1/* 2 * Copyright © 2018 Valve 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 25#ifndef ACO_DOMINANCE_CPP 26#define ACO_DOMINANCE_CPP 27 28#include "aco_ir.h" 29 30/* 31 * Implements the algorithms for computing the dominator tree from 32 * "A Simple, Fast Dominance Algorithm" by Cooper, Harvey, and Kennedy. 33 * 34 * Different from the paper, our CFG allows to compute the dominator tree 35 * in a single pass as it is guaranteed that the dominating predecessors 36 * are processed before the current block. 37 */ 38 39namespace aco { 40 41void 42dominator_tree(Program* program) 43{ 44 program->blocks[0].logical_idom = 0; 45 program->blocks[0].linear_idom = 0; 46 47 for (unsigned i = 1; i < program->blocks.size(); i++) { 48 Block& block = program->blocks[i]; 49 int new_logical_idom = -1; 50 int new_linear_idom = -1; 51 for (unsigned pred_idx : block.logical_preds) { 52 if ((int)program->blocks[pred_idx].logical_idom == -1) 53 continue; 54 55 if (new_logical_idom == -1) { 56 new_logical_idom = pred_idx; 57 continue; 58 } 59 60 while ((int)pred_idx != new_logical_idom) { 61 if ((int)pred_idx > new_logical_idom) 62 pred_idx = program->blocks[pred_idx].logical_idom; 63 if ((int)pred_idx < new_logical_idom) 64 new_logical_idom = program->blocks[new_logical_idom].logical_idom; 65 } 66 } 67 68 for (unsigned pred_idx : block.linear_preds) { 69 if ((int)program->blocks[pred_idx].linear_idom == -1) 70 continue; 71 72 if (new_linear_idom == -1) { 73 new_linear_idom = pred_idx; 74 continue; 75 } 76 77 while ((int)pred_idx != new_linear_idom) { 78 if ((int)pred_idx > new_linear_idom) 79 pred_idx = program->blocks[pred_idx].linear_idom; 80 if ((int)pred_idx < new_linear_idom) 81 new_linear_idom = program->blocks[new_linear_idom].linear_idom; 82 } 83 } 84 85 block.logical_idom = new_logical_idom; 86 block.linear_idom = new_linear_idom; 87 } 88} 89 90} // namespace aco 91#endif 92