src/compiler/glsl/gl_nir_lower_buffers.c

   1 /*
   2  * Copyright © 2019 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
  21  * DEALINGS IN THE SOFTWARE.
  22  */
  23
  24 #include "compiler/nir/nir.h"
  25 #include "compiler/nir/nir_builder.h"
  26 #include "gl_nir.h"
  27 #include "ir_uniform.h"
  28
  29 #include "main/compiler.h"
  30 #include "main/mtypes.h"
  31
  32 static nir_ssa_def *
  33 get_block_array_index(nir_builder *b, nir_deref_instr *deref,
  34                       const struct gl_shader_program *shader_program)
  35 {
  36    unsigned array_elements = 1;
  37
  38    /* Build a block name such as "block[2][0]" for finding in the list of
  39     * blocks later on as well as an optional dynamic index which gets added
  40     * to the block index later.
  41     */
  42    const char *block_name = "";
  43    nir_ssa_def *nonconst_index = NULL;
  44    while (deref->deref_type == nir_deref_type_array) {
  45       nir_deref_instr *parent = nir_deref_instr_parent(deref);
  46       assert(parent && glsl_type_is_array(parent->type));
  47       unsigned arr_size = glsl_get_length(parent->type);
  48
  49       if (nir_src_is_const(deref->arr.index)) {
  50          unsigned arr_index = nir_src_as_uint(deref->arr.index);
  51          arr_index = MIN2(arr_index, arr_size - 1);
  52
  53          /* We're walking the deref from the tail so prepend the array index */
  54          block_name = ralloc_asprintf(b->shader, "[%u]%s", arr_index,
  55                                       block_name);
  56       } else {
  57          nir_ssa_def *arr_index = nir_ssa_for_src(b, deref->arr.index, 1);
  58          arr_index = nir_umin(b, arr_index, nir_imm_int(b, arr_size - 1));
  59          nir_ssa_def *arr_offset = nir_imul_imm(b, arr_index, array_elements);
  60          if (nonconst_index)
  61             nonconst_index = nir_iadd(b, nonconst_index, arr_offset);
  62          else
  63             nonconst_index = arr_offset;
  64
  65          /* We're walking the deref from the tail so prepend the array index */
  66          block_name = ralloc_asprintf(b->shader, "[0]%s", block_name);
  67       }
  68
  69       array_elements *= arr_size;
  70       deref = parent;
  71    }
  72
  73    assert(deref->deref_type == nir_deref_type_var);
  74    block_name = ralloc_asprintf(b->shader, "%s%s",
  75                                 glsl_get_type_name(deref->var->interface_type),
  76                                 block_name);
  77
  78    struct gl_linked_shader *linked_shader =
  79       shader_program->_LinkedShaders[b->shader->info.stage];
  80
  81    unsigned num_blocks;
  82    struct gl_uniform_block **blocks;
  83    if (deref->mode == nir_var_mem_ubo) {
  84       num_blocks = linked_shader->Program->info.num_ubos;
  85       blocks = linked_shader->Program->sh.UniformBlocks;
  86    } else {
  87       assert(deref->mode == nir_var_mem_ssbo);
  88       num_blocks = linked_shader->Program->info.num_ssbos;
  89       blocks = linked_shader->Program->sh.ShaderStorageBlocks;
  90    }
  91
  92    for (unsigned i = 0; i < num_blocks; i++) {
  93       if (strcmp(block_name, blocks[i]->Name) == 0) {
  94          if (nonconst_index)
  95             return nir_iadd_imm(b, nonconst_index, i);
  96          else
  97             return nir_imm_int(b, i);
  98       }
  99    }
 100
 101    unreachable("Failed to find the block by name");
 102 }
 103
 104 static void
 105 get_block_index_offset(nir_variable *var,
 106                        const struct gl_shader_program *shader_program,
 107                        gl_shader_stage stage,
 108                        unsigned *index, unsigned *offset)
 109 {
 110
 111    struct gl_linked_shader *linked_shader =
 112       shader_program->_LinkedShaders[stage];
 113
 114    unsigned num_blocks;
 115    struct gl_uniform_block **blocks;
 116    if (var->data.mode == nir_var_mem_ubo) {
 117       num_blocks = linked_shader->Program->info.num_ubos;
 118       blocks = linked_shader->Program->sh.UniformBlocks;
 119    } else {
 120       assert(var->data.mode == nir_var_mem_ssbo);
 121       num_blocks = linked_shader->Program->info.num_ssbos;
 122       blocks = linked_shader->Program->sh.ShaderStorageBlocks;
 123    }
 124
 125    const char *block_name = glsl_get_type_name(var->interface_type);
 126    for (unsigned i = 0; i < num_blocks; i++) {
 127       if (strcmp(block_name, blocks[i]->Name) == 0) {
 128          *index = i;
 129          *offset = blocks[i]->Uniforms[var->data.location].Offset;
 130          return;
 131       }
 132    }
 133
 134    unreachable("Failed to find the block by name");
 135 }
 136
 137 static bool
 138 lower_buffer_interface_derefs_impl(nir_function_impl *impl,
 139                                    const struct gl_shader_program *shader_program)
 140 {
 141    bool progress = false;
 142
 143    nir_builder b;
 144    nir_builder_init(&b, impl);
 145
 146    nir_foreach_block(block, impl) {
 147       nir_foreach_instr_safe(instr, block) {
 148          switch (instr->type) {
 149          case nir_instr_type_deref: {
 150             nir_deref_instr *deref = nir_instr_as_deref(instr);
 151             if (!(deref->mode & (nir_var_mem_ubo | nir_var_mem_ssbo)))
 152                break;
 153
 154             /* We use nir_address_format_32bit_index_offset */
 155             assert(deref->dest.is_ssa);
 156             assert(deref->dest.ssa.bit_size == 32);
 157             deref->dest.ssa.num_components = 2;
 158
 159             progress = true;
 160
 161             b.cursor = nir_before_instr(&deref->instr);
 162
 163             nir_ssa_def *ptr;
 164             if (deref->deref_type == nir_deref_type_var &&
 165                 !glsl_type_is_interface(glsl_without_array(deref->var->type))) {
 166                /* This variable is contained in an interface block rather than
 167                 * containing one.  We need the block index and its offset
 168                 * inside that block
 169                 */
 170                unsigned index, offset;
 171                get_block_index_offset(deref->var, shader_program,
 172                                       b.shader->info.stage,
 173                                       &index, &offset);
 174                ptr = nir_imm_ivec2(&b, index, offset);
 175             } else if (glsl_type_is_interface(deref->type)) {
 176                /* This is the last deref before the block boundary.
 177                 * Everything after this point is a byte offset and will be
 178                 * handled by nir_lower_explicit_io().
 179                 */
 180                nir_ssa_def *index = get_block_array_index(&b, deref,
 181                                                           shader_program);
 182                ptr = nir_vec2(&b, index, nir_imm_int(&b, 0));
 183             } else {
 184                /* This will get handled by nir_lower_explicit_io(). */
 185                break;
 186             }
 187
 188             nir_deref_instr *cast = nir_build_deref_cast(&b, ptr, deref->mode,
 189                                                          deref->type, 0);
 190             nir_ssa_def_rewrite_uses(&deref->dest.ssa,
 191                                      nir_src_for_ssa(&cast->dest.ssa));
 192             nir_deref_instr_remove_if_unused(deref);
 193             break;
 194          }
 195
 196          case nir_instr_type_intrinsic: {
 197             nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);
 198             switch (intrin->intrinsic) {
 199             case nir_intrinsic_load_deref: {
 200                nir_deref_instr *deref = nir_src_as_deref(intrin->src[0]);
 201                if (!(deref->mode & (nir_var_mem_ubo | nir_var_mem_ssbo)))
 202                   break;
 203
 204                /* UBO and SSBO Booleans are 32-bit integers where any non-zero
 205                 * value is considered true.  NIR Booleans, on the other hand
 206                 * are 1-bit values until you get to a very late stage of the
 207                 * compilation process.  We need to turn those 1-bit loads into
 208                 * a 32-bit load wrapped in an i2b to get a proper NIR boolean
 209                 * from the SSBO.
 210                 */
 211                if (glsl_type_is_boolean(deref->type)) {
 212                   assert(intrin->dest.is_ssa);
 213                   b.cursor = nir_after_instr(&intrin->instr);
 214                   intrin->dest.ssa.bit_size = 32;
 215                   nir_ssa_def *bval = nir_i2b(&b, &intrin->dest.ssa);
 216                   nir_ssa_def_rewrite_uses_after(&intrin->dest.ssa,
 217                                                  nir_src_for_ssa(bval),
 218                                                  bval->parent_instr);
 219                   progress = true;
 220                }
 221                break;
 222             }
 223
 224             case nir_intrinsic_store_deref: {
 225                nir_deref_instr *deref = nir_src_as_deref(intrin->src[0]);
 226                if (!(deref->mode & (nir_var_mem_ubo | nir_var_mem_ssbo)))
 227                   break;
 228
 229                /* SSBO Booleans are 32-bit integers where any non-zero value
 230                 * is considered true.  NIR Booleans, on the other hand are
 231                 * 1-bit values until you get to a very late stage of the
 232                 * compilation process.  We need to turn those 1-bit stores
 233                 * into a b2i32 followed by a 32-bit store.  Technically the
 234                 * value we write doesn't have to be 0/1 so once Booleans are
 235                 * lowered to 32-bit values, we have an unneeded sanitation
 236                 * step but in practice it doesn't cost much.
 237                 */
 238                if (glsl_type_is_boolean(deref->type)) {
 239                   assert(intrin->src[1].is_ssa);
 240                   b.cursor = nir_before_instr(&intrin->instr);
 241                   nir_ssa_def *ival = nir_b2i32(&b, intrin->src[1].ssa);
 242                   nir_instr_rewrite_src(&intrin->instr, &intrin->src[1],
 243                                         nir_src_for_ssa(ival));
 244                   progress = true;
 245                }
 246                break;
 247             }
 248
 249             case nir_intrinsic_copy_deref:
 250                unreachable("copy_deref should be lowered by now");
 251                break;
 252
 253             default:
 254                /* Nothing to do */
 255                break;
 256             }
 257             break;
 258          }
 259
 260          default:
 261             break; /* Nothing to do */
 262          }
 263       }
 264    }
 265
 266    if (progress) {
 267       nir_metadata_preserve(impl, nir_metadata_block_index |
 268                                   nir_metadata_dominance);
 269    }
 270
 271    return progress;
 272 }
 273
 274 bool
 275 gl_nir_lower_buffers(nir_shader *shader,
 276                      const struct gl_shader_program *shader_program)
 277 {
 278    bool progress = false;
 279
 280    /* First, we lower the derefs to turn block variable and array derefs into
 281     * a nir_address_format_32bit_index_offset pointer.  From there forward,
 282     * we leave the derefs in place and let nir_lower_explicit_io handle them.
 283     */
 284    nir_foreach_function(function, shader) {
 285       if (function->impl &&
 286           lower_buffer_interface_derefs_impl(function->impl, shader_program))
 287          progress = true;
 288    }
 289
 290    /* If that did something, we validate and then call nir_lower_explicit_io
 291     * to finish the process.
 292     */
 293    if (progress) {
 294       nir_validate_shader(shader, "Lowering buffer interface derefs");
 295       nir_lower_explicit_io(shader, nir_var_mem_ubo | nir_var_mem_ssbo,
 296                             nir_address_format_32bit_index_offset);
 297    }
 298
 299    return progress;
 300 }