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/*
* Copyright © 2016 Intel Corporation
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice (including the next
* paragraph) shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*/
#ifndef NIR_PHI_BUILDER_H
#define NIR_PHI_BUILDER_H
#include "nir.h"
/** A helper for placing phi nodes in a NIR shader
*
* Basic usage goes something like this:
*
* each variable, var, has:
* a bitset var.defs of blocks where the variable is defined
* a struct nir_phi_builder_value *pb_val
*
* // initialize bitsets
* foreach block:
* foreach def of variable var:
* var.defs[def.block] = true;
*
* // initialize phi builder
* pb = nir_phi_builder_create()
* foreach var:
* var.pb_val = nir_phi_builder_add_value(pb, var.defs)
*
* // Visit each block. This needs to visit dominators first;
* // nir_foreach_block() will be ok.
*
* foreach block:
* foreach instruction:
* foreach use of variable var:
* replace use with nir_phi_builder_get_block_def(var.pb_val)
* foreach def of variable var:
* create ssa def, register with
* nir_phi_builder_set_block_def(var.pb_val)
*
* nir_phi_builder_finish(pb)
*/
struct nir_phi_builder;
struct nir_phi_builder_value;
/* Create a new phi builder.
*
* While this is fairly cheap, it does allocate some memory and walk the list
* of blocks so it's recommended that you only call it once and use it to
* build phis for several values.
*/
struct nir_phi_builder *nir_phi_builder_create(nir_function_impl *impl);
/* Register a value with the builder.
*
* The 'defs' parameter specifies a bitset of blocks in which the given value
* is defined. This is used to determine where to place the phi nodes.
*/
struct nir_phi_builder_value *
nir_phi_builder_add_value(struct nir_phi_builder *pb, unsigned num_components,
unsigned bit_size, const BITSET_WORD *defs);
/* Register a definition for the given value and block.
*
* It is safe to call this function as many times as you wish for any given
* block/value pair. However, it always replaces whatever was there
* previously even if that definition is from a phi node. The phi builder
* always uses the latest information it has, so you must be careful about the
* order in which you register definitions. The final value at the end of the
* block must be the last value registered.
*/
void
nir_phi_builder_value_set_block_def(struct nir_phi_builder_value *val,
nir_block *block, nir_ssa_def *def);
/* Get the definition for the given value in the given block.
*
* This definition will always be the latest definition known for the given
* block. If no definition is immediately available, it will crawl up the
* dominance tree and insert phi nodes as needed until it finds one. In the
* case that no suitable definition is found, it will return the result of a
* nir_ssa_undef_instr with the correct number of components.
*
* Because this function only uses the latest available information for any
* given block, you must have already finished registering definitions for any
* blocks that dominate the current block in order to get the correct result.
*/
nir_ssa_def *
nir_phi_builder_value_get_block_def(struct nir_phi_builder_value *val,
nir_block *block);
/* Finish building phi nodes and free the builder.
*
* This function does far more than just free memory. Prior to calling
* nir_phi_builder_finish, no phi nodes have actually been inserted in the
* program. This function is what finishes setting up phi node sources and
* adds the phi nodes to the program.
*/
void nir_phi_builder_finish(struct nir_phi_builder *pb);
#endif /* NIR_PHI_BUILDER_H */
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