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_store_ssbo:
  61    case nir_intrinsic_load_ssbo:
  62    case nir_intrinsic_get_buffer_size:
  63       /* easy case, keep same opcode and just remap SSBO buffer index: */
  64       op = instr->intrinsic;
  65       idx_src = (op == nir_intrinsic_store_ssbo) ? 1 : 0;
  66       nir_ssa_def *old_idx = nir_ssa_for_src(b, instr->src[idx_src], 1);
  67       nir_ssa_def *new_idx = nir_iadd(b, old_idx, nir_imm_int(b, ssbo_offset));
  68       nir_instr_rewrite_src(&instr->instr,
  69                             &instr->src[idx_src],
  70                             nir_src_for_ssa(new_idx));
  71       return true;
  72    case nir_intrinsic_atomic_counter_inc:
  73    case nir_intrinsic_atomic_counter_add:
  74    case nir_intrinsic_atomic_counter_dec:
  75       /* inc and dec get remapped to add: */
  76       op = nir_intrinsic_ssbo_atomic_add;
  77       break;
  78    case nir_intrinsic_atomic_counter_read:
  79       op = nir_intrinsic_load_ssbo;
  80       break;
  81    case nir_intrinsic_atomic_counter_min:
  82       op = nir_intrinsic_ssbo_atomic_umin;
  83       break;
  84    case nir_intrinsic_atomic_counter_max:
  85       op = nir_intrinsic_ssbo_atomic_umax;
  86       break;
  87    case nir_intrinsic_atomic_counter_and:
  88       op = nir_intrinsic_ssbo_atomic_and;
  89       break;
  90    case nir_intrinsic_atomic_counter_or:
  91       op = nir_intrinsic_ssbo_atomic_or;
  92       break;
  93    case nir_intrinsic_atomic_counter_xor:
  94       op = nir_intrinsic_ssbo_atomic_xor;
  95       break;
  96    case nir_intrinsic_atomic_counter_exchange:
  97       op = nir_intrinsic_ssbo_atomic_exchange;
  98       break;
  99    case nir_intrinsic_atomic_counter_comp_swap:
 100       op = nir_intrinsic_ssbo_atomic_comp_swap;
 101       break;
 102    default:
 103       return false;
 104    }
 105
 106    nir_ssa_def *buffer = nir_imm_int(b, nir_intrinsic_base(instr));
 107    nir_ssa_def *temp = NULL;
 108    nir_intrinsic_instr *new_instr =
 109          nir_intrinsic_instr_create(ralloc_parent(instr), op);
 110
 111    /* a couple instructions need special handling since they don't map
 112     * 1:1 with ssbo atomics
 113     */
 114    switch (instr->intrinsic) {
 115    case nir_intrinsic_atomic_counter_inc:
 116       /* remapped to ssbo_atomic_add: { buffer_idx, offset, +1 } */
 117       temp = nir_imm_int(b, +1);
 118       new_instr->src[0] = nir_src_for_ssa(buffer);
 119       nir_src_copy(&new_instr->src[1], &instr->src[0], new_instr);
 120       new_instr->src[2] = nir_src_for_ssa(temp);
 121       break;
 122    case nir_intrinsic_atomic_counter_dec:
 123       /* remapped to ssbo_atomic_add: { buffer_idx, offset, -1 } */
 124       /* NOTE semantic difference so we adjust the return value below */
 125       temp = nir_imm_int(b, -1);
 126       new_instr->src[0] = nir_src_for_ssa(buffer);
 127       nir_src_copy(&new_instr->src[1], &instr->src[0], new_instr);
 128       new_instr->src[2] = nir_src_for_ssa(temp);
 129       break;
 130    case nir_intrinsic_atomic_counter_read:
 131       /* remapped to load_ssbo: { buffer_idx, offset } */
 132       new_instr->src[0] = nir_src_for_ssa(buffer);
 133       nir_src_copy(&new_instr->src[1], &instr->src[0], new_instr);
 134       break;
 135    default:
 136       /* remapped to ssbo_atomic_x: { buffer_idx, offset, data, (compare)? } */
 137       new_instr->src[0] = nir_src_for_ssa(buffer);
 138       nir_src_copy(&new_instr->src[1], &instr->src[0], new_instr);
 139       nir_src_copy(&new_instr->src[2], &instr->src[1], new_instr);
 140       if (op == nir_intrinsic_ssbo_atomic_comp_swap)
 141          nir_src_copy(&new_instr->src[3], &instr->src[2], new_instr);
 142       break;
 143    }
 144
 145    nir_ssa_dest_init(&new_instr->instr, &new_instr->dest,
 146                      instr->dest.ssa.num_components,
 147                      instr->dest.ssa.bit_size, NULL);
 148    nir_instr_insert_before(&instr->instr, &new_instr->instr);
 149    nir_instr_remove(&instr->instr);
 150
 151    if (instr->intrinsic == nir_intrinsic_atomic_counter_dec) {
 152       b->cursor = nir_after_instr(&new_instr->instr);
 153       nir_ssa_def *result = nir_iadd(b, &new_instr->dest.ssa, temp);
 154       nir_ssa_def_rewrite_uses(&instr->dest.ssa, nir_src_for_ssa(result));
 155    } else {
 156       nir_ssa_def_rewrite_uses(&instr->dest.ssa, nir_src_for_ssa(&new_instr->dest.ssa));
 157    }
 158
 159    /* we could be replacing an intrinsic with fixed # of dest num_components
 160     * with one that has variable number.  So best to take this from the dest:
 161     */
 162    new_instr->num_components = instr->dest.ssa.num_components;
 163
 164    return true;
 165 }
 166
 167 static bool
 168 is_atomic_uint(const struct glsl_type *type)
 169 {
 170    if (glsl_get_base_type(type) == GLSL_TYPE_ARRAY)
 171       return is_atomic_uint(glsl_get_array_element(type));
 172    return glsl_get_base_type(type) == GLSL_TYPE_ATOMIC_UINT;
 173 }
 174
 175 bool
 176 nir_lower_atomics_to_ssbo(nir_shader *shader, unsigned ssbo_offset)
 177 {
 178    bool progress = false;
 179
 180    nir_foreach_function(function, shader) {
 181       if (function->impl) {
 182          nir_builder builder;
 183          nir_builder_init(&builder, function->impl);
 184          nir_foreach_block(block, function->impl) {
 185             nir_foreach_instr_safe(instr, block) {
 186                if (instr->type == nir_instr_type_intrinsic)
 187                   progress |= lower_instr(nir_instr_as_intrinsic(instr),
 188                                           ssbo_offset, &builder);
 189             }
 190          }
 191
 192          nir_metadata_preserve(function->impl, nir_metadata_block_index |
 193                                                nir_metadata_dominance);
 194       }
 195    }
 196
 197    if (progress) {
 198       /* replace atomic_uint uniforms with ssbo's: */
 199       unsigned replaced = 0;
 200       nir_foreach_variable_safe(var, &shader->uniforms) {
 201          if (is_atomic_uint(var->type)) {
 202             exec_node_remove(&var->node);
 203
 204             if (replaced & (1 << var->data.binding))
 205                continue;
 206
 207             nir_variable *ssbo;
 208             char name[16];
 209
 210             /* A length of 0 is used to denote unsized arrays */
 211             const struct glsl_type *type = glsl_array_type(glsl_uint_type(), 0);
 212
 213             snprintf(name, sizeof(name), "counter%d", var->data.binding);
 214
 215             ssbo = nir_variable_create(shader, nir_var_shader_storage,
 216                                        type, name);
 217             ssbo->data.binding = var->data.binding;
 218
 219             struct glsl_struct_field field = {
 220                   .type = type,
 221                   .name = "counters",
 222                   .location = -1,
 223             };
 224
 225             ssbo->interface_type =
 226                   glsl_interface_type(&field, 1, GLSL_INTERFACE_PACKING_STD430,
 227                                       false, "counters");
 228
 229             replaced |= (1 << var->data.binding);
 230          }
 231       }
 232    }
 233
 234    return progress;
 235 }
 236