Home | History | Annotate | Download | only in nir 
      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 (at) gmail.com)
     25  *
     26  */
     27 
     28 #include "nir.h"
     29 
     30 static void
     31 add_var_use_intrinsic(nir_intrinsic_instr *instr, struct set *live)
     32 {
     33    unsigned num_vars = nir_intrinsic_infos[instr->intrinsic].num_variables;
     34 
     35    switch (instr->intrinsic) {
     36    case nir_intrinsic_copy_var:
     37       _mesa_set_add(live, instr->variables[1]->var);
     38       /* Fall through */
     39    case nir_intrinsic_store_var: {
     40       /* The first source in both copy_var and store_var is the destination.
     41        * If the variable is a local that never escapes the shader, then we
     42        * don't mark it as live for just a store.
     43        */
     44       nir_variable_mode mode = instr->variables[0]->var->data.mode;
     45       if (!(mode & (nir_var_local | nir_var_global | nir_var_shared)))
     46          _mesa_set_add(live, instr->variables[0]->var);
     47       break;
     48    }
     49 
     50    default:
     51       for (unsigned i = 0; i < num_vars; i++) {
     52          _mesa_set_add(live, instr->variables[i]->var);
     53       }
     54       break;
     55    }
     56 }
     57 
     58 static void
     59 add_var_use_call(nir_call_instr *instr, struct set *live)
     60 {
     61    if (instr->return_deref != NULL) {
     62       nir_variable *var = instr->return_deref->var;
     63       _mesa_set_add(live, var);
     64    }
     65 
     66    for (unsigned i = 0; i < instr->num_params; i++) {
     67       nir_variable *var = instr->params[i]->var;
     68       _mesa_set_add(live, var);
     69    }
     70 }
     71 
     72 static void
     73 add_var_use_tex(nir_tex_instr *instr, struct set *live)
     74 {
     75    if (instr->texture != NULL) {
     76       nir_variable *var = instr->texture->var;
     77       _mesa_set_add(live, var);
     78    }
     79 
     80    if (instr->sampler != NULL) {
     81       nir_variable *var = instr->sampler->var;
     82       _mesa_set_add(live, var);
     83    }
     84 }
     85 
     86 static void
     87 add_var_use_shader(nir_shader *shader, struct set *live)
     88 {
     89    nir_foreach_function(function, shader) {
     90       if (function->impl) {
     91          nir_foreach_block(block, function->impl) {
     92             nir_foreach_instr(instr, block) {
     93                switch(instr->type) {
     94                case nir_instr_type_intrinsic:
     95                   add_var_use_intrinsic(nir_instr_as_intrinsic(instr), live);
     96                   break;
     97 
     98                case nir_instr_type_call:
     99                   add_var_use_call(nir_instr_as_call(instr), live);
    100                   break;
    101 
    102                case nir_instr_type_tex:
    103                   add_var_use_tex(nir_instr_as_tex(instr), live);
    104                   break;
    105 
    106                default:
    107                   break;
    108                }
    109             }
    110          }
    111       }
    112    }
    113 }
    114 
    115 static void
    116 remove_dead_var_writes(nir_shader *shader, struct set *live)
    117 {
    118    nir_foreach_function(function, shader) {
    119       if (!function->impl)
    120          continue;
    121 
    122       nir_foreach_block(block, function->impl) {
    123          nir_foreach_instr_safe(instr, block) {
    124             if (instr->type != nir_instr_type_intrinsic)
    125                continue;
    126 
    127             nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);
    128             if (intrin->intrinsic != nir_intrinsic_copy_var &&
    129                 intrin->intrinsic != nir_intrinsic_store_var)
    130                continue;
    131 
    132             /* Stores to dead variables need to be removed */
    133             if (intrin->variables[0]->var->data.mode == 0)
    134                nir_instr_remove(instr);
    135          }
    136       }
    137    }
    138 }
    139 
    140 static bool
    141 remove_dead_vars(struct exec_list *var_list, struct set *live)
    142 {
    143    bool progress = false;
    144 
    145    foreach_list_typed_safe(nir_variable, var, node, var_list) {
    146       struct set_entry *entry = _mesa_set_search(live, var);
    147       if (entry == NULL) {
    148          /* Mark this variable as used by setting the mode to 0 */
    149          var->data.mode = 0;
    150          exec_node_remove(&var->node);
    151          progress = true;
    152       }
    153    }
    154 
    155    return progress;
    156 }
    157 
    158 bool
    159 nir_remove_dead_variables(nir_shader *shader, nir_variable_mode modes)
    160 {
    161    bool progress = false;
    162    struct set *live =
    163       _mesa_set_create(NULL, _mesa_hash_pointer, _mesa_key_pointer_equal);
    164 
    165    add_var_use_shader(shader, live);
    166 
    167    if (modes & nir_var_uniform)
    168       progress = remove_dead_vars(&shader->uniforms, live) || progress;
    169 
    170    if (modes & nir_var_shader_in)
    171       progress = remove_dead_vars(&shader->inputs, live) || progress;
    172 
    173    if (modes & nir_var_shader_out)
    174       progress = remove_dead_vars(&shader->outputs, live) || progress;
    175 
    176    if (modes & nir_var_global)
    177       progress = remove_dead_vars(&shader->globals, live) || progress;
    178 
    179    if (modes & nir_var_system_value)
    180       progress = remove_dead_vars(&shader->system_values, live) || progress;
    181 
    182    if (modes & nir_var_shared)
    183       progress = remove_dead_vars(&shader->shared, live) || progress;
    184 
    185    if (modes & nir_var_local) {
    186       nir_foreach_function(function, shader) {
    187          if (function->impl) {
    188             if (remove_dead_vars(&function->impl->locals, live))
    189                progress = true;
    190          }
    191       }
    192    }
    193 
    194    if (progress) {
    195       remove_dead_var_writes(shader, live);
    196 
    197       nir_foreach_function(function, shader) {
    198          if (function->impl) {
    199             nir_metadata_preserve(function->impl, nir_metadata_block_index |
    200                                                   nir_metadata_dominance);
    201          }
    202       }
    203    }
    204 
    205    _mesa_set_destroy(live, NULL);
    206    return progress;
    207 }
    208