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