src/compiler/nir/nir_lower_system_values.c

   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
  31 static nir_ssa_def*
  32 build_local_group_size(nir_builder *b, unsigned bit_size)
  33 {
  34    nir_ssa_def *local_size;
  35
  36    /*
  37     * If the local work group size is variable it can't be lowered at this
  38     * point, but its intrinsic can still be used.
  39     */
  40    if (b->shader->info.cs.local_size_variable) {
  41       local_size = nir_load_local_group_size(b);
  42    } else {
  43       /* using a 32 bit constant is safe here as no device/driver needs more
  44        * than 32 bits for the local size */
  45       nir_const_value local_size_const[3];
  46       memset(local_size_const, 0, sizeof(local_size_const));
  47       local_size_const[0].u32 = b->shader->info.cs.local_size[0];
  48       local_size_const[1].u32 = b->shader->info.cs.local_size[1];
  49       local_size_const[2].u32 = b->shader->info.cs.local_size[2];
  50       local_size = nir_build_imm(b, 3, 32, local_size_const);
  51    }
  52
  53    return nir_u2u(b, local_size, bit_size);
  54 }
  55
  56 static nir_ssa_def *
  57 build_local_invocation_id(nir_builder *b, unsigned bit_size)
  58 {
  59    /* If lower_cs_local_id_from_index is true, then we derive the local
  60     * index from the local id.
  61     */
  62    if (b->shader->options->lower_cs_local_id_from_index) {
  63       /* We lower gl_LocalInvocationID from gl_LocalInvocationIndex based
  64        * on this formula:
  65        *
  66        *    gl_LocalInvocationID.x =
  67        *       gl_LocalInvocationIndex % gl_WorkGroupSize.x;
  68        *    gl_LocalInvocationID.y =
  69        *       (gl_LocalInvocationIndex / gl_WorkGroupSize.x) %
  70        *       gl_WorkGroupSize.y;
  71        *    gl_LocalInvocationID.z =
  72        *       (gl_LocalInvocationIndex /
  73        *        (gl_WorkGroupSize.x * gl_WorkGroupSize.y)) %
  74        *       gl_WorkGroupSize.z;
  75        *
  76        * However, the final % gl_WorkGroupSize.z does nothing unless we
  77        * accidentally end up with a gl_LocalInvocationIndex that is too
  78        * large so it can safely be omitted.
  79        */
  80       nir_ssa_def *local_index = nir_load_local_invocation_index(b);
  81       nir_ssa_def *local_size = build_local_group_size(b, 32);
  82
  83       /* Because no hardware supports a local workgroup size greater than
  84        * about 1K, this calculation can be done in 32-bit and can save some
  85        * 64-bit arithmetic.
  86        */
  87       nir_ssa_def *id_x, *id_y, *id_z;
  88       id_x = nir_umod(b, local_index,
  89                          nir_channel(b, local_size, 0));
  90       id_y = nir_umod(b, nir_udiv(b, local_index,
  91                                      nir_channel(b, local_size, 0)),
  92                          nir_channel(b, local_size, 1));
  93       id_z = nir_udiv(b, local_index,
  94                          nir_imul(b, nir_channel(b, local_size, 0),
  95                                      nir_channel(b, local_size, 1)));
  96       return nir_u2u(b, nir_vec3(b, id_x, id_y, id_z), bit_size);
  97    } else {
  98       return nir_u2u(b, nir_load_local_invocation_id(b), bit_size);
  99    }
 100 }
 101
 102 static nir_ssa_def*
 103 build_global_group_size(nir_builder *b, unsigned bit_size)
 104 {
 105    nir_ssa_def *group_size = build_local_group_size(b, bit_size);
 106    nir_ssa_def *num_work_groups = nir_u2u(b, nir_load_num_work_groups(b), bit_size);
 107    return nir_imul(b, group_size, num_work_groups);
 108 }
 109
 110 static nir_ssa_def*
 111 build_global_invocation_id(nir_builder *b, unsigned bit_size)
 112 {
 113    /* From the GLSL man page for gl_GlobalInvocationID:
 114     *
 115     *    "The value of gl_GlobalInvocationID is equal to
 116     *    gl_WorkGroupID * gl_WorkGroupSize + gl_LocalInvocationID"
 117     */
 118    nir_ssa_def *group_size = build_local_group_size(b, bit_size);
 119    nir_ssa_def *group_id = nir_u2u(b, nir_load_work_group_id(b), bit_size);
 120    nir_ssa_def *local_id = build_local_invocation_id(b, bit_size);
 121
 122    return nir_iadd(b, nir_imul(b, group_id, group_size), local_id);
 123 }
 124
 125 static bool
 126 convert_block(nir_block *block, nir_builder *b)
 127 {
 128    bool progress = false;
 129
 130    nir_foreach_instr_safe(instr, block) {
 131       if (instr->type != nir_instr_type_intrinsic)
 132          continue;
 133
 134       nir_intrinsic_instr *load_deref = nir_instr_as_intrinsic(instr);
 135       if (load_deref->intrinsic != nir_intrinsic_load_deref)
 136          continue;
 137
 138       nir_deref_instr *deref = nir_src_as_deref(load_deref->src[0]);
 139       if (deref->mode != nir_var_system_value)
 140          continue;
 141
 142       if (deref->deref_type != nir_deref_type_var) {
 143          /* The only one system value that is an array and that is
 144           * gl_SampleMask which is always an array of one element.
 145           */
 146          assert(deref->deref_type == nir_deref_type_array);
 147          deref = nir_deref_instr_parent(deref);
 148          assert(deref->deref_type == nir_deref_type_var);
 149          assert(deref->var->data.location == SYSTEM_VALUE_SAMPLE_MASK_IN);
 150       }
 151       nir_variable *var = deref->var;
 152
 153       b->cursor = nir_after_instr(&load_deref->instr);
 154
 155       unsigned bit_size = nir_dest_bit_size(load_deref->dest);
 156       nir_ssa_def *sysval = NULL;
 157       switch (var->data.location) {
 158       case SYSTEM_VALUE_GLOBAL_INVOCATION_ID: {
 159          sysval = build_global_invocation_id(b, bit_size);
 160          break;
 161       }
 162
 163       case SYSTEM_VALUE_GLOBAL_INVOCATION_INDEX: {
 164          nir_ssa_def *global_id = build_global_invocation_id(b, bit_size);
 165          nir_ssa_def *global_size = build_global_group_size(b, bit_size);
 166
 167          /* index = id.x + ((id.y + (id.z * size.y)) * size.x) */
 168          sysval = nir_imul(b, nir_channel(b, global_id, 2),
 169                               nir_channel(b, global_size, 1));
 170          sysval = nir_iadd(b, nir_channel(b, global_id, 1), sysval);
 171          sysval = nir_imul(b, nir_channel(b, global_size, 0), sysval);
 172          sysval = nir_iadd(b, nir_channel(b, global_id, 0), sysval);
 173          break;
 174       }
 175
 176       case SYSTEM_VALUE_LOCAL_INVOCATION_INDEX: {
 177          /* If lower_cs_local_index_from_id is true, then we derive the local
 178           * index from the local id.
 179           */
 180          if (!b->shader->options->lower_cs_local_index_from_id)
 181             break;
 182
 183          /* From the GLSL man page for gl_LocalInvocationIndex:
 184           *
 185           *    "The value of gl_LocalInvocationIndex is equal to
 186           *    gl_LocalInvocationID.z * gl_WorkGroupSize.x *
 187           *    gl_WorkGroupSize.y + gl_LocalInvocationID.y *
 188           *    gl_WorkGroupSize.x + gl_LocalInvocationID.x"
 189           */
 190          nir_ssa_def *local_id = nir_load_local_invocation_id(b);
 191
 192          nir_ssa_def *size_x =
 193             nir_imm_int(b, b->shader->info.cs.local_size[0]);
 194          nir_ssa_def *size_y =
 195             nir_imm_int(b, b->shader->info.cs.local_size[1]);
 196
 197          /* Because no hardware supports a local workgroup size greater than
 198           * about 1K, this calculation can be done in 32-bit and can save some
 199           * 64-bit arithmetic.
 200           */
 201          sysval = nir_imul(b, nir_channel(b, local_id, 2),
 202                               nir_imul(b, size_x, size_y));
 203          sysval = nir_iadd(b, sysval,
 204                               nir_imul(b, nir_channel(b, local_id, 1), size_x));
 205          sysval = nir_iadd(b, sysval, nir_channel(b, local_id, 0));
 206          sysval = nir_u2u(b, sysval, bit_size);
 207          break;
 208       }
 209
 210       case SYSTEM_VALUE_LOCAL_INVOCATION_ID:
 211          sysval = build_local_invocation_id(b, bit_size);
 212          break;
 213
 214       case SYSTEM_VALUE_LOCAL_GROUP_SIZE: {
 215          sysval = build_local_group_size(b, bit_size);
 216          break;
 217       }
 218
 219       case SYSTEM_VALUE_VERTEX_ID:
 220          if (b->shader->options->vertex_id_zero_based) {
 221             sysval = nir_iadd(b,
 222                               nir_load_vertex_id_zero_base(b),
 223                               nir_load_first_vertex(b));
 224          } else {
 225             sysval = nir_load_vertex_id(b);
 226          }
 227          break;
 228
 229       case SYSTEM_VALUE_BASE_VERTEX:
 230          /**
 231           * From the OpenGL 4.6 (11.1.3.9 Shader Inputs) specification:
 232           *
 233           * "gl_BaseVertex holds the integer value passed to the baseVertex
 234           * parameter to the command that resulted in the current shader
 235           * invocation. In the case where the command has no baseVertex
 236           * parameter, the value of gl_BaseVertex is zero."
 237           */
 238          if (b->shader->options->lower_base_vertex)
 239             sysval = nir_iand(b,
 240                               nir_load_is_indexed_draw(b),
 241                               nir_load_first_vertex(b));
 242          break;
 243
 244       case SYSTEM_VALUE_HELPER_INVOCATION:
 245          if (b->shader->options->lower_helper_invocation) {
 246             nir_ssa_def *tmp;
 247
 248             tmp = nir_ishl(b,
 249                            nir_imm_int(b, 1),
 250                            nir_load_sample_id_no_per_sample(b));
 251
 252             tmp = nir_iand(b,
 253                            nir_load_sample_mask_in(b),
 254                            tmp);
 255
 256             sysval = nir_inot(b, nir_i2b(b, tmp));
 257          }
 258
 259          break;
 260
 261       case SYSTEM_VALUE_INSTANCE_INDEX:
 262          sysval = nir_iadd(b,
 263                            nir_load_instance_id(b),
 264                            nir_load_base_instance(b));
 265          break;
 266
 267       case SYSTEM_VALUE_SUBGROUP_EQ_MASK:
 268       case SYSTEM_VALUE_SUBGROUP_GE_MASK:
 269       case SYSTEM_VALUE_SUBGROUP_GT_MASK:
 270       case SYSTEM_VALUE_SUBGROUP_LE_MASK:
 271       case SYSTEM_VALUE_SUBGROUP_LT_MASK: {
 272          nir_intrinsic_op op =
 273             nir_intrinsic_from_system_value(var->data.location);
 274          nir_intrinsic_instr *load = nir_intrinsic_instr_create(b->shader, op);
 275          nir_ssa_dest_init_for_type(&load->instr, &load->dest,
 276                                     var->type, NULL);
 277          load->num_components = load->dest.ssa.num_components;
 278          nir_builder_instr_insert(b, &load->instr);
 279          sysval = &load->dest.ssa;
 280          break;
 281       }
 282
 283       case SYSTEM_VALUE_DEVICE_INDEX:
 284          if (b->shader->options->lower_device_index_to_zero)
 285             sysval = nir_imm_int(b, 0);
 286          break;
 287
 288       case SYSTEM_VALUE_GLOBAL_GROUP_SIZE: {
 289          sysval = build_global_group_size(b, bit_size);
 290          break;
 291       }
 292
 293       default:
 294          break;
 295       }
 296
 297       if (sysval == NULL) {
 298          nir_intrinsic_op sysval_op =
 299             nir_intrinsic_from_system_value(var->data.location);
 300          sysval = nir_load_system_value(b, sysval_op, 0,
 301                                         load_deref->dest.ssa.bit_size);
 302       }
 303
 304       nir_ssa_def_rewrite_uses(&load_deref->dest.ssa, nir_src_for_ssa(sysval));
 305       nir_instr_remove(&load_deref->instr);
 306
 307       progress = true;
 308    }
 309
 310    return progress;
 311 }
 312
 313 static bool
 314 convert_impl(nir_function_impl *impl)
 315 {
 316    bool progress = false;
 317    nir_builder builder;
 318    nir_builder_init(&builder, impl);
 319
 320    nir_foreach_block(block, impl) {
 321       progress |= convert_block(block, &builder);
 322    }
 323
 324    nir_metadata_preserve(impl, nir_metadata_block_index |
 325                                nir_metadata_dominance);
 326    return progress;
 327 }
 328
 329 bool
 330 nir_lower_system_values(nir_shader *shader)
 331 {
 332    bool progress = false;
 333
 334    nir_foreach_function(function, shader) {
 335       if (function->impl)
 336          progress = convert_impl(function->impl) || progress;
 337    }
 338
 339    /* We're going to delete the variables so we need to clean up all those
 340     * derefs we left lying around.
 341     */
 342    nir_remove_dead_derefs(shader);
 343
 344    exec_list_make_empty(&shader->system_values);
 345
 346    return progress;
 347 }