src/compiler/nir/nir_lower_atomics_to_ssbo.c

   1 /*
   2  * Copyright © 2017 Red Hat
   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  *    Rob Clark <robclark@freedesktop.org>
  25  */
  26
  27 #include "nir.h"
  28 #include "nir_builder.h"
  29
  30 #if defined(_WIN32) && !defined(snprintf)
  31 #define snprintf _snprintf
  32 #endif
  33
  34 /*
  35  * Remap atomic counters to SSBOs.  Atomic counters get remapped to
  36  * SSBO binding points [0..ssbo_offset) and the original SSBOs are
  37  * remapped to [ssbo_offset..n) (mostly to align with what mesa/st
  38  * does.
  39  */
  40
  41 static bool
  42 lower_instr(nir_intrinsic_instr *instr, unsigned ssbo_offset, nir_builder *b)
  43 {
  44    nir_intrinsic_op op;
  45    int idx_src;
  46
  47    b->cursor = nir_before_instr(&instr->instr);
  48
  49    switch (instr->intrinsic) {
  50    case nir_intrinsic_ssbo_atomic_add:
  51    case nir_intrinsic_ssbo_atomic_imin:
  52    case nir_intrinsic_ssbo_atomic_umin:
  53    case nir_intrinsic_ssbo_atomic_imax:
  54    case nir_intrinsic_ssbo_atomic_umax:
  55    case nir_intrinsic_ssbo_atomic_and:
  56    case nir_intrinsic_ssbo_atomic_or:
  57    case nir_intrinsic_ssbo_atomic_xor:
  58    case nir_intrinsic_ssbo_atomic_exchange:
  59    case nir_intrinsic_ssbo_atomic_comp_swap:
  60    case nir_intrinsic_ssbo_atomic_fadd:
  61    case nir_intrinsic_ssbo_atomic_fmin:
  62    case nir_intrinsic_ssbo_atomic_fmax:
  63    case nir_intrinsic_ssbo_atomic_fcomp_swap:
  64    case nir_intrinsic_store_ssbo:
  65    case nir_intrinsic_load_ssbo:
  66    case nir_intrinsic_get_buffer_size:
  67       /* easy case, keep same opcode and just remap SSBO buffer index: */
  68       op = instr->intrinsic;
  69       idx_src = (op == nir_intrinsic_store_ssbo) ? 1 : 0;
  70       nir_ssa_def *old_idx = nir_ssa_for_src(b, instr->src[idx_src], 1);
  71       nir_ssa_def *new_idx = nir_iadd(b, old_idx, nir_imm_int(b, ssbo_offset));
  72       nir_instr_rewrite_src(&instr->instr,
  73                             &instr->src[idx_src],
  74                             nir_src_for_ssa(new_idx));
  75       return true;
  76    case nir_intrinsic_atomic_counter_inc:
  77    case nir_intrinsic_atomic_counter_add:
  78    case nir_intrinsic_atomic_counter_pre_dec:
  79    case nir_intrinsic_atomic_counter_post_dec:
  80       /* inc and dec get remapped to add: */
  81       op = nir_intrinsic_ssbo_atomic_add;
  82       break;
  83    case nir_intrinsic_atomic_counter_read:
  84       op = nir_intrinsic_load_ssbo;
  85       break;
  86    case nir_intrinsic_atomic_counter_min:
  87       op = nir_intrinsic_ssbo_atomic_umin;
  88       break;
  89    case nir_intrinsic_atomic_counter_max:
  90       op = nir_intrinsic_ssbo_atomic_umax;
  91       break;
  92    case nir_intrinsic_atomic_counter_and:
  93       op = nir_intrinsic_ssbo_atomic_and;
  94       break;
  95    case nir_intrinsic_atomic_counter_or:
  96       op = nir_intrinsic_ssbo_atomic_or;
  97       break;
  98    case nir_intrinsic_atomic_counter_xor:
  99       op = nir_intrinsic_ssbo_atomic_xor;
 100       break;
 101    case nir_intrinsic_atomic_counter_exchange:
 102       op = nir_intrinsic_ssbo_atomic_exchange;
 103       break;
 104    case nir_intrinsic_atomic_counter_comp_swap:
 105       op = nir_intrinsic_ssbo_atomic_comp_swap;
 106       break;
 107    default:
 108       return false;
 109    }
 110
 111    nir_ssa_def *buffer = nir_imm_int(b, nir_intrinsic_base(instr));
 112    nir_ssa_def *temp = NULL;
 113    nir_intrinsic_instr *new_instr =
 114          nir_intrinsic_instr_create(ralloc_parent(instr), op);
 115
 116    /* a couple instructions need special handling since they don't map
 117     * 1:1 with ssbo atomics
 118     */
 119    switch (instr->intrinsic) {
 120    case nir_intrinsic_atomic_counter_inc:
 121       /* remapped to ssbo_atomic_add: { buffer_idx, offset, +1 } */
 122       temp = nir_imm_int(b, +1);
 123       new_instr->src[0] = nir_src_for_ssa(buffer);
 124       nir_src_copy(&new_instr->src[1], &instr->src[0], new_instr);
 125       new_instr->src[2] = nir_src_for_ssa(temp);
 126       break;
 127    case nir_intrinsic_atomic_counter_pre_dec:
 128    case nir_intrinsic_atomic_counter_post_dec:
 129       /* remapped to ssbo_atomic_add: { buffer_idx, offset, -1 } */
 130       /* NOTE semantic difference so we adjust the return value below */
 131       temp = nir_imm_int(b, -1);
 132       new_instr->src[0] = nir_src_for_ssa(buffer);
 133       nir_src_copy(&new_instr->src[1], &instr->src[0], new_instr);
 134       new_instr->src[2] = nir_src_for_ssa(temp);
 135       break;
 136    case nir_intrinsic_atomic_counter_read:
 137       /* remapped to load_ssbo: { buffer_idx, offset } */
 138       new_instr->src[0] = nir_src_for_ssa(buffer);
 139       nir_src_copy(&new_instr->src[1], &instr->src[0], new_instr);
 140       break;
 141    default:
 142       /* remapped to ssbo_atomic_x: { buffer_idx, offset, data, (compare)? } */
 143       new_instr->src[0] = nir_src_for_ssa(buffer);
 144       nir_src_copy(&new_instr->src[1], &instr->src[0], new_instr);
 145       nir_src_copy(&new_instr->src[2], &instr->src[1], new_instr);
 146       if (op == nir_intrinsic_ssbo_atomic_comp_swap ||
 147           op == nir_intrinsic_ssbo_atomic_fcomp_swap)
 148          nir_src_copy(&new_instr->src[3], &instr->src[2], new_instr);
 149       break;
 150    }
 151
 152    if (new_instr->intrinsic == nir_intrinsic_load_ssbo ||
 153        new_instr->intrinsic == nir_intrinsic_store_ssbo)
 154       nir_intrinsic_set_align(new_instr, 4, 0);
 155
 156    nir_ssa_dest_init(&new_instr->instr, &new_instr->dest,
 157                      instr->dest.ssa.num_components,
 158                      instr->dest.ssa.bit_size, NULL);
 159    nir_instr_insert_before(&instr->instr, &new_instr->instr);
 160    nir_instr_remove(&instr->instr);
 161
 162    if (instr->intrinsic == nir_intrinsic_atomic_counter_pre_dec) {
 163       b->cursor = nir_after_instr(&new_instr->instr);
 164       nir_ssa_def *result = nir_iadd(b, &new_instr->dest.ssa, temp);
 165       nir_ssa_def_rewrite_uses(&instr->dest.ssa, nir_src_for_ssa(result));
 166    } else {
 167       nir_ssa_def_rewrite_uses(&instr->dest.ssa, nir_src_for_ssa(&new_instr->dest.ssa));
 168    }
 169
 170    /* we could be replacing an intrinsic with fixed # of dest num_components
 171     * with one that has variable number.  So best to take this from the dest:
 172     */
 173    new_instr->num_components = instr->dest.ssa.num_components;
 174
 175    return true;
 176 }
 177
 178 static bool
 179 is_atomic_uint(const struct glsl_type *type)
 180 {
 181    if (glsl_get_base_type(type) == GLSL_TYPE_ARRAY)
 182       return is_atomic_uint(glsl_get_array_element(type));
 183    return glsl_get_base_type(type) == GLSL_TYPE_ATOMIC_UINT;
 184 }
 185
 186 bool
 187 nir_lower_atomics_to_ssbo(nir_shader *shader, unsigned ssbo_offset)
 188 {
 189    bool progress = false;
 190
 191    nir_foreach_function(function, shader) {
 192       if (function->impl) {
 193          nir_builder builder;
 194          nir_builder_init(&builder, function->impl);
 195          nir_foreach_block(block, function->impl) {
 196             nir_foreach_instr_safe(instr, block) {
 197                if (instr->type == nir_instr_type_intrinsic)
 198                   progress |= lower_instr(nir_instr_as_intrinsic(instr),
 199                                           ssbo_offset, &builder);
 200             }
 201          }
 202
 203          nir_metadata_preserve(function->impl, nir_metadata_block_index |
 204                                                nir_metadata_dominance);
 205       }
 206    }
 207
 208    if (progress) {
 209       /* replace atomic_uint uniforms with ssbo's: */
 210       unsigned replaced = 0;
 211       nir_foreach_variable_safe(var, &shader->uniforms) {
 212          if (is_atomic_uint(var->type)) {
 213             exec_node_remove(&var->node);
 214
 215             if (replaced & (1 << var->data.binding))
 216                continue;
 217
 218             nir_variable *ssbo;
 219             char name[16];
 220
 221             /* A length of 0 is used to denote unsized arrays */
 222             const struct glsl_type *type = glsl_array_type(glsl_uint_type(), 0, 0);
 223
 224             snprintf(name, sizeof(name), "counter%d", var->data.binding);
 225
 226             ssbo = nir_variable_create(shader, nir_var_mem_ssbo, type, name);
 227             ssbo->data.binding = var->data.binding;
 228
 229             struct glsl_struct_field field = {
 230                   .type = type,
 231                   .name = "counters",
 232                   .location = -1,
 233             };
 234
 235             ssbo->interface_type =
 236                   glsl_interface_type(&field, 1, GLSL_INTERFACE_PACKING_STD430,
 237                                       false, "counters");
 238
 239             replaced |= (1 << var->data.binding);
 240          }
 241       }
 242
 243       /* Make sure that shader->info.num_ssbos still reflects the maximum SSBO
 244        * index that can be used in the shader.
 245        */
 246       if (shader->info.num_ssbos > 0) {
 247          shader->info.num_ssbos += ssbo_offset;
 248       } else {
 249          /* We can't use num_abos, because it only represents the number of
 250           * active atomic counters, and currently unlike SSBO's they aren't
 251           * compacted so num_abos actually isn't a bound on the index passed
 252           * to nir_intrinsic_atomic_counter_*. e.g. if we have a single atomic
 253           * counter declared like:
 254           *
 255           * layout(binding=1) atomic_uint counter0;
 256           *
 257           * then when we lower accesses to it the atomic_counter_* intrinsics
 258           * will have 1 as the index but num_abos will still be 1.
 259           * */
 260          shader->info.num_ssbos = util_last_bit(replaced);
 261       }
 262       shader->info.num_abos = 0;
 263    }
 264
 265    return progress;
 266 }
 267