src/compiler/nir/nir_gather_info.c

   1 /*
   2  * Copyright © 2015 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
  24 #include "nir.h"
  25 #include "nir_deref.h"
  26 #include "main/menums.h"
  27
  28 static void
  29 get_deref_info(nir_shader *shader, nir_variable *var, nir_deref_instr *deref,
  30                bool *cross_invocation, bool *indirect)
  31 {
  32    *cross_invocation = false;
  33    *indirect = false;
  34
  35    const bool per_vertex = nir_is_per_vertex_io(var, shader->info.stage);
  36
  37    nir_deref_path path;
  38    nir_deref_path_init(&path, deref, NULL);
  39    assert(path.path[0]->deref_type == nir_deref_type_var);
  40    nir_deref_instr **p = &path.path[1];
  41
  42    /* Vertex index is the outermost array index. */
  43    if (per_vertex) {
  44       assert((*p)->deref_type == nir_deref_type_array);
  45       nir_instr *vertex_index_instr = (*p)->arr.index.ssa->parent_instr;
  46       *cross_invocation =
  47          vertex_index_instr->type != nir_instr_type_intrinsic ||
  48          nir_instr_as_intrinsic(vertex_index_instr)->intrinsic !=
  49             nir_intrinsic_load_invocation_id;
  50       p++;
  51    }
  52
  53    /* We always lower indirect dereferences for "compact" array vars. */
  54    if (!path.path[0]->var->data.compact) {
  55       /* Non-compact array vars: find out if they are indirect. */
  56       for (; *p; p++) {
  57          if ((*p)->deref_type == nir_deref_type_array) {
  58             *indirect |= !nir_src_is_const((*p)->arr.index);
  59          } else if ((*p)->deref_type == nir_deref_type_struct) {
  60             /* Struct indices are always constant. */
  61          } else {
  62             unreachable("Unsupported deref type");
  63          }
  64       }
  65    }
  66
  67    nir_deref_path_finish(&path);
  68 }
  69
  70 static void
  71 set_io_mask(nir_shader *shader, nir_variable *var, int offset, int len,
  72             nir_deref_instr *deref, bool is_output_read)
  73 {
  74    for (int i = 0; i < len; i++) {
  75       assert(var->data.location != -1);
  76
  77       int idx = var->data.location + offset + i;
  78       bool is_patch_generic = var->data.patch &&
  79                               idx != VARYING_SLOT_TESS_LEVEL_INNER &&
  80                               idx != VARYING_SLOT_TESS_LEVEL_OUTER &&
  81                               idx != VARYING_SLOT_BOUNDING_BOX0 &&
  82                               idx != VARYING_SLOT_BOUNDING_BOX1;
  83       uint64_t bitfield;
  84
  85       if (is_patch_generic) {
  86          assert(idx >= VARYING_SLOT_PATCH0 && idx < VARYING_SLOT_TESS_MAX);
  87          bitfield = BITFIELD64_BIT(idx - VARYING_SLOT_PATCH0);
  88       }
  89       else {
  90          assert(idx < VARYING_SLOT_MAX);
  91          bitfield = BITFIELD64_BIT(idx);
  92       }
  93
  94       bool cross_invocation;
  95       bool indirect;
  96       get_deref_info(shader, var, deref, &cross_invocation, &indirect);
  97
  98       if (var->data.mode == nir_var_shader_in) {
  99          if (is_patch_generic) {
 100             shader->info.patch_inputs_read |= bitfield;
 101             if (indirect)
 102                shader->info.patch_inputs_read_indirectly |= bitfield;
 103          } else {
 104             shader->info.inputs_read |= bitfield;
 105             if (indirect)
 106                shader->info.inputs_read_indirectly |= bitfield;
 107          }
 108
 109          if (cross_invocation && shader->info.stage == MESA_SHADER_TESS_CTRL)
 110             shader->info.tess.tcs_cross_invocation_inputs_read |= bitfield;
 111
 112          if (shader->info.stage == MESA_SHADER_FRAGMENT) {
 113             shader->info.fs.uses_sample_qualifier |= var->data.sample;
 114          }
 115       } else {
 116          assert(var->data.mode == nir_var_shader_out);
 117          if (is_output_read) {
 118             if (is_patch_generic) {
 119                shader->info.patch_outputs_read |= bitfield;
 120                if (indirect)
 121                   shader->info.patch_outputs_accessed_indirectly |= bitfield;
 122             } else {
 123                shader->info.outputs_read |= bitfield;
 124                if (indirect)
 125                   shader->info.outputs_accessed_indirectly |= bitfield;
 126             }
 127
 128             if (cross_invocation && shader->info.stage == MESA_SHADER_TESS_CTRL)
 129                shader->info.tess.tcs_cross_invocation_outputs_read |= bitfield;
 130          } else {
 131             if (is_patch_generic) {
 132                shader->info.patch_outputs_written |= bitfield;
 133                if (indirect)
 134                   shader->info.patch_outputs_accessed_indirectly |= bitfield;
 135             } else if (!var->data.read_only) {
 136                shader->info.outputs_written |= bitfield;
 137                if (indirect)
 138                   shader->info.outputs_accessed_indirectly |= bitfield;
 139             }
 140          }
 141
 142
 143          if (var->data.fb_fetch_output)
 144             shader->info.outputs_read |= bitfield;
 145       }
 146    }
 147 }
 148
 149 /**
 150  * Mark an entire variable as used.  Caller must ensure that the variable
 151  * represents a shader input or output.
 152  */
 153 static void
 154 mark_whole_variable(nir_shader *shader, nir_variable *var,
 155                     nir_deref_instr *deref, bool is_output_read)
 156 {
 157    const struct glsl_type *type = var->type;
 158
 159    if (nir_is_per_vertex_io(var, shader->info.stage)) {
 160       assert(glsl_type_is_array(type));
 161       type = glsl_get_array_element(type);
 162    }
 163
 164    if (var->data.per_view) {
 165       /* TODO: Per view and Per Vertex are not currently used together.  When
 166        * they start to be used (e.g. when adding Primitive Replication for GS
 167        * on Intel), verify that "peeling" the type twice is correct.  This
 168        * assert ensures we remember it.
 169        */
 170       assert(!nir_is_per_vertex_io(var, shader->info.stage));
 171       assert(glsl_type_is_array(type));
 172       type = glsl_get_array_element(type);
 173    }
 174
 175    const unsigned slots =
 176       var->data.compact ? DIV_ROUND_UP(glsl_get_length(type), 4)
 177                         : glsl_count_attribute_slots(type, false);
 178
 179    set_io_mask(shader, var, 0, slots, deref, is_output_read);
 180 }
 181
 182 static unsigned
 183 get_io_offset(nir_deref_instr *deref, bool is_vertex_input, bool per_vertex)
 184 {
 185    unsigned offset = 0;
 186
 187    for (nir_deref_instr *d = deref; d; d = nir_deref_instr_parent(d)) {
 188       if (d->deref_type == nir_deref_type_array) {
 189          if (per_vertex && nir_deref_instr_parent(d)->deref_type == nir_deref_type_var)
 190             break;
 191
 192          if (!nir_src_is_const(d->arr.index))
 193             return -1;
 194
 195          offset += glsl_count_attribute_slots(d->type, is_vertex_input) *
 196                    nir_src_as_uint(d->arr.index);
 197       }
 198       /* TODO: we can get the offset for structs here see nir_lower_io() */
 199    }
 200
 201    return offset;
 202 }
 203
 204 /**
 205  * Try to mark a portion of the given varying as used.  Caller must ensure
 206  * that the variable represents a shader input or output.
 207  *
 208  * If the index can't be interpreted as a constant, or some other problem
 209  * occurs, then nothing will be marked and false will be returned.
 210  */
 211 static bool
 212 try_mask_partial_io(nir_shader *shader, nir_variable *var,
 213                     nir_deref_instr *deref, bool is_output_read)
 214 {
 215    const struct glsl_type *type = var->type;
 216    bool per_vertex = nir_is_per_vertex_io(var, shader->info.stage);
 217
 218    if (per_vertex) {
 219       assert(glsl_type_is_array(type));
 220       type = glsl_get_array_element(type);
 221    }
 222
 223    /* Per view variables will be considered as a whole. */
 224    if (var->data.per_view)
 225       return false;
 226
 227    /* The code below only handles:
 228     *
 229     * - Indexing into matrices
 230     * - Indexing into arrays of (arrays, matrices, vectors, or scalars)
 231     *
 232     * For now, we just give up if we see varying structs and arrays of structs
 233     * here marking the entire variable as used.
 234     */
 235    if (!(glsl_type_is_matrix(type) ||
 236          (glsl_type_is_array(type) && !var->data.compact &&
 237           (glsl_type_is_numeric(glsl_without_array(type)) ||
 238            glsl_type_is_boolean(glsl_without_array(type)))))) {
 239
 240       /* If we don't know how to handle this case, give up and let the
 241        * caller mark the whole variable as used.
 242        */
 243       return false;
 244    }
 245
 246    unsigned offset = get_io_offset(deref, false, per_vertex);
 247    if (offset == -1)
 248       return false;
 249
 250    unsigned num_elems;
 251    unsigned elem_width = 1;
 252    unsigned mat_cols = 1;
 253    if (glsl_type_is_array(type)) {
 254       num_elems = glsl_get_aoa_size(type);
 255       if (glsl_type_is_matrix(glsl_without_array(type)))
 256          mat_cols = glsl_get_matrix_columns(glsl_without_array(type));
 257    } else {
 258       num_elems = glsl_get_matrix_columns(type);
 259    }
 260
 261    /* double element width for double types that takes two slots */
 262    if (glsl_type_is_dual_slot(glsl_without_array(type)))
 263       elem_width *= 2;
 264
 265    if (offset >= num_elems * elem_width * mat_cols) {
 266       /* Constant index outside the bounds of the matrix/array.  This could
 267        * arise as a result of constant folding of a legal GLSL program.
 268        *
 269        * Even though the spec says that indexing outside the bounds of a
 270        * matrix/array results in undefined behaviour, we don't want to pass
 271        * out-of-range values to set_io_mask() (since this could result in
 272        * slots that don't exist being marked as used), so just let the caller
 273        * mark the whole variable as used.
 274        */
 275       return false;
 276    }
 277
 278    set_io_mask(shader, var, offset, elem_width, deref, is_output_read);
 279    return true;
 280 }
 281
 282 static void
 283 gather_intrinsic_info(nir_intrinsic_instr *instr, nir_shader *shader,
 284                       void *dead_ctx)
 285 {
 286    switch (instr->intrinsic) {
 287    case nir_intrinsic_demote:
 288    case nir_intrinsic_demote_if:
 289       shader->info.fs.uses_demote = true;
 290    /* fallthrough: quads with helper lanes only might be discarded entirely */
 291    case nir_intrinsic_discard:
 292    case nir_intrinsic_discard_if:
 293       /* Freedreno uses the discard_if intrinsic to end GS invocations that
 294        * don't produce a vertex, so we only set uses_discard if executing on
 295        * a fragment shader. */
 296       if (shader->info.stage == MESA_SHADER_FRAGMENT)
 297          shader->info.fs.uses_discard = true;
 298       break;
 299
 300    case nir_intrinsic_interp_deref_at_centroid:
 301    case nir_intrinsic_interp_deref_at_sample:
 302    case nir_intrinsic_interp_deref_at_offset:
 303    case nir_intrinsic_interp_deref_at_vertex:
 304    case nir_intrinsic_load_deref:
 305    case nir_intrinsic_store_deref:{
 306       nir_deref_instr *deref = nir_src_as_deref(instr->src[0]);
 307       if (deref->mode == nir_var_shader_in ||
 308           deref->mode == nir_var_shader_out) {
 309          nir_variable *var = nir_deref_instr_get_variable(deref);
 310          bool is_output_read = false;
 311          if (var->data.mode == nir_var_shader_out &&
 312              instr->intrinsic == nir_intrinsic_load_deref)
 313             is_output_read = true;
 314
 315          if (!try_mask_partial_io(shader, var, deref, is_output_read))
 316             mark_whole_variable(shader, var, deref, is_output_read);
 317
 318          /* We need to track which input_reads bits correspond to a
 319           * dvec3/dvec4 input attribute */
 320          if (shader->info.stage == MESA_SHADER_VERTEX &&
 321              var->data.mode == nir_var_shader_in &&
 322              glsl_type_is_dual_slot(glsl_without_array(var->type))) {
 323             for (unsigned i = 0; i < glsl_count_attribute_slots(var->type, false); i++) {
 324                int idx = var->data.location + i;
 325                shader->info.vs.double_inputs |= BITFIELD64_BIT(idx);
 326             }
 327          }
 328       }
 329       break;
 330    }
 331
 332    case nir_intrinsic_load_draw_id:
 333    case nir_intrinsic_load_frag_coord:
 334    case nir_intrinsic_load_point_coord:
 335    case nir_intrinsic_load_front_face:
 336    case nir_intrinsic_load_vertex_id:
 337    case nir_intrinsic_load_vertex_id_zero_base:
 338    case nir_intrinsic_load_base_vertex:
 339    case nir_intrinsic_load_first_vertex:
 340    case nir_intrinsic_load_is_indexed_draw:
 341    case nir_intrinsic_load_base_instance:
 342    case nir_intrinsic_load_instance_id:
 343    case nir_intrinsic_load_sample_id:
 344    case nir_intrinsic_load_sample_pos:
 345    case nir_intrinsic_load_sample_mask_in:
 346    case nir_intrinsic_load_primitive_id:
 347    case nir_intrinsic_load_invocation_id:
 348    case nir_intrinsic_load_local_invocation_id:
 349    case nir_intrinsic_load_local_invocation_index:
 350    case nir_intrinsic_load_work_group_id:
 351    case nir_intrinsic_load_num_work_groups:
 352    case nir_intrinsic_load_tess_coord:
 353    case nir_intrinsic_load_tess_level_outer:
 354    case nir_intrinsic_load_tess_level_inner:
 355    case nir_intrinsic_load_patch_vertices_in:
 356       shader->info.system_values_read |=
 357          (1ull << nir_system_value_from_intrinsic(instr->intrinsic));
 358       break;
 359
 360    case nir_intrinsic_quad_broadcast:
 361    case nir_intrinsic_quad_swap_horizontal:
 362    case nir_intrinsic_quad_swap_vertical:
 363    case nir_intrinsic_quad_swap_diagonal:
 364       if (shader->info.stage == MESA_SHADER_FRAGMENT)
 365          shader->info.fs.needs_helper_invocations = true;
 366       break;
 367
 368    case nir_intrinsic_end_primitive:
 369    case nir_intrinsic_end_primitive_with_counter:
 370       assert(shader->info.stage == MESA_SHADER_GEOMETRY);
 371       shader->info.gs.uses_end_primitive = 1;
 372       /* fall through */
 373
 374    case nir_intrinsic_emit_vertex:
 375    case nir_intrinsic_emit_vertex_with_counter:
 376       if (nir_intrinsic_stream_id(instr) > 0)
 377          shader->info.gs.uses_streams = true;
 378
 379       break;
 380
 381    case nir_intrinsic_bindless_image_atomic_add:
 382    case nir_intrinsic_bindless_image_atomic_and:
 383    case nir_intrinsic_bindless_image_atomic_comp_swap:
 384    case nir_intrinsic_bindless_image_atomic_dec_wrap:
 385    case nir_intrinsic_bindless_image_atomic_exchange:
 386    case nir_intrinsic_bindless_image_atomic_fadd:
 387    case nir_intrinsic_bindless_image_atomic_imax:
 388    case nir_intrinsic_bindless_image_atomic_imin:
 389    case nir_intrinsic_bindless_image_atomic_inc_wrap:
 390    case nir_intrinsic_bindless_image_atomic_or:
 391    case nir_intrinsic_bindless_image_atomic_umax:
 392    case nir_intrinsic_bindless_image_atomic_umin:
 393    case nir_intrinsic_bindless_image_atomic_xor:
 394    case nir_intrinsic_bindless_image_store:
 395    case nir_intrinsic_bindless_image_store_raw_intel:
 396    case nir_intrinsic_global_atomic_add:
 397    case nir_intrinsic_global_atomic_and:
 398    case nir_intrinsic_global_atomic_comp_swap:
 399    case nir_intrinsic_global_atomic_exchange:
 400    case nir_intrinsic_global_atomic_fadd:
 401    case nir_intrinsic_global_atomic_fcomp_swap:
 402    case nir_intrinsic_global_atomic_fmax:
 403    case nir_intrinsic_global_atomic_fmin:
 404    case nir_intrinsic_global_atomic_imax:
 405    case nir_intrinsic_global_atomic_imin:
 406    case nir_intrinsic_global_atomic_or:
 407    case nir_intrinsic_global_atomic_umax:
 408    case nir_intrinsic_global_atomic_umin:
 409    case nir_intrinsic_global_atomic_xor:
 410    case nir_intrinsic_image_atomic_add:
 411    case nir_intrinsic_image_atomic_and:
 412    case nir_intrinsic_image_atomic_comp_swap:
 413    case nir_intrinsic_image_atomic_dec_wrap:
 414    case nir_intrinsic_image_atomic_exchange:
 415    case nir_intrinsic_image_atomic_fadd:
 416    case nir_intrinsic_image_atomic_imax:
 417    case nir_intrinsic_image_atomic_imin:
 418    case nir_intrinsic_image_atomic_inc_wrap:
 419    case nir_intrinsic_image_atomic_or:
 420    case nir_intrinsic_image_atomic_umax:
 421    case nir_intrinsic_image_atomic_umin:
 422    case nir_intrinsic_image_atomic_xor:
 423    case nir_intrinsic_image_deref_atomic_add:
 424    case nir_intrinsic_image_deref_atomic_and:
 425    case nir_intrinsic_image_deref_atomic_comp_swap:
 426    case nir_intrinsic_image_deref_atomic_dec_wrap:
 427    case nir_intrinsic_image_deref_atomic_exchange:
 428    case nir_intrinsic_image_deref_atomic_fadd:
 429    case nir_intrinsic_image_deref_atomic_imax:
 430    case nir_intrinsic_image_deref_atomic_imin:
 431    case nir_intrinsic_image_deref_atomic_inc_wrap:
 432    case nir_intrinsic_image_deref_atomic_or:
 433    case nir_intrinsic_image_deref_atomic_umax:
 434    case nir_intrinsic_image_deref_atomic_umin:
 435    case nir_intrinsic_image_deref_atomic_xor:
 436    case nir_intrinsic_image_deref_store:
 437    case nir_intrinsic_image_deref_store_raw_intel:
 438    case nir_intrinsic_image_store:
 439    case nir_intrinsic_image_store_raw_intel:
 440    case nir_intrinsic_ssbo_atomic_add:
 441    case nir_intrinsic_ssbo_atomic_add_ir3:
 442    case nir_intrinsic_ssbo_atomic_and:
 443    case nir_intrinsic_ssbo_atomic_and_ir3:
 444    case nir_intrinsic_ssbo_atomic_comp_swap:
 445    case nir_intrinsic_ssbo_atomic_comp_swap_ir3:
 446    case nir_intrinsic_ssbo_atomic_exchange:
 447    case nir_intrinsic_ssbo_atomic_exchange_ir3:
 448    case nir_intrinsic_ssbo_atomic_fadd:
 449    case nir_intrinsic_ssbo_atomic_fcomp_swap:
 450    case nir_intrinsic_ssbo_atomic_fmax:
 451    case nir_intrinsic_ssbo_atomic_fmin:
 452    case nir_intrinsic_ssbo_atomic_imax:
 453    case nir_intrinsic_ssbo_atomic_imax_ir3:
 454    case nir_intrinsic_ssbo_atomic_imin:
 455    case nir_intrinsic_ssbo_atomic_imin_ir3:
 456    case nir_intrinsic_ssbo_atomic_or:
 457    case nir_intrinsic_ssbo_atomic_or_ir3:
 458    case nir_intrinsic_ssbo_atomic_umax:
 459    case nir_intrinsic_ssbo_atomic_umax_ir3:
 460    case nir_intrinsic_ssbo_atomic_umin:
 461    case nir_intrinsic_ssbo_atomic_umin_ir3:
 462    case nir_intrinsic_ssbo_atomic_xor:
 463    case nir_intrinsic_ssbo_atomic_xor_ir3:
 464    case nir_intrinsic_store_global:
 465    case nir_intrinsic_store_global_ir3:
 466    case nir_intrinsic_store_ssbo:
 467    case nir_intrinsic_store_ssbo_ir3:
 468       /* Only set this for globally visible memory, not scratch and not
 469        * shared.
 470        */
 471       shader->info.writes_memory = true;
 472       break;
 473
 474    default:
 475       break;
 476    }
 477 }
 478
 479 static void
 480 gather_tex_info(nir_tex_instr *instr, nir_shader *shader)
 481 {
 482    if (shader->info.stage == MESA_SHADER_FRAGMENT &&
 483        nir_tex_instr_has_implicit_derivative(instr))
 484       shader->info.fs.needs_helper_invocations = true;
 485
 486    switch (instr->op) {
 487    case nir_texop_tg4:
 488       shader->info.uses_texture_gather = true;
 489       break;
 490    default:
 491       break;
 492    }
 493 }
 494
 495 static void
 496 gather_alu_info(nir_alu_instr *instr, nir_shader *shader)
 497 {
 498    switch (instr->op) {
 499    case nir_op_fddx:
 500    case nir_op_fddy:
 501       shader->info.uses_fddx_fddy = true;
 502       /* Fall through */
 503    case nir_op_fddx_fine:
 504    case nir_op_fddy_fine:
 505    case nir_op_fddx_coarse:
 506    case nir_op_fddy_coarse:
 507       if (shader->info.stage == MESA_SHADER_FRAGMENT)
 508          shader->info.fs.needs_helper_invocations = true;
 509       break;
 510    default:
 511       break;
 512    }
 513
 514    shader->info.uses_64bit |= instr->dest.dest.ssa.bit_size == 64;
 515    unsigned num_srcs = nir_op_infos[instr->op].num_inputs;
 516    for (unsigned i = 0; i < num_srcs; i++) {
 517       shader->info.uses_64bit |= nir_src_bit_size(instr->src[i].src) == 64;
 518    }
 519 }
 520
 521 static void
 522 gather_info_block(nir_block *block, nir_shader *shader, void *dead_ctx)
 523 {
 524    nir_foreach_instr(instr, block) {
 525       switch (instr->type) {
 526       case nir_instr_type_alu:
 527          gather_alu_info(nir_instr_as_alu(instr), shader);
 528          break;
 529       case nir_instr_type_intrinsic:
 530          gather_intrinsic_info(nir_instr_as_intrinsic(instr), shader, dead_ctx);
 531          break;
 532       case nir_instr_type_tex:
 533          gather_tex_info(nir_instr_as_tex(instr), shader);
 534          break;
 535       case nir_instr_type_call:
 536          assert(!"nir_shader_gather_info only works if functions are inlined");
 537          break;
 538       default:
 539          break;
 540       }
 541    }
 542 }
 543
 544 void
 545 nir_shader_gather_info(nir_shader *shader, nir_function_impl *entrypoint)
 546 {
 547    shader->info.num_textures = 0;
 548    shader->info.num_images = 0;
 549    shader->info.last_msaa_image = -1;
 550
 551    nir_foreach_variable(var, &shader->uniforms) {
 552       /* Bindless textures and images don't use non-bindless slots. */
 553       if (var->data.bindless)
 554          continue;
 555
 556       shader->info.num_textures += glsl_type_get_sampler_count(var->type);
 557       shader->info.num_images += glsl_type_get_image_count(var->type);
 558
 559       /* Assuming image slots don't have holes (e.g. OpenGL) */
 560       if (glsl_type_is_image(var->type) &&
 561           glsl_get_sampler_dim(var->type) == GLSL_SAMPLER_DIM_MS)
 562          shader->info.last_msaa_image = shader->info.num_images - 1;
 563    }
 564
 565    shader->info.inputs_read = 0;
 566    shader->info.outputs_written = 0;
 567    shader->info.outputs_read = 0;
 568    shader->info.patch_outputs_read = 0;
 569    shader->info.patch_inputs_read = 0;
 570    shader->info.patch_outputs_written = 0;
 571    shader->info.system_values_read = 0;
 572    shader->info.inputs_read_indirectly = 0;
 573    shader->info.outputs_accessed_indirectly = 0;
 574    shader->info.patch_inputs_read_indirectly = 0;
 575    shader->info.patch_outputs_accessed_indirectly = 0;
 576
 577    if (shader->info.stage == MESA_SHADER_VERTEX) {
 578       shader->info.vs.double_inputs = 0;
 579    }
 580    if (shader->info.stage == MESA_SHADER_FRAGMENT) {
 581       shader->info.fs.uses_sample_qualifier = false;
 582       shader->info.fs.uses_discard = false;
 583       shader->info.fs.uses_demote = false;
 584       shader->info.fs.needs_helper_invocations = false;
 585    }
 586    if (shader->info.stage == MESA_SHADER_TESS_CTRL) {
 587       shader->info.tess.tcs_cross_invocation_inputs_read = 0;
 588       shader->info.tess.tcs_cross_invocation_outputs_read = 0;
 589    }
 590
 591    shader->info.writes_memory = shader->info.has_transform_feedback_varyings;
 592
 593    void *dead_ctx = ralloc_context(NULL);
 594    nir_foreach_block(block, entrypoint) {
 595       gather_info_block(block, shader, dead_ctx);
 596    }
 597    ralloc_free(dead_ctx);
 598 }