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:
lower_texture_projection_visitor()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
visit_leave(ir_texture * ir)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);
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 
95 bool
do_lower_texture_projection(exec_list * instructions)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