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  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_declared_implicitly;
  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_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.       link_get_main_function_signature(shader);
  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.