1 /* 2 * Copyright 2013 Intel 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 21 * DEALINGS IN THE SOFTWARE. 22 */ 23 24 /** 25 * \file opt_flatten_nested_if_blocks.cpp 26 * 27 * Flattens nested if blocks such as: 28 * 29 * if (x) { 30 * if (y) { 31 * ... 32 * } 33 * } 34 * 35 * into a single if block with a combined condition: 36 * 37 * if (x && y) { 38 * ... 39 * } 40 */ 41 42 #include "ir.h" 43 #include "ir_builder.h" 44 45 using namespace ir_builder; 46 47 namespace { 48 49 class nested_if_flattener : public ir_hierarchical_visitor { 50 public: 51 nested_if_flattener() 52 { 53 progress = false; 54 } 55 56 ir_visitor_status visit_leave(ir_if *); 57 ir_visitor_status visit_enter(ir_assignment *); 58 59 bool progress; 60 }; 61 62 } /* unnamed namespace */ 63 64 /* We only care about the top level "if" instructions, so don't 65 * descend into expressions. 66 */ 67 ir_visitor_status 68 nested_if_flattener::visit_enter(ir_assignment *ir) 69 { 70 (void) ir; 71 return visit_continue_with_parent; 72 } 73 74 bool 75 opt_flatten_nested_if_blocks(exec_list *instructions) 76 { 77 nested_if_flattener v; 78 79 v.run(instructions); 80 return v.progress; 81 } 82 83 84 ir_visitor_status 85 nested_if_flattener::visit_leave(ir_if *ir) 86 { 87 /* Only handle a single ir_if within the then clause of an ir_if. No extra 88 * instructions, no else clauses, nothing. 89 */ 90 if (ir->then_instructions.is_empty() || !ir->else_instructions.is_empty()) 91 return visit_continue; 92 93 ir_if *inner = ((ir_instruction *) ir->then_instructions.get_head_raw())->as_if(); 94 if (!inner || !inner->next->is_tail_sentinel() || 95 !inner->else_instructions.is_empty()) 96 return visit_continue; 97 98 ir->condition = logic_and(ir->condition, inner->condition); 99 inner->then_instructions.move_nodes_to(&ir->then_instructions); 100 101 progress = true; 102 return visit_continue; 103 } 104