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Member "mesa-20.1.8/src/compiler/nir/nir_lower_indirect_derefs.c" (16 Sep 2020, 7659 Bytes) of package /linux/misc/mesa-20.1.8.tar.xz:


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    1 /*
    2  * Copyright © 2016 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 
   24 #include "nir.h"
   25 #include "nir_builder.h"
   26 #include "nir_deref.h"
   27 
   28 static void
   29 emit_load_store_deref(nir_builder *b, nir_intrinsic_instr *orig_instr,
   30                       nir_deref_instr *parent,
   31                       nir_deref_instr **deref_arr,
   32                       nir_ssa_def **dest, nir_ssa_def *src);
   33 
   34 static void
   35 emit_indirect_load_store_deref(nir_builder *b, nir_intrinsic_instr *orig_instr,
   36                                nir_deref_instr *parent,
   37                                nir_deref_instr **deref_arr,
   38                                int start, int end,
   39                                nir_ssa_def **dest, nir_ssa_def *src)
   40 {
   41    assert(start < end);
   42    if (start == end - 1) {
   43       emit_load_store_deref(b, orig_instr,
   44                             nir_build_deref_array_imm(b, parent, start),
   45                             deref_arr + 1, dest, src);
   46    } else {
   47       int mid = start + (end - start) / 2;
   48 
   49       nir_ssa_def *then_dest, *else_dest;
   50 
   51       nir_deref_instr *deref = *deref_arr;
   52       assert(deref->deref_type == nir_deref_type_array);
   53 
   54       nir_push_if(b, nir_ilt(b, deref->arr.index.ssa, nir_imm_intN_t(b, mid, parent->dest.ssa.bit_size)));
   55       emit_indirect_load_store_deref(b, orig_instr, parent, deref_arr,
   56                                      start, mid, &then_dest, src);
   57       nir_push_else(b, NULL);
   58       emit_indirect_load_store_deref(b, orig_instr, parent, deref_arr,
   59                                      mid, end, &else_dest, src);
   60       nir_pop_if(b, NULL);
   61 
   62       if (src == NULL)
   63          *dest = nir_if_phi(b, then_dest, else_dest);
   64    }
   65 }
   66 
   67 static void
   68 emit_load_store_deref(nir_builder *b, nir_intrinsic_instr *orig_instr,
   69                       nir_deref_instr *parent,
   70                       nir_deref_instr **deref_arr,
   71                       nir_ssa_def **dest, nir_ssa_def *src)
   72 {
   73    for (; *deref_arr; deref_arr++) {
   74       nir_deref_instr *deref = *deref_arr;
   75       if (deref->deref_type == nir_deref_type_array &&
   76           !nir_src_is_const(deref->arr.index)) {
   77          int length = glsl_get_length(parent->type);
   78 
   79          emit_indirect_load_store_deref(b, orig_instr, parent, deref_arr,
   80                                         0, length, dest, src);
   81          return;
   82       }
   83 
   84       parent = nir_build_deref_follower(b, parent, deref);
   85    }
   86 
   87    /* We reached the end of the deref chain.  Emit the instruction */
   88    assert(*deref_arr == NULL);
   89 
   90    if (src == NULL) {
   91       /* This is a load instruction */
   92       nir_intrinsic_instr *load =
   93          nir_intrinsic_instr_create(b->shader, orig_instr->intrinsic);
   94       load->num_components = orig_instr->num_components;
   95 
   96       load->src[0] = nir_src_for_ssa(&parent->dest.ssa);
   97 
   98       /* Copy over any other sources.  This is needed for interp_deref_at */
   99       for (unsigned i = 1;
  100            i < nir_intrinsic_infos[orig_instr->intrinsic].num_srcs; i++)
  101          nir_src_copy(&load->src[i], &orig_instr->src[i], load);
  102 
  103       nir_ssa_dest_init(&load->instr, &load->dest,
  104                         orig_instr->dest.ssa.num_components,
  105                         orig_instr->dest.ssa.bit_size, NULL);
  106       nir_builder_instr_insert(b, &load->instr);
  107       *dest = &load->dest.ssa;
  108    } else {
  109       assert(orig_instr->intrinsic == nir_intrinsic_store_deref);
  110       nir_store_deref(b, parent, src, nir_intrinsic_write_mask(orig_instr));
  111    }
  112 }
  113 
  114 static bool
  115 lower_indirect_derefs_block(nir_block *block, nir_builder *b,
  116                             nir_variable_mode modes)
  117 {
  118    bool progress = false;
  119 
  120    nir_foreach_instr_safe(instr, block) {
  121       if (instr->type != nir_instr_type_intrinsic)
  122          continue;
  123 
  124       nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);
  125       if (intrin->intrinsic != nir_intrinsic_load_deref &&
  126           intrin->intrinsic != nir_intrinsic_interp_deref_at_centroid &&
  127           intrin->intrinsic != nir_intrinsic_interp_deref_at_sample &&
  128           intrin->intrinsic != nir_intrinsic_interp_deref_at_offset &&
  129           intrin->intrinsic != nir_intrinsic_interp_deref_at_vertex &&
  130           intrin->intrinsic != nir_intrinsic_store_deref)
  131          continue;
  132 
  133       nir_deref_instr *deref = nir_src_as_deref(intrin->src[0]);
  134 
  135       /* Walk the deref chain back to the base and look for indirects */
  136       bool has_indirect = false;
  137       nir_deref_instr *base = deref;
  138       while (base && base->deref_type != nir_deref_type_var) {
  139          if (base->deref_type == nir_deref_type_array &&
  140              !nir_src_is_const(base->arr.index))
  141             has_indirect = true;
  142 
  143          base = nir_deref_instr_parent(base);
  144       }
  145 
  146       if (!has_indirect || !base)
  147          continue;
  148 
  149       /* Only lower variables whose mode is in the mask, or compact
  150        * array variables.  (We can't handle indirects on tightly packed
  151        * scalar arrays, so we need to lower them regardless.)
  152        */
  153       if (!(modes & base->var->data.mode) && !base->var->data.compact)
  154          continue;
  155 
  156       b->cursor = nir_instr_remove(&intrin->instr);
  157 
  158       nir_deref_path path;
  159       nir_deref_path_init(&path, deref, NULL);
  160       assert(path.path[0] == base);
  161 
  162       if (intrin->intrinsic == nir_intrinsic_store_deref) {
  163          assert(intrin->src[1].is_ssa);
  164          emit_load_store_deref(b, intrin, base, &path.path[1],
  165                                NULL, intrin->src[1].ssa);
  166       } else {
  167          nir_ssa_def *result;
  168          emit_load_store_deref(b, intrin, base, &path.path[1],
  169                                &result, NULL);
  170          nir_ssa_def_rewrite_uses(&intrin->dest.ssa, nir_src_for_ssa(result));
  171       }
  172 
  173       nir_deref_path_finish(&path);
  174 
  175       progress = true;
  176    }
  177 
  178    return progress;
  179 }
  180 
  181 static bool
  182 lower_indirects_impl(nir_function_impl *impl, nir_variable_mode modes)
  183 {
  184    nir_builder builder;
  185    nir_builder_init(&builder, impl);
  186    bool progress = false;
  187 
  188    nir_foreach_block_safe(block, impl) {
  189       progress |= lower_indirect_derefs_block(block, &builder, modes);
  190    }
  191 
  192    if (progress)
  193       nir_metadata_preserve(impl, nir_metadata_none);
  194 
  195    return progress;
  196 }
  197 
  198 /** Lowers indirect variable loads/stores to direct loads/stores.
  199  *
  200  * The pass works by replacing any indirect load or store with an if-ladder
  201  * that does a binary search on the array index.
  202  */
  203 bool
  204 nir_lower_indirect_derefs(nir_shader *shader, nir_variable_mode modes)
  205 {
  206    bool progress = false;
  207 
  208    nir_foreach_function(function, shader) {
  209       if (function->impl)
  210          progress = lower_indirects_impl(function->impl, modes) || progress;
  211    }
  212 
  213    return progress;
  214 }