1 /* 2 * Copyright 2015 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 DEALINGS 21 * IN THE SOFTWARE. 22 */ 23 24 #include "nir.h" 25 #include "nir_builder.h" 26 27 static nir_intrinsic_instr * 28 as_intrinsic(nir_instr *instr, nir_intrinsic_op op) 29 { 30 if (instr->type != nir_instr_type_intrinsic) 31 return NULL; 32 33 nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr); 34 if (intrin->intrinsic != op) 35 return NULL; 36 37 return intrin; 38 } 39 40 static nir_intrinsic_instr * 41 as_set_vertex_count(nir_instr *instr) 42 { 43 return as_intrinsic(instr, nir_intrinsic_set_vertex_count); 44 } 45 46 /** 47 * If a geometry shader emits a constant number of vertices, return the 48 * number of vertices. Otherwise, return -1 (unknown). 49 * 50 * This only works if you've used nir_lower_gs_intrinsics() to do vertex 51 * counting at the NIR level. 52 */ 53 int 54 nir_gs_count_vertices(const nir_shader *shader) 55 { 56 int count = -1; 57 58 nir_foreach_function(function, shader) { 59 if (!function->impl) 60 continue; 61 62 /* set_vertex_count intrinsics only appear in predecessors of the 63 * end block. So we don't need to walk all of them. 64 */ 65 struct set_entry *entry; 66 set_foreach(function->impl->end_block->predecessors, entry) { 67 nir_block *block = (nir_block *) entry->key; 68 69 nir_foreach_instr_reverse(instr, block) { 70 nir_intrinsic_instr *intrin = as_set_vertex_count(instr); 71 if (!intrin) 72 continue; 73 74 nir_const_value *val = nir_src_as_const_value(intrin->src[0]); 75 /* We've found a non-constant value. Bail. */ 76 if (!val) 77 return -1; 78 79 if (count == -1) 80 count = val->i32[0]; 81 82 /* We've found contradictory set_vertex_count intrinsics. 83 * This can happen if there are early-returns in main() and 84 * different paths emit different numbers of vertices. 85 */ 86 if (count != val->i32[0]) 87 return -1; 88 } 89 } 90 } 91 92 return count; 93 } 94