1 /*
2 * Copyright © 2010 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
21 * DEALINGS IN THE SOFTWARE.
22 */
23
24 /**
25 * \file lower_vec_index_to_swizzle.cpp
26 *
27 * Turns constant indexing into vector types to swizzles. This will
28 * let other swizzle-aware optimization passes catch these constructs,
29 * and codegen backends not have to worry about this case.
30 */
31
32 #include "ir.h"
33 #include "ir_visitor.h"
34 #include "ir_optimization.h"
35 #include "glsl_types.h"
36 #include "main/macros.h"
37
38 /**
39 * Visitor class for replacing expressions with ir_constant values.
40 */
41
42 class ir_vec_index_to_swizzle_visitor : public ir_hierarchical_visitor {
43 public:
ir_vec_index_to_swizzle_visitor()44 ir_vec_index_to_swizzle_visitor()
45 {
46 progress = false;
47 }
48
49 ir_rvalue *convert_vec_index_to_swizzle(ir_rvalue *val);
50
51 virtual ir_visitor_status visit_enter(ir_expression *);
52 virtual ir_visitor_status visit_enter(ir_swizzle *);
53 virtual ir_visitor_status visit_enter(ir_assignment *);
54 virtual ir_visitor_status visit_enter(ir_return *);
55 virtual ir_visitor_status visit_enter(ir_call *);
56 virtual ir_visitor_status visit_enter(ir_if *);
57
58 bool progress;
59 };
60
61 ir_rvalue *
convert_vec_index_to_swizzle(ir_rvalue * ir)62 ir_vec_index_to_swizzle_visitor::convert_vec_index_to_swizzle(ir_rvalue *ir)
63 {
64 ir_dereference_array *deref = ir->as_dereference_array();
65 ir_constant *ir_constant;
66
67 if (!deref)
68 return ir;
69
70 if (deref->array->type->is_matrix() || deref->array->type->is_array())
71 return ir;
72
73 assert(deref->array_index->type->base_type == GLSL_TYPE_INT);
74 ir_constant = deref->array_index->constant_expression_value();
75 if (!ir_constant)
76 return ir;
77
78 void *ctx = ralloc_parent(ir);
79 this->progress = true;
80
81 /* Page 40 of the GLSL 1.20 spec says:
82 *
83 * "When indexing with non-constant expressions, behavior is undefined
84 * if the index is negative, or greater than or equal to the size of
85 * the vector."
86 *
87 * The quoted spec text mentions non-constant expressions, but this code
88 * operates on constants. These constants are the result of non-constant
89 * expressions that have been optimized to constants. The common case here
90 * is a loop counter from an unrolled loop that is used to index a vector.
91 *
92 * The ir_swizzle constructor gets angry if the index is negative or too
93 * large. For simplicity sake, just clamp the index to [0, size-1].
94 */
95 const int i = MIN2(MAX2(ir_constant->value.i[0], 0),
96 (deref->array->type->vector_elements - 1));
97
98 return new(ctx) ir_swizzle(deref->array, i, 0, 0, 0, 1);
99 }
100
101 ir_visitor_status
visit_enter(ir_expression * ir)102 ir_vec_index_to_swizzle_visitor::visit_enter(ir_expression *ir)
103 {
104 unsigned int i;
105
106 for (i = 0; i < ir->get_num_operands(); i++) {
107 ir->operands[i] = convert_vec_index_to_swizzle(ir->operands[i]);
108 }
109
110 return visit_continue;
111 }
112
113 ir_visitor_status
visit_enter(ir_swizzle * ir)114 ir_vec_index_to_swizzle_visitor::visit_enter(ir_swizzle *ir)
115 {
116 /* Can't be hit from normal GLSL, since you can't swizzle a scalar (which
117 * the result of indexing a vector is. But maybe at some point we'll end up
118 * using swizzling of scalars for vector construction.
119 */
120 ir->val = convert_vec_index_to_swizzle(ir->val);
121
122 return visit_continue;
123 }
124
125 ir_visitor_status
visit_enter(ir_assignment * ir)126 ir_vec_index_to_swizzle_visitor::visit_enter(ir_assignment *ir)
127 {
128 ir->set_lhs(convert_vec_index_to_swizzle(ir->lhs));
129 ir->rhs = convert_vec_index_to_swizzle(ir->rhs);
130
131 return visit_continue;
132 }
133
134 ir_visitor_status
visit_enter(ir_call * ir)135 ir_vec_index_to_swizzle_visitor::visit_enter(ir_call *ir)
136 {
137 foreach_iter(exec_list_iterator, iter, *ir) {
138 ir_rvalue *param = (ir_rvalue *)iter.get();
139 ir_rvalue *new_param = convert_vec_index_to_swizzle(param);
140
141 if (new_param != param) {
142 param->replace_with(new_param);
143 }
144 }
145
146 return visit_continue;
147 }
148
149 ir_visitor_status
visit_enter(ir_return * ir)150 ir_vec_index_to_swizzle_visitor::visit_enter(ir_return *ir)
151 {
152 if (ir->value) {
153 ir->value = convert_vec_index_to_swizzle(ir->value);
154 }
155
156 return visit_continue;
157 }
158
159 ir_visitor_status
visit_enter(ir_if * ir)160 ir_vec_index_to_swizzle_visitor::visit_enter(ir_if *ir)
161 {
162 ir->condition = convert_vec_index_to_swizzle(ir->condition);
163
164 return visit_continue;
165 }
166
167 bool
do_vec_index_to_swizzle(exec_list * instructions)168 do_vec_index_to_swizzle(exec_list *instructions)
169 {
170 ir_vec_index_to_swizzle_visitor v;
171
172 v.run(instructions);
173
174 return v.progress;
175 }
176