| /* |
| * Copyright © 2014 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. |
| * |
| * Authors: |
| * Connor Abbott (cwabbott0@gmail.com) |
| * |
| */ |
| |
| #ifndef NIR_CONTROL_FLOW_H |
| #define NIR_CONTROL_FLOW_H |
| |
| #include "nir.h" |
| |
| #ifdef __cplusplus |
| extern "C" { |
| #endif |
| |
| /** NIR Control Flow Modification |
| * |
| * This file contains various APIs that make modifying control flow in NIR, |
| * while maintaining the invariants checked by the validator, much easier. |
| * There are two parts to this: |
| * |
| * 1. Inserting control flow (ifs and loops) in various places, for creating |
| * IR either from scratch or as part of some lowering pass. |
| * 2. Taking existing pieces of the IR and either moving them around or |
| * deleting them. |
| */ |
| |
| /** Control flow insertion. */ |
| |
| /** puts a control flow node where the cursor is */ |
| void nir_cf_node_insert(nir_cursor cursor, nir_cf_node *node); |
| |
| /** puts a control flow node immediately after another control flow node */ |
| static inline void |
| nir_cf_node_insert_after(nir_cf_node *node, nir_cf_node *after) |
| { |
| nir_cf_node_insert(nir_after_cf_node(node), after); |
| } |
| |
| /** puts a control flow node immediately before another control flow node */ |
| static inline void |
| nir_cf_node_insert_before(nir_cf_node *node, nir_cf_node *before) |
| { |
| nir_cf_node_insert(nir_before_cf_node(node), before); |
| } |
| |
| /** puts a control flow node at the beginning of a list from an if, loop, or function */ |
| static inline void |
| nir_cf_node_insert_begin(struct exec_list *list, nir_cf_node *node) |
| { |
| nir_cf_node_insert(nir_before_cf_list(list), node); |
| } |
| |
| /** puts a control flow node at the end of a list from an if, loop, or function */ |
| static inline void |
| nir_cf_node_insert_end(struct exec_list *list, nir_cf_node *node) |
| { |
| nir_cf_node_insert(nir_after_cf_list(list), node); |
| } |
| |
| |
| /** Control flow motion. |
| * |
| * These functions let you take a part of a control flow list (basically |
| * equivalent to a series of statement in GLSL) and "extract" it from the IR, |
| * so that it's a free-floating piece of IR that can be either re-inserted |
| * somewhere else or deleted entirely. A few notes on using it: |
| * |
| * 1. Phi nodes are considered attached to the piece of control flow that |
| * their sources come from. There are three places where phi nodes can |
| * occur, which are the three places where a block can have multiple |
| * predecessors: |
| * |
| * 1) After an if statement, if neither branch ends in a jump. |
| * 2) After a loop, if there are multiple breaks. |
| * 3) At the beginning of a loop. |
| * |
| * For #1, the phi node is considered to be part of the if, and for #2 and |
| * #3 the phi node is considered to be part of the loop. This allows us to |
| * keep phis intact, but it means that phi nodes cannot be separated from |
| * the control flow they come from. For example, extracting an if without |
| * extracting all the phi nodes after it is not allowed, and neither is |
| * extracting only some of the phi nodes at the beginning of a block. It |
| * also means that extracting from the beginning of a basic block actually |
| * means extracting from the first non-phi instruction, since there's no |
| * situation where extracting phi nodes without extracting what comes |
| * before them makes any sense. |
| * |
| * 2. Phi node sources are guaranteed to remain valid, meaning that they still |
| * correspond one-to-one with the predecessors of the basic block they're |
| * part of. In addition, the original sources will be preserved unless they |
| * correspond to a break or continue that was deleted. However, no attempt |
| * is made to ensure that SSA form is maintained. In particular, it is |
| * *not* guaranteed that definitions of SSA values will dominate all their |
| * uses after all is said and done. Either the caller must ensure that this |
| * is the case, or it must insert extra phi nodes to restore SSA. |
| * |
| * 3. It is invalid to move a piece of IR with a break/continue outside of the |
| * loop it references. Doing this will result in invalid |
| * successors/predecessors and phi node sources. |
| * |
| * 4. It is invalid to move a piece of IR from one function implementation to |
| * another. |
| * |
| * 5. Extracting a control flow list will leave lots of dangling references to |
| * and from other pieces of the IR. It also leaves things in a not 100% |
| * consistent state. This means that some things (e.g. inserting |
| * instructions) might not work reliably on the extracted control flow. It |
| * also means that extracting control flow without re-inserting it or |
| * deleting it is a Bad Thing (tm). |
| */ |
| |
| typedef struct { |
| struct exec_list list; |
| nir_function_impl *impl; /* for cleaning up if the list is deleted */ |
| } nir_cf_list; |
| |
| void nir_cf_extract(nir_cf_list *extracted, nir_cursor begin, nir_cursor end); |
| |
| void nir_cf_reinsert(nir_cf_list *cf_list, nir_cursor cursor); |
| |
| void nir_cf_delete(nir_cf_list *cf_list); |
| |
| void nir_cf_list_clone(nir_cf_list *dst, nir_cf_list *src, nir_cf_node *parent, |
| struct hash_table *remap_table); |
| |
| static inline void |
| nir_cf_list_clone_and_reinsert(nir_cf_list *src_list, nir_cf_node *parent, |
| nir_cursor cursor, |
| struct hash_table *remap_table) |
| { |
| nir_cf_list list; |
| nir_cf_list_clone(&list, src_list, parent, remap_table); |
| nir_cf_reinsert(&list, cursor); |
| } |
| |
| static inline void |
| nir_cf_list_extract(nir_cf_list *extracted, struct exec_list *cf_list) |
| { |
| nir_cf_extract(extracted, nir_before_cf_list(cf_list), |
| nir_after_cf_list(cf_list)); |
| } |
| |
| /** removes a control flow node, doing any cleanup necessary */ |
| static inline void |
| nir_cf_node_remove(nir_cf_node *node) |
| { |
| nir_cf_list list; |
| nir_cf_extract(&list, nir_before_cf_node(node), nir_after_cf_node(node)); |
| nir_cf_delete(&list); |
| } |
| |
| #ifdef __cplusplus |
| } |
| #endif |
| |
| #endif /* NIR_CONTROL_FLOW_H */ |