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: 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 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 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