src/compiler/nir/nir_opt_copy_propagate.c

   1 /*
   2  * Copyright © 2014 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 DEALINGS
  21  * IN THE SOFTWARE.
  22  *
  23  * Authors:
  24  *    Connor Abbott (cwabbott0@gmail.com)
  25  *
  26  */
  27
  28 #include "nir.h"
  29
  30 /**
  31  * SSA-based copy propagation
  32  */
  33
  34 static bool is_move(nir_alu_instr *instr)
  35 {
  36    assert(instr->src[0].src.is_ssa);
  37
  38    if (instr->op != nir_op_mov)
  39       return false;
  40
  41    if (instr->dest.saturate)
  42       return false;
  43
  44    /* we handle modifiers in a separate pass */
  45
  46    if (instr->src[0].abs || instr->src[0].negate)
  47       return false;
  48
  49    return true;
  50
  51 }
  52
  53 static bool is_vec(nir_alu_instr *instr)
  54 {
  55    for (unsigned i = 0; i < nir_op_infos[instr->op].num_inputs; i++) {
  56       assert(instr->src[i].src.is_ssa);
  57
  58       /* we handle modifiers in a separate pass */
  59       if (instr->src[i].abs || instr->src[i].negate)
  60          return false;
  61    }
  62
  63    assert(instr->dest.dest.is_ssa);
  64    return nir_op_is_vec(instr->op);
  65 }
  66
  67 static bool
  68 is_swizzleless_move(nir_alu_instr *instr)
  69 {
  70    if (is_move(instr)) {
  71       for (unsigned i = 0; i < 4; i++) {
  72          if (!((instr->dest.write_mask >> i) & 1))
  73             break;
  74          if (instr->src[0].swizzle[i] != i)
  75             return false;
  76       }
  77       return true;
  78    } else if (is_vec(instr)) {
  79       nir_ssa_def *def = NULL;
  80       for (unsigned i = 0; i < nir_op_infos[instr->op].num_inputs; i++) {
  81          if (instr->src[i].swizzle[0] != i)
  82             return false;
  83
  84          if (def == NULL) {
  85             def = instr->src[i].src.ssa;
  86          } else if (instr->src[i].src.ssa != def) {
  87             return false;
  88          }
  89       }
  90       return true;
  91    } else {
  92       return false;
  93    }
  94 }
  95
  96 static bool
  97 copy_prop_src(nir_src *src, nir_instr *parent_instr, nir_if *parent_if,
  98               unsigned num_components)
  99 {
 100    assert(src->is_ssa);
 101
 102    nir_instr *src_instr = src->ssa->parent_instr;
 103    nir_ssa_def *copy_def;
 104    if (src_instr->type == nir_instr_type_alu) {
 105       nir_alu_instr *alu_instr = nir_instr_as_alu(src_instr);
 106       if (!is_swizzleless_move(alu_instr))
 107          return false;
 108
 109       if (alu_instr->src[0].src.ssa->num_components != num_components)
 110          return false;
 111
 112       copy_def= alu_instr->src[0].src.ssa;
 113    } else {
 114       return false;
 115    }
 116
 117    if (parent_instr) {
 118       nir_instr_rewrite_src(parent_instr, src, nir_src_for_ssa(copy_def));
 119    } else {
 120       assert(src == &parent_if->condition);
 121       nir_if_rewrite_condition(parent_if, nir_src_for_ssa(copy_def));
 122    }
 123
 124    return true;
 125 }
 126
 127 static bool
 128 copy_prop_alu_src(nir_alu_instr *parent_alu_instr, unsigned index)
 129 {
 130    nir_alu_src *src = &parent_alu_instr->src[index];
 131    assert(src->src.is_ssa);
 132
 133    nir_instr *src_instr =  src->src.ssa->parent_instr;
 134    if (src_instr->type != nir_instr_type_alu)
 135       return false;
 136
 137    nir_alu_instr *alu_instr = nir_instr_as_alu(src_instr);
 138    if (!is_move(alu_instr) && !is_vec(alu_instr))
 139       return false;
 140
 141    nir_ssa_def *def;
 142    unsigned new_swizzle[NIR_MAX_VEC_COMPONENTS] = {0, 0, 0, 0};
 143
 144    if (alu_instr->op == nir_op_mov) {
 145       for (unsigned i = 0; i < NIR_MAX_VEC_COMPONENTS; i++)
 146          new_swizzle[i] = alu_instr->src[0].swizzle[src->swizzle[i]];
 147       def = alu_instr->src[0].src.ssa;
 148    } else {
 149       def = NULL;
 150
 151       for (unsigned i = 0; i < NIR_MAX_VEC_COMPONENTS; i++) {
 152          if (!nir_alu_instr_channel_used(parent_alu_instr, index, i))
 153             continue;
 154
 155          nir_ssa_def *new_def = alu_instr->src[src->swizzle[i]].src.ssa;
 156          if (def == NULL)
 157             def = new_def;
 158          else {
 159             if (def != new_def)
 160                return false;
 161          }
 162          new_swizzle[i] = alu_instr->src[src->swizzle[i]].swizzle[0];
 163       }
 164    }
 165
 166    for (unsigned i = 0; i < NIR_MAX_VEC_COMPONENTS; i++)
 167       src->swizzle[i] = new_swizzle[i];
 168
 169    nir_instr_rewrite_src(&parent_alu_instr->instr, &src->src,
 170                          nir_src_for_ssa(def));
 171
 172    return true;
 173 }
 174
 175 static bool
 176 copy_prop_instr(nir_instr *instr)
 177 {
 178    bool progress = false;
 179    switch (instr->type) {
 180    case nir_instr_type_alu: {
 181       nir_alu_instr *alu_instr = nir_instr_as_alu(instr);
 182
 183       for (unsigned i = 0; i < nir_op_infos[alu_instr->op].num_inputs; i++)
 184          while (copy_prop_alu_src(alu_instr, i))
 185             progress = true;
 186
 187       return progress;
 188    }
 189
 190    case nir_instr_type_deref: {
 191       nir_deref_instr *deref = nir_instr_as_deref(instr);
 192
 193       if (deref->deref_type != nir_deref_type_var) {
 194          assert(deref->dest.is_ssa);
 195          const unsigned comps = deref->dest.ssa.num_components;
 196          while (copy_prop_src(&deref->parent, instr, NULL, comps))
 197             progress = true;
 198       }
 199
 200       if (deref->deref_type == nir_deref_type_array ||
 201           deref->deref_type == nir_deref_type_ptr_as_array) {
 202          while (copy_prop_src(&deref->arr.index, instr, NULL, 1))
 203             progress = true;
 204       }
 205
 206       return progress;
 207    }
 208
 209    case nir_instr_type_tex: {
 210       nir_tex_instr *tex = nir_instr_as_tex(instr);
 211       for (unsigned i = 0; i < tex->num_srcs; i++) {
 212          unsigned num_components = nir_tex_instr_src_size(tex, i);
 213          while (copy_prop_src(&tex->src[i].src, instr, NULL, num_components))
 214             progress = true;
 215       }
 216
 217       return progress;
 218    }
 219
 220    case nir_instr_type_intrinsic: {
 221       nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);
 222       for (unsigned i = 0;
 223            i < nir_intrinsic_infos[intrin->intrinsic].num_srcs; i++) {
 224          unsigned num_components = nir_intrinsic_src_components(intrin, i);
 225
 226          while (copy_prop_src(&intrin->src[i], instr, NULL, num_components))
 227             progress = true;
 228       }
 229
 230       return progress;
 231    }
 232
 233    case nir_instr_type_phi: {
 234       nir_phi_instr *phi = nir_instr_as_phi(instr);
 235       assert(phi->dest.is_ssa);
 236       unsigned num_components = phi->dest.ssa.num_components;
 237       nir_foreach_phi_src(src, phi) {
 238          while (copy_prop_src(&src->src, instr, NULL, num_components))
 239             progress = true;
 240       }
 241
 242       return progress;
 243    }
 244
 245    default:
 246       return false;
 247    }
 248 }
 249
 250 static bool
 251 copy_prop_if(nir_if *if_stmt)
 252 {
 253    return copy_prop_src(&if_stmt->condition, NULL, if_stmt, 1);
 254 }
 255
 256 static bool
 257 nir_copy_prop_impl(nir_function_impl *impl)
 258 {
 259    bool progress = false;
 260
 261    nir_foreach_block(block, impl) {
 262       nir_foreach_instr(instr, block) {
 263          if (copy_prop_instr(instr))
 264             progress = true;
 265       }
 266
 267       nir_if *if_stmt = nir_block_get_following_if(block);
 268       if (if_stmt && copy_prop_if(if_stmt))
 269          progress = true;
 270       }
 271
 272    if (progress) {
 273       nir_metadata_preserve(impl, nir_metadata_block_index |
 274                                   nir_metadata_dominance);
 275    } else {
 276       nir_metadata_preserve(impl, nir_metadata_all);
 277    }
 278
 279    return progress;
 280 }
 281
 282 bool
 283 nir_copy_prop(nir_shader *shader)
 284 {
 285    bool progress = false;
 286
 287    nir_foreach_function(function, shader) {
 288       if (function->impl && nir_copy_prop_impl(function->impl))
 289          progress = true;
 290    }
 291
 292    return progress;
 293 }