1 /* Definitions for simple data type for real numbers.
2 Copyright (C) 2002-2020 Free Software Foundation, Inc.
3
4 This file is part of GCC.
5
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 3, or (at your option) any later
9 version.
10
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 for more details.
15
16 You should have received a copy of the GNU General Public License
17 along 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 #define SREAL_PART_BITS 31
24
25 #define UINT64_BITS 64
26
27 #define SREAL_MIN_SIG ((int64_t) 1 << (SREAL_PART_BITS - 2))
28 #define SREAL_MAX_SIG (((int64_t) 1 << (SREAL_PART_BITS - 1)) - 1)
29 #define SREAL_MAX_EXP (INT_MAX / 4)
30
31 #define SREAL_BITS SREAL_PART_BITS
32
33 #define SREAL_SIGN(v) (v < 0 ? -1: 1)
34 #define SREAL_ABS(v) (v < 0 ? -v: v)
35
36 struct output_block;
37 class lto_input_block;
38
39 /* Structure for holding a simple real number. */
40 class sreal
41 {
42 public:
43 /* Construct an uninitialized sreal. */
sreal()44 sreal () : m_sig (-1), m_exp (-1) {}
45
46 /* Construct a sreal. */
47 sreal (int64_t sig, int exp = 0)
48 {
49 normalize (sig, exp);
50 }
51
52 void dump (FILE *) const;
53 int64_t to_int () const;
54 double to_double () const;
55 void stream_out (struct output_block *);
56 static sreal stream_in (class lto_input_block *);
57 sreal operator+ (const sreal &other) const;
58 sreal operator- (const sreal &other) const;
59 sreal operator* (const sreal &other) const;
60 sreal operator/ (const sreal &other) const;
61
62 bool operator< (const sreal &other) const
63 {
64 if (m_exp == other.m_exp)
65 return m_sig < other.m_sig;
66 else
67 {
68 bool negative = m_sig < 0;
69 bool other_negative = other.m_sig < 0;
70
71 if (negative != other_negative)
72 return negative > other_negative;
73
74 bool r = m_exp < other.m_exp;
75 return negative ? !r : r;
76 }
77 }
78
79 bool operator== (const sreal &other) const
80 {
81 return m_exp == other.m_exp && m_sig == other.m_sig;
82 }
83
84 sreal operator- () const
85 {
86 sreal tmp = *this;
87 tmp.m_sig *= -1;
88
89 return tmp;
90 }
91
shift(int s)92 sreal shift (int s) const
93 {
94 /* Zero needs no shifting. */
95 if (!m_sig)
96 return *this;
97 gcc_checking_assert (s <= SREAL_MAX_EXP);
98 gcc_checking_assert (s >= -SREAL_MAX_EXP);
99
100 /* Overflows/drop to 0 could be handled gracefully, but hopefully we do not
101 need to do so. */
102 gcc_checking_assert (m_exp + s <= SREAL_MAX_EXP);
103 gcc_checking_assert (m_exp + s >= -SREAL_MAX_EXP);
104
105 sreal tmp = *this;
106 tmp.m_exp += s;
107
108 return tmp;
109 }
110
111 /* Global minimum sreal can hold. */
min()112 inline static sreal min ()
113 {
114 sreal min;
115 /* This never needs normalization. */
116 min.m_sig = -SREAL_MAX_SIG;
117 min.m_exp = SREAL_MAX_EXP;
118 return min;
119 }
120
121 /* Global minimum sreal can hold. */
max()122 inline static sreal max ()
123 {
124 sreal max;
125 /* This never needs normalization. */
126 max.m_sig = SREAL_MAX_SIG;
127 max.m_exp = SREAL_MAX_EXP;
128 return max;
129 }
130
131 private:
132 inline void normalize (int64_t new_sig, signed int new_exp);
133 inline void normalize_up (int64_t new_sig, signed int new_exp);
134 inline void normalize_down (int64_t new_sig, signed int new_exp);
135 void shift_right (int amount);
136 static sreal signedless_plus (const sreal &a, const sreal &b, bool negative);
137 static sreal signedless_minus (const sreal &a, const sreal &b, bool negative);
138
139 int32_t m_sig; /* Significant. */
140 signed int m_exp; /* Exponent. */
141 };
142
143 extern void debug (const sreal &ref);
144 extern void debug (const sreal *ptr);
145
146 inline sreal &operator+= (sreal &a, const sreal &b)
147 {
148 return a = a + b;
149 }
150
151 inline sreal &operator-= (sreal &a, const sreal &b)
152 {
153 return a = a - b;
154 }
155
156 inline sreal &operator/= (sreal &a, const sreal &b)
157 {
158 return a = a / b;
159 }
160
161 inline sreal &operator*= (sreal &a, const sreal &b)
162 {
163 return a = a * b;
164 }
165
166 inline bool operator!= (const sreal &a, const sreal &b)
167 {
168 return !(a == b);
169 }
170
171 inline bool operator> (const sreal &a, const sreal &b)
172 {
173 return !(a == b || a < b);
174 }
175
176 inline bool operator<= (const sreal &a, const sreal &b)
177 {
178 return a < b || a == b;
179 }
180
181 inline bool operator>= (const sreal &a, const sreal &b)
182 {
183 return a == b || a > b;
184 }
185
186 inline sreal operator<< (const sreal &a, int exp)
187 {
188 return a.shift (exp);
189 }
190
191 inline sreal operator>> (const sreal &a, int exp)
192 {
193 return a.shift (-exp);
194 }
195
196 /* Make significant to be >= SREAL_MIN_SIG.
197
198 Make this separate method so inliner can handle hot path better. */
199
200 inline void
normalize_up(int64_t new_sig,signed int new_exp)201 sreal::normalize_up (int64_t new_sig, signed int new_exp)
202 {
203 unsigned HOST_WIDE_INT sig = absu_hwi (new_sig);
204 int shift = SREAL_PART_BITS - 2 - floor_log2 (sig);
205
206 gcc_checking_assert (shift > 0);
207 sig <<= shift;
208 new_exp -= shift;
209 gcc_checking_assert (sig <= SREAL_MAX_SIG && sig >= SREAL_MIN_SIG);
210
211 /* Check underflow. */
212 if (new_exp < -SREAL_MAX_EXP)
213 {
214 new_exp = -SREAL_MAX_EXP;
215 sig = 0;
216 }
217 m_exp = new_exp;
218 if (SREAL_SIGN (new_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
228 inline void
normalize_down(int64_t new_sig,signed int new_exp)229 sreal::normalize_down (int64_t new_sig, signed int new_exp)
230 {
231 int last_bit;
232 unsigned HOST_WIDE_INT sig = absu_hwi (new_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 new_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 new_exp++;
247 }
248
249 /* Check overflow. */
250 if (new_exp > SREAL_MAX_EXP)
251 {
252 new_exp = SREAL_MAX_EXP;
253 sig = SREAL_MAX_SIG;
254 }
255 m_exp = new_exp;
256 if (SREAL_SIGN (new_sig) == -1)
257 m_sig = -sig;
258 else
259 m_sig = sig;
260 }
261
262 /* Normalize *this; the hot path. */
263
264 inline void
normalize(int64_t new_sig,signed int new_exp)265 sreal::normalize (int64_t new_sig, signed int new_exp)
266 {
267 unsigned HOST_WIDE_INT sig = absu_hwi (new_sig);
268
269 if (sig == 0)
270 {
271 m_sig = 0;
272 m_exp = -SREAL_MAX_EXP;
273 }
274 else if (sig > SREAL_MAX_SIG)
275 normalize_down (new_sig, new_exp);
276 else if (sig < SREAL_MIN_SIG)
277 normalize_up (new_sig, new_exp);
278 else
279 {
280 m_sig = new_sig;
281 m_exp = new_exp;
282 }
283 }
284
285 #endif
286