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 #include <main/imports.h>
  30
  31 /**
  32  * SSA-based copy propagation
  33  */
  34
  35 static bool is_move(nir_alu_instr *instr)
  36 {
  37    assert(instr->src[0].src.is_ssa);
  38
  39    if (instr->op != nir_op_fmov &&
  40        instr->op != nir_op_imov)
  41       return false;
  42
  43    if (instr->dest.saturate)
  44       return false;
  45
  46    /* we handle modifiers in a separate pass */
  47
  48    if (instr->src[0].abs || instr->src[0].negate)
  49       return false;
  50
  51    return true;
  52
  53 }
  54
  55 static bool is_vec(nir_alu_instr *instr)
  56 {
  57    for (unsigned i = 0; i < nir_op_infos[instr->op].num_inputs; i++) {
  58       assert(instr->src[i].src.is_ssa);
  59
  60       /* we handle modifiers in a separate pass */
  61       if (instr->src[i].abs || instr->src[i].negate)
  62          return false;
  63    }
  64
  65    return instr->op == nir_op_vec2 ||
  66           instr->op == nir_op_vec3 ||
  67           instr->op == nir_op_vec4;
  68 }
  69
  70 static bool
  71 is_swizzleless_move(nir_alu_instr *instr)
  72 {
  73    if (is_move(instr)) {
  74       for (unsigned i = 0; i < 4; i++) {
  75          if (!((instr->dest.write_mask >> i) & 1))
  76             break;
  77          if (instr->src[0].swizzle[i] != i)
  78             return false;
  79       }
  80       return true;
  81    } else if (is_vec(instr)) {
  82       nir_ssa_def *def = NULL;
  83       for (unsigned i = 0; i < nir_op_infos[instr->op].num_inputs; i++) {
  84          if (instr->src[i].swizzle[0] != i)
  85             return false;
  86
  87          if (def == NULL) {
  88             def = instr->src[i].src.ssa;
  89          } else if (instr->src[i].src.ssa != def) {
  90             return false;
  91          }
  92       }
  93       return true;
  94    } else {
  95       return false;
  96    }
  97 }
  98
  99 static bool
 100 copy_prop_src(nir_src *src, nir_instr *parent_instr, nir_if *parent_if,
 101               unsigned num_components)
 102 {
 103    assert(src->is_ssa);
 104
 105    nir_instr *src_instr = src->ssa->parent_instr;
 106    nir_ssa_def *copy_def;
 107    if (src_instr->type == nir_instr_type_alu) {
 108       nir_alu_instr *alu_instr = nir_instr_as_alu(src_instr);
 109       if (!is_swizzleless_move(alu_instr))
 110          return false;
 111
 112       if (alu_instr->src[0].src.ssa->num_components != num_components)
 113          return false;
 114
 115       copy_def= alu_instr->src[0].src.ssa;
 116    } else {
 117       return false;
 118    }
 119
 120    if (parent_instr) {
 121       nir_instr_rewrite_src(parent_instr, src, nir_src_for_ssa(copy_def));
 122    } else {
 123       assert(src == &parent_if->condition);
 124       nir_if_rewrite_condition(parent_if, nir_src_for_ssa(copy_def));
 125    }
 126
 127    return true;
 128 }
 129
 130 static bool
 131 copy_prop_alu_src(nir_alu_instr *parent_alu_instr, unsigned index)
 132 {
 133    nir_alu_src *src = &parent_alu_instr->src[index];
 134    assert(src->src.is_ssa);
 135
 136    nir_instr *src_instr =  src->src.ssa->parent_instr;
 137    if (src_instr->type != nir_instr_type_alu)
 138       return false;
 139
 140    nir_alu_instr *alu_instr = nir_instr_as_alu(src_instr);
 141    if (!is_move(alu_instr) && !is_vec(alu_instr))
 142       return false;
 143
 144    nir_ssa_def *def;
 145    unsigned new_swizzle[NIR_MAX_VEC_COMPONENTS] = {0, 0, 0, 0};
 146
 147    if (alu_instr->op == nir_op_fmov ||
 148        alu_instr->op == nir_op_imov) {
 149       for (unsigned i = 0; i < NIR_MAX_VEC_COMPONENTS; i++)
 150          new_swizzle[i] = alu_instr->src[0].swizzle[src->swizzle[i]];
 151       def = alu_instr->src[0].src.ssa;
 152    } else {
 153       def = NULL;
 154
 155       for (unsigned i = 0; i < NIR_MAX_VEC_COMPONENTS; i++) {
 156          if (!nir_alu_instr_channel_used(parent_alu_instr, index, i))
 157             continue;
 158
 159          nir_ssa_def *new_def = alu_instr->src[src->swizzle[i]].src.ssa;
 160          if (def == NULL)
 161             def = new_def;
 162          else {
 163             if (def != new_def)
 164                return false;
 165          }
 166          new_swizzle[i] = alu_instr->src[src->swizzle[i]].swizzle[0];
 167       }
 168    }
 169
 170    for (unsigned i = 0; i < NIR_MAX_VEC_COMPONENTS; i++)
 171       src->swizzle[i] = new_swizzle[i];
 172
 173    nir_instr_rewrite_src(&parent_alu_instr->instr, &src->src,
 174                          nir_src_for_ssa(def));
 175
 176    return true;
 177 }
 178
 179 static bool
 180 copy_prop_instr(nir_instr *instr)
 181 {
 182    bool progress = false;
 183    switch (instr->type) {
 184    case nir_instr_type_alu: {
 185       nir_alu_instr *alu_instr = nir_instr_as_alu(instr);
 186
 187       for (unsigned i = 0; i < nir_op_infos[alu_instr->op].num_inputs; i++)
 188          while (copy_prop_alu_src(alu_instr, i))
 189             progress = true;
 190
 191       return progress;
 192    }
 193
 194    case nir_instr_type_deref: {
 195       nir_deref_instr *deref = nir_instr_as_deref(instr);
 196
 197       if (deref->deref_type != nir_deref_type_var) {
 198          assert(deref->dest.is_ssa);
 199          const unsigned comps = deref->dest.ssa.num_components;
 200          while (copy_prop_src(&deref->parent, instr, NULL, comps))
 201             progress = true;
 202       }
 203
 204       if (deref->deref_type == nir_deref_type_array ||
 205           deref->deref_type == nir_deref_type_ptr_as_array) {
 206          while (copy_prop_src(&deref->arr.index, instr, NULL, 1))
 207             progress = true;
 208       }
 209
 210       return progress;
 211    }
 212
 213    case nir_instr_type_tex: {
 214       nir_tex_instr *tex = nir_instr_as_tex(instr);
 215       for (unsigned i = 0; i < tex->num_srcs; i++) {
 216          unsigned num_components = nir_tex_instr_src_size(tex, i);
 217          while (copy_prop_src(&tex->src[i].src, instr, NULL, num_components))
 218             progress = true;
 219       }
 220
 221       return progress;
 222    }
 223
 224    case nir_instr_type_intrinsic: {
 225       nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);
 226       for (unsigned i = 0;
 227            i < nir_intrinsic_infos[intrin->intrinsic].num_srcs; i++) {
 228          unsigned num_components = nir_intrinsic_src_components(intrin, i);
 229
 230          while (copy_prop_src(&intrin->src[i], instr, NULL, num_components))
 231             progress = true;
 232       }
 233
 234       return progress;
 235    }
 236
 237    case nir_instr_type_phi: {
 238       nir_phi_instr *phi = nir_instr_as_phi(instr);
 239       assert(phi->dest.is_ssa);
 240       unsigned num_components = phi->dest.ssa.num_components;
 241       nir_foreach_phi_src(src, phi) {
 242          while (copy_prop_src(&src->src, instr, NULL, num_components))
 243             progress = true;
 244       }
 245
 246       return progress;
 247    }
 248
 249    default:
 250       return false;
 251    }
 252 }
 253
 254 static bool
 255 copy_prop_if(nir_if *if_stmt)
 256 {
 257    return copy_prop_src(&if_stmt->condition, NULL, if_stmt, 1);
 258 }
 259
 260 static bool
 261 nir_copy_prop_impl(nir_function_impl *impl)
 262 {
 263    bool progress = false;
 264
 265    nir_foreach_block(block, impl) {
 266       nir_foreach_instr(instr, block) {
 267          if (copy_prop_instr(instr))
 268             progress = true;
 269       }
 270
 271       nir_if *if_stmt = nir_block_get_following_if(block);
 272       if (if_stmt && copy_prop_if(if_stmt))
 273          progress = true;
 274       }
 275
 276    if (progress) {
 277       nir_metadata_preserve(impl, nir_metadata_block_index |
 278                                   nir_metadata_dominance);
 279    } else {
 280 #ifndef NDEBUG
 281       impl->valid_metadata &= ~nir_metadata_not_properly_reset;
 282 #endif
 283    }
 284
 285    return progress;
 286 }
 287
 288 bool
 289 nir_copy_prop(nir_shader *shader)
 290 {
 291    bool progress = false;
 292
 293    nir_foreach_function(function, shader) {
 294       if (function->impl && nir_copy_prop_impl(function->impl))
 295          progress = true;
 296    }
 297
 298    return progress;
 299 }