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       /* easy case, keep same opcode and just remap SSBO buffer index: */
  63       op = instr->intrinsic;
  64       idx_src = (op == nir_intrinsic_store_ssbo) ? 1 : 0;
  65       nir_ssa_def *old_idx = nir_ssa_for_src(b, instr->src[idx_src], 1);
  66       nir_ssa_def *new_idx = nir_iadd(b, old_idx, nir_imm_int(b, ssbo_offset));
  67       nir_instr_rewrite_src(&instr->instr,
  68                             &instr->src[idx_src],
  69                             nir_src_for_ssa(new_idx));
  70       return true;
  71    case nir_intrinsic_atomic_counter_inc:
  72    case nir_intrinsic_atomic_counter_add:
  73    case nir_intrinsic_atomic_counter_dec:
  74       /* inc and dec get remapped to add: */
  75       op = nir_intrinsic_ssbo_atomic_add;
  76       break;
  77    case nir_intrinsic_atomic_counter_read:
  78       op = nir_intrinsic_load_ssbo;
  79       break;
  80    case nir_intrinsic_atomic_counter_min:
  81       op = nir_intrinsic_ssbo_atomic_umin;
  82       break;
  83    case nir_intrinsic_atomic_counter_max:
  84       op = nir_intrinsic_ssbo_atomic_umax;
  85       break;
  86    case nir_intrinsic_atomic_counter_and:
  87       op = nir_intrinsic_ssbo_atomic_and;
  88       break;
  89    case nir_intrinsic_atomic_counter_or:
  90       op = nir_intrinsic_ssbo_atomic_or;
  91       break;
  92    case nir_intrinsic_atomic_counter_xor:
  93       op = nir_intrinsic_ssbo_atomic_xor;
  94       break;
  95    case nir_intrinsic_atomic_counter_exchange:
  96       op = nir_intrinsic_ssbo_atomic_exchange;
  97       break;
  98    case nir_intrinsic_atomic_counter_comp_swap:
  99       op = nir_intrinsic_ssbo_atomic_comp_swap;
 100       break;
 101    default:
 102       return false;
 103    }
 104
 105    nir_ssa_def *buffer = nir_imm_int(b, nir_intrinsic_base(instr));
 106    nir_ssa_def *temp = NULL;
 107    nir_intrinsic_instr *new_instr =
 108          nir_intrinsic_instr_create(ralloc_parent(instr), op);
 109
 110    /* a couple instructions need special handling since they don't map
 111     * 1:1 with ssbo atomics
 112     */
 113    switch (instr->intrinsic) {
 114    case nir_intrinsic_atomic_counter_inc:
 115       /* remapped to ssbo_atomic_add: { buffer_idx, offset, +1 } */
 116       temp = nir_imm_int(b, +1);
 117       new_instr->src[0] = nir_src_for_ssa(buffer);
 118       new_instr->src[1] = instr->src[0];
 119       new_instr->src[2] = nir_src_for_ssa(temp);
 120       break;
 121    case nir_intrinsic_atomic_counter_dec:
 122       /* remapped to ssbo_atomic_add: { buffer_idx, offset, -1 } */
 123       /* NOTE semantic difference so we adjust the return value below */
 124       temp = nir_imm_int(b, -1);
 125       new_instr->src[0] = nir_src_for_ssa(buffer);
 126       new_instr->src[1] = instr->src[0];
 127       new_instr->src[2] = nir_src_for_ssa(temp);
 128       break;
 129    case nir_intrinsic_atomic_counter_read:
 130       /* remapped to load_ssbo: { buffer_idx, offset } */
 131       new_instr->src[0] = nir_src_for_ssa(buffer);
 132       new_instr->src[1] = instr->src[0];
 133       break;
 134    default:
 135       /* remapped to ssbo_atomic_x: { buffer_idx, offset, data, (compare)? } */
 136       new_instr->src[0] = nir_src_for_ssa(buffer);
 137       new_instr->src[1] = instr->src[0];
 138       new_instr->src[2] = instr->src[1];
 139       if (op == nir_intrinsic_ssbo_atomic_comp_swap)
 140          new_instr->src[3] = instr->src[2];
 141       break;
 142    }
 143
 144    nir_ssa_dest_init(&new_instr->instr, &new_instr->dest,
 145                      instr->dest.ssa.num_components,
 146                      instr->dest.ssa.bit_size, NULL);
 147    nir_instr_insert_before(&instr->instr, &new_instr->instr);
 148    nir_instr_remove(&instr->instr);
 149
 150    if (instr->intrinsic == nir_intrinsic_atomic_counter_dec) {
 151       b->cursor = nir_after_instr(&new_instr->instr);
 152       nir_ssa_def *result = nir_iadd(b, &new_instr->dest.ssa, temp);
 153       nir_ssa_def_rewrite_uses(&instr->dest.ssa, nir_src_for_ssa(result));
 154    } else {
 155       nir_ssa_def_rewrite_uses(&instr->dest.ssa, nir_src_for_ssa(&new_instr->dest.ssa));
 156    }
 157
 158    /* we could be replacing an intrinsic with fixed # of dest num_components
 159     * with one that has variable number.  So best to take this from the dest:
 160     */
 161    new_instr->num_components = instr->dest.ssa.num_components;
 162
 163    return true;
 164 }
 165
 166 bool
 167 nir_lower_atomics_to_ssbo(nir_shader *shader, unsigned ssbo_offset)
 168 {
 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_variable_safe(var, &shader->uniforms) {
 192          if (glsl_get_base_type(var->type) == GLSL_TYPE_ATOMIC_UINT) {
 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);
 203
 204             snprintf(name, sizeof(name), "counter%d", var->data.binding);
 205
 206             ssbo = nir_variable_create(shader, nir_var_shader_storage,
 207                                        type, name);
 208             ssbo->data.binding = var->data.binding;
 209
 210             struct glsl_struct_field field = {
 211                   .type = type,
 212                   .name = "counters",
 213                   .location = -1,
 214             };
 215
 216             ssbo->interface_type =
 217                   glsl_interface_type(&field, 1, GLSL_INTERFACE_PACKING_STD430,
 218                                       false, "counters");
 219
 220             replaced |= (1 << var->data.binding);
 221          }
 222       }
 223    }
 224
 225    return progress;
 226 }
 227