js/src/jsutil.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
   2  * vim: set ts=8 sts=4 et sw=4 tw=99:
   3  * This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 /*
   8  * PR assertion checker.
   9  */
  10
  11 #ifndef jsutil_h
  12 #define jsutil_h
  13
  14 #include "mozilla/Assertions.h"
  15 #include "mozilla/Compiler.h"
  16 #include "mozilla/GuardObjects.h"
  17
  18 #include <limits.h>
  19
  20 #include "js/Utility.h"
  21
  22 #define JS_ALWAYS_TRUE(expr)      MOZ_ALWAYS_TRUE(expr)
  23 #define JS_ALWAYS_FALSE(expr)     MOZ_ALWAYS_FALSE(expr)
  24
  25 #if defined(JS_DEBUG)
  26 # define JS_DIAGNOSTICS_ASSERT(expr) MOZ_ASSERT(expr)
  27 #elif defined(JS_CRASH_DIAGNOSTICS)
  28 # define JS_DIAGNOSTICS_ASSERT(expr) do { if (MOZ_UNLIKELY(!(expr))) MOZ_CRASH(); } while(0)
  29 #else
  30 # define JS_DIAGNOSTICS_ASSERT(expr) ((void) 0)
  31 #endif
  32
  33 static MOZ_ALWAYS_INLINE void *
  34 js_memcpy(void *dst_, const void *src_, size_t len)
  35 {
  36     char *dst = (char *) dst_;
  37     const char *src = (const char *) src_;
  38     JS_ASSERT_IF(dst >= src, (size_t) (dst - src) >= len);
  39     JS_ASSERT_IF(src >= dst, (size_t) (src - dst) >= len);
  40
  41     return memcpy(dst, src, len);
  42 }
  43
  44 namespace js {
  45
  46 template <class T>
  47 struct AlignmentTestStruct
  48 {
  49     char c;
  50     T t;
  51 };
  52
  53 /* This macro determines the alignment requirements of a type. */
  54 #define JS_ALIGNMENT_OF(t_) \
  55   (sizeof(js::AlignmentTestStruct<t_>) - sizeof(t_))
  56
  57 template <class T>
  58 class AlignedPtrAndFlag
  59 {
  60     uintptr_t bits;
  61
  62   public:
  63     AlignedPtrAndFlag(T *t, bool aFlag) {
  64         JS_ASSERT((uintptr_t(t) & 1) == 0);
  65         bits = uintptr_t(t) | uintptr_t(aFlag);
  66     }
  67
  68     T *ptr() const {
  69         return (T *)(bits & ~uintptr_t(1));
  70     }
  71
  72     bool flag() const {
  73         return (bits & 1) != 0;
  74     }
  75
  76     void setPtr(T *t) {
  77         JS_ASSERT((uintptr_t(t) & 1) == 0);
  78         bits = uintptr_t(t) | uintptr_t(flag());
  79     }
  80
  81     void setFlag() {
  82         bits |= 1;
  83     }
  84
  85     void unsetFlag() {
  86         bits &= ~uintptr_t(1);
  87     }
  88
  89     void set(T *t, bool aFlag) {
  90         JS_ASSERT((uintptr_t(t) & 1) == 0);
  91         bits = uintptr_t(t) | aFlag;
  92     }
  93 };
  94
  95 template <class T>
  96 static inline void
  97 Reverse(T *beg, T *end)
  98 {
  99     while (beg != end) {
 100         if (--end == beg)
 101             return;
 102         T tmp = *beg;
 103         *beg = *end;
 104         *end = tmp;
 105         ++beg;
 106     }
 107 }
 108
 109 template <class T>
 110 static inline T *
 111 Find(T *beg, T *end, const T &v)
 112 {
 113     for (T *p = beg; p != end; ++p) {
 114         if (*p == v)
 115             return p;
 116     }
 117     return end;
 118 }
 119
 120 template <class Container>
 121 static inline typename Container::ElementType *
 122 Find(Container &c, const typename Container::ElementType &v)
 123 {
 124     return Find(c.begin(), c.end(), v);
 125 }
 126
 127 template <typename InputIterT, typename CallableT>
 128 void
 129 ForEach(InputIterT begin, InputIterT end, CallableT f)
 130 {
 131     for (; begin != end; ++begin)
 132         f(*begin);
 133 }
 134
 135 template <class T>
 136 static inline T
 137 Min(T t1, T t2)
 138 {
 139     return t1 < t2 ? t1 : t2;
 140 }
 141
 142 template <class T>
 143 static inline T
 144 Max(T t1, T t2)
 145 {
 146     return t1 > t2 ? t1 : t2;
 147 }
 148
 149 /* Allows a const variable to be initialized after its declaration. */
 150 template <class T>
 151 static T&
 152 InitConst(const T &t)
 153 {
 154     return const_cast<T &>(t);
 155 }
 156
 157 template <class T, class U>
 158 MOZ_ALWAYS_INLINE T &
 159 ImplicitCast(U &u)
 160 {
 161     T &t = u;
 162     return t;
 163 }
 164
 165 template<typename T>
 166 class AutoScopedAssign
 167 {
 168   public:
 169     AutoScopedAssign(T *addr, const T &value
 170                      MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
 171         : addr_(addr), old(*addr_)
 172     {
 173         MOZ_GUARD_OBJECT_NOTIFIER_INIT;
 174         *addr_ = value;
 175     }
 176
 177     ~AutoScopedAssign() { *addr_ = old; }
 178
 179   private:
 180     MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER
 181     T *addr_;
 182     T old;
 183 };
 184
 185 template <typename T>
 186 static inline bool
 187 IsPowerOfTwo(T t)
 188 {
 189     return t && !(t & (t - 1));
 190 }
 191
 192 template <typename T, typename U>
 193 static inline U
 194 ComputeByteAlignment(T bytes, U alignment)
 195 {
 196     JS_ASSERT(IsPowerOfTwo(alignment));
 197     return (alignment - (bytes % alignment)) % alignment;
 198 }
 199
 200 template <typename T, typename U>
 201 static inline T
 202 AlignBytes(T bytes, U alignment)
 203 {
 204     return bytes + ComputeByteAlignment(bytes, alignment);
 205 }
 206
 207 static MOZ_ALWAYS_INLINE size_t
 208 UnsignedPtrDiff(const void *bigger, const void *smaller)
 209 {
 210     return size_t(bigger) - size_t(smaller);
 211 }
 212
 213 /*****************************************************************************/
 214
 215 /* A bit array is an array of bits represented by an array of words (size_t). */
 216
 217 static const size_t BitArrayElementBits = sizeof(size_t) * CHAR_BIT;
 218
 219 static inline unsigned
 220 NumWordsForBitArrayOfLength(size_t length)
 221 {
 222     return (length + (BitArrayElementBits - 1)) / BitArrayElementBits;
 223 }
 224
 225 static inline unsigned
 226 BitArrayIndexToWordIndex(size_t length, size_t bitIndex)
 227 {
 228     unsigned wordIndex = bitIndex / BitArrayElementBits;
 229     JS_ASSERT(wordIndex < length);
 230     return wordIndex;
 231 }
 232
 233 static inline size_t
 234 BitArrayIndexToWordMask(size_t i)
 235 {
 236     return size_t(1) << (i % BitArrayElementBits);
 237 }
 238
 239 static inline bool
 240 IsBitArrayElementSet(size_t *array, size_t length, size_t i)
 241 {
 242     return array[BitArrayIndexToWordIndex(length, i)] & BitArrayIndexToWordMask(i);
 243 }
 244
 245 static inline bool
 246 IsAnyBitArrayElementSet(size_t *array, size_t length)
 247 {
 248     unsigned numWords = NumWordsForBitArrayOfLength(length);
 249     for (unsigned i = 0; i < numWords; ++i) {
 250         if (array[i])
 251             return true;
 252     }
 253     return false;
 254 }
 255
 256 static inline void
 257 SetBitArrayElement(size_t *array, size_t length, size_t i)
 258 {
 259     array[BitArrayIndexToWordIndex(length, i)] |= BitArrayIndexToWordMask(i);
 260 }
 261
 262 static inline void
 263 ClearBitArrayElement(size_t *array, size_t length, size_t i)
 264 {
 265     array[BitArrayIndexToWordIndex(length, i)] &= ~BitArrayIndexToWordMask(i);
 266 }
 267
 268 static inline void
 269 ClearAllBitArrayElements(size_t *array, size_t length)
 270 {
 271     for (unsigned i = 0; i < length; ++i)
 272         array[i] = 0;
 273 }
 274
 275 }  /* namespace js */
 276
 277 static inline void *
 278 Poison(void *ptr, int value, size_t num)
 279 {
 280     static bool inited = false;
 281     static bool poison = true;
 282     if (!inited) {
 283         char *env = getenv("JSGC_DISABLE_POISONING");
 284         if (env)
 285             poison = false;
 286         inited = true;
 287     }
 288
 289     if (poison)
 290         return memset(ptr, value, num);
 291
 292     return nullptr;
 293 }
 294
 295 /* Crash diagnostics */
 296 #ifdef DEBUG
 297 # define JS_CRASH_DIAGNOSTICS 1
 298 #endif
 299 #if defined(JS_CRASH_DIAGNOSTICS) || defined(JS_GC_ZEAL)
 300 # define JS_POISON(p, val, size) Poison(p, val, size)
 301 #else
 302 # define JS_POISON(p, val, size) ((void) 0)
 303 #endif
 304
 305 /* Bug 984101: Disable labeled poisoning until we have poison checking. */
 306 #define JS_EXTRA_POISON(p, val, size) ((void) 0)
 307
 308 /* Basic stats */
 309 #ifdef DEBUG
 310 # define JS_BASIC_STATS 1
 311 #endif
 312 #ifdef JS_BASIC_STATS
 313 # include <stdio.h>
 314 typedef struct JSBasicStats {
 315     uint32_t    num;
 316     uint32_t    max;
 317     double      sum;
 318     double      sqsum;
 319     uint32_t    logscale;           /* logarithmic scale: 0 (linear), 2, 10 */
 320     uint32_t    hist[11];
 321 } JSBasicStats;
 322 # define JS_INIT_STATIC_BASIC_STATS  {0,0,0,0,0,{0,0,0,0,0,0,0,0,0,0,0}}
 323 # define JS_BASIC_STATS_INIT(bs)     memset((bs), 0, sizeof(JSBasicStats))
 324 # define JS_BASIC_STATS_ACCUM(bs,val)                                         \
 325     JS_BasicStatsAccum(bs, val)
 326 # define JS_MeanAndStdDevBS(bs,sigma)                                         \
 327     JS_MeanAndStdDev((bs)->num, (bs)->sum, (bs)->sqsum, sigma)
 328 extern void
 329 JS_BasicStatsAccum(JSBasicStats *bs, uint32_t val);
 330 extern double
 331 JS_MeanAndStdDev(uint32_t num, double sum, double sqsum, double *sigma);
 332 extern void
 333 JS_DumpBasicStats(JSBasicStats *bs, const char *title, FILE *fp);
 334 extern void
 335 JS_DumpHistogram(JSBasicStats *bs, FILE *fp);
 336 #else
 337 # define JS_BASIC_STATS_ACCUM(bs,val)
 338 #endif
 339
 340 /* A jsbitmap_t is a long integer that can be used for bitmaps. */
 341 typedef size_t jsbitmap;
 342 #define JS_BITMAP_NBITS (sizeof(jsbitmap) * CHAR_BIT)
 343 #define JS_TEST_BIT(_map,_bit)  ((_map)[(_bit)/JS_BITMAP_NBITS] &             \
 344                                  (jsbitmap(1)<<((_bit)%JS_BITMAP_NBITS)))
 345 #define JS_SET_BIT(_map,_bit)   ((_map)[(_bit)/JS_BITMAP_NBITS] |=            \
 346                                  (jsbitmap(1)<<((_bit)%JS_BITMAP_NBITS)))
 347 #define JS_CLEAR_BIT(_map,_bit) ((_map)[(_bit)/JS_BITMAP_NBITS] &=            \
 348                                  ~(jsbitmap(1)<<((_bit)%JS_BITMAP_NBITS)))
 349
 350 /* Wrapper for various macros to stop warnings coming from their expansions. */
 351 #if defined(__clang__)
 352 # define JS_SILENCE_UNUSED_VALUE_IN_EXPR(expr)                                \
 353     JS_BEGIN_MACRO                                                            \
 354         _Pragma("clang diagnostic push")                                      \
 355         /* If these _Pragmas cause warnings for you, try disabling ccache. */ \
 356         _Pragma("clang diagnostic ignored \"-Wunused-value\"")                \
 357         { expr; }                                                             \
 358         _Pragma("clang diagnostic pop")                                       \
 359     JS_END_MACRO
 360 #elif MOZ_IS_GCC
 361
 362 #if MOZ_GCC_VERSION_AT_LEAST(4, 6, 0)
 363 # define JS_SILENCE_UNUSED_VALUE_IN_EXPR(expr)                                \
 364     JS_BEGIN_MACRO                                                            \
 365         _Pragma("GCC diagnostic push")                                        \
 366         _Pragma("GCC diagnostic ignored \"-Wunused-but-set-variable\"")       \
 367         expr;                                                                 \
 368         _Pragma("GCC diagnostic pop")                                         \
 369     JS_END_MACRO
 370 #endif
 371 #endif
 372
 373 #if !defined(JS_SILENCE_UNUSED_VALUE_IN_EXPR)
 374 # define JS_SILENCE_UNUSED_VALUE_IN_EXPR(expr)                                \
 375     JS_BEGIN_MACRO                                                            \
 376         expr;                                                                 \
 377     JS_END_MACRO
 378 #endif
 379
 380 #endif /* jsutil_h */