1/*
2 * Copyright © 2014 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 * Authors:
24 *    Jason Ekstrand (jason@jlekstrand.net)
25 *
26 */
27
28#include "nir.h"
29#include "nir_builder.h"
30#include "nir_deref.h"
31#include "compiler/nir_types.h"
32
33/*
34 * Lowers all copy intrinsics to sequences of load/store intrinsics.
35 */
36
37static nir_deref_instr *
38build_deref_to_next_wildcard(nir_builder *b,
39                             nir_deref_instr *parent,
40                             nir_deref_instr ***deref_arr)
41{
42   for (; **deref_arr; (*deref_arr)++) {
43      if ((**deref_arr)->deref_type == nir_deref_type_array_wildcard)
44         return parent;
45
46      parent = nir_build_deref_follower(b, parent, **deref_arr);
47   }
48
49   assert(**deref_arr == NULL);
50   *deref_arr = NULL;
51   return parent;
52}
53
54static void
55emit_deref_copy_load_store(nir_builder *b,
56                           nir_deref_instr *dst_deref,
57                           nir_deref_instr **dst_deref_arr,
58                           nir_deref_instr *src_deref,
59                           nir_deref_instr **src_deref_arr,
60                           enum gl_access_qualifier dst_access,
61                           enum gl_access_qualifier src_access)
62{
63   if (dst_deref_arr || src_deref_arr) {
64      assert(dst_deref_arr && src_deref_arr);
65      dst_deref = build_deref_to_next_wildcard(b, dst_deref, &dst_deref_arr);
66      src_deref = build_deref_to_next_wildcard(b, src_deref, &src_deref_arr);
67   }
68
69   if (dst_deref_arr || src_deref_arr) {
70      assert(dst_deref_arr && src_deref_arr);
71      assert((*dst_deref_arr)->deref_type == nir_deref_type_array_wildcard);
72      assert((*src_deref_arr)->deref_type == nir_deref_type_array_wildcard);
73
74      unsigned length = glsl_get_length(src_deref->type);
75      /* The wildcards should represent the same number of elements */
76      assert(length == glsl_get_length(dst_deref->type));
77      assert(length > 0);
78
79      for (unsigned i = 0; i < length; i++) {
80         emit_deref_copy_load_store(b,
81                                    nir_build_deref_array_imm(b, dst_deref, i),
82                                    dst_deref_arr + 1,
83                                    nir_build_deref_array_imm(b, src_deref, i),
84                                    src_deref_arr + 1, dst_access, src_access);
85      }
86   } else {
87      assert(glsl_get_bare_type(dst_deref->type) ==
88             glsl_get_bare_type(src_deref->type));
89      assert(glsl_type_is_vector_or_scalar(dst_deref->type));
90
91      nir_store_deref_with_access(b, dst_deref,
92                                  nir_load_deref_with_access(b, src_deref, src_access),
93                                  ~0, src_access);
94   }
95}
96
97void
98nir_lower_deref_copy_instr(nir_builder *b, nir_intrinsic_instr *copy)
99{
100   /* Unfortunately, there's just no good way to handle wildcards except to
101    * flip the chain around and walk the list from variable to final pointer.
102    */
103   assert(copy->src[0].is_ssa && copy->src[1].is_ssa);
104   nir_deref_instr *dst = nir_instr_as_deref(copy->src[0].ssa->parent_instr);
105   nir_deref_instr *src = nir_instr_as_deref(copy->src[1].ssa->parent_instr);
106
107   nir_deref_path dst_path, src_path;
108   nir_deref_path_init(&dst_path, dst, NULL);
109   nir_deref_path_init(&src_path, src, NULL);
110
111   b->cursor = nir_before_instr(&copy->instr);
112   emit_deref_copy_load_store(b, dst_path.path[0], &dst_path.path[1],
113                                 src_path.path[0], &src_path.path[1],
114                                 nir_intrinsic_dst_access(copy),
115                                 nir_intrinsic_src_access(copy));
116
117   nir_deref_path_finish(&dst_path);
118   nir_deref_path_finish(&src_path);
119}
120
121static bool
122lower_var_copies_impl(nir_function_impl *impl)
123{
124   bool progress = false;
125
126   nir_builder b;
127   nir_builder_init(&b, impl);
128
129   nir_foreach_block(block, impl) {
130      nir_foreach_instr_safe(instr, block) {
131         if (instr->type != nir_instr_type_intrinsic)
132            continue;
133
134         nir_intrinsic_instr *copy = nir_instr_as_intrinsic(instr);
135         if (copy->intrinsic != nir_intrinsic_copy_deref)
136            continue;
137
138         nir_lower_deref_copy_instr(&b, copy);
139
140         nir_instr_remove(&copy->instr);
141         nir_deref_instr_remove_if_unused(nir_src_as_deref(copy->src[0]));
142         nir_deref_instr_remove_if_unused(nir_src_as_deref(copy->src[1]));
143
144         progress = true;
145         nir_instr_free(&copy->instr);
146      }
147   }
148
149   if (progress) {
150      nir_metadata_preserve(impl, nir_metadata_block_index |
151                                  nir_metadata_dominance);
152   } else {
153      nir_metadata_preserve(impl, nir_metadata_all);
154   }
155
156   return progress;
157}
158
159/* Lowers every copy_var instruction in the program to a sequence of
160 * load/store instructions.
161 */
162bool
163nir_lower_var_copies(nir_shader *shader)
164{
165   bool progress = false;
166
167   nir_foreach_function(function, shader) {
168      if (function->impl)
169         progress |= lower_var_copies_impl(function->impl);
170   }
171
172   return progress;
173}
174