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