src/compiler/nir/nir_inline_functions.c

   1 /*
   2  * Copyright © 2015 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_control_flow.h"
  27
  28 static bool inline_function_impl(nir_function_impl *impl, struct set *inlined);
  29
  30 static void
  31 convert_deref_to_param_deref(nir_instr *instr, nir_deref_var **deref,
  32                              nir_call_instr *call)
  33 {
  34    /* This isn't a parameter, just return the deref */
  35    if ((*deref)->var->data.mode != nir_var_param)
  36       return;
  37
  38    int param_idx = (*deref)->var->data.location;
  39
  40    nir_deref_var *call_deref;
  41    if (param_idx >= 0) {
  42       assert(param_idx < call->callee->num_params);
  43       call_deref = call->params[param_idx];
  44    } else {
  45       call_deref = call->return_deref;
  46    }
  47    assert(call_deref);
  48
  49    /* Now we make a new deref by concatenating the deref in the call's
  50     * parameter with the deref we were given.
  51     */
  52    nir_deref_var *new_deref = nir_deref_var_clone(call_deref, instr);
  53    nir_deref *new_tail = nir_deref_tail(&new_deref->deref);
  54    new_tail->child = (*deref)->deref.child;
  55    ralloc_steal(new_tail, new_tail->child);
  56    *deref = new_deref;
  57 }
  58
  59 static void
  60 rewrite_param_derefs(nir_instr *instr, nir_call_instr *call)
  61 {
  62    switch (instr->type) {
  63    case nir_instr_type_intrinsic: {
  64       nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);
  65
  66       for (unsigned i = 0;
  67            i < nir_intrinsic_infos[intrin->intrinsic].num_variables; i++) {
  68          convert_deref_to_param_deref(instr, &intrin->variables[i], call);
  69       }
  70       break;
  71    }
  72
  73    case nir_instr_type_tex: {
  74       nir_tex_instr *tex = nir_instr_as_tex(instr);
  75       if (tex->texture)
  76          convert_deref_to_param_deref(&tex->instr, &tex->texture, call);
  77       if (tex->sampler)
  78          convert_deref_to_param_deref(&tex->instr, &tex->sampler, call);
  79       break;
  80    }
  81
  82    default:
  83       break; /* Nothing else has derefs */
  84    }
  85 }
  86
  87 static void
  88 lower_param_to_local(nir_variable *param, nir_function_impl *impl, bool write)
  89 {
  90    if (param->data.mode != nir_var_param)
  91       return;
  92
  93    nir_parameter_type param_type;
  94    if (param->data.location >= 0) {
  95       assert(param->data.location < impl->num_params);
  96       param_type = impl->function->params[param->data.location].param_type;
  97    } else {
  98       /* Return variable */
  99       param_type = nir_parameter_out;
 100    }
 101
 102    if ((write && param_type == nir_parameter_in) ||
 103        (!write && param_type == nir_parameter_out)) {
 104       /* In this case, we need a shadow copy.  Turn it into a local */
 105       param->data.mode = nir_var_local;
 106       exec_list_push_tail(&impl->locals, &param->node);
 107    }
 108 }
 109
 110 static bool
 111 lower_params_to_locals_block(nir_block *block, nir_function_impl *impl)
 112 {
 113    nir_foreach_instr(instr, block) {
 114       if (instr->type != nir_instr_type_intrinsic)
 115          continue;
 116
 117       nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);
 118
 119       switch (intrin->intrinsic) {
 120       case nir_intrinsic_store_var:
 121          lower_param_to_local(intrin->variables[0]->var, impl, true);
 122          break;
 123
 124       case nir_intrinsic_copy_var:
 125          lower_param_to_local(intrin->variables[0]->var, impl, true);
 126          lower_param_to_local(intrin->variables[1]->var, impl, false);
 127          break;
 128
 129       case nir_intrinsic_load_var:
 130          /* All other intrinsics which access variables (image_load_store)
 131           * do so in a read-only fasion.
 132           */
 133          for (unsigned i = 0;
 134               i < nir_intrinsic_infos[intrin->intrinsic].num_variables; i++) {
 135             lower_param_to_local(intrin->variables[i]->var, impl, false);
 136          }
 137          break;
 138
 139       default:
 140          continue;
 141       }
 142    }
 143
 144    return true;
 145 }
 146
 147 static bool
 148 inline_functions_block(nir_block *block, nir_builder *b,
 149                        struct set *inlined)
 150 {
 151    bool progress = false;
 152    /* This is tricky.  We're iterating over instructions in a block but, as
 153     * we go, the block and its instruction list are being split into
 154     * pieces.  However, this *should* be safe since foreach_safe always
 155     * stashes the next thing in the iteration.  That next thing will
 156     * properly get moved to the next block when it gets split, and we
 157     * continue iterating there.
 158     */
 159    nir_foreach_instr_safe(instr, block) {
 160       if (instr->type != nir_instr_type_call)
 161          continue;
 162
 163       progress = true;
 164
 165       nir_call_instr *call = nir_instr_as_call(instr);
 166       assert(call->callee->impl);
 167
 168       inline_function_impl(call->callee->impl, inlined);
 169
 170       nir_function_impl *callee_copy =
 171          nir_function_impl_clone(call->callee->impl);
 172       callee_copy->function = call->callee;
 173
 174       /* Add copies of all in parameters */
 175       assert(call->num_params == callee_copy->num_params);
 176
 177       exec_list_append(&b->impl->locals, &callee_copy->locals);
 178       exec_list_append(&b->impl->registers, &callee_copy->registers);
 179
 180       b->cursor = nir_before_instr(&call->instr);
 181
 182       /* We now need to tie the two functions together using the
 183        * parameters.  There are two ways we do this: One is to turn the
 184        * parameter into a local variable and do a shadow-copy.  The other
 185        * is to treat the parameter as a "proxy" and rewrite derefs to use
 186        * the actual variable that comes from the call instruction.  We
 187        * implement both schemes.  The first is needed in the case where we
 188        * have an in parameter that we write or similar.  The second case is
 189        * needed for handling things such as images and uniforms properly.
 190        */
 191
 192       /* Figure out when we need to lower to a shadow local */
 193       nir_foreach_block(block, callee_copy) {
 194          lower_params_to_locals_block(block, callee_copy);
 195       }
 196
 197       for (unsigned i = 0; i < callee_copy->num_params; i++) {
 198          nir_variable *param = callee_copy->params[i];
 199
 200          if (param->data.mode == nir_var_local &&
 201              call->callee->params[i].param_type != nir_parameter_out) {
 202             nir_copy_deref_var(b, nir_deref_var_create(b->shader, param),
 203                                   call->params[i]);
 204          }
 205       }
 206
 207       nir_foreach_block(block, callee_copy) {
 208          nir_foreach_instr(instr, block)
 209             rewrite_param_derefs(instr, call);
 210       }
 211
 212       /* Pluck the body out of the function and place it here */
 213       nir_cf_list body;
 214       nir_cf_list_extract(&body, &callee_copy->body);
 215       nir_cf_reinsert(&body, b->cursor);
 216
 217       b->cursor = nir_before_instr(&call->instr);
 218
 219       /* Add copies of all out parameters and the return */
 220       assert(call->num_params == callee_copy->num_params);
 221       for (unsigned i = 0; i < callee_copy->num_params; i++) {
 222          nir_variable *param = callee_copy->params[i];
 223
 224          if (param->data.mode == nir_var_local &&
 225              call->callee->params[i].param_type != nir_parameter_in) {
 226             nir_copy_deref_var(b, call->params[i],
 227                                   nir_deref_var_create(b->shader, param));
 228          }
 229       }
 230       if (!glsl_type_is_void(call->callee->return_type) &&
 231           callee_copy->return_var->data.mode == nir_var_local) {
 232          nir_copy_deref_var(b, call->return_deref,
 233                                nir_deref_var_create(b->shader,
 234                                                     callee_copy->return_var));
 235       }
 236
 237       nir_instr_remove(&call->instr);
 238    }
 239
 240    return progress;
 241 }
 242
 243 static bool
 244 inline_function_impl(nir_function_impl *impl, struct set *inlined)
 245 {
 246    if (_mesa_set_search(inlined, impl))
 247       return false; /* Already inlined */
 248
 249    nir_builder b;
 250    nir_builder_init(&b, impl);
 251
 252    bool progress = false;
 253    nir_foreach_block_safe(block, impl) {
 254       progress |= inline_functions_block(block, &b, inlined);
 255    }
 256
 257    if (progress) {
 258       /* SSA and register indices are completely messed up now */
 259       nir_index_ssa_defs(impl);
 260       nir_index_local_regs(impl);
 261
 262       nir_metadata_preserve(impl, nir_metadata_none);
 263    }
 264
 265    _mesa_set_add(inlined, impl);
 266
 267    return progress;
 268 }
 269
 270 bool
 271 nir_inline_functions(nir_shader *shader)
 272 {
 273    struct set *inlined = _mesa_set_create(NULL, _mesa_hash_pointer,
 274                                           _mesa_key_pointer_equal);
 275    bool progress = false;
 276
 277    nir_foreach_function(function, shader) {
 278       if (function->impl)
 279          progress = inline_function_impl(function->impl, inlined) || progress;
 280    }
 281
 282    _mesa_set_destroy(inlined, NULL);
 283
 284    return progress;
 285 }