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 *
as_intrinsic(nir_instr * instr,nir_intrinsic_op op)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 *
as_set_vertex_count(nir_instr * 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
nir_gs_count_vertices(const nir_shader * shader)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