src/compiler/nir/nir_lower_alu_to_scalar.c

   1 /*
   2  * Copyright © 2014-2015 Broadcom
   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
  24 #include "nir.h"
  25 #include "nir_builder.h"
  26
  27 /** @file nir_lower_alu_to_scalar.c
  28  *
  29  * Replaces nir_alu_instr operations with more than one channel used in the
  30  * arguments with individual per-channel operations.
  31  */
  32
  33 static void
  34 nir_alu_ssa_dest_init(nir_alu_instr *instr, unsigned num_components,
  35                       unsigned bit_size)
  36 {
  37    nir_ssa_dest_init(&instr->instr, &instr->dest.dest, num_components,
  38                      bit_size, NULL);
  39    instr->dest.write_mask = (1 << num_components) - 1;
  40 }
  41
  42 static void
  43 lower_reduction(nir_alu_instr *instr, nir_op chan_op, nir_op merge_op,
  44                 nir_builder *builder)
  45 {
  46    unsigned num_components = nir_op_infos[instr->op].input_sizes[0];
  47
  48    nir_ssa_def *last = NULL;
  49    for (unsigned i = 0; i < num_components; i++) {
  50       nir_alu_instr *chan = nir_alu_instr_create(builder->shader, chan_op);
  51       nir_alu_ssa_dest_init(chan, 1, instr->dest.dest.ssa.bit_size);
  52       nir_alu_src_copy(&chan->src[0], &instr->src[0], chan);
  53       chan->src[0].swizzle[0] = chan->src[0].swizzle[i];
  54       if (nir_op_infos[chan_op].num_inputs > 1) {
  55          assert(nir_op_infos[chan_op].num_inputs == 2);
  56          nir_alu_src_copy(&chan->src[1], &instr->src[1], chan);
  57          chan->src[1].swizzle[0] = chan->src[1].swizzle[i];
  58       }
  59       chan->exact = instr->exact;
  60
  61       nir_builder_instr_insert(builder, &chan->instr);
  62
  63       if (i == 0) {
  64          last = &chan->dest.dest.ssa;
  65       } else {
  66          last = nir_build_alu(builder, merge_op,
  67                               last, &chan->dest.dest.ssa, NULL, NULL);
  68       }
  69    }
  70
  71    assert(instr->dest.write_mask == 1);
  72    nir_ssa_def_rewrite_uses(&instr->dest.dest.ssa, nir_src_for_ssa(last));
  73    nir_instr_remove(&instr->instr);
  74 }
  75
  76 static bool
  77 lower_alu_instr_scalar(nir_alu_instr *instr, nir_builder *b)
  78 {
  79    unsigned num_src = nir_op_infos[instr->op].num_inputs;
  80    unsigned i, chan;
  81
  82    assert(instr->dest.dest.is_ssa);
  83    assert(instr->dest.write_mask != 0);
  84
  85    b->cursor = nir_before_instr(&instr->instr);
  86    b->exact = instr->exact;
  87
  88 #define LOWER_REDUCTION(name, chan, merge) \
  89    case name##2: \
  90    case name##3: \
  91    case name##4: \
  92       lower_reduction(instr, chan, merge, b); \
  93       return true;
  94
  95    switch (instr->op) {
  96    case nir_op_vec4:
  97    case nir_op_vec3:
  98    case nir_op_vec2:
  99    case nir_op_cube_face_coord:
 100    case nir_op_cube_face_index:
 101       /* We don't need to scalarize these ops, they're the ones generated to
 102        * group up outputs into a value that can be SSAed.
 103        */
 104       return false;
 105
 106    case nir_op_pack_half_2x16:
 107       if (!b->shader->options->lower_pack_half_2x16)
 108          return false;
 109
 110       nir_ssa_def *src_vec2 = nir_ssa_for_alu_src(b, instr, 0);
 111
 112       nir_ssa_def *val =
 113          nir_pack_half_2x16_split(b, nir_channel(b, src_vec2, 0),
 114                                      nir_channel(b, src_vec2, 1));
 115
 116       nir_ssa_def_rewrite_uses(&instr->dest.dest.ssa, nir_src_for_ssa(val));
 117       nir_instr_remove(&instr->instr);
 118       return true;
 119
 120    case nir_op_unpack_unorm_4x8:
 121    case nir_op_unpack_snorm_4x8:
 122    case nir_op_unpack_unorm_2x16:
 123    case nir_op_unpack_snorm_2x16:
 124       /* There is no scalar version of these ops, unless we were to break it
 125        * down to bitshifts and math (which is definitely not intended).
 126        */
 127       return false;
 128
 129    case nir_op_unpack_half_2x16: {
 130       if (!b->shader->options->lower_unpack_half_2x16)
 131          return false;
 132
 133       nir_ssa_def *packed = nir_ssa_for_alu_src(b, instr, 0);
 134
 135       nir_ssa_def *comps[2];
 136       comps[0] = nir_unpack_half_2x16_split_x(b, packed);
 137       comps[1] = nir_unpack_half_2x16_split_y(b, packed);
 138       nir_ssa_def *vec = nir_vec(b, comps, 2);
 139
 140       nir_ssa_def_rewrite_uses(&instr->dest.dest.ssa, nir_src_for_ssa(vec));
 141       nir_instr_remove(&instr->instr);
 142       return true;
 143    }
 144
 145    case nir_op_pack_uvec2_to_uint: {
 146       assert(b->shader->options->lower_pack_snorm_2x16 ||
 147              b->shader->options->lower_pack_unorm_2x16);
 148
 149       nir_ssa_def *word = nir_extract_u16(b, nir_ssa_for_alu_src(b, instr, 0),
 150                                              nir_imm_int(b, 0));
 151       nir_ssa_def *val =
 152          nir_ior(b, nir_ishl(b, nir_channel(b, word, 1), nir_imm_int(b, 16)),
 153                                 nir_channel(b, word, 0));
 154
 155       nir_ssa_def_rewrite_uses(&instr->dest.dest.ssa, nir_src_for_ssa(val));
 156       nir_instr_remove(&instr->instr);
 157       break;
 158    }
 159
 160    case nir_op_pack_uvec4_to_uint: {
 161       assert(b->shader->options->lower_pack_snorm_4x8 ||
 162              b->shader->options->lower_pack_unorm_4x8);
 163
 164       nir_ssa_def *byte = nir_extract_u8(b, nir_ssa_for_alu_src(b, instr, 0),
 165                                             nir_imm_int(b, 0));
 166       nir_ssa_def *val =
 167          nir_ior(b, nir_ior(b, nir_ishl(b, nir_channel(b, byte, 3), nir_imm_int(b, 24)),
 168                                nir_ishl(b, nir_channel(b, byte, 2), nir_imm_int(b, 16))),
 169                     nir_ior(b, nir_ishl(b, nir_channel(b, byte, 1), nir_imm_int(b, 8)),
 170                                nir_channel(b, byte, 0)));
 171
 172       nir_ssa_def_rewrite_uses(&instr->dest.dest.ssa, nir_src_for_ssa(val));
 173       nir_instr_remove(&instr->instr);
 174       break;
 175    }
 176
 177    case nir_op_fdph: {
 178       nir_ssa_def *src0_vec = nir_ssa_for_alu_src(b, instr, 0);
 179       nir_ssa_def *src1_vec = nir_ssa_for_alu_src(b, instr, 1);
 180
 181       nir_ssa_def *sum[4];
 182       for (unsigned i = 0; i < 3; i++) {
 183          sum[i] = nir_fmul(b, nir_channel(b, src0_vec, i),
 184                               nir_channel(b, src1_vec, i));
 185       }
 186       sum[3] = nir_channel(b, src1_vec, 3);
 187
 188       nir_ssa_def *val = nir_fadd(b, nir_fadd(b, sum[0], sum[1]),
 189                                      nir_fadd(b, sum[2], sum[3]));
 190
 191       nir_ssa_def_rewrite_uses(&instr->dest.dest.ssa, nir_src_for_ssa(val));
 192       nir_instr_remove(&instr->instr);
 193       return true;
 194    }
 195
 196    case nir_op_unpack_64_2x32:
 197    case nir_op_unpack_32_2x16:
 198       return false;
 199
 200       LOWER_REDUCTION(nir_op_fdot, nir_op_fmul, nir_op_fadd);
 201       LOWER_REDUCTION(nir_op_b32all_fequal, nir_op_feq32, nir_op_iand);
 202       LOWER_REDUCTION(nir_op_b32all_iequal, nir_op_ieq32, nir_op_iand);
 203       LOWER_REDUCTION(nir_op_b32any_fnequal, nir_op_fne32, nir_op_ior);
 204       LOWER_REDUCTION(nir_op_b32any_inequal, nir_op_ine32, nir_op_ior);
 205       LOWER_REDUCTION(nir_op_fall_equal, nir_op_seq, nir_op_fand);
 206       LOWER_REDUCTION(nir_op_fany_nequal, nir_op_sne, nir_op_for);
 207
 208    default:
 209       break;
 210    }
 211
 212    if (instr->dest.dest.ssa.num_components == 1)
 213       return false;
 214
 215    unsigned num_components = instr->dest.dest.ssa.num_components;
 216    nir_ssa_def *comps[NIR_MAX_VEC_COMPONENTS] = { NULL };
 217
 218    for (chan = 0; chan < NIR_MAX_VEC_COMPONENTS; chan++) {
 219       if (!(instr->dest.write_mask & (1 << chan)))
 220          continue;
 221
 222       nir_alu_instr *lower = nir_alu_instr_create(b->shader, instr->op);
 223       for (i = 0; i < num_src; i++) {
 224          /* We only handle same-size-as-dest (input_sizes[] == 0) or scalar
 225           * args (input_sizes[] == 1).
 226           */
 227          assert(nir_op_infos[instr->op].input_sizes[i] < 2);
 228          unsigned src_chan = (nir_op_infos[instr->op].input_sizes[i] == 1 ?
 229                               0 : chan);
 230
 231          nir_alu_src_copy(&lower->src[i], &instr->src[i], lower);
 232          for (int j = 0; j < NIR_MAX_VEC_COMPONENTS; j++)
 233             lower->src[i].swizzle[j] = instr->src[i].swizzle[src_chan];
 234       }
 235
 236       nir_alu_ssa_dest_init(lower, 1, instr->dest.dest.ssa.bit_size);
 237       lower->dest.saturate = instr->dest.saturate;
 238       comps[chan] = &lower->dest.dest.ssa;
 239       lower->exact = instr->exact;
 240
 241       nir_builder_instr_insert(b, &lower->instr);
 242    }
 243
 244    nir_ssa_def *vec = nir_vec(b, comps, num_components);
 245
 246    nir_ssa_def_rewrite_uses(&instr->dest.dest.ssa, nir_src_for_ssa(vec));
 247
 248    nir_instr_remove(&instr->instr);
 249    return true;
 250 }
 251
 252 static bool
 253 nir_lower_alu_to_scalar_impl(nir_function_impl *impl)
 254 {
 255    nir_builder builder;
 256    nir_builder_init(&builder, impl);
 257    bool progress = false;
 258
 259    nir_foreach_block(block, impl) {
 260       nir_foreach_instr_safe(instr, block) {
 261          if (instr->type == nir_instr_type_alu) {
 262             progress = lower_alu_instr_scalar(nir_instr_as_alu(instr),
 263                                               &builder) || progress;
 264          }
 265       }
 266    }
 267
 268    nir_metadata_preserve(impl, nir_metadata_block_index |
 269                                nir_metadata_dominance);
 270
 271    return progress;
 272 }
 273
 274 bool
 275 nir_lower_alu_to_scalar(nir_shader *shader)
 276 {
 277    bool progress = false;
 278
 279    nir_foreach_function(function, shader) {
 280       if (function->impl)
 281          progress = nir_lower_alu_to_scalar_impl(function->impl) || progress;
 282    }
 283
 284    return progress;
 285 }