src/compiler/nir/nir_lower_variable_initializers.c

   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
  27 static void
  28 build_constant_load(nir_builder *b, nir_deref_instr *deref, nir_constant *c)
  29 {
  30    if (glsl_type_is_vector_or_scalar(deref->type)) {
  31       nir_load_const_instr *load =
  32          nir_load_const_instr_create(b->shader,
  33                                      glsl_get_vector_elements(deref->type),
  34                                      glsl_get_bit_size(deref->type));
  35       memcpy(load->value, c->values, sizeof(*load->value) * load->def.num_components);
  36       nir_builder_instr_insert(b, &load->instr);
  37       nir_store_deref(b, deref, &load->def, ~0);
  38    } else if (glsl_type_is_struct_or_ifc(deref->type)) {
  39       unsigned len = glsl_get_length(deref->type);
  40       for (unsigned i = 0; i < len; i++) {
  41          build_constant_load(b, nir_build_deref_struct(b, deref, i),
  42                              c->elements[i]);
  43       }
  44    } else {
  45       assert(glsl_type_is_array(deref->type) ||
  46              glsl_type_is_matrix(deref->type));
  47       unsigned len = glsl_get_length(deref->type);
  48       for (unsigned i = 0; i < len; i++) {
  49          build_constant_load(b,
  50                              nir_build_deref_array_imm(b, deref, i),
  51                              c->elements[i]);
  52       }
  53    }
  54 }
  55
  56 static bool
  57 lower_const_initializer(struct nir_builder *b, struct exec_list *var_list,
  58                         nir_variable_mode modes)
  59 {
  60    bool progress = false;
  61
  62    b->cursor = nir_before_cf_list(&b->impl->body);
  63
  64    nir_foreach_variable_in_list(var, var_list) {
  65       if (!(var->data.mode & modes))
  66          continue;
  67
  68       if (var->constant_initializer) {
  69          build_constant_load(b, nir_build_deref_var(b, var),
  70                              var->constant_initializer);
  71
  72          progress = true;
  73          var->constant_initializer = NULL;
  74       } else if (var->pointer_initializer) {
  75          nir_deref_instr *src_deref = nir_build_deref_var(b, var->pointer_initializer);
  76          nir_deref_instr *dst_deref = nir_build_deref_var(b, var);
  77
  78          /* Note that this stores a pointer to src into dst */
  79          nir_store_deref(b, dst_deref, &src_deref->dest.ssa, ~0);
  80
  81          progress = true;
  82          var->pointer_initializer = NULL;
  83       }
  84
  85    }
  86
  87    return progress;
  88 }
  89
  90 bool
  91 nir_lower_variable_initializers(nir_shader *shader, nir_variable_mode modes)
  92 {
  93    bool progress = false;
  94
  95    /* Only some variables have initializers that we want to lower.  Others
  96     * such as uniforms have initializers which are useful later during linking
  97     * so we want to skip over those.  Restrict to only variable types where
  98     * initializers make sense so that callers can use nir_var_all.
  99     */
 100    modes &= nir_var_shader_out |
 101             nir_var_shader_temp |
 102             nir_var_function_temp |
 103             nir_var_system_value;
 104
 105    nir_foreach_function(function, shader) {
 106       if (!function->impl)
 107          continue;
 108
 109       bool impl_progress = false;
 110
 111       nir_builder builder;
 112       nir_builder_init(&builder, function->impl);
 113
 114       if ((modes & ~nir_var_function_temp) && function->is_entrypoint) {
 115          impl_progress |= lower_const_initializer(&builder,
 116                                                   &shader->variables,
 117                                                   modes);
 118       }
 119
 120       if (modes & nir_var_function_temp) {
 121          impl_progress |= lower_const_initializer(&builder,
 122                                                   &function->impl->locals,
 123                                                   nir_var_function_temp);
 124       }
 125
 126       if (impl_progress) {
 127          progress = true;
 128          nir_metadata_preserve(function->impl, nir_metadata_block_index |
 129                                                nir_metadata_dominance |
 130                                                nir_metadata_live_ssa_defs);
 131       } else {
 132          nir_metadata_preserve(function->impl, nir_metadata_all);
 133       }
 134    }
 135
 136    return progress;
 137 }