1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
|
/*
* Copyright © 2015 Red Hat
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice (including the next
* paragraph) shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*
* Authors:
* Rob Clark <robclark@freedesktop.org>
*/
#include "nir.h"
#include "nir_builder.h"
/* Lowers idiv/udiv/umod
* Based on NV50LegalizeSSA::handleDIV()
*
* Note that this is probably not enough precision for compute shaders.
* Perhaps we want a second higher precision (looping) version of this?
* Or perhaps we assume if you can do compute shaders you can also
* branch out to a pre-optimized shader library routine..
*/
static void
convert_instr(nir_builder *bld, nir_alu_instr *alu)
{
nir_ssa_def *numer, *denom, *af, *bf, *a, *b, *q, *r;
nir_op op = alu->op;
bool is_signed;
if ((op != nir_op_idiv) &&
(op != nir_op_udiv) &&
(op != nir_op_umod))
return;
is_signed = (op == nir_op_idiv);
bld->cursor = nir_before_instr(&alu->instr);
numer = nir_ssa_for_alu_src(bld, alu, 0);
denom = nir_ssa_for_alu_src(bld, alu, 1);
if (is_signed) {
af = nir_i2f(bld, numer);
bf = nir_i2f(bld, denom);
af = nir_fabs(bld, af);
bf = nir_fabs(bld, bf);
a = nir_iabs(bld, numer);
b = nir_iabs(bld, denom);
} else {
af = nir_u2f(bld, numer);
bf = nir_u2f(bld, denom);
a = numer;
b = denom;
}
/* get first result: */
bf = nir_frcp(bld, bf);
bf = nir_isub(bld, bf, nir_imm_int(bld, 2)); /* yes, really */
q = nir_fmul(bld, af, bf);
if (is_signed) {
q = nir_f2i(bld, q);
} else {
q = nir_f2u(bld, q);
}
/* get error of first result: */
r = nir_imul(bld, q, b);
r = nir_isub(bld, a, r);
r = nir_u2f(bld, r);
r = nir_fmul(bld, r, bf);
r = nir_f2u(bld, r);
/* add quotients: */
q = nir_iadd(bld, q, r);
/* correction: if modulus >= divisor, add 1 */
r = nir_imul(bld, q, b);
r = nir_isub(bld, a, r);
r = nir_uge(bld, r, b);
r = nir_b2i(bld, r);
q = nir_iadd(bld, q, r);
if (is_signed) {
/* fix the sign: */
r = nir_ixor(bld, numer, denom);
r = nir_ushr(bld, r, nir_imm_int(bld, 31));
r = nir_i2b(bld, r);
b = nir_ineg(bld, q);
q = nir_bcsel(bld, r, b, q);
}
if (op == nir_op_umod) {
/* division result in q */
r = nir_imul(bld, q, b);
q = nir_isub(bld, a, r);
}
assert(alu->dest.dest.is_ssa);
nir_ssa_def_rewrite_uses(&alu->dest.dest.ssa, nir_src_for_ssa(q));
}
static bool
convert_block(nir_block *block, void *state)
{
nir_builder *b = state;
nir_foreach_instr_safe(block, instr) {
if (instr->type == nir_instr_type_alu)
convert_instr(b, nir_instr_as_alu(instr));
}
return true;
}
static void
convert_impl(nir_function_impl *impl)
{
nir_builder b;
nir_builder_init(&b, impl);
nir_foreach_block(impl, convert_block, &b);
nir_metadata_preserve(impl, nir_metadata_block_index |
nir_metadata_dominance);
}
void
nir_lower_idiv(nir_shader *shader)
{
nir_foreach_function(shader, function) {
if (function->impl)
convert_impl(function->impl);
}
}
|
