| /* Generic dominator tree walker |
| Copyright (C) 2003-2017 Free Software Foundation, Inc. |
| Contributed by Diego Novillo <dnovillo@redhat.com> |
| |
| This file is part of GCC. |
| |
| GCC is free software; you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 3, or (at your option) |
| any later version. |
| |
| GCC is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| GNU General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with GCC; see the file COPYING3. If not see |
| <http://www.gnu.org/licenses/>. */ |
| |
| #ifndef GCC_DOM_WALK_H |
| #define GCC_DOM_WALK_H |
| |
| /** |
| * This is the main class for the dominator walker. It is expected that |
| * consumers will have a custom class inheriting from it, which will over ride |
| * at least one of before_dom_children and after_dom_children to implement the |
| * custom behavior. |
| */ |
| class dom_walker |
| { |
| public: |
| /* Use SKIP_UNREACHBLE_BLOCKS = true when your client can discover |
| that some edges are not executable. |
| |
| If a client can discover that a COND, SWITCH or GOTO has a static |
| target in the before_dom_children callback, the taken edge should |
| be returned. The generic walker will clear EDGE_EXECUTABLE on all |
| edges it can determine are not executable. */ |
| dom_walker (cdi_direction direction, bool skip_unreachable_blocks = false); |
| |
| /* Walk the dominator tree. */ |
| void walk (basic_block); |
| |
| /* Function to call before the recursive walk of the dominator children. |
| |
| Return value is the always taken edge if the block has multiple outgoing |
| edges, NULL otherwise. When skipping unreachable blocks, the walker |
| uses the taken edge information to clear EDGE_EXECUTABLE on the other |
| edges, exposing unreachable blocks. A NULL return value means all |
| outgoing edges should still be considered executable. */ |
| virtual edge before_dom_children (basic_block) { return NULL; } |
| |
| /* Function to call after the recursive walk of the dominator children. */ |
| virtual void after_dom_children (basic_block) {} |
| |
| private: |
| /* This is the direction of the dominator tree we want to walk. i.e., |
| if it is set to CDI_DOMINATORS, then we walk the dominator tree, |
| if it is set to CDI_POST_DOMINATORS, then we walk the post |
| dominator tree. */ |
| const ENUM_BITFIELD (cdi_direction) m_dom_direction : 2; |
| bool m_skip_unreachable_blocks; |
| basic_block m_unreachable_dom; |
| |
| /* Query whether or not the given block is reachable or not. */ |
| bool bb_reachable (struct function *, basic_block); |
| |
| /* Given an unreachable block, propagate that property to outgoing |
| and possibly incoming edges for the block. Typically called after |
| determining a block is unreachable in the before_dom_children |
| callback. */ |
| void propagate_unreachable_to_edges (basic_block, FILE *, int); |
| |
| }; |
| |
| #endif |