src/compiler/nir/nir_phi_builder.h

   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 #pragma once
  25
  26 #include "nir.h"
  27
  28 struct nir_phi_builder;
  29 struct nir_phi_builder_value;
  30
  31 /* Create a new phi builder.
  32  *
  33  * While this is fairly cheap, it does allocate some memory and walk the list
  34  * of blocks so it's recommended that you only call it once and use it to
  35  * build phis for several values.
  36  */
  37 struct nir_phi_builder *nir_phi_builder_create(nir_function_impl *impl);
  38
  39 /* Register a value with the builder.
  40  *
  41  * The 'defs' parameter specifies a bitset of blocks in which the given value
  42  * is defined.  This is used to determine where to place the phi nodes.
  43  */
  44 struct nir_phi_builder_value *
  45 nir_phi_builder_add_value(struct nir_phi_builder *pb, unsigned num_components,
  46                           const BITSET_WORD *defs);
  47
  48 /* Register a definition for the given value and block.
  49  *
  50  * It is safe to call this function as many times as you wish for any given
  51  * block/value pair.  However, it always replaces whatever was there
  52  * previously even if that definition is from a phi node.  The phi builder
  53  * always uses the latest information it has, so you must be careful about the
  54  * order in which you register definitions.  The final value at the end of the
  55  * block must be the last value registered.
  56  */
  57 void
  58 nir_phi_builder_value_set_block_def(struct nir_phi_builder_value *val,
  59                                     nir_block *block, nir_ssa_def *def);
  60
  61 /* Get the definition for the given value in the given block.
  62  *
  63  * This definition will always be the latest definition known for the given
  64  * block.  If no definition is immediately available, it will crawl up the
  65  * dominance tree and insert phi nodes as needed until it finds one.  In the
  66  * case that no suitable definition is found, it will return the result of a
  67  * nir_ssa_undef_instr with the correct number of components.
  68  *
  69  * Because this function only uses the latest available information for any
  70  * given block, you must have already finished registering definitions for any
  71  * blocks that dominate the current block in order to get the correct result.
  72  */
  73 nir_ssa_def *
  74 nir_phi_builder_value_get_block_def(struct nir_phi_builder_value *val,
  75                                     nir_block *block);
  76
  77 /* Finish building phi nodes and free the builder.
  78  *
  79  * This function does far more than just free memory.  Prior to calling
  80  * nir_phi_builder_finish, no phi nodes have actually been inserted in the
  81  * program.  This function is what finishes setting up phi node sources and
  82  * adds the phi nodes to the program.
  83  */
  84 void nir_phi_builder_finish(struct nir_phi_builder *pb);