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_vertex_id.cpp
26 *
27 * There exists hardware, such as i965, that does not implement the OpenGL
28 * semantic for gl_VertexID. Instead, that hardware does not include the
29 * value of basevertex in the gl_VertexID value. To implement the OpenGL
30 * semantic, we'll have to convert gl_Vertex_ID to
31 * gl_VertexIDMESA+gl_BaseVertexMESA.
32 */
33
34 #include "glsl_symbol_table.h"
35 #include "ir_hierarchical_visitor.h"
36 #include "ir.h"
37 #include "ir_builder.h"
38 #include "linker.h"
39 #include "program/prog_statevars.h"
40 #include "builtin_functions.h"
41 #include "main/mtypes.h"
42
43 namespace {
44
45 class lower_vertex_id_visitor : public ir_hierarchical_visitor {
46 public:
lower_vertex_id_visitor(ir_function_signature * main_sig,exec_list * ir_list)47 explicit lower_vertex_id_visitor(ir_function_signature *main_sig,
48 exec_list *ir_list)
49 : progress(false), VertexID(NULL), gl_VertexID(NULL),
50 gl_BaseVertex(NULL), main_sig(main_sig), ir_list(ir_list)
51 {
52 foreach_in_list(ir_instruction, ir, ir_list) {
53 ir_variable *const var = ir->as_variable();
54
55 if (var != NULL && var->data.mode == ir_var_system_value &&
56 var->data.location == SYSTEM_VALUE_BASE_VERTEX) {
57 gl_BaseVertex = var;
58 break;
59 }
60 }
61 }
62
63 virtual ir_visitor_status visit(ir_dereference_variable *);
64
65 bool progress;
66
67 private:
68 ir_variable *VertexID;
69 ir_variable *gl_VertexID;
70 ir_variable *gl_BaseVertex;
71
72 ir_function_signature *main_sig;
73 exec_list *ir_list;
74 };
75
76 } /* anonymous namespace */
77
78 ir_visitor_status
visit(ir_dereference_variable * ir)79 lower_vertex_id_visitor::visit(ir_dereference_variable *ir)
80 {
81 if (ir->var->data.mode != ir_var_system_value ||
82 ir->var->data.location != SYSTEM_VALUE_VERTEX_ID)
83 return visit_continue;
84
85 if (VertexID == NULL) {
86 const glsl_type *const int_t = glsl_type::int_type;
87 void *const mem_ctx = ralloc_parent(ir);
88
89 VertexID = new(mem_ctx) ir_variable(int_t, "__VertexID",
90 ir_var_temporary);
91 ir_list->push_head(VertexID);
92
93 gl_VertexID = new(mem_ctx) ir_variable(int_t, "gl_VertexIDMESA",
94 ir_var_system_value);
95 gl_VertexID->data.how_declared = ir_var_declared_implicitly;
96 gl_VertexID->data.read_only = true;
97 gl_VertexID->data.location = SYSTEM_VALUE_VERTEX_ID_ZERO_BASE;
98 gl_VertexID->data.explicit_location = true;
99 gl_VertexID->data.explicit_index = 0;
100 ir_list->push_head(gl_VertexID);
101
102 if (gl_BaseVertex == NULL) {
103 gl_BaseVertex = new(mem_ctx) ir_variable(int_t, "gl_BaseVertex",
104 ir_var_system_value);
105 gl_BaseVertex->data.how_declared = ir_var_hidden;
106 gl_BaseVertex->data.read_only = true;
107 gl_BaseVertex->data.location = SYSTEM_VALUE_BASE_VERTEX;
108 gl_BaseVertex->data.explicit_location = true;
109 gl_BaseVertex->data.explicit_index = 0;
110 ir_list->push_head(gl_BaseVertex);
111 }
112
113 ir_instruction *const inst =
114 ir_builder::assign(VertexID,
115 ir_builder::add(gl_VertexID, gl_BaseVertex));
116
117 main_sig->body.push_head(inst);
118 }
119
120 ir->var = VertexID;
121 progress = true;
122
123 return visit_continue;
124 }
125
126 bool
lower_vertex_id(gl_linked_shader * shader)127 lower_vertex_id(gl_linked_shader *shader)
128 {
129 /* gl_VertexID only exists in the vertex shader.
130 */
131 if (shader->Stage != MESA_SHADER_VERTEX)
132 return false;
133
134 ir_function_signature *const main_sig =
135 _mesa_get_main_function_signature(shader->symbols);
136 if (main_sig == NULL) {
137 assert(main_sig != NULL);
138 return false;
139 }
140
141 lower_vertex_id_visitor v(main_sig, shader->ir);
142
143 v.run(shader->ir);
144
145 return v.progress;
146 }
147