183 lines
6.9 KiB
C
183 lines
6.9 KiB
C
/*
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* Copyright © 2014 Intel Corporation
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice (including the next
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* paragraph) shall be included in all copies or substantial portions of the
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* Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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* IN THE SOFTWARE.
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*
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* Authors:
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* Connor Abbott (cwabbott0@gmail.com)
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*
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*/
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#ifndef NIR_CONTROL_FLOW_H
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#define NIR_CONTROL_FLOW_H
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#include "nir.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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/** NIR Control Flow Modification
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*
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* This file contains various APIs that make modifying control flow in NIR,
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* while maintaining the invariants checked by the validator, much easier.
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* There are two parts to this:
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*
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* 1. Inserting control flow (ifs and loops) in various places, for creating
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* IR either from scratch or as part of some lowering pass.
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* 2. Taking existing pieces of the IR and either moving them around or
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* deleting them.
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*/
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/** Control flow insertion. */
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/** puts a control flow node where the cursor is */
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void nir_cf_node_insert(nir_cursor cursor, nir_cf_node *node);
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/** puts a control flow node immediately after another control flow node */
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static inline void
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nir_cf_node_insert_after(nir_cf_node *node, nir_cf_node *after)
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{
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nir_cf_node_insert(nir_after_cf_node(node), after);
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}
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/** puts a control flow node immediately before another control flow node */
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static inline void
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nir_cf_node_insert_before(nir_cf_node *node, nir_cf_node *before)
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{
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nir_cf_node_insert(nir_before_cf_node(node), before);
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}
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/** puts a control flow node at the beginning of a list from an if, loop, or function */
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static inline void
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nir_cf_node_insert_begin(struct exec_list *list, nir_cf_node *node)
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{
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nir_cf_node_insert(nir_before_cf_list(list), node);
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}
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/** puts a control flow node at the end of a list from an if, loop, or function */
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static inline void
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nir_cf_node_insert_end(struct exec_list *list, nir_cf_node *node)
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{
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nir_cf_node_insert(nir_after_cf_list(list), node);
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}
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/** Control flow motion.
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*
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* These functions let you take a part of a control flow list (basically
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* equivalent to a series of statement in GLSL) and "extract" it from the IR,
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* so that it's a free-floating piece of IR that can be either re-inserted
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* somewhere else or deleted entirely. A few notes on using it:
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*
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* 1. Phi nodes are considered attached to the piece of control flow that
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* their sources come from. There are three places where phi nodes can
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* occur, which are the three places where a block can have multiple
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* predecessors:
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*
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* 1) After an if statement, if neither branch ends in a jump.
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* 2) After a loop, if there are multiple breaks.
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* 3) At the beginning of a loop.
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*
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* For #1, the phi node is considered to be part of the if, and for #2 and
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* #3 the phi node is considered to be part of the loop. This allows us to
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* keep phis intact, but it means that phi nodes cannot be separated from
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* the control flow they come from. For example, extracting an if without
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* extracting all the phi nodes after it is not allowed, and neither is
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* extracting only some of the phi nodes at the beginning of a block. It
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* also means that extracting from the beginning of a basic block actually
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* means extracting from the first non-phi instruction, since there's no
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* situation where extracting phi nodes without extracting what comes
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* before them makes any sense.
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*
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* 2. Phi node sources are guaranteed to remain valid, meaning that they still
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* correspond one-to-one with the predecessors of the basic block they're
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* part of. In addition, the original sources will be preserved unless they
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* correspond to a break or continue that was deleted. However, no attempt
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* is made to ensure that SSA form is maintained. In particular, it is
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* *not* guaranteed that definitions of SSA values will dominate all their
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* uses after all is said and done. Either the caller must ensure that this
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* is the case, or it must insert extra phi nodes to restore SSA.
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*
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* 3. It is invalid to move a piece of IR with a break/continue outside of the
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* loop it references. Doing this will result in invalid
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* successors/predecessors and phi node sources.
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*
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* 4. It is invalid to move a piece of IR from one function implementation to
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* another.
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*
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* 5. Extracting a control flow list will leave lots of dangling references to
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* and from other pieces of the IR. It also leaves things in a not 100%
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* consistent state. This means that some things (e.g. inserting
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* instructions) might not work reliably on the extracted control flow. It
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* also means that extracting control flow without re-inserting it or
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* deleting it is a Bad Thing (tm).
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*/
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typedef struct {
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struct exec_list list;
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nir_function_impl *impl; /* for cleaning up if the list is deleted */
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} nir_cf_list;
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nir_cursor nir_cf_extract(nir_cf_list *extracted, nir_cursor begin,
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nir_cursor end);
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nir_cursor nir_cf_reinsert(nir_cf_list *cf_list, nir_cursor cursor);
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void nir_cf_delete(nir_cf_list *cf_list);
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void nir_cf_list_clone(nir_cf_list *dst, nir_cf_list *src, nir_cf_node *parent,
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struct hash_table *remap_table);
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static inline void
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nir_cf_list_clone_and_reinsert(nir_cf_list *src_list, nir_cf_node *parent,
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nir_cursor cursor,
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struct hash_table *remap_table)
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{
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nir_cf_list list;
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nir_cf_list_clone(&list, src_list, parent, remap_table);
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nir_cf_reinsert(&list, cursor);
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}
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static inline void
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nir_cf_list_extract(nir_cf_list *extracted, struct exec_list *cf_list)
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{
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nir_cf_extract(extracted, nir_before_cf_list(cf_list),
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nir_after_cf_list(cf_list));
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}
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/** removes a control flow node, doing any cleanup necessary */
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static inline void
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nir_cf_node_remove(nir_cf_node *node)
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{
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nir_cf_list list;
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nir_cf_extract(&list, nir_before_cf_node(node), nir_after_cf_node(node));
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nir_cf_delete(&list);
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}
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/** inserts undef phi sources from predcessor into phis of the block */
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void nir_insert_phi_undef(nir_block *block, nir_block *pred);
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#ifdef __cplusplus
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}
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#endif
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#endif /* NIR_CONTROL_FLOW_H */
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