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_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 nir_deref_instr *parent =
43 nir_instr_as_deref(deref->parent.ssa->parent_instr);
44
45 assert(deref->deref_type == nir_deref_type_array);
46
47 if (nir_src_is_const(deref->arr.index) && index == NULL) {
48 /* We're still building a direct index */
49 unsigned index_in_array = nir_src_as_uint(deref->arr.index);
50
51 /* Section 5.11 (Out-of-Bounds Accesses) of the GLSL 4.60 spec says:
52 *
53 * In the subsections described above for array, vector, matrix and
54 * structure accesses, any out-of-bounds access produced undefined
55 * behavior.... Out-of-bounds reads return undefined values, which
56 * include values from other variables of the active program or zero.
57 *
58 * Robustness extensions suggest to return zero on out-of-bounds
59 * accesses, however it's not applicable to the arrays of samplers,
60 * so just clamp the index.
61 *
62 * Otherwise instr->sampler_index or instr->texture_index would be out
63 * of bounds, and they are used as an index to arrays of driver state.
64 */
65 if (index_in_array < glsl_array_size(parent->type)) {
66 base_index += index_in_array * array_elements;
67 } else {
68 base_index = glsl_array_size(parent->type) - 1;
69 }
70 } else {
71 if (index == NULL) {
72 /* We used to be direct but not anymore */
73 index = nir_imm_int(b, base_index);
74 base_index = 0;
75 }
76
77 index = nir_iadd(b, index,
78 nir_imul_imm(b,
79 deref->arr.index.ssa,
80 array_elements));
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_src_rewrite(&src->src, index);
101
102 src->src_type = is_sampler ? nir_tex_src_sampler_offset : nir_tex_src_texture_offset;
103 } else {
104 nir_tex_instr_remove_src(instr, src_idx);
105 }
106
107 if (is_sampler) {
108 instr->sampler_index = base_index;
109 } else {
110 instr->texture_index = base_index;
111 }
112 }
113
114 static bool
lower_sampler(nir_builder * b,nir_instr * instr_,UNUSED void * cb_data)115 lower_sampler(nir_builder *b, nir_instr *instr_, UNUSED void *cb_data)
116 {
117 if (instr_->type != nir_instr_type_tex)
118 return false;
119
120 nir_tex_instr *instr = nir_instr_as_tex(instr_);
121
122 int texture_idx =
123 nir_tex_instr_src_index(instr, nir_tex_src_texture_deref);
124
125 if (texture_idx >= 0) {
126 b->cursor = nir_before_instr(&instr->instr);
127
128 lower_tex_src_to_offset(b, instr, texture_idx);
129 }
130
131 int sampler_idx =
132 nir_tex_instr_src_index(instr, nir_tex_src_sampler_deref);
133
134 if (sampler_idx >= 0) {
135 lower_tex_src_to_offset(b, instr, sampler_idx);
136 }
137
138 if (texture_idx < 0 && sampler_idx < 0)
139 return false;
140
141 return true;
142 }
143
144 bool
nir_lower_samplers(nir_shader * shader)145 nir_lower_samplers(nir_shader *shader)
146 {
147 return nir_shader_instructions_pass(shader, lower_sampler,
148 nir_metadata_control_flow,
149 NULL);
150 }
151