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  1. /*
  2.  * Copyright © 2010 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_texture_projection.cpp
  26.  *
  27.  * IR lower pass to perform the division of texture coordinates by the texture
  28.  * projector if present.
  29.  *
  30.  * Many GPUs have a texture sampling opcode that takes the projector
  31.  * and does the divide internally, thus the presence of the projector
  32.  * in the IR.  For GPUs that don't, this saves the driver needing the
  33.  * logic for handling the divide.
  34.  *
  35.  * \author Eric Anholt <eric@anholt.net>
  36.  */
  37.  
  38. #include "ir.h"
  39.  
  40. namespace {
  41.  
  42. class lower_texture_projection_visitor : public ir_hierarchical_visitor {
  43. public:
  44.    lower_texture_projection_visitor()
  45.    {
  46.       progress = false;
  47.    }
  48.  
  49.    ir_visitor_status visit_leave(ir_texture *ir);
  50.  
  51.    bool progress;
  52. };
  53.  
  54. } /* anonymous namespace */
  55.  
  56. ir_visitor_status
  57. lower_texture_projection_visitor::visit_leave(ir_texture *ir)
  58. {
  59.    if (!ir->projector)
  60.       return visit_continue;
  61.  
  62.    void *mem_ctx = ralloc_parent(ir);
  63.  
  64.    ir_variable *var = new(mem_ctx) ir_variable(ir->projector->type,
  65.                                                "projector", ir_var_temporary);
  66.    base_ir->insert_before(var);
  67.    ir_dereference *deref = new(mem_ctx) ir_dereference_variable(var);
  68.    ir_expression *expr = new(mem_ctx) ir_expression(ir_unop_rcp,
  69.                                                     ir->projector->type,
  70.                                                     ir->projector,
  71.                                                     NULL);
  72.    ir_assignment *assign = new(mem_ctx) ir_assignment(deref, expr, NULL);
  73.    base_ir->insert_before(assign);
  74.  
  75.    deref = new(mem_ctx) ir_dereference_variable(var);
  76.    ir->coordinate = new(mem_ctx) ir_expression(ir_binop_mul,
  77.                                                ir->coordinate->type,
  78.                                                ir->coordinate,
  79.                                                deref);
  80.  
  81.    if (ir->shadow_comparitor) {
  82.       deref = new(mem_ctx) ir_dereference_variable(var);
  83.       ir->shadow_comparitor = new(mem_ctx) ir_expression(ir_binop_mul,
  84.                                                   ir->shadow_comparitor->type,
  85.                                                   ir->shadow_comparitor,
  86.                                                   deref);
  87.    }
  88.  
  89.    ir->projector = NULL;
  90.  
  91.    progress = true;
  92.    return visit_continue;
  93. }
  94.  
  95. bool
  96. do_lower_texture_projection(exec_list *instructions)
  97. {
  98.    lower_texture_projection_visitor v;
  99.  
  100.    visit_list_elements(&v, instructions);
  101.  
  102.    return v.progress;
  103. }
  104.