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 {
  36    nir_ssa_dest_init(&instr->instr, &instr->dest.dest, num_components, NULL);
  37    instr->dest.write_mask = (1 << num_components) - 1;
  38 }
  39
  40 static void
  41 lower_reduction(nir_alu_instr *instr, nir_op chan_op, nir_op merge_op,
  42                 nir_builder *builder)
  43 {
  44    unsigned num_components = nir_op_infos[instr->op].input_sizes[0];
  45
  46    nir_ssa_def *last = NULL;
  47    for (unsigned i = 0; i < num_components; i++) {
  48       nir_alu_instr *chan = nir_alu_instr_create(builder->shader, chan_op);
  49       nir_alu_ssa_dest_init(chan, 1);
  50       nir_alu_src_copy(&chan->src[0], &instr->src[0], chan);
  51       chan->src[0].swizzle[0] = chan->src[0].swizzle[i];
  52       if (nir_op_infos[chan_op].num_inputs > 1) {
  53          assert(nir_op_infos[chan_op].num_inputs == 2);
  54          nir_alu_src_copy(&chan->src[1], &instr->src[1], chan);
  55          chan->src[1].swizzle[0] = chan->src[1].swizzle[i];
  56       }
  57
  58       nir_builder_instr_insert(builder, &chan->instr);
  59
  60       if (i == 0) {
  61          last = &chan->dest.dest.ssa;
  62       } else {
  63          last = nir_build_alu(builder, merge_op,
  64                               last, &chan->dest.dest.ssa, NULL, NULL);
  65       }
  66    }
  67
  68    assert(instr->dest.write_mask == 1);
  69    nir_ssa_def_rewrite_uses(&instr->dest.dest.ssa, nir_src_for_ssa(last));
  70    nir_instr_remove(&instr->instr);
  71 }
  72
  73 static void
  74 lower_alu_instr_scalar(nir_alu_instr *instr, nir_builder *b)
  75 {
  76    unsigned num_src = nir_op_infos[instr->op].num_inputs;
  77    unsigned i, chan;
  78
  79    assert(instr->dest.dest.is_ssa);
  80    assert(instr->dest.write_mask != 0);
  81
  82    b->cursor = nir_before_instr(&instr->instr);
  83
  84 #define LOWER_REDUCTION(name, chan, merge) \
  85    case name##2: \
  86    case name##3: \
  87    case name##4: \
  88       lower_reduction(instr, chan, merge, b); \
  89       return;
  90
  91    switch (instr->op) {
  92    case nir_op_vec4:
  93    case nir_op_vec3:
  94    case nir_op_vec2:
  95       /* We don't need to scalarize these ops, they're the ones generated to
  96        * group up outputs into a value that can be SSAed.
  97        */
  98       return;
  99
 100    case nir_op_pack_half_2x16:
 101       if (!b->shader->options->lower_pack_half_2x16)
 102          return;
 103
 104       nir_ssa_def *val =
 105          nir_pack_half_2x16_split(b, nir_channel(b, instr->src[0].src.ssa,
 106                                                  instr->src[0].swizzle[0]),
 107                                      nir_channel(b, instr->src[0].src.ssa,
 108                                                  instr->src[0].swizzle[1]));
 109
 110       nir_ssa_def_rewrite_uses(&instr->dest.dest.ssa, nir_src_for_ssa(val));
 111       nir_instr_remove(&instr->instr);
 112       return;
 113
 114    case nir_op_unpack_unorm_4x8:
 115    case nir_op_unpack_snorm_4x8:
 116    case nir_op_unpack_unorm_2x16:
 117    case nir_op_unpack_snorm_2x16:
 118       /* There is no scalar version of these ops, unless we were to break it
 119        * down to bitshifts and math (which is definitely not intended).
 120        */
 121       return;
 122
 123    case nir_op_unpack_half_2x16: {
 124       if (!b->shader->options->lower_unpack_half_2x16)
 125          return;
 126
 127       nir_ssa_def *comps[2];
 128       comps[0] = nir_unpack_half_2x16_split_x(b, instr->src[0].src.ssa);
 129       comps[1] = nir_unpack_half_2x16_split_y(b, instr->src[0].src.ssa);
 130       nir_ssa_def *vec = nir_vec(b, comps, 2);
 131
 132       nir_ssa_def_rewrite_uses(&instr->dest.dest.ssa, nir_src_for_ssa(vec));
 133       nir_instr_remove(&instr->instr);
 134       return;
 135    }
 136
 137    case nir_op_fdph: {
 138       nir_ssa_def *sum[4];
 139       for (unsigned i = 0; i < 3; i++) {
 140          sum[i] = nir_fmul(b, nir_channel(b, instr->src[0].src.ssa,
 141                                           instr->src[0].swizzle[i]),
 142                               nir_channel(b, instr->src[1].src.ssa,
 143                                           instr->src[1].swizzle[i]));
 144       }
 145       sum[3] = nir_channel(b, instr->src[1].src.ssa, instr->src[1].swizzle[3]);
 146
 147       nir_ssa_def *val = nir_fadd(b, nir_fadd(b, sum[0], sum[1]),
 148                                      nir_fadd(b, sum[2], sum[3]));
 149
 150       nir_ssa_def_rewrite_uses(&instr->dest.dest.ssa, nir_src_for_ssa(val));
 151       nir_instr_remove(&instr->instr);
 152       return;
 153    }
 154
 155       LOWER_REDUCTION(nir_op_fdot, nir_op_fmul, nir_op_fadd);
 156       LOWER_REDUCTION(nir_op_ball_fequal, nir_op_feq, nir_op_iand);
 157       LOWER_REDUCTION(nir_op_ball_iequal, nir_op_ieq, nir_op_iand);
 158       LOWER_REDUCTION(nir_op_bany_fnequal, nir_op_fne, nir_op_ior);
 159       LOWER_REDUCTION(nir_op_bany_inequal, nir_op_ine, nir_op_ior);
 160       LOWER_REDUCTION(nir_op_fall_equal, nir_op_seq, nir_op_fand);
 161       LOWER_REDUCTION(nir_op_fany_nequal, nir_op_sne, nir_op_for);
 162
 163    default:
 164       break;
 165    }
 166
 167    if (instr->dest.dest.ssa.num_components == 1)
 168       return;
 169
 170    unsigned num_components = instr->dest.dest.ssa.num_components;
 171    nir_ssa_def *comps[] = { NULL, NULL, NULL, NULL };
 172
 173    for (chan = 0; chan < 4; chan++) {
 174       if (!(instr->dest.write_mask & (1 << chan)))
 175          continue;
 176
 177       nir_alu_instr *lower = nir_alu_instr_create(b->shader, instr->op);
 178       for (i = 0; i < num_src; i++) {
 179          /* We only handle same-size-as-dest (input_sizes[] == 0) or scalar
 180           * args (input_sizes[] == 1).
 181           */
 182          assert(nir_op_infos[instr->op].input_sizes[i] < 2);
 183          unsigned src_chan = (nir_op_infos[instr->op].input_sizes[i] == 1 ?
 184                               0 : chan);
 185
 186          nir_alu_src_copy(&lower->src[i], &instr->src[i], lower);
 187          for (int j = 0; j < 4; j++)
 188             lower->src[i].swizzle[j] = instr->src[i].swizzle[src_chan];
 189       }
 190
 191       nir_alu_ssa_dest_init(lower, 1);
 192       lower->dest.saturate = instr->dest.saturate;
 193       comps[chan] = &lower->dest.dest.ssa;
 194
 195       nir_builder_instr_insert(b, &lower->instr);
 196    }
 197
 198    nir_ssa_def *vec = nir_vec(b, comps, num_components);
 199
 200    nir_ssa_def_rewrite_uses(&instr->dest.dest.ssa, nir_src_for_ssa(vec));
 201
 202    nir_instr_remove(&instr->instr);
 203 }
 204
 205 static bool
 206 lower_alu_to_scalar_block(nir_block *block, void *builder)
 207 {
 208    nir_foreach_instr_safe(block, instr) {
 209       if (instr->type == nir_instr_type_alu)
 210          lower_alu_instr_scalar(nir_instr_as_alu(instr), builder);
 211    }
 212
 213    return true;
 214 }
 215
 216 static void
 217 nir_lower_alu_to_scalar_impl(nir_function_impl *impl)
 218 {
 219    nir_builder builder;
 220    nir_builder_init(&builder, impl);
 221
 222    nir_foreach_block(impl, lower_alu_to_scalar_block, &builder);
 223 }
 224
 225 void
 226 nir_lower_alu_to_scalar(nir_shader *shader)
 227 {
 228    nir_foreach_function(shader, function) {
 229       if (function->impl)
 230          nir_lower_alu_to_scalar_impl(function->impl);
 231    }
 232 }