llvm.org GIT mirror llvm / release_26 include / llvm / Support / MathExtras.h
release_26

Tree @release_26 (Download .tar.gz)

MathExtras.h @release_26raw · history · blame

  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
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
//===-- llvm/Support/MathExtras.h - Useful math functions -------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains some functions that are useful for math stuff.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_SUPPORT_MATHEXTRAS_H
#define LLVM_SUPPORT_MATHEXTRAS_H

#include "llvm/Support/DataTypes.h"

namespace llvm {

// NOTE: The following support functions use the _32/_64 extensions instead of
// type overloading so that signed and unsigned integers can be used without
// ambiguity.

/// Hi_32 - This function returns the high 32 bits of a 64 bit value.
inline uint32_t Hi_32(uint64_t Value) {
  return static_cast<uint32_t>(Value >> 32);
}

/// Lo_32 - This function returns the low 32 bits of a 64 bit value.
inline uint32_t Lo_32(uint64_t Value) {
  return static_cast<uint32_t>(Value);
}

/// is?Type - these functions produce optimal testing for integer data types.
inline bool isInt8  (int64_t Value) {
  return static_cast<int8_t>(Value) == Value;
}
inline bool isUInt8 (int64_t Value) {
  return static_cast<uint8_t>(Value) == Value;
}
inline bool isInt16 (int64_t Value) {
  return static_cast<int16_t>(Value) == Value;
}
inline bool isUInt16(int64_t Value) {
  return static_cast<uint16_t>(Value) == Value;
}
inline bool isInt32 (int64_t Value) {
  return static_cast<int32_t>(Value) == Value;
}
inline bool isUInt32(int64_t Value) {
  return static_cast<uint32_t>(Value) == Value;
}

template<unsigned N>
inline bool isInt(int64_t x) {
  return N >= 64 || (-(INT64_C(1)<<(N-1)) <= x && x < (INT64_C(1)<<(N-1)));
}

template<unsigned N>
inline bool isUint(uint64_t x) {
  return N >= 64 || x < (UINT64_C(1)<<N);
}

/// isMask_32 - This function returns true if the argument is a sequence of ones
/// starting at the least significant bit with the remainder zero (32 bit
/// version).   Ex. isMask_32(0x0000FFFFU) == true.
inline bool isMask_32(uint32_t Value) {
  return Value && ((Value + 1) & Value) == 0;
}

/// isMask_64 - This function returns true if the argument is a sequence of ones
/// starting at the least significant bit with the remainder zero (64 bit
/// version).
inline bool isMask_64(uint64_t Value) {
  return Value && ((Value + 1) & Value) == 0;
}

/// isShiftedMask_32 - This function returns true if the argument contains a
/// sequence of ones with the remainder zero (32 bit version.)
/// Ex. isShiftedMask_32(0x0000FF00U) == true.
inline bool isShiftedMask_32(uint32_t Value) {
  return isMask_32((Value - 1) | Value);
}

/// isShiftedMask_64 - This function returns true if the argument contains a
/// sequence of ones with the remainder zero (64 bit version.)
inline bool isShiftedMask_64(uint64_t Value) {
  return isMask_64((Value - 1) | Value);
}

/// isPowerOf2_32 - This function returns true if the argument is a power of
/// two > 0. Ex. isPowerOf2_32(0x00100000U) == true (32 bit edition.)
inline bool isPowerOf2_32(uint32_t Value) {
  return Value && !(Value & (Value - 1));
}

/// isPowerOf2_64 - This function returns true if the argument is a power of two
/// > 0 (64 bit edition.)
inline bool isPowerOf2_64(uint64_t Value) {
  return Value && !(Value & (Value - int64_t(1L)));
}

/// ByteSwap_16 - This function returns a byte-swapped representation of the
/// 16-bit argument, Value.
inline uint16_t ByteSwap_16(uint16_t Value) {
#if defined(_MSC_VER) && !defined(_DEBUG)
  // The DLL version of the runtime lacks these functions (bug!?), but in a
  // release build they're replaced with BSWAP instructions anyway.
  return _byteswap_ushort(Value);
#else
  uint16_t Hi = Value << 8;
  uint16_t Lo = Value >> 8;
  return Hi | Lo;
#endif
}

/// ByteSwap_32 - This function returns a byte-swapped representation of the
/// 32-bit argument, Value.
inline uint32_t ByteSwap_32(uint32_t Value) {
#if (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 3)) && !defined(__ICC)
  return __builtin_bswap32(Value);
#elif defined(_MSC_VER) && !defined(_DEBUG)
  return _byteswap_ulong(Value);
#else
  uint32_t Byte0 = Value & 0x000000FF;
  uint32_t Byte1 = Value & 0x0000FF00;
  uint32_t Byte2 = Value & 0x00FF0000;
  uint32_t Byte3 = Value & 0xFF000000;
  return (Byte0 << 24) | (Byte1 << 8) | (Byte2 >> 8) | (Byte3 >> 24);
#endif
}

/// ByteSwap_64 - This function returns a byte-swapped representation of the
/// 64-bit argument, Value.
inline uint64_t ByteSwap_64(uint64_t Value) {
#if (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 3)) && !defined(__ICC)
  return __builtin_bswap64(Value);
#elif defined(_MSC_VER) && !defined(_DEBUG)
  return _byteswap_uint64(Value);
#else
  uint64_t Hi = ByteSwap_32(uint32_t(Value));
  uint32_t Lo = ByteSwap_32(uint32_t(Value >> 32));
  return (Hi << 32) | Lo;
#endif
}

/// CountLeadingZeros_32 - this function performs the platform optimal form of
/// counting the number of zeros from the most significant bit to the first one
/// bit.  Ex. CountLeadingZeros_32(0x00F000FF) == 8.
/// Returns 32 if the word is zero.
inline unsigned CountLeadingZeros_32(uint32_t Value) {
  unsigned Count; // result
#if __GNUC__ >= 4
  // PowerPC is defined for __builtin_clz(0)
#if !defined(__ppc__) && !defined(__ppc64__)
  if (!Value) return 32;
#endif
  Count = __builtin_clz(Value);
#else
  if (!Value) return 32;
  Count = 0;
  // bisecton method for count leading zeros
  for (unsigned Shift = 32 >> 1; Shift; Shift >>= 1) {
    uint32_t Tmp = Value >> Shift;
    if (Tmp) {
      Value = Tmp;
    } else {
      Count |= Shift;
    }
  }
#endif
  return Count;
}

/// CountLeadingOnes_32 - this function performs the operation of
/// counting the number of ones from the most significant bit to the first zero
/// bit.  Ex. CountLeadingOnes_32(0xFF0FFF00) == 8.
/// Returns 32 if the word is all ones.
inline unsigned CountLeadingOnes_32(uint32_t Value) {
  return CountLeadingZeros_32(~Value);
}

/// CountLeadingZeros_64 - This function performs the platform optimal form
/// of counting the number of zeros from the most significant bit to the first
/// one bit (64 bit edition.)
/// Returns 64 if the word is zero.
inline unsigned CountLeadingZeros_64(uint64_t Value) {
  unsigned Count; // result
#if __GNUC__ >= 4
  // PowerPC is defined for __builtin_clzll(0)
#if !defined(__ppc__) && !defined(__ppc64__)
  if (!Value) return 64;
#endif
  Count = __builtin_clzll(Value);
#else
  if (sizeof(long) == sizeof(int64_t)) {
    if (!Value) return 64;
    Count = 0;
    // bisecton method for count leading zeros
    for (unsigned Shift = 64 >> 1; Shift; Shift >>= 1) {
      uint64_t Tmp = Value >> Shift;
      if (Tmp) {
        Value = Tmp;
      } else {
        Count |= Shift;
      }
    }
  } else {
    // get hi portion
    uint32_t Hi = Hi_32(Value);

    // if some bits in hi portion
    if (Hi) {
        // leading zeros in hi portion plus all bits in lo portion
        Count = CountLeadingZeros_32(Hi);
    } else {
        // get lo portion
        uint32_t Lo = Lo_32(Value);
        // same as 32 bit value
        Count = CountLeadingZeros_32(Lo)+32;
    }
  }
#endif
  return Count;
}

/// CountLeadingOnes_64 - This function performs the operation
/// of counting the number of ones from the most significant bit to the first
/// zero bit (64 bit edition.)
/// Returns 64 if the word is all ones.
inline unsigned CountLeadingOnes_64(uint64_t Value) {
  return CountLeadingZeros_64(~Value);
}

/// CountTrailingZeros_32 - this function performs the platform optimal form of
/// counting the number of zeros from the least significant bit to the first one
/// bit.  Ex. CountTrailingZeros_32(0xFF00FF00) == 8.
/// Returns 32 if the word is zero.
inline unsigned CountTrailingZeros_32(uint32_t Value) {
#if __GNUC__ >= 4
  return Value ? __builtin_ctz(Value) : 32;
#else
  static const unsigned Mod37BitPosition[] = {
    32, 0, 1, 26, 2, 23, 27, 0, 3, 16, 24, 30, 28, 11, 0, 13,
    4, 7, 17, 0, 25, 22, 31, 15, 29, 10, 12, 6, 0, 21, 14, 9,
    5, 20, 8, 19, 18
  };
  return Mod37BitPosition[(-Value & Value) % 37];
#endif
}

/// CountTrailingOnes_32 - this function performs the operation of
/// counting the number of ones from the least significant bit to the first zero
/// bit.  Ex. CountTrailingOnes_32(0x00FF00FF) == 8.
/// Returns 32 if the word is all ones.
inline unsigned CountTrailingOnes_32(uint32_t Value) {
  return CountTrailingZeros_32(~Value);
}

/// CountTrailingZeros_64 - This function performs the platform optimal form
/// of counting the number of zeros from the least significant bit to the first
/// one bit (64 bit edition.)
/// Returns 64 if the word is zero.
inline unsigned CountTrailingZeros_64(uint64_t Value) {
#if __GNUC__ >= 4
  return Value ? __builtin_ctzll(Value) : 64;
#else
  static const unsigned Mod67Position[] = {
    64, 0, 1, 39, 2, 15, 40, 23, 3, 12, 16, 59, 41, 19, 24, 54,
    4, 64, 13, 10, 17, 62, 60, 28, 42, 30, 20, 51, 25, 44, 55,
    47, 5, 32, 65, 38, 14, 22, 11, 58, 18, 53, 63, 9, 61, 27,
    29, 50, 43, 46, 31, 37, 21, 57, 52, 8, 26, 49, 45, 36, 56,
    7, 48, 35, 6, 34, 33, 0
  };
  return Mod67Position[(-Value & Value) % 67];
#endif
}

/// CountTrailingOnes_64 - This function performs the operation
/// of counting the number of ones from the least significant bit to the first
/// zero bit (64 bit edition.)
/// Returns 64 if the word is all ones.
inline unsigned CountTrailingOnes_64(uint64_t Value) {
  return CountTrailingZeros_64(~Value);
}

/// CountPopulation_32 - this function counts the number of set bits in a value.
/// Ex. CountPopulation(0xF000F000) = 8
/// Returns 0 if the word is zero.
inline unsigned CountPopulation_32(uint32_t Value) {
#if __GNUC__ >= 4
  return __builtin_popcount(Value);
#else
  uint32_t v = Value - ((Value >> 1) & 0x55555555);
  v = (v & 0x33333333) + ((v >> 2) & 0x33333333);
  return ((v + (v >> 4) & 0xF0F0F0F) * 0x1010101) >> 24;
#endif
}

/// CountPopulation_64 - this function counts the number of set bits in a value,
/// (64 bit edition.)
inline unsigned CountPopulation_64(uint64_t Value) {
#if __GNUC__ >= 4
  return __builtin_popcountll(Value);
#else
  uint64_t v = Value - ((Value >> 1) & 0x5555555555555555ULL);
  v = (v & 0x3333333333333333ULL) + ((v >> 2) & 0x3333333333333333ULL);
  v = (v + (v >> 4)) & 0x0F0F0F0F0F0F0F0FULL;
  return unsigned((uint64_t)(v * 0x0101010101010101ULL) >> 56);
#endif
}

/// Log2_32 - This function returns the floor log base 2 of the specified value,
/// -1 if the value is zero. (32 bit edition.)
/// Ex. Log2_32(32) == 5, Log2_32(1) == 0, Log2_32(0) == -1, Log2_32(6) == 2
inline unsigned Log2_32(uint32_t Value) {
  return 31 - CountLeadingZeros_32(Value);
}

/// Log2_64 - This function returns the floor log base 2 of the specified value,
/// -1 if the value is zero. (64 bit edition.)
inline unsigned Log2_64(uint64_t Value) {
  return 63 - CountLeadingZeros_64(Value);
}

/// Log2_32_Ceil - This function returns the ceil log base 2 of the specified
/// value, 32 if the value is zero. (32 bit edition).
/// Ex. Log2_32_Ceil(32) == 5, Log2_32_Ceil(1) == 0, Log2_32_Ceil(6) == 3
inline unsigned Log2_32_Ceil(uint32_t Value) {
  return 32-CountLeadingZeros_32(Value-1);
}

/// Log2_64_Ceil - This function returns the ceil log base 2 of the specified
/// value, 64 if the value is zero. (64 bit edition.)
inline unsigned Log2_64_Ceil(uint64_t Value) {
  return 64-CountLeadingZeros_64(Value-1);
}

/// GreatestCommonDivisor64 - Return the greatest common divisor of the two
/// values using Euclid's algorithm.
inline uint64_t GreatestCommonDivisor64(uint64_t A, uint64_t B) {
  while (B) {
    uint64_t T = B;
    B = A % B;
    A = T;
  }
  return A;
}

/// BitsToDouble - This function takes a 64-bit integer and returns the bit
/// equivalent double.
inline double BitsToDouble(uint64_t Bits) {
  union {
    uint64_t L;
    double D;
  } T;
  T.L = Bits;
  return T.D;
}

/// BitsToFloat - This function takes a 32-bit integer and returns the bit
/// equivalent float.
inline float BitsToFloat(uint32_t Bits) {
  union {
    uint32_t I;
    float F;
  } T;
  T.I = Bits;
  return T.F;
}

/// DoubleToBits - This function takes a double and returns the bit
/// equivalent 64-bit integer.  Note that copying doubles around
/// changes the bits of NaNs on some hosts, notably x86, so this
/// routine cannot be used if these bits are needed.
inline uint64_t DoubleToBits(double Double) {
  union {
    uint64_t L;
    double D;
  } T;
  T.D = Double;
  return T.L;
}

/// FloatToBits - This function takes a float and returns the bit
/// equivalent 32-bit integer.  Note that copying floats around
/// changes the bits of NaNs on some hosts, notably x86, so this
/// routine cannot be used if these bits are needed.
inline uint32_t FloatToBits(float Float) {
  union {
    uint32_t I;
    float F;
  } T;
  T.F = Float;
  return T.I;
}

/// Platform-independent wrappers for the C99 isnan() function.
int IsNAN(float f);
int IsNAN(double d);

/// Platform-independent wrappers for the C99 isinf() function.
int IsInf(float f);
int IsInf(double d);

/// MinAlign - A and B are either alignments or offsets.  Return the minimum
/// alignment that may be assumed after adding the two together.
static inline uint64_t MinAlign(uint64_t A, uint64_t B) {
  // The largest power of 2 that divides both A and B.
  return (A | B) & -(A | B);
}

/// NextPowerOf2 - Returns the next power of two (in 64-bits)
/// that is strictly greater than A.  Returns zero on overflow.
static inline uint64_t NextPowerOf2(uint64_t A) {
  A |= (A >> 1);
  A |= (A >> 2);
  A |= (A >> 4);
  A |= (A >> 8);
  A |= (A >> 16);
  A |= (A >> 32);
  return A + 1;
}

/// RoundUpToAlignment - Returns the next integer (mod 2**64) that is
/// greater than or equal to \arg Value and is a multiple of \arg
/// Align. Align must be non-zero.
///
/// Examples:
/// RoundUpToAlignment(5, 8) = 8
/// RoundUpToAlignment(17, 8) = 24
/// RoundUpToAlignment(~0LL, 8) = 0
inline uint64_t RoundUpToAlignment(uint64_t Value, uint64_t Align) {
  return ((Value + Align - 1) / Align) * Align;
}

/// abs64 - absolute value of a 64-bit int.  Not all environments support
/// "abs" on whatever their name for the 64-bit int type is.  The absolute
/// value of the largest negative number is undefined, as with "abs".
inline int64_t abs64(int64_t x) {
  return (x < 0) ? -x : x;
}

} // End llvm namespace

#endif