src/gallium/drivers/vc4/vc4_nir_lower_io.c

   1 /*
   2  * Copyright © 2015 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 "vc4_qir.h"
  25 #include "compiler/nir/nir_builder.h"
  26 #include "util/u_format.h"
  27
  28 /**
  29  * Walks the NIR generated by TGSI-to-NIR to lower its io intrinsics into
  30  * something amenable to the VC4 architecture.
  31  *
  32  * Currently, it split inputs, outputs, and uniforms into scalars, drops any
  33  * non-position outputs in coordinate shaders, and fixes up the addressing on
  34  * indirect uniform loads.
  35  */
  36
  37 static void
  38 replace_intrinsic_with_vec4(nir_builder *b, nir_intrinsic_instr *intr,
  39                             nir_ssa_def **comps)
  40 {
  41
  42         /* Batch things back together into a vec4.  This will get split by the
  43          * later ALU scalarization pass.
  44          */
  45         nir_ssa_def *vec = nir_vec4(b, comps[0], comps[1], comps[2], comps[3]);
  46
  47         /* Replace the old intrinsic with a reference to our reconstructed
  48          * vec4.
  49          */
  50         nir_ssa_def_rewrite_uses(&intr->dest.ssa, nir_src_for_ssa(vec));
  51         nir_instr_remove(&intr->instr);
  52 }
  53
  54 static nir_ssa_def *
  55 vc4_nir_unpack_8i(nir_builder *b, nir_ssa_def *src, unsigned chan)
  56 {
  57         return nir_ubitfield_extract(b,
  58                                      src,
  59                                      nir_imm_int(b, 8 * chan),
  60                                      nir_imm_int(b, 8));
  61 }
  62
  63 /** Returns the 16 bit field as a sign-extended 32-bit value. */
  64 static nir_ssa_def *
  65 vc4_nir_unpack_16i(nir_builder *b, nir_ssa_def *src, unsigned chan)
  66 {
  67         return nir_ibitfield_extract(b,
  68                                      src,
  69                                      nir_imm_int(b, 16 * chan),
  70                                      nir_imm_int(b, 16));
  71 }
  72
  73 /** Returns the 16 bit field as an unsigned 32 bit value. */
  74 static nir_ssa_def *
  75 vc4_nir_unpack_16u(nir_builder *b, nir_ssa_def *src, unsigned chan)
  76 {
  77         if (chan == 0) {
  78                 return nir_iand(b, src, nir_imm_int(b, 0xffff));
  79         } else {
  80                 return nir_ushr(b, src, nir_imm_int(b, 16));
  81         }
  82 }
  83
  84 static nir_ssa_def *
  85 vc4_nir_unpack_8f(nir_builder *b, nir_ssa_def *src, unsigned chan)
  86 {
  87         return nir_channel(b, nir_unpack_unorm_4x8(b, src), chan);
  88 }
  89
  90 static nir_ssa_def *
  91 vc4_nir_get_vattr_channel_vpm(struct vc4_compile *c,
  92                               nir_builder *b,
  93                               nir_ssa_def **vpm_reads,
  94                               uint8_t swiz,
  95                               const struct util_format_description *desc)
  96 {
  97         const struct util_format_channel_description *chan =
  98                 &desc->channel[swiz];
  99         nir_ssa_def *temp;
 100
 101         if (swiz > PIPE_SWIZZLE_W) {
 102                 return vc4_nir_get_swizzled_channel(b, vpm_reads, swiz);
 103         } else if (chan->size == 32 && chan->type == UTIL_FORMAT_TYPE_FLOAT) {
 104                 return vc4_nir_get_swizzled_channel(b, vpm_reads, swiz);
 105         } else if (chan->size == 32 && chan->type == UTIL_FORMAT_TYPE_SIGNED) {
 106                 if (chan->normalized) {
 107                         return nir_fmul(b,
 108                                         nir_i2f(b, vpm_reads[swiz]),
 109                                         nir_imm_float(b,
 110                                                       1.0 / 0x7fffffff));
 111                 } else {
 112                         return nir_i2f(b, vpm_reads[swiz]);
 113                 }
 114         } else if (chan->size == 8 &&
 115                    (chan->type == UTIL_FORMAT_TYPE_UNSIGNED ||
 116                     chan->type == UTIL_FORMAT_TYPE_SIGNED)) {
 117                 nir_ssa_def *vpm = vpm_reads[0];
 118                 if (chan->type == UTIL_FORMAT_TYPE_SIGNED) {
 119                         temp = nir_ixor(b, vpm, nir_imm_int(b, 0x80808080));
 120                         if (chan->normalized) {
 121                                 return nir_fsub(b, nir_fmul(b,
 122                                                             vc4_nir_unpack_8f(b, temp, swiz),
 123                                                             nir_imm_float(b, 2.0)),
 124                                                 nir_imm_float(b, 1.0));
 125                         } else {
 126                                 return nir_fadd(b,
 127                                                 nir_i2f(b,
 128                                                         vc4_nir_unpack_8i(b, temp,
 129                                                                           swiz)),
 130                                                 nir_imm_float(b, -128.0));
 131                         }
 132                 } else {
 133                         if (chan->normalized) {
 134                                 return vc4_nir_unpack_8f(b, vpm, swiz);
 135                         } else {
 136                                 return nir_i2f(b, vc4_nir_unpack_8i(b, vpm, swiz));
 137                         }
 138                 }
 139         } else if (chan->size == 16 &&
 140                    (chan->type == UTIL_FORMAT_TYPE_UNSIGNED ||
 141                     chan->type == UTIL_FORMAT_TYPE_SIGNED)) {
 142                 nir_ssa_def *vpm = vpm_reads[swiz / 2];
 143
 144                 /* Note that UNPACK_16F eats a half float, not ints, so we use
 145                  * UNPACK_16_I for all of these.
 146                  */
 147                 if (chan->type == UTIL_FORMAT_TYPE_SIGNED) {
 148                         temp = nir_i2f(b, vc4_nir_unpack_16i(b, vpm, swiz & 1));
 149                         if (chan->normalized) {
 150                                 return nir_fmul(b, temp,
 151                                                 nir_imm_float(b, 1/32768.0f));
 152                         } else {
 153                                 return temp;
 154                         }
 155                 } else {
 156                         temp = nir_i2f(b, vc4_nir_unpack_16u(b, vpm, swiz & 1));
 157                         if (chan->normalized) {
 158                                 return nir_fmul(b, temp,
 159                                                 nir_imm_float(b, 1 / 65535.0));
 160                         } else {
 161                                 return temp;
 162                         }
 163                 }
 164         } else {
 165                 return NULL;
 166         }
 167 }
 168
 169 static void
 170 vc4_nir_lower_vertex_attr(struct vc4_compile *c, nir_builder *b,
 171                           nir_intrinsic_instr *intr)
 172 {
 173         b->cursor = nir_before_instr(&intr->instr);
 174
 175         int attr = intr->const_index[0];
 176         enum pipe_format format = c->vs_key->attr_formats[attr];
 177         uint32_t attr_size = util_format_get_blocksize(format);
 178
 179         /* All TGSI-to-NIR inputs are vec4. */
 180         assert(intr->num_components == 4);
 181
 182         /* We only accept direct outputs and TGSI only ever gives them to us
 183          * with an offset value of 0.
 184          */
 185         assert(nir_src_as_const_value(intr->src[0]) &&
 186                nir_src_as_const_value(intr->src[0])->u32[0] == 0);
 187
 188         /* Generate dword loads for the VPM values (Since these intrinsics may
 189          * be reordered, the actual reads will be generated at the top of the
 190          * shader by ntq_setup_inputs().
 191          */
 192         nir_ssa_def *vpm_reads[4];
 193         for (int i = 0; i < align(attr_size, 4) / 4; i++) {
 194                 nir_intrinsic_instr *intr_comp =
 195                         nir_intrinsic_instr_create(c->s,
 196                                                    nir_intrinsic_load_input);
 197                 intr_comp->num_components = 1;
 198                 intr_comp->const_index[0] = intr->const_index[0] * 4 + i;
 199                 intr_comp->src[0] = nir_src_for_ssa(nir_imm_int(b, 0));
 200                 nir_ssa_dest_init(&intr_comp->instr, &intr_comp->dest, 1, 32, NULL);
 201                 nir_builder_instr_insert(b, &intr_comp->instr);
 202
 203                 vpm_reads[i] = &intr_comp->dest.ssa;
 204         }
 205
 206         bool format_warned = false;
 207         const struct util_format_description *desc =
 208                 util_format_description(format);
 209
 210         nir_ssa_def *dests[4];
 211         for (int i = 0; i < 4; i++) {
 212                 uint8_t swiz = desc->swizzle[i];
 213                 dests[i] = vc4_nir_get_vattr_channel_vpm(c, b, vpm_reads, swiz,
 214                                                          desc);
 215
 216                 if (!dests[i]) {
 217                         if (!format_warned) {
 218                                 fprintf(stderr,
 219                                         "vtx element %d unsupported type: %s\n",
 220                                         attr, util_format_name(format));
 221                                 format_warned = true;
 222                         }
 223                         dests[i] = nir_imm_float(b, 0.0);
 224                 }
 225         }
 226
 227         replace_intrinsic_with_vec4(b, intr, dests);
 228 }
 229
 230 static void
 231 vc4_nir_lower_fs_input(struct vc4_compile *c, nir_builder *b,
 232                        nir_intrinsic_instr *intr)
 233 {
 234         b->cursor = nir_before_instr(&intr->instr);
 235
 236         if (intr->const_index[0] >= VC4_NIR_TLB_COLOR_READ_INPUT &&
 237             intr->const_index[0] < (VC4_NIR_TLB_COLOR_READ_INPUT +
 238                                     VC4_MAX_SAMPLES)) {
 239                 /* This doesn't need any lowering. */
 240                 return;
 241         }
 242
 243         nir_variable *input_var = NULL;
 244         nir_foreach_variable(var, &c->s->inputs) {
 245                 if (var->data.driver_location == intr->const_index[0]) {
 246                         input_var = var;
 247                         break;
 248                 }
 249         }
 250         assert(input_var);
 251
 252         /* All TGSI-to-NIR inputs are vec4. */
 253         assert(intr->num_components == 4);
 254
 255         /* We only accept direct inputs and TGSI only ever gives them to us
 256          * with an offset value of 0.
 257          */
 258         assert(nir_src_as_const_value(intr->src[0]) &&
 259                nir_src_as_const_value(intr->src[0])->u32[0] == 0);
 260
 261         /* Generate scalar loads equivalent to the original VEC4. */
 262         nir_ssa_def *dests[4];
 263         for (unsigned i = 0; i < intr->num_components; i++) {
 264                 nir_intrinsic_instr *intr_comp =
 265                         nir_intrinsic_instr_create(c->s, nir_intrinsic_load_input);
 266                 intr_comp->num_components = 1;
 267                 intr_comp->const_index[0] = intr->const_index[0] * 4 + i;
 268                 intr_comp->src[0] = nir_src_for_ssa(nir_imm_int(b, 0));
 269
 270                 nir_ssa_dest_init(&intr_comp->instr, &intr_comp->dest, 1, 32, NULL);
 271                 nir_builder_instr_insert(b, &intr_comp->instr);
 272
 273                 dests[i] = &intr_comp->dest.ssa;
 274         }
 275
 276         if (input_var->data.location == VARYING_SLOT_FACE) {
 277                 /* TGSI-to-NIR's front face.  Convert to using the system
 278                  * value boolean instead.
 279                  */
 280                 nir_ssa_def *face =
 281                         nir_load_system_value(b,
 282                                               nir_intrinsic_load_front_face,
 283                                               0);
 284                 dests[0] = nir_bcsel(b, face, nir_imm_float(b, 1.0),
 285                                      nir_imm_float(b, -1.0));
 286                 dests[1] = nir_imm_float(b, 0.0);
 287                 dests[2] = nir_imm_float(b, 0.0);
 288                 dests[3] = nir_imm_float(b, 1.0);
 289         } else if (input_var->data.location >= VARYING_SLOT_VAR0) {
 290                 if (c->fs_key->point_sprite_mask &
 291                     (1 << (input_var->data.location -
 292                            VARYING_SLOT_VAR0))) {
 293                         if (!c->fs_key->is_points) {
 294                                 dests[0] = nir_imm_float(b, 0.0);
 295                                 dests[1] = nir_imm_float(b, 0.0);
 296                         }
 297                         if (c->fs_key->point_coord_upper_left) {
 298                                 dests[1] = nir_fsub(b,
 299                                                     nir_imm_float(b, 1.0),
 300                                                     dests[1]);
 301                         }
 302                         dests[2] = nir_imm_float(b, 0.0);
 303                         dests[3] = nir_imm_float(b, 1.0);
 304                 }
 305         }
 306
 307         replace_intrinsic_with_vec4(b, intr, dests);
 308 }
 309
 310 static void
 311 vc4_nir_lower_output(struct vc4_compile *c, nir_builder *b,
 312                      nir_intrinsic_instr *intr)
 313 {
 314         nir_variable *output_var = NULL;
 315         nir_foreach_variable(var, &c->s->outputs) {
 316                 if (var->data.driver_location == intr->const_index[0]) {
 317                         output_var = var;
 318                         break;
 319                 }
 320         }
 321         assert(output_var);
 322
 323         if (c->stage == QSTAGE_COORD &&
 324             output_var->data.location != VARYING_SLOT_POS &&
 325             output_var->data.location != VARYING_SLOT_PSIZ) {
 326                 nir_instr_remove(&intr->instr);
 327                 return;
 328         }
 329
 330         /* Color output is lowered by vc4_nir_lower_blend(). */
 331         if (c->stage == QSTAGE_FRAG &&
 332             (output_var->data.location == FRAG_RESULT_COLOR ||
 333              output_var->data.location == FRAG_RESULT_DATA0 ||
 334              output_var->data.location == FRAG_RESULT_SAMPLE_MASK)) {
 335                 intr->const_index[0] *= 4;
 336                 return;
 337         }
 338
 339         /* All TGSI-to-NIR outputs are VEC4. */
 340         assert(intr->num_components == 4);
 341
 342         /* We only accept direct outputs and TGSI only ever gives them to us
 343          * with an offset value of 0.
 344          */
 345         assert(nir_src_as_const_value(intr->src[1]) &&
 346                nir_src_as_const_value(intr->src[1])->u32[0] == 0);
 347
 348         b->cursor = nir_before_instr(&intr->instr);
 349
 350         for (unsigned i = 0; i < intr->num_components; i++) {
 351                 nir_intrinsic_instr *intr_comp =
 352                         nir_intrinsic_instr_create(c->s, nir_intrinsic_store_output);
 353                 intr_comp->num_components = 1;
 354                 intr_comp->const_index[0] = intr->const_index[0] * 4 + i;
 355
 356                 assert(intr->src[0].is_ssa);
 357                 intr_comp->src[0] =
 358                         nir_src_for_ssa(nir_channel(b, intr->src[0].ssa, i));
 359                 intr_comp->src[1] = nir_src_for_ssa(nir_imm_int(b, 0));
 360                 nir_builder_instr_insert(b, &intr_comp->instr);
 361         }
 362
 363         nir_instr_remove(&intr->instr);
 364 }
 365
 366 static void
 367 vc4_nir_lower_uniform(struct vc4_compile *c, nir_builder *b,
 368                       nir_intrinsic_instr *intr)
 369 {
 370         /* All TGSI-to-NIR uniform loads are vec4, but we need byte offsets
 371          * in the backend.
 372          */
 373         if (intr->num_components == 1)
 374                 return;
 375         assert(intr->num_components == 4);
 376
 377         b->cursor = nir_before_instr(&intr->instr);
 378
 379         /* Generate scalar loads equivalent to the original VEC4. */
 380         nir_ssa_def *dests[4];
 381         for (unsigned i = 0; i < intr->num_components; i++) {
 382                 nir_intrinsic_instr *intr_comp =
 383                         nir_intrinsic_instr_create(c->s, intr->intrinsic);
 384                 intr_comp->num_components = 1;
 385                 nir_ssa_dest_init(&intr_comp->instr, &intr_comp->dest, 1, 32, NULL);
 386
 387                 /* Convert the uniform offset to bytes.  If it happens to be a
 388                  * constant, constant-folding will clean up the shift for us.
 389                  */
 390                 intr_comp->const_index[0] = (intr->const_index[0] * 16 + i * 4);
 391
 392                 intr_comp->src[0] =
 393                         nir_src_for_ssa(nir_ishl(b, intr->src[0].ssa,
 394                                                  nir_imm_int(b, 4)));
 395
 396                 dests[i] = &intr_comp->dest.ssa;
 397
 398                 nir_builder_instr_insert(b, &intr_comp->instr);
 399         }
 400
 401         replace_intrinsic_with_vec4(b, intr, dests);
 402 }
 403
 404 static void
 405 vc4_nir_lower_io_instr(struct vc4_compile *c, nir_builder *b,
 406                        struct nir_instr *instr)
 407 {
 408         if (instr->type != nir_instr_type_intrinsic)
 409                 return;
 410         nir_intrinsic_instr *intr = nir_instr_as_intrinsic(instr);
 411
 412         switch (intr->intrinsic) {
 413         case nir_intrinsic_load_input:
 414                 if (c->stage == QSTAGE_FRAG)
 415                         vc4_nir_lower_fs_input(c, b, intr);
 416                 else
 417                         vc4_nir_lower_vertex_attr(c, b, intr);
 418                 break;
 419
 420         case nir_intrinsic_store_output:
 421                 vc4_nir_lower_output(c, b, intr);
 422                 break;
 423
 424         case nir_intrinsic_load_uniform:
 425                 vc4_nir_lower_uniform(c, b, intr);
 426                 break;
 427
 428         case nir_intrinsic_load_user_clip_plane:
 429         default:
 430                 break;
 431         }
 432 }
 433
 434 static bool
 435 vc4_nir_lower_io_impl(struct vc4_compile *c, nir_function_impl *impl)
 436 {
 437         nir_builder b;
 438         nir_builder_init(&b, impl);
 439
 440         nir_foreach_block(block, impl) {
 441                 nir_foreach_instr_safe(instr, block)
 442                         vc4_nir_lower_io_instr(c, &b, instr);
 443         }
 444
 445         nir_metadata_preserve(impl, nir_metadata_block_index |
 446                               nir_metadata_dominance);
 447
 448         return true;
 449 }
 450
 451 void
 452 vc4_nir_lower_io(nir_shader *s, struct vc4_compile *c)
 453 {
 454         nir_foreach_function(function, s) {
 455                 if (function->impl)
 456                         vc4_nir_lower_io_impl(c, function->impl);
 457         }
 458 }