1 /*
2 * Copyright © 2020 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_builder.h"
25
26 static bool
opt_memcpy_deref_cast(nir_intrinsic_instr * cpy,nir_src * deref_src)27 opt_memcpy_deref_cast(nir_intrinsic_instr *cpy, nir_src *deref_src)
28 {
29 assert(cpy->intrinsic == nir_intrinsic_memcpy_deref);
30
31 nir_deref_instr *cast = nir_src_as_deref(*deref_src);
32 if (cast == NULL || cast->deref_type != nir_deref_type_cast)
33 return false;
34
35 /* We always have to replace the source with a deref, not a bare uint
36 * pointer. If it's the first deref in the chain, bail.
37 */
38 nir_deref_instr *parent = nir_src_as_deref(cast->parent);
39 if (parent == NULL)
40 return false;
41
42 /* If it has useful alignment information, we want to keep that */
43 if (cast->cast.align_mul > 0)
44 return false;
45
46 /* Casts to uint8 or int8 never do us any good; get rid of them */
47 if (cast->type == glsl_int8_t_type() ||
48 cast->type == glsl_uint8_t_type()) {
49 nir_instr_rewrite_src(&cpy->instr, deref_src,
50 nir_src_for_ssa(&parent->dest.ssa));
51 return true;
52 }
53
54 int64_t parent_type_size = glsl_get_explicit_size(parent->type, false);
55 if (parent_type_size < 0)
56 return false;
57
58 if (!nir_src_is_const(cpy->src[2]))
59 return false;
60
61 /* We don't want to get rid of the cast if the resulting type would be
62 * smaller than the amount of data we're copying.
63 */
64 if (nir_src_as_uint(cpy->src[2]) < (uint64_t)parent_type_size)
65 return false;
66
67 nir_instr_rewrite_src(&cpy->instr, deref_src,
68 nir_src_for_ssa(&parent->dest.ssa));
69 return true;
70 }
71
72 static bool
type_is_tightly_packed(const struct glsl_type * type,unsigned * size_out)73 type_is_tightly_packed(const struct glsl_type *type, unsigned *size_out)
74 {
75 unsigned size = 0;
76 if (glsl_type_is_struct_or_ifc(type)) {
77 unsigned num_fields = glsl_get_length(type);
78 for (unsigned i = 0; i < num_fields; i++) {
79 const struct glsl_struct_field *field =
80 glsl_get_struct_field_data(type, i);
81
82 if (field->offset < 0 || field->offset != size)
83 return false;
84
85 unsigned field_size;
86 if (!type_is_tightly_packed(field->type, &field_size))
87 return false;
88
89 size = field->offset + field_size;
90 }
91 } else if (glsl_type_is_array_or_matrix(type)) {
92 if (glsl_type_is_unsized_array(type))
93 return false;
94
95 unsigned stride = glsl_get_explicit_stride(type);
96 if (stride == 0)
97 return false;
98
99 const struct glsl_type *elem_type = glsl_get_array_element(type);
100
101 unsigned elem_size;
102 if (!type_is_tightly_packed(elem_type, &elem_size))
103 return false;
104
105 if (elem_size != stride)
106 return false;
107
108 size = stride * glsl_get_length(type);
109 } else {
110 assert(glsl_type_is_vector_or_scalar(type));
111 if (glsl_get_explicit_stride(type) > 0)
112 return false;
113
114 if (glsl_type_is_boolean(type))
115 return false;
116
117 size = glsl_get_explicit_size(type, false);
118 }
119
120 if (size_out)
121 *size_out = size;
122 return true;
123 }
124
125 static bool
try_lower_memcpy(nir_builder * b,nir_intrinsic_instr * cpy)126 try_lower_memcpy(nir_builder *b, nir_intrinsic_instr *cpy)
127 {
128 nir_deref_instr *dst = nir_src_as_deref(cpy->src[0]);
129 nir_deref_instr *src = nir_src_as_deref(cpy->src[1]);
130
131 /* A self-copy can always be eliminated */
132 if (dst == src) {
133 nir_instr_remove(&cpy->instr);
134 return true;
135 }
136
137 if (!nir_src_is_const(cpy->src[2]))
138 return false;
139
140 uint64_t size = nir_src_as_uint(cpy->src[2]);
141 if (size == 0) {
142 nir_instr_remove(&cpy->instr);
143 return true;
144 }
145
146 if (glsl_type_is_vector_or_scalar(src->type) &&
147 glsl_type_is_vector_or_scalar(dst->type) &&
148 glsl_get_explicit_size(dst->type, false) == size &&
149 glsl_get_explicit_size(src->type, false) == size) {
150 b->cursor = nir_instr_remove(&cpy->instr);
151 nir_ssa_def *data =
152 nir_load_deref_with_access(b, src, nir_intrinsic_src_access(cpy));
153 data = nir_bitcast_vector(b, data, glsl_get_bit_size(dst->type));
154 assert(data->num_components == glsl_get_vector_elements(dst->type));
155 nir_store_deref_with_access(b, dst, data, ~0 /* write mask */,
156 nir_intrinsic_dst_access(cpy));
157 return true;
158 }
159
160 unsigned type_size;
161 if (dst->type == src->type &&
162 type_is_tightly_packed(dst->type, &type_size) &&
163 type_size == size) {
164 b->cursor = nir_instr_remove(&cpy->instr);
165 nir_copy_deref_with_access(b, dst, src,
166 nir_intrinsic_dst_access(cpy),
167 nir_intrinsic_src_access(cpy));
168 return true;
169 }
170
171 return false;
172 }
173
174 static bool
opt_memcpy_impl(nir_function_impl * impl)175 opt_memcpy_impl(nir_function_impl *impl)
176 {
177 bool progress = false;
178
179 nir_builder b;
180 nir_builder_init(&b, impl);
181
182 nir_foreach_block(block, impl) {
183 nir_foreach_instr_safe(instr, block) {
184 if (instr->type != nir_instr_type_intrinsic)
185 continue;
186
187 nir_intrinsic_instr *cpy = nir_instr_as_intrinsic(instr);
188 if (cpy->intrinsic != nir_intrinsic_memcpy_deref)
189 continue;
190
191 while (opt_memcpy_deref_cast(cpy, &cpy->src[0]))
192 progress = true;
193 while (opt_memcpy_deref_cast(cpy, &cpy->src[1]))
194 progress = true;
195
196 if (try_lower_memcpy(&b, cpy)) {
197 progress = true;
198 continue;
199 }
200 }
201 }
202
203 if (progress) {
204 nir_metadata_preserve(impl, nir_metadata_block_index |
205 nir_metadata_dominance);
206 } else {
207 nir_metadata_preserve(impl, nir_metadata_all);
208 }
209
210 return progress;
211 }
212
213 bool
nir_opt_memcpy(nir_shader * shader)214 nir_opt_memcpy(nir_shader *shader)
215 {
216 bool progress = false;
217
218 nir_foreach_function(function, shader) {
219 if (function->impl && opt_memcpy_impl(function->impl))
220 progress = true;
221 }
222
223 return progress;
224 }
225