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, starting from the shader's next SSBO slot
  36  * (info.num_ssbos).
  37  */
  38
  39 static bool
  40 lower_instr(nir_intrinsic_instr *instr, unsigned ssbo_offset, nir_builder *b)
  41 {
  42    nir_intrinsic_op op;
  43
  44    b->cursor = nir_before_instr(&instr->instr);
  45
  46    switch (instr->intrinsic) {
  47    case nir_intrinsic_memory_barrier_atomic_counter:
  48       /* Atomic counters are now SSBOs so memoryBarrierAtomicCounter() is now
  49        * memoryBarrierBuffer().
  50        */
  51       instr->intrinsic = nir_intrinsic_memory_barrier_buffer;
  52       return true;
  53
  54    case nir_intrinsic_atomic_counter_inc:
  55    case nir_intrinsic_atomic_counter_add:
  56    case nir_intrinsic_atomic_counter_pre_dec:
  57    case nir_intrinsic_atomic_counter_post_dec:
  58       /* inc and dec get remapped to add: */
  59       op = nir_intrinsic_ssbo_atomic_add;
  60       break;
  61    case nir_intrinsic_atomic_counter_read:
  62       op = nir_intrinsic_load_ssbo;
  63       break;
  64    case nir_intrinsic_atomic_counter_min:
  65       op = nir_intrinsic_ssbo_atomic_umin;
  66       break;
  67    case nir_intrinsic_atomic_counter_max:
  68       op = nir_intrinsic_ssbo_atomic_umax;
  69       break;
  70    case nir_intrinsic_atomic_counter_and:
  71       op = nir_intrinsic_ssbo_atomic_and;
  72       break;
  73    case nir_intrinsic_atomic_counter_or:
  74       op = nir_intrinsic_ssbo_atomic_or;
  75       break;
  76    case nir_intrinsic_atomic_counter_xor:
  77       op = nir_intrinsic_ssbo_atomic_xor;
  78       break;
  79    case nir_intrinsic_atomic_counter_exchange:
  80       op = nir_intrinsic_ssbo_atomic_exchange;
  81       break;
  82    case nir_intrinsic_atomic_counter_comp_swap:
  83       op = nir_intrinsic_ssbo_atomic_comp_swap;
  84       break;
  85    default:
  86       return false;
  87    }
  88
  89    nir_ssa_def *buffer = nir_imm_int(b, ssbo_offset + nir_intrinsic_base(instr));
  90    nir_ssa_def *temp = NULL;
  91    nir_intrinsic_instr *new_instr =
  92          nir_intrinsic_instr_create(ralloc_parent(instr), op);
  93
  94    /* a couple instructions need special handling since they don't map
  95     * 1:1 with ssbo atomics
  96     */
  97    switch (instr->intrinsic) {
  98    case nir_intrinsic_atomic_counter_inc:
  99       /* remapped to ssbo_atomic_add: { buffer_idx, offset, +1 } */
 100       temp = nir_imm_int(b, +1);
 101       new_instr->src[0] = nir_src_for_ssa(buffer);
 102       nir_src_copy(&new_instr->src[1], &instr->src[0], new_instr);
 103       new_instr->src[2] = nir_src_for_ssa(temp);
 104       break;
 105    case nir_intrinsic_atomic_counter_pre_dec:
 106    case nir_intrinsic_atomic_counter_post_dec:
 107       /* remapped to ssbo_atomic_add: { buffer_idx, offset, -1 } */
 108       /* NOTE semantic difference so we adjust the return value below */
 109       temp = nir_imm_int(b, -1);
 110       new_instr->src[0] = nir_src_for_ssa(buffer);
 111       nir_src_copy(&new_instr->src[1], &instr->src[0], new_instr);
 112       new_instr->src[2] = nir_src_for_ssa(temp);
 113       break;
 114    case nir_intrinsic_atomic_counter_read:
 115       /* remapped to load_ssbo: { buffer_idx, offset } */
 116       new_instr->src[0] = nir_src_for_ssa(buffer);
 117       nir_src_copy(&new_instr->src[1], &instr->src[0], new_instr);
 118       break;
 119    default:
 120       /* remapped to ssbo_atomic_x: { buffer_idx, offset, data, (compare)? } */
 121       new_instr->src[0] = nir_src_for_ssa(buffer);
 122       nir_src_copy(&new_instr->src[1], &instr->src[0], new_instr);
 123       nir_src_copy(&new_instr->src[2], &instr->src[1], new_instr);
 124       if (op == nir_intrinsic_ssbo_atomic_comp_swap ||
 125           op == nir_intrinsic_ssbo_atomic_fcomp_swap)
 126          nir_src_copy(&new_instr->src[3], &instr->src[2], new_instr);
 127       break;
 128    }
 129
 130    if (new_instr->intrinsic == nir_intrinsic_load_ssbo) {
 131       nir_intrinsic_set_align(new_instr, 4, 0);
 132
 133       /* we could be replacing an intrinsic with fixed # of dest
 134        * num_components with one that has variable number.  So
 135        * best to take this from the dest:
 136        */
 137       new_instr->num_components = instr->dest.ssa.num_components;
 138    }
 139
 140    nir_ssa_dest_init(&new_instr->instr, &new_instr->dest,
 141                      instr->dest.ssa.num_components,
 142                      instr->dest.ssa.bit_size, NULL);
 143    nir_instr_insert_before(&instr->instr, &new_instr->instr);
 144    nir_instr_remove(&instr->instr);
 145
 146    if (instr->intrinsic == nir_intrinsic_atomic_counter_pre_dec) {
 147       b->cursor = nir_after_instr(&new_instr->instr);
 148       nir_ssa_def *result = nir_iadd(b, &new_instr->dest.ssa, temp);
 149       nir_ssa_def_rewrite_uses(&instr->dest.ssa, nir_src_for_ssa(result));
 150    } else {
 151       nir_ssa_def_rewrite_uses(&instr->dest.ssa, nir_src_for_ssa(&new_instr->dest.ssa));
 152    }
 153
 154    return true;
 155 }
 156
 157 static bool
 158 is_atomic_uint(const struct glsl_type *type)
 159 {
 160    if (glsl_get_base_type(type) == GLSL_TYPE_ARRAY)
 161       return is_atomic_uint(glsl_get_array_element(type));
 162    return glsl_get_base_type(type) == GLSL_TYPE_ATOMIC_UINT;
 163 }
 164
 165 bool
 166 nir_lower_atomics_to_ssbo(nir_shader *shader)
 167 {
 168    unsigned ssbo_offset = shader->info.num_ssbos;
 169    bool progress = false;
 170
 171    nir_foreach_function(function, shader) {
 172       if (function->impl) {
 173          nir_builder builder;
 174          nir_builder_init(&builder, function->impl);
 175          nir_foreach_block(block, function->impl) {
 176             nir_foreach_instr_safe(instr, block) {
 177                if (instr->type == nir_instr_type_intrinsic)
 178                   progress |= lower_instr(nir_instr_as_intrinsic(instr),
 179                                           ssbo_offset, &builder);
 180             }
 181          }
 182
 183          nir_metadata_preserve(function->impl, nir_metadata_block_index |
 184                                                nir_metadata_dominance);
 185       }
 186    }
 187
 188    if (progress) {
 189       /* replace atomic_uint uniforms with ssbo's: */
 190       unsigned replaced = 0;
 191       nir_foreach_uniform_variable_safe(var, shader) {
 192          if (is_atomic_uint(var->type)) {
 193             exec_node_remove(&var->node);
 194
 195             if (replaced & (1 << var->data.binding))
 196                continue;
 197
 198             nir_variable *ssbo;
 199             char name[16];
 200
 201             /* A length of 0 is used to denote unsized arrays */
 202             const struct glsl_type *type = glsl_array_type(glsl_uint_type(), 0, 0);
 203
 204             snprintf(name, sizeof(name), "counter%d", var->data.binding);
 205
 206             ssbo = nir_variable_create(shader, nir_var_mem_ssbo, type, name);
 207             ssbo->data.binding = ssbo_offset + var->data.binding;
 208
 209             /* We can't use num_abos, because it only represents the number of
 210              * active atomic counters, and currently unlike SSBO's they aren't
 211              * compacted so num_abos actually isn't a bound on the index passed
 212              * to nir_intrinsic_atomic_counter_*. e.g. if we have a single atomic
 213              * counter declared like:
 214              *
 215              * layout(binding=1) atomic_uint counter0;
 216              *
 217              * then when we lower accesses to it the atomic_counter_* intrinsics
 218              * will have 1 as the index but num_abos will still be 1.
 219              */
 220             shader->info.num_ssbos = MAX2(shader->info.num_ssbos,
 221                                           ssbo->data.binding + 1);
 222
 223             struct glsl_struct_field field = {
 224                   .type = type,
 225                   .name = "counters",
 226                   .location = -1,
 227             };
 228
 229             ssbo->interface_type =
 230                   glsl_interface_type(&field, 1, GLSL_INTERFACE_PACKING_STD430,
 231                                       false, "counters");
 232
 233             replaced |= (1 << var->data.binding);
 234          }
 235       }
 236
 237       shader->info.num_abos = 0;
 238    }
 239
 240    return progress;
 241 }
 242