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
37/**
38 * Visitor class for replacing expressions with ir_constant values.
39 */
40
41class ir_vec_index_to_swizzle_visitor : public ir_hierarchical_visitor {
42public:
43   ir_vec_index_to_swizzle_visitor()
44   {
45      progress = false;
46   }
47
48   ir_rvalue *convert_vec_index_to_swizzle(ir_rvalue *val);
49
50   virtual ir_visitor_status visit_enter(ir_expression *);
51   virtual ir_visitor_status visit_enter(ir_swizzle *);
52   virtual ir_visitor_status visit_enter(ir_assignment *);
53   virtual ir_visitor_status visit_enter(ir_return *);
54   virtual ir_visitor_status visit_enter(ir_call *);
55   virtual ir_visitor_status visit_enter(ir_if *);
56
57   bool progress;
58};
59
60ir_rvalue *
61ir_vec_index_to_swizzle_visitor::convert_vec_index_to_swizzle(ir_rvalue *ir)
62{
63   ir_dereference_array *deref = ir->as_dereference_array();
64   ir_constant *ir_constant;
65
66   if (!deref)
67      return ir;
68
69   if (deref->array->type->is_matrix() || deref->array->type->is_array())
70      return ir;
71
72   assert(deref->array_index->type->base_type == GLSL_TYPE_INT);
73   ir_constant = deref->array_index->constant_expression_value();
74   if (!ir_constant)
75      return ir;
76
77   void *ctx = hieralloc_parent(ir);
78   this->progress = true;
79   return new(ctx) ir_swizzle(deref->array,
80			      ir_constant->value.i[0], 0, 0, 0, 1);
81}
82
83ir_visitor_status
84ir_vec_index_to_swizzle_visitor::visit_enter(ir_expression *ir)
85{
86   unsigned int i;
87
88   for (i = 0; i < ir->get_num_operands(); i++) {
89      ir->operands[i] = convert_vec_index_to_swizzle(ir->operands[i]);
90   }
91
92   return visit_continue;
93}
94
95ir_visitor_status
96ir_vec_index_to_swizzle_visitor::visit_enter(ir_swizzle *ir)
97{
98   /* Can't be hit from normal GLSL, since you can't swizzle a scalar (which
99    * the result of indexing a vector is.  But maybe at some point we'll end up
100    * using swizzling of scalars for vector construction.
101    */
102   ir->val = convert_vec_index_to_swizzle(ir->val);
103
104   return visit_continue;
105}
106
107ir_visitor_status
108ir_vec_index_to_swizzle_visitor::visit_enter(ir_assignment *ir)
109{
110   ir->set_lhs(convert_vec_index_to_swizzle(ir->lhs));
111   ir->rhs = convert_vec_index_to_swizzle(ir->rhs);
112
113   return visit_continue;
114}
115
116ir_visitor_status
117ir_vec_index_to_swizzle_visitor::visit_enter(ir_call *ir)
118{
119   foreach_iter(exec_list_iterator, iter, *ir) {
120      ir_rvalue *param = (ir_rvalue *)iter.get();
121      ir_rvalue *new_param = convert_vec_index_to_swizzle(param);
122
123      if (new_param != param) {
124	 param->replace_with(new_param);
125      }
126   }
127
128   return visit_continue;
129}
130
131ir_visitor_status
132ir_vec_index_to_swizzle_visitor::visit_enter(ir_return *ir)
133{
134   if (ir->value) {
135      ir->value = convert_vec_index_to_swizzle(ir->value);
136   }
137
138   return visit_continue;
139}
140
141ir_visitor_status
142ir_vec_index_to_swizzle_visitor::visit_enter(ir_if *ir)
143{
144   ir->condition = convert_vec_index_to_swizzle(ir->condition);
145
146   return visit_continue;
147}
148
149bool
150do_vec_index_to_swizzle(exec_list *instructions)
151{
152   ir_vec_index_to_swizzle_visitor v;
153
154   v.run(instructions);
155
156   return v.progress;
157}
158