1/* Definitions for simple data type for real numbers.
2 Copyright (C) 2002-2017 Free Software Foundation, Inc.
3
4This file is part of GCC.
5
6GCC is free software; you can redistribute it and/or modify it under
7the terms of the GNU General Public License as published by the Free
8Software Foundation; either version 3, or (at your option) any later
9version.
10
11GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12WARRANTY; without even the implied warranty of MERCHANTABILITY or
13FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14for more details.
15
16You should have received a copy of the GNU General Public License
17along with GCC; see the file COPYING3. If not see
18<http://www.gnu.org/licenses/>. */
19
20#ifndef GCC_SREAL_H
21#define GCC_SREAL_H
22
23/* SREAL_PART_BITS has to be an even number. */
24#define SREAL_PART_BITS 32
25
26#define UINT64_BITS 64
27
28#define SREAL_MIN_SIG ((int64_t) 1 << (SREAL_PART_BITS - 2))
29#define SREAL_MAX_SIG (((int64_t) 1 << (SREAL_PART_BITS - 1)) - 1)
30#define SREAL_MAX_EXP (INT_MAX / 4)
31
32#define SREAL_BITS SREAL_PART_BITS
33
34#define SREAL_SIGN(v) (v < 0 ? -1: 1)
35#define SREAL_ABS(v) (v < 0 ? -v: v)
36
37struct output_block;
38struct lto_input_block;
39
40/* Structure for holding a simple real number. */
41class sreal
42{
43public:
44 /* Construct an uninitialized sreal. */
45 sreal () : m_sig (-1), m_exp (-1) {}
46
47 /* Construct a sreal. */
48 sreal (int64_t sig, int exp = 0) : m_sig (sig), m_exp (exp)
49 {
50 normalize ();
51 }
52
53 void dump (FILE *) const;
54 int64_t to_int () const;
55 double to_double () const;
56 void stream_out (struct output_block *);
57 static sreal stream_in (struct lto_input_block *);
58 sreal operator+ (const sreal &other) const;
59 sreal operator- (const sreal &other) const;
60 sreal operator* (const sreal &other) const;
61 sreal operator/ (const sreal &other) const;
62
63 bool operator< (const sreal &other) const
64 {
65 if (m_exp == other.m_exp)
66 return m_sig < other.m_sig;
67 else
68 {
69 bool negative = m_sig < 0;
70 bool other_negative = other.m_sig < 0;
71
72 if (negative != other_negative)
73 return negative > other_negative;
74
75 bool r = m_exp < other.m_exp;
76 return negative ? !r : r;
77 }
78 }
79
80 bool operator== (const sreal &other) const
81 {
82 return m_exp == other.m_exp && m_sig == other.m_sig;
83 }
84
85 sreal operator- () const
86 {
87 sreal tmp = *this;
88 tmp.m_sig *= -1;
89
90 return tmp;
91 }
92
93 sreal shift (int s) const
94 {
95 /* Zero needs no shifting. */
96 if (!m_sig)
97 return *this;
98 gcc_checking_assert (s <= SREAL_MAX_EXP);
99 gcc_checking_assert (s >= -SREAL_MAX_EXP);
100
101 /* Overflows/drop to 0 could be handled gracefully, but hopefully we do not
102 need to do so. */
103 gcc_checking_assert (m_exp + s <= SREAL_MAX_EXP);
104 gcc_checking_assert (m_exp + s >= -SREAL_MAX_EXP);
105
106 sreal tmp = *this;
107 tmp.m_exp += s;
108
109 return tmp;
110 }
111
112 /* Global minimum sreal can hold. */
113 inline static sreal min ()
114 {
115 sreal min;
116 /* This never needs normalization. */
117 min.m_sig = -SREAL_MAX_SIG;
118 min.m_exp = SREAL_MAX_EXP;
119 return min;
120 }
121
122 /* Global minimum sreal can hold. */
123 inline static sreal max ()
124 {
125 sreal max;
126 /* This never needs normalization. */
127 max.m_sig = SREAL_MAX_SIG;
128 max.m_exp = SREAL_MAX_EXP;
129 return max;
130 }
131
132private:
133 inline void normalize ();
134 inline void normalize_up ();
135 inline void normalize_down ();
136 void shift_right (int amount);
137 static sreal signedless_plus (const sreal &a, const sreal &b, bool negative);
138 static sreal signedless_minus (const sreal &a, const sreal &b, bool negative);
139
140 int64_t m_sig; /* Significant. */
141 signed int m_exp; /* Exponent. */
142};
143
144extern void debug (const sreal &ref);
145extern void debug (const sreal *ptr);
146
147inline sreal &operator+= (sreal &a, const sreal &b)
148{
149 return a = a + b;
150}
151
152inline sreal &operator-= (sreal &a, const sreal &b)
153{
154 return a = a - b;
155}
156
157inline sreal &operator/= (sreal &a, const sreal &b)
158{
159 return a = a / b;
160}
161
162inline sreal &operator*= (sreal &a, const sreal &b)
163{
164 return a = a * b;
165}
166
167inline bool operator!= (const sreal &a, const sreal &b)
168{
169 return !(a == b);
170}
171
172inline bool operator> (const sreal &a, const sreal &b)
173{
174 return !(a == b || a < b);
175}
176
177inline bool operator<= (const sreal &a, const sreal &b)
178{
179 return a < b || a == b;
180}
181
182inline bool operator>= (const sreal &a, const sreal &b)
183{
184 return a == b || a > b;
185}
186
187inline sreal operator<< (const sreal &a, int exp)
188{
189 return a.shift (exp);
190}
191
192inline sreal operator>> (const sreal &a, int exp)
193{
194 return a.shift (-exp);
195}
196
197/* Make significant to be >= SREAL_MIN_SIG.
198
199 Make this separate method so inliner can handle hot path better. */
200
201inline void
202sreal::normalize_up ()
203{
204 unsigned HOST_WIDE_INT sig = absu_hwi (m_sig);
205 int shift = SREAL_PART_BITS - 2 - floor_log2 (sig);
206
207 gcc_checking_assert (shift > 0);
208 sig <<= shift;
209 m_exp -= shift;
210 gcc_checking_assert (sig <= SREAL_MAX_SIG && sig >= SREAL_MIN_SIG);
211
212 /* Check underflow. */
213 if (m_exp < -SREAL_MAX_EXP)
214 {
215 m_exp = -SREAL_MAX_EXP;
216 sig = 0;
217 }
218 if (SREAL_SIGN (m_sig) == -1)
219 m_sig = -sig;
220 else
221 m_sig = sig;
222}
223
224/* Make significant to be <= SREAL_MAX_SIG.
225
226 Make this separate method so inliner can handle hot path better. */
227
228inline void
229sreal::normalize_down ()
230{
231 int last_bit;
232 unsigned HOST_WIDE_INT sig = absu_hwi (m_sig);
233 int shift = floor_log2 (sig) - SREAL_PART_BITS + 2;
234
235 gcc_checking_assert (shift > 0);
236 last_bit = (sig >> (shift-1)) & 1;
237 sig >>= shift;
238 m_exp += shift;
239 gcc_checking_assert (sig <= SREAL_MAX_SIG && sig >= SREAL_MIN_SIG);
240
241 /* Round the number. */
242 sig += last_bit;
243 if (sig > SREAL_MAX_SIG)
244 {
245 sig >>= 1;
246 m_exp++;
247 }
248
249 /* Check overflow. */
250 if (m_exp > SREAL_MAX_EXP)
251 {
252 m_exp = SREAL_MAX_EXP;
253 sig = SREAL_MAX_SIG;
254 }
255 if (SREAL_SIGN (m_sig) == -1)
256 m_sig = -sig;
257 else
258 m_sig = sig;
259}
260
261/* Normalize *this; the hot path. */
262
263inline void
264sreal::normalize ()
265{
266 unsigned HOST_WIDE_INT sig = absu_hwi (m_sig);
267
268 if (sig == 0)
269 m_exp = -SREAL_MAX_EXP;
270 else if (sig > SREAL_MAX_SIG)
271 normalize_down ();
272 else if (sig < SREAL_MIN_SIG)
273 normalize_up ();
274}
275
276#endif
277