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 struct alu_to_scalar_data {
  28    nir_instr_filter_cb cb;
  29    const void *data;
  30 };
  31
  32 /** @file nir_lower_alu_to_scalar.c
  33  *
  34  * Replaces nir_alu_instr operations with more than one channel used in the
  35  * arguments with individual per-channel operations.
  36  */
  37
  38 static bool
  39 inst_is_vector_alu(const nir_instr *instr, const void *_state)
  40 {
  41    if (instr->type != nir_instr_type_alu)
  42       return false;
  43
  44    nir_alu_instr *alu = nir_instr_as_alu(instr);
  45
  46    /* There is no ALU instruction which has a scalar destination, scalar
  47     * src[0], and some other vector source.
  48     */
  49    assert(alu->dest.dest.is_ssa);
  50    assert(alu->src[0].src.is_ssa);
  51    return alu->dest.dest.ssa.num_components > 1 ||
  52           nir_op_infos[alu->op].input_sizes[0] > 1;
  53 }
  54
  55 static void
  56 nir_alu_ssa_dest_init(nir_alu_instr *alu, unsigned num_components,
  57                       unsigned bit_size)
  58 {
  59    nir_ssa_dest_init(&alu->instr, &alu->dest.dest, num_components,
  60                      bit_size, NULL);
  61    alu->dest.write_mask = (1 << num_components) - 1;
  62 }
  63
  64 static nir_ssa_def *
  65 lower_reduction(nir_alu_instr *alu, nir_op chan_op, nir_op merge_op,
  66                 nir_builder *builder)
  67 {
  68    unsigned num_components = nir_op_infos[alu->op].input_sizes[0];
  69
  70    nir_ssa_def *last = NULL;
  71    for (unsigned i = 0; i < num_components; i++) {
  72       nir_alu_instr *chan = nir_alu_instr_create(builder->shader, chan_op);
  73       nir_alu_ssa_dest_init(chan, 1, alu->dest.dest.ssa.bit_size);
  74       nir_alu_src_copy(&chan->src[0], &alu->src[0], chan);
  75       chan->src[0].swizzle[0] = chan->src[0].swizzle[i];
  76       if (nir_op_infos[chan_op].num_inputs > 1) {
  77          assert(nir_op_infos[chan_op].num_inputs == 2);
  78          nir_alu_src_copy(&chan->src[1], &alu->src[1], chan);
  79          chan->src[1].swizzle[0] = chan->src[1].swizzle[i];
  80       }
  81       chan->exact = alu->exact;
  82
  83       nir_builder_instr_insert(builder, &chan->instr);
  84
  85       if (i == 0) {
  86          last = &chan->dest.dest.ssa;
  87       } else {
  88          last = nir_build_alu(builder, merge_op,
  89                               last, &chan->dest.dest.ssa, NULL, NULL);
  90       }
  91    }
  92
  93    return last;
  94 }
  95
  96 static nir_ssa_def *
  97 lower_alu_instr_scalar(nir_builder *b, nir_instr *instr, void *_data)
  98 {
  99    struct alu_to_scalar_data *data = _data;
 100    nir_alu_instr *alu = nir_instr_as_alu(instr);
 101    unsigned num_src = nir_op_infos[alu->op].num_inputs;
 102    unsigned i, chan;
 103
 104    assert(alu->dest.dest.is_ssa);
 105    assert(alu->dest.write_mask != 0);
 106
 107    b->cursor = nir_before_instr(&alu->instr);
 108    b->exact = alu->exact;
 109
 110    if (data->cb && !data->cb(instr, data->data))
 111       return NULL;
 112
 113 #define LOWER_REDUCTION(name, chan, merge) \
 114    case name##2: \
 115    case name##3: \
 116    case name##4: \
 117       return lower_reduction(alu, chan, merge, b); \
 118
 119    switch (alu->op) {
 120    case nir_op_vec4:
 121    case nir_op_vec3:
 122    case nir_op_vec2:
 123    case nir_op_cube_face_coord:
 124    case nir_op_cube_face_index:
 125       /* We don't need to scalarize these ops, they're the ones generated to
 126        * group up outputs into a value that can be SSAed.
 127        */
 128       return NULL;
 129
 130    case nir_op_pack_half_2x16: {
 131       if (!b->shader->options->lower_pack_half_2x16)
 132          return NULL;
 133
 134       nir_ssa_def *src_vec2 = nir_ssa_for_alu_src(b, alu, 0);
 135       return nir_pack_half_2x16_split(b, nir_channel(b, src_vec2, 0),
 136                                          nir_channel(b, src_vec2, 1));
 137    }
 138
 139    case nir_op_unpack_unorm_4x8:
 140    case nir_op_unpack_snorm_4x8:
 141    case nir_op_unpack_unorm_2x16:
 142    case nir_op_unpack_snorm_2x16:
 143       /* There is no scalar version of these ops, unless we were to break it
 144        * down to bitshifts and math (which is definitely not intended).
 145        */
 146       return NULL;
 147
 148    case nir_op_unpack_half_2x16: {
 149       if (!b->shader->options->lower_unpack_half_2x16)
 150          return NULL;
 151
 152       nir_ssa_def *packed = nir_ssa_for_alu_src(b, alu, 0);
 153       return nir_vec2(b, nir_unpack_half_2x16_split_x(b, packed),
 154                          nir_unpack_half_2x16_split_y(b, packed));
 155    }
 156
 157    case nir_op_pack_uvec2_to_uint: {
 158       assert(b->shader->options->lower_pack_snorm_2x16 ||
 159              b->shader->options->lower_pack_unorm_2x16);
 160
 161       nir_ssa_def *word = nir_extract_u16(b, nir_ssa_for_alu_src(b, alu, 0),
 162                                              nir_imm_int(b, 0));
 163       return nir_ior(b, nir_ishl(b, nir_channel(b, word, 1),
 164                                     nir_imm_int(b, 16)),
 165                         nir_channel(b, word, 0));
 166    }
 167
 168    case nir_op_pack_uvec4_to_uint: {
 169       assert(b->shader->options->lower_pack_snorm_4x8 ||
 170              b->shader->options->lower_pack_unorm_4x8);
 171
 172       nir_ssa_def *byte = nir_extract_u8(b, nir_ssa_for_alu_src(b, alu, 0),
 173                                             nir_imm_int(b, 0));
 174       return nir_ior(b, nir_ior(b, nir_ishl(b, nir_channel(b, byte, 3),
 175                                                nir_imm_int(b, 24)),
 176                                    nir_ishl(b, nir_channel(b, byte, 2),
 177                                                nir_imm_int(b, 16))),
 178                         nir_ior(b, nir_ishl(b, nir_channel(b, byte, 1),
 179                                                nir_imm_int(b, 8)),
 180                                    nir_channel(b, byte, 0)));
 181    }
 182
 183    case nir_op_fdph: {
 184       nir_ssa_def *src0_vec = nir_ssa_for_alu_src(b, alu, 0);
 185       nir_ssa_def *src1_vec = nir_ssa_for_alu_src(b, alu, 1);
 186
 187       nir_ssa_def *sum[4];
 188       for (unsigned i = 0; i < 3; i++) {
 189          sum[i] = nir_fmul(b, nir_channel(b, src0_vec, i),
 190                               nir_channel(b, src1_vec, i));
 191       }
 192       sum[3] = nir_channel(b, src1_vec, 3);
 193
 194       return nir_fadd(b, nir_fadd(b, sum[0], sum[1]),
 195                          nir_fadd(b, sum[2], sum[3]));
 196    }
 197
 198    case nir_op_unpack_64_2x32:
 199    case nir_op_unpack_32_2x16:
 200       return NULL;
 201
 202       LOWER_REDUCTION(nir_op_fdot, nir_op_fmul, nir_op_fadd);
 203       LOWER_REDUCTION(nir_op_ball_fequal, nir_op_feq, nir_op_iand);
 204       LOWER_REDUCTION(nir_op_ball_iequal, nir_op_ieq, nir_op_iand);
 205       LOWER_REDUCTION(nir_op_bany_fnequal, nir_op_fne, nir_op_ior);
 206       LOWER_REDUCTION(nir_op_bany_inequal, nir_op_ine, nir_op_ior);
 207       LOWER_REDUCTION(nir_op_b32all_fequal, nir_op_feq32, nir_op_iand);
 208       LOWER_REDUCTION(nir_op_b32all_iequal, nir_op_ieq32, nir_op_iand);
 209       LOWER_REDUCTION(nir_op_b32any_fnequal, nir_op_fne32, nir_op_ior);
 210       LOWER_REDUCTION(nir_op_b32any_inequal, nir_op_ine32, nir_op_ior);
 211       LOWER_REDUCTION(nir_op_fall_equal, nir_op_seq, nir_op_fmin);
 212       LOWER_REDUCTION(nir_op_fany_nequal, nir_op_sne, nir_op_fmax);
 213
 214    default:
 215       break;
 216    }
 217
 218    if (alu->dest.dest.ssa.num_components == 1)
 219       return NULL;
 220
 221    unsigned num_components = alu->dest.dest.ssa.num_components;
 222    nir_ssa_def *comps[NIR_MAX_VEC_COMPONENTS] = { NULL };
 223
 224    for (chan = 0; chan < NIR_MAX_VEC_COMPONENTS; chan++) {
 225       if (!(alu->dest.write_mask & (1 << chan)))
 226          continue;
 227
 228       nir_alu_instr *lower = nir_alu_instr_create(b->shader, alu->op);
 229       for (i = 0; i < num_src; i++) {
 230          /* We only handle same-size-as-dest (input_sizes[] == 0) or scalar
 231           * args (input_sizes[] == 1).
 232           */
 233          assert(nir_op_infos[alu->op].input_sizes[i] < 2);
 234          unsigned src_chan = (nir_op_infos[alu->op].input_sizes[i] == 1 ?
 235                               0 : chan);
 236
 237          nir_alu_src_copy(&lower->src[i], &alu->src[i], lower);
 238          for (int j = 0; j < NIR_MAX_VEC_COMPONENTS; j++)
 239             lower->src[i].swizzle[j] = alu->src[i].swizzle[src_chan];
 240       }
 241
 242       nir_alu_ssa_dest_init(lower, 1, alu->dest.dest.ssa.bit_size);
 243       lower->dest.saturate = alu->dest.saturate;
 244       comps[chan] = &lower->dest.dest.ssa;
 245       lower->exact = alu->exact;
 246
 247       nir_builder_instr_insert(b, &lower->instr);
 248    }
 249
 250    return nir_vec(b, comps, num_components);
 251 }
 252
 253 bool
 254 nir_lower_alu_to_scalar(nir_shader *shader, nir_instr_filter_cb cb, const void *_data)
 255 {
 256    struct alu_to_scalar_data data = {
 257       .cb = cb,
 258       .data = _data,
 259    };
 260
 261    return nir_shader_lower_instructions(shader,
 262                                         inst_is_vector_alu,
 263                                         lower_alu_instr_scalar,
 264                                         &data);
 265 }