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
152
153
154
155
156
157
158
159
160
161
162
163
164
|
/* Global, SSA-based optimizations using mathematical identities.
Copyright (C) 2005 Free Software Foundation, Inc.
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 2, or (at your option) any
later version.
GCC is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
for more details.
You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING. If not, write to the Free
Software Foundation, 59 Temple Place - Suite 330, Boston, MA
02111-1307, USA. */
/* Currently, the only mini-pass in this file tries to CSE reciprocal
operations. These are common in sequences such as this one:
modulus = sqrt(x*x + y*y + z*z);
x = x / modulus;
y = y / modulus;
z = z / modulus;
that can be optimized to
modulus = sqrt(x*x + y*y + z*z);
rmodulus = 1.0 / modulus;
x = x * rmodulus;
y = y * rmodulus;
z = z * rmodulus;
We do this for loop invariant divisors, and with this pass whenever
we notice that a division has the same divisor multiple times. */
#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "flags.h"
#include "tree.h"
#include "tree-flow.h"
#include "real.h"
#include "timevar.h"
#include "tree-pass.h"
static bool
gate_cse_reciprocals (void)
{
return optimize && !optimize_size && flag_unsafe_math_optimizations;
}
/* Check if DEF's uses include more than one floating-point division,
and if so replace them by multiplications with the reciprocal. If
PHI is true, insert the reciprocal calculation before BSI, otherwise
insert it after and move BSI to the new statement.
Does not check the type of DEF, nor that DEF is a GIMPLE register.
This is done in the caller for speed, because otherwise this routine
would be called for every definition and phi node. */
static void
execute_cse_reciprocals_1 (block_stmt_iterator *bsi, tree def, bool phi)
{
use_operand_p use_p;
imm_use_iterator use_iter;
tree t, new_stmt, type;
int count = 0;
/* Find uses. */
FOR_EACH_IMM_USE_FAST (use_p, use_iter, def)
{
tree use_stmt = USE_STMT (use_p);
if (TREE_CODE (use_stmt) == MODIFY_EXPR
&& TREE_CODE (TREE_OPERAND (use_stmt, 1)) == RDIV_EXPR
&& TREE_OPERAND (TREE_OPERAND (use_stmt, 1), 1) == def)
{
if (++count == 2)
break;
}
}
if (count < 2)
return;
/* Make a variable with the replacement and substitute it. */
type = TREE_TYPE (def);
t = make_rename_temp (type, "reciptmp");
new_stmt = build2 (MODIFY_EXPR, void_type_node, t,
fold_build2 (RDIV_EXPR, type, build_real (type, dconst1),
def));
if (phi)
bsi_insert_before (bsi, new_stmt, BSI_SAME_STMT);
else
bsi_insert_after (bsi, new_stmt, BSI_NEW_STMT);
FOR_EACH_IMM_USE_SAFE (use_p, use_iter, def)
{
tree use_stmt = USE_STMT (use_p);
if (use_stmt != new_stmt
&& TREE_CODE (use_stmt) == MODIFY_EXPR
&& TREE_CODE (TREE_OPERAND (use_stmt, 1)) == RDIV_EXPR
&& TREE_OPERAND (TREE_OPERAND (use_stmt, 1), 1) == def)
{
TREE_SET_CODE (TREE_OPERAND (use_stmt, 1), MULT_EXPR);
SET_USE (use_p, t);
}
}
}
static void
execute_cse_reciprocals (void)
{
basic_block bb;
FOR_EACH_BB (bb)
{
block_stmt_iterator bsi;
tree phi, def;
for (bsi = bsi_start (bb);
!bsi_end_p (bsi) && TREE_CODE (bsi_stmt (bsi)) == LABEL_EXPR;
bsi_next (&bsi))
;
for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
{
def = PHI_RESULT (phi);
if (FLOAT_TYPE_P (TREE_TYPE (def))
&& is_gimple_reg (def))
execute_cse_reciprocals_1 (&bsi, def, true);
}
for (; !bsi_end_p (bsi); bsi_next (&bsi))
{
tree stmt = bsi_stmt (bsi);
if (TREE_CODE (stmt) == MODIFY_EXPR
&& (def = SINGLE_SSA_TREE_OPERAND (stmt, SSA_OP_DEF)) != NULL
&& FLOAT_TYPE_P (TREE_TYPE (def))
&& is_gimple_reg (def))
execute_cse_reciprocals_1 (&bsi, def, false);
}
}
}
struct tree_opt_pass pass_cse_reciprocals =
{
"recip", /* name */
gate_cse_reciprocals, /* gate */
execute_cse_reciprocals, /* execute */
NULL, /* sub */
NULL, /* next */
0, /* static_pass_number */
0, /* tv_id */
PROP_ssa, /* properties_required */
0, /* properties_provided */
0, /* properties_destroyed */
0, /* todo_flags_start */
TODO_dump_func | TODO_update_ssa | TODO_verify_ssa
| TODO_verify_stmts, /* todo_flags_finish */
0 /* letter */
};
|
