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
40namespace {
41
42class lower_texture_projection_visitor : public ir_hierarchical_visitor {
43public:
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
56ir_visitor_status
57lower_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);
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_comparator) {
82      deref = new(mem_ctx) ir_dereference_variable(var);
83      ir->shadow_comparator = new(mem_ctx) ir_expression(ir_binop_mul,
84						  ir->shadow_comparator->type,
85						  ir->shadow_comparator,
86						  deref);
87   }
88
89   ir->projector = NULL;
90
91   progress = true;
92   return visit_continue;
93}
94
95bool
96do_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