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
21 * DEALINGS IN THE SOFTWARE.
22 */
23
24 /**
25 * \file lower_const_arrays_to_uniforms.cpp
26 *
27 * Lower constant arrays to uniform arrays.
28 *
29 * Some driver backends (such as i965 and nouveau) don't handle constant arrays
30 * gracefully, instead treating them as ordinary writable temporary arrays.
31 * Since arrays can be large, this often means spilling them to scratch memory,
32 * which usually involves a large number of instructions.
33 *
34 * This must be called prior to link_set_uniform_initializers(); we need the
35 * linker to process our new uniform's constant initializer.
36 *
37 * This should be called after optimizations, since those can result in
38 * splitting and removing arrays that are indexed by constant expressions.
39 */
40 #include "ir.h"
41 #include "ir_visitor.h"
42 #include "ir_rvalue_visitor.h"
43 #include "compiler/glsl_types.h"
44
45 namespace {
46 class lower_const_array_visitor : public ir_rvalue_visitor {
47 public:
lower_const_array_visitor(exec_list * insts,unsigned s)48 lower_const_array_visitor(exec_list *insts, unsigned s)
49 {
50 instructions = insts;
51 stage = s;
52 const_count = 0;
53 progress = false;
54 }
55
run()56 bool run()
57 {
58 visit_list_elements(this, instructions);
59 return progress;
60 }
61
62 ir_visitor_status visit_enter(ir_texture *);
63 void handle_rvalue(ir_rvalue **rvalue);
64
65 private:
66 exec_list *instructions;
67 unsigned stage;
68 unsigned const_count;
69 bool progress;
70 };
71
72 ir_visitor_status
visit_enter(ir_texture *)73 lower_const_array_visitor::visit_enter(ir_texture *)
74 {
75 return visit_continue_with_parent;
76 }
77
78 void
handle_rvalue(ir_rvalue ** rvalue)79 lower_const_array_visitor::handle_rvalue(ir_rvalue **rvalue)
80 {
81 if (!*rvalue)
82 return;
83
84 ir_constant *con = (*rvalue)->as_constant();
85 if (!con || !con->type->is_array())
86 return;
87
88 void *mem_ctx = ralloc_parent(con);
89
90 /* In the very unlikely event of 4294967295 constant arrays in a single
91 * shader, don't promote this to a uniform.
92 */
93 unsigned limit = ~0;
94 if (const_count == limit)
95 return;
96
97 char *uniform_name = ralloc_asprintf(mem_ctx, "constarray_%x_%u",
98 const_count, stage);
99 const_count++;
100
101 ir_variable *uni =
102 new(mem_ctx) ir_variable(con->type, uniform_name, ir_var_uniform);
103 uni->constant_initializer = con;
104 uni->constant_value = con;
105 uni->data.has_initializer = true;
106 uni->data.how_declared = ir_var_hidden;
107 uni->data.read_only = true;
108 /* Assume the whole thing is accessed. */
109 uni->data.max_array_access = uni->type->length - 1;
110 instructions->push_head(uni);
111
112 *rvalue = new(mem_ctx) ir_dereference_variable(uni);
113
114 progress = true;
115 }
116
117 } /* anonymous namespace */
118
119 bool
lower_const_arrays_to_uniforms(exec_list * instructions,unsigned stage)120 lower_const_arrays_to_uniforms(exec_list *instructions, unsigned stage)
121 {
122 lower_const_array_visitor v(instructions, stage);
123 return v.run();
124 }
125