 217       deref = clone_deref_array(b, deref, nir_src_as_deref(intr->src[0]));
 218
 219       chan_intr->src[0] = nir_src_for_ssa(&deref->dest.ssa);
 220
 221       if (intr->intrinsic == nir_intrinsic_interp_deref_at_offset ||
 222           intr->intrinsic == nir_intrinsic_interp_deref_at_sample ||
 223           intr->intrinsic == nir_intrinsic_interp_deref_at_vertex)
 224          nir_src_copy(&chan_intr->src[1], &intr->src[1], &chan_intr->instr);
 225
 226       nir_builder_instr_insert(b, &chan_intr->instr);
 227
 228       loads[i] = &chan_intr->dest.ssa;
 229    }
 230
 231    nir_ssa_def_rewrite_uses(&intr->dest.ssa,
 232                             nir_src_for_ssa(nir_vec(b, loads,
 233                                                     intr->num_components)));
 234
 235    /* Remove the old load intrinsic */
 236    nir_instr_remove(&intr->instr);
 237 }
 238
 239 static void
 240 lower_store_output_to_scalar_early(nir_builder *b, nir_intrinsic_instr *intr,
 241                                    nir_variable *var,
 242                                    struct hash_table *split_outputs)
 243 {
 244    b->cursor = nir_before_instr(&intr->instr);
 245
 246    nir_ssa_def *value = nir_ssa_for_src(b, intr->src[1], intr->num_components);
 247
 248    nir_variable **chan_vars = get_channel_variables(split_outputs, var);
 249    for (unsigned i = 0; i < intr->num_components; i++) {
 250       if (!(nir_intrinsic_write_mask(intr) & (1 << i)))
 251          continue;
 252
 253       nir_variable *chan_var = chan_vars[var->data.location_frac + i];
 254       if (!chan_vars[var->data.location_frac + i]) {
 255          chan_var = nir_variable_clone(var, b->shader);
 256          chan_var->data.location_frac =  var->data.location_frac + i;
 257          chan_var->type = glsl_channel_type(chan_var->type);
 258          if (var->data.explicit_offset) {
 259             unsigned comp_size = glsl_get_bit_size(chan_var->type) / 8;
 260             chan_var->data.offset = var->data.offset + i * comp_size;
 261          }
 262
 263          chan_vars[var->data.location_frac + i] = chan_var;
 264
 265          nir_shader_add_variable(b->shader, chan_var);
 266       }
 267
 268       nir_intrinsic_instr *chan_intr =
 269          nir_intrinsic_instr_create(b->shader, intr->intrinsic);
 270       chan_intr->num_components = 1;
 271
 272       nir_intrinsic_set_write_mask(chan_intr, 0x1);
 273
 274       nir_deref_instr *deref = nir_build_deref_var(b, chan_var);
 275
 276       deref = clone_deref_array(b, deref, nir_src_as_deref(intr->src[0]));
 277
 278       chan_intr->src[0] = nir_src_for_ssa(&deref->dest.ssa);
 279       chan_intr->src[1] = nir_src_for_ssa(nir_channel(b, value, i));
 280
 281       nir_builder_instr_insert(b, &chan_intr->instr);
 282    }
 283
 284    /* Remove the old store intrinsic */
 285    nir_instr_remove(&intr->instr);
 286 }
 287
 288 struct io_to_scalar_early_state {
 289    struct hash_table *split_inputs, *split_outputs;
 290    nir_variable_mode mask;
 291 };
 292
 293 static bool
 294 nir_lower_io_to_scalar_early_instr(nir_builder *b, nir_instr *instr, void *data)
 295 {
 296    struct io_to_scalar_early_state *state = data;
 297
 298    if (instr->type != nir_instr_type_intrinsic)
 299       return false;
 300
 301    nir_intrinsic_instr *intr = nir_instr_as_intrinsic(instr);
 302
 303    if (intr->num_components == 1)
 304       return false;
 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        intr->intrinsic != nir_intrinsic_interp_deref_at_vertex)
 312       return false;
 313
 314    nir_deref_instr *deref = nir_src_as_deref(intr->src[0]);
 315    nir_variable_mode mode = deref->mode;
 316    if (!(mode & state->mask))
 317       return false;
 318
 319    nir_variable *var = nir_deref_instr_get_variable(deref);
 320
 321    /* TODO: add patch support */
 322    if (var->data.patch)
 323       return false;
 324
 325    /* TODO: add doubles support */
 326    if (glsl_type_is_64bit(glsl_without_array(var->type)))
 327       return false;
 328
 329    if (!(b->shader->info.stage == MESA_SHADER_VERTEX &&
 330          mode == nir_var_shader_in) &&
 331        var->data.location < VARYING_SLOT_VAR0 &&
 332        var->data.location >= 0)
 333       return false;
 334
 335    /* Don't bother splitting if we can't opt away any unused
 336     * components.
 337     */
 338    if (var->data.always_active_io)
 339       return false;
 340
 341    /* Skip types we cannot split */
 342    if (glsl_type_is_matrix(glsl_without_array(var->type)) ||
 343        glsl_type_is_struct_or_ifc(glsl_without_array(var->type)))
 344       return false;
 345
 346    switch (intr->intrinsic) {
 347    case nir_intrinsic_interp_deref_at_centroid:
 348    case nir_intrinsic_interp_deref_at_sample:
 349    case nir_intrinsic_interp_deref_at_offset:
 350    case nir_intrinsic_interp_deref_at_vertex:
 351    case nir_intrinsic_load_deref:
 352       if ((state->mask & nir_var_shader_in && mode == nir_var_shader_in) ||
 353           (state->mask & nir_var_shader_out && mode == nir_var_shader_out)) {
 354          lower_load_to_scalar_early(b, intr, var, state->split_inputs,
 355                                     state->split_outputs);
 356          return true;
 357       }
 358       break;
 359    case nir_intrinsic_store_deref:
 360       if (state->mask & nir_var_shader_out &&
 361           mode == nir_var_shader_out) {
 362          lower_store_output_to_scalar_early(b, intr, var, state->split_outputs);
 363          return true;
 364       }
 365       break;
 366    default:
 367       break;
 368    }
 369
 370    return false;
 371 }
 372
 373 /*
 374  * This function is intended to be called earlier than nir_lower_io_to_scalar()
 375  * i.e. before nir_lower_io() is called.
 376  */
 377 void
 378 nir_lower_io_to_scalar_early(nir_shader *shader, nir_variable_mode mask)
 379 {
 380    struct io_to_scalar_early_state state = {
 381       .split_inputs = _mesa_pointer_hash_table_create(NULL),
 382       .split_outputs = _mesa_pointer_hash_table_create(NULL),
 383       .mask = mask
 384    };
 385
 386    nir_shader_instructions_pass(shader,
 387                                 nir_lower_io_to_scalar_early_instr,
 388                                 nir_metadata_block_index |
 389                                 nir_metadata_dominance,
 390                                 &state);
 391
 392    /* Remove old input from the shaders inputs list */
 393    hash_table_foreach(state.split_inputs, entry) {
 394       nir_variable *var = (nir_variable *) entry->key;
 395       exec_node_remove(&var->node);
 396
 397       free(entry->data);
 398    }
 399
 400    /* Remove old output from the shaders outputs list */
 401    hash_table_foreach(state.split_outputs, entry) {
 402       nir_variable *var = (nir_variable *) entry->key;
 403       exec_node_remove(&var->node);
 404
 405       free(entry->data);
 406    }
 407
 408    _mesa_hash_table_destroy(state.split_inputs, NULL);
 409    _mesa_hash_table_destroy(state.split_outputs, NULL);
 410
 411    nir_remove_dead_derefs(shader);
 412 }