1 /*
2 * Copyright (C) 2005-2007 Brian Paul All Rights Reserved.
3 * Copyright (C) 2008 VMware, Inc. All Rights Reserved.
4 * Copyright © 2014 Intel Corporation
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a
7 * copy of this software and associated documentation files (the "Software"),
8 * to deal in the Software without restriction, including without limitation
9 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
10 * and/or sell copies of the Software, and to permit persons to whom the
11 * Software is furnished to do so, subject to the following conditions:
12 *
13 * The above copyright notice and this permission notice (including the next
14 * paragraph) shall be included in all copies or substantial portions of the
15 * Software.
16 *
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
20 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
21 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
22 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
23 * DEALINGS IN THE SOFTWARE.
24 */
25
26 #include "nir/nir.h"
27 #include "nir_builder.h"
28
29 static void
lower_tex_src_to_offset(nir_builder * b,nir_tex_instr * instr,unsigned src_idx)30 lower_tex_src_to_offset(nir_builder *b,
31 nir_tex_instr *instr, unsigned src_idx)
32 {
33 nir_ssa_def *index = NULL;
34 unsigned base_index = 0;
35 unsigned array_elements = 1;
36 nir_tex_src *src = &instr->src[src_idx];
37 bool is_sampler = src->src_type == nir_tex_src_sampler_deref;
38
39 /* We compute first the offsets */
40 nir_deref_instr *deref = nir_instr_as_deref(src->src.ssa->parent_instr);
41 while (deref->deref_type != nir_deref_type_var) {
42 assert(deref->parent.is_ssa);
43 nir_deref_instr *parent =
44 nir_instr_as_deref(deref->parent.ssa->parent_instr);
45
46 assert(deref->deref_type == nir_deref_type_array);
47
48 if (nir_src_is_const(deref->arr.index) && index == NULL) {
49 /* We're still building a direct index */
50 unsigned index_in_array = nir_src_as_uint(deref->arr.index);
51
52 /* Section 5.11 (Out-of-Bounds Accesses) of the GLSL 4.60 spec says:
53 *
54 * In the subsections described above for array, vector, matrix and
55 * structure accesses, any out-of-bounds access produced undefined
56 * behavior.... Out-of-bounds reads return undefined values, which
57 * include values from other variables of the active program or zero.
58 *
59 * Robustness extensions suggest to return zero on out-of-bounds
60 * accesses, however it's not applicable to the arrays of samplers,
61 * so just clamp the index.
62 *
63 * Otherwise instr->sampler_index or instr->texture_index would be out
64 * of bounds, and they are used as an index to arrays of driver state.
65 */
66 if (index_in_array < glsl_array_size(parent->type)) {
67 base_index += index_in_array * array_elements;
68 } else {
69 base_index = glsl_array_size(parent->type) - 1;
70 }
71 } else {
72 if (index == NULL) {
73 /* We used to be direct but not anymore */
74 index = nir_imm_int(b, base_index);
75 base_index = 0;
76 }
77
78 index = nir_iadd(b, index,
79 nir_imul(b, nir_imm_int(b, array_elements),
80 nir_ssa_for_src(b, deref->arr.index, 1)));
81 }
82
83 array_elements *= glsl_get_length(parent->type);
84
85 deref = parent;
86 }
87
88 if (index)
89 index = nir_umin(b, index, nir_imm_int(b, array_elements - 1));
90
91 /* We hit the deref_var. This is the end of the line */
92 assert(deref->deref_type == nir_deref_type_var);
93
94 base_index += deref->var->data.binding;
95
96 /* We have the offsets, we apply them, rewriting the source or removing
97 * instr if needed
98 */
99 if (index) {
100 nir_instr_rewrite_src(&instr->instr, &src->src,
101 nir_src_for_ssa(index));
102
103 src->src_type = is_sampler ?
104 nir_tex_src_sampler_offset :
105 nir_tex_src_texture_offset;
106 } else {
107 nir_tex_instr_remove_src(instr, src_idx);
108 }
109
110 if (is_sampler) {
111 instr->sampler_index = base_index;
112 } else {
113 instr->texture_index = base_index;
114 }
115 }
116
117 static bool
lower_sampler(nir_builder * b,nir_tex_instr * instr)118 lower_sampler(nir_builder *b, nir_tex_instr *instr)
119 {
120 int texture_idx =
121 nir_tex_instr_src_index(instr, nir_tex_src_texture_deref);
122
123 if (texture_idx >= 0) {
124 b->cursor = nir_before_instr(&instr->instr);
125
126 lower_tex_src_to_offset(b, instr, texture_idx);
127 }
128
129 int sampler_idx =
130 nir_tex_instr_src_index(instr, nir_tex_src_sampler_deref);
131
132 if (sampler_idx >= 0) {
133 lower_tex_src_to_offset(b, instr, sampler_idx);
134 }
135
136 if (texture_idx < 0 && sampler_idx < 0)
137 return false;
138
139 return true;
140 }
141
142 static bool
lower_impl(nir_function_impl * impl)143 lower_impl(nir_function_impl *impl)
144 {
145 nir_builder b;
146 nir_builder_init(&b, impl);
147 bool progress = false;
148
149 nir_foreach_block(block, impl) {
150 nir_foreach_instr(instr, block) {
151 if (instr->type == nir_instr_type_tex)
152 progress |= lower_sampler(&b, nir_instr_as_tex(instr));
153 }
154 }
155
156 if (progress) {
157 nir_metadata_preserve(impl, nir_metadata_block_index |
158 nir_metadata_dominance);
159 } else {
160 nir_metadata_preserve(impl, nir_metadata_all);
161 }
162
163 return progress;
164 }
165
166 bool
nir_lower_samplers(nir_shader * shader)167 nir_lower_samplers(nir_shader *shader)
168 {
169 bool progress = false;
170
171 /* Next, lower derefs to offsets. */
172 nir_foreach_function(function, shader) {
173 if (function->impl)
174 progress |= lower_impl(function->impl);
175 }
176
177 return progress;
178 }
179