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
41 namespace {
42
43 class lower_vertex_id_visitor : public ir_hierarchical_visitor {
44 public:
lower_vertex_id_visitor(ir_function_signature * main_sig,exec_list * ir_list)45 explicit lower_vertex_id_visitor(ir_function_signature *main_sig,
46 exec_list *ir_list)
47 : progress(false), VertexID(NULL), gl_VertexID(NULL),
48 gl_BaseVertex(NULL), main_sig(main_sig), ir_list(ir_list)
49 {
50 foreach_in_list(ir_instruction, ir, ir_list) {
51 ir_variable *const var = ir->as_variable();
52
53 if (var != NULL && var->data.mode == ir_var_system_value &&
54 var->data.location == SYSTEM_VALUE_BASE_VERTEX) {
55 gl_BaseVertex = var;
56 break;
57 }
58 }
59 }
60
61 virtual ir_visitor_status visit(ir_dereference_variable *);
62
63 bool progress;
64
65 private:
66 ir_variable *VertexID;
67 ir_variable *gl_VertexID;
68 ir_variable *gl_BaseVertex;
69
70 ir_function_signature *main_sig;
71 exec_list *ir_list;
72 };
73
74 } /* anonymous namespace */
75
76 ir_visitor_status
visit(ir_dereference_variable * ir)77 lower_vertex_id_visitor::visit(ir_dereference_variable *ir)
78 {
79 if (ir->var->data.mode != ir_var_system_value ||
80 ir->var->data.location != SYSTEM_VALUE_VERTEX_ID)
81 return visit_continue;
82
83 if (VertexID == NULL) {
84 const glsl_type *const int_t = glsl_type::int_type;
85 void *const mem_ctx = ralloc_parent(ir);
86
87 VertexID = new(mem_ctx) ir_variable(int_t, "__VertexID",
88 ir_var_temporary);
89 ir_list->push_head(VertexID);
90
91 gl_VertexID = new(mem_ctx) ir_variable(int_t, "gl_VertexIDMESA",
92 ir_var_system_value);
93 gl_VertexID->data.how_declared = ir_var_declared_implicitly;
94 gl_VertexID->data.read_only = true;
95 gl_VertexID->data.location = SYSTEM_VALUE_VERTEX_ID_ZERO_BASE;
96 gl_VertexID->data.explicit_location = true;
97 gl_VertexID->data.explicit_index = 0;
98 ir_list->push_head(gl_VertexID);
99
100 if (gl_BaseVertex == NULL) {
101 gl_BaseVertex = new(mem_ctx) ir_variable(int_t, "gl_BaseVertex",
102 ir_var_system_value);
103 gl_BaseVertex->data.how_declared = ir_var_hidden;
104 gl_BaseVertex->data.read_only = true;
105 gl_BaseVertex->data.location = SYSTEM_VALUE_BASE_VERTEX;
106 gl_BaseVertex->data.explicit_location = true;
107 gl_BaseVertex->data.explicit_index = 0;
108 ir_list->push_head(gl_BaseVertex);
109 }
110
111 ir_instruction *const inst =
112 ir_builder::assign(VertexID,
113 ir_builder::add(gl_VertexID, gl_BaseVertex));
114
115 main_sig->body.push_head(inst);
116 }
117
118 ir->var = VertexID;
119 progress = true;
120
121 return visit_continue;
122 }
123
124 bool
lower_vertex_id(gl_linked_shader * shader)125 lower_vertex_id(gl_linked_shader *shader)
126 {
127 /* gl_VertexID only exists in the vertex shader.
128 */
129 if (shader->Stage != MESA_SHADER_VERTEX)
130 return false;
131
132 ir_function_signature *const main_sig =
133 _mesa_get_main_function_signature(shader->symbols);
134 if (main_sig == NULL) {
135 assert(main_sig != NULL);
136 return false;
137 }
138
139 lower_vertex_id_visitor v(main_sig, shader->ir);
140
141 v.run(shader->ir);
142
143 return v.progress;
144 }
145