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