1 /*
2 * Copyright © 2019 Raspberry Pi
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_builder.h"
25
26 /** @file nir_lower_point_size.c
27 *
28 * The OpenGL spec requires that implementations clamp gl_PointSize to an
29 * implementation-dependant point size range. The OpenGL ES 3.0 spec further
30 * requires that this range must match GL_ALIASED_POINT_SIZE_RANGE.
31 * Some hardware such as V3D don't clamp to a valid range automatically so
32 * the driver must clamp the point size written by the shader manually to a
33 * valid range.
34 */
35
36 static void
lower_point_size_instr(nir_builder * b,nir_instr * psiz_instr,float min,float max)37 lower_point_size_instr(nir_builder *b, nir_instr *psiz_instr,
38 float min, float max)
39 {
40 b->cursor = nir_before_instr(psiz_instr);
41
42 nir_intrinsic_instr *instr = nir_instr_as_intrinsic(psiz_instr);
43
44 assert(instr->src[1].is_ssa);
45 assert(instr->src[1].ssa->num_components == 1);
46 nir_ssa_def *psiz = instr->src[1].ssa;
47
48 if (min > 0.0f)
49 psiz = nir_fmax(b, psiz, nir_imm_float(b, min));
50
51 if (max > 0.0f)
52 psiz = nir_fmin(b, psiz, nir_imm_float(b, max));
53
54 nir_instr_rewrite_src(&instr->instr, &instr->src[1], nir_src_for_ssa(psiz));
55 }
56
57 static bool
instr_is_point_size(const nir_instr * instr)58 instr_is_point_size(const nir_instr *instr)
59 {
60 if (instr->type != nir_instr_type_intrinsic)
61 return false;
62
63 nir_intrinsic_instr *intr = nir_instr_as_intrinsic(instr);
64 if (intr->intrinsic != nir_intrinsic_store_deref)
65 return false;
66
67 nir_deref_instr *deref = nir_src_as_deref(intr->src[0]);
68 nir_variable *var = nir_deref_instr_get_variable(deref);
69 if (var->data.location != VARYING_SLOT_PSIZ)
70 return false;
71
72 return true;
73 }
74
75 /**
76 * Clamps gl_PointSize to the range [min, max]. If either min or max are not
77 * greater than 0 then no clamping is done for that side of the range.
78 */
79 bool
nir_lower_point_size(nir_shader * s,float min,float max)80 nir_lower_point_size(nir_shader *s, float min, float max)
81 {
82 assert(s->info.stage != MESA_SHADER_FRAGMENT &&
83 s->info.stage != MESA_SHADER_COMPUTE);
84
85 assert(min > 0.0f || max > 0.0f);
86 assert(min <= 0.0f || max <= 0.0f || min <= max);
87
88 bool progress = false;
89 nir_foreach_function(function, s) {
90 if (!function->impl)
91 continue;
92
93 nir_builder b;
94 nir_builder_init(&b, function->impl);
95
96 nir_foreach_block(block, function->impl) {
97 nir_foreach_instr_safe(instr, block) {
98 if (instr_is_point_size(instr)) {
99 lower_point_size_instr(&b, instr, min, max);
100 progress = true;
101 }
102 }
103 }
104
105 if (progress) {
106 nir_metadata_preserve(function->impl,
107 nir_metadata_block_index |
108 nir_metadata_dominance);
109 }
110 }
111
112 return progress;
113 }
114