The Tor Browser: js/src/jsmath.cpp@6474c204b198 (annotated)

js/src/jsmath.cpp@6474c204b198 (annotated)

js/src/jsmath.cpp

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
  * vim: set ts=8 sts=4 et sw=4 tw=99:
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 /*
  * JS math package.
  */
 #include "jsmath.h"
 #include "mozilla/Constants.h"
 #include "mozilla/FloatingPoint.h"
 #include "mozilla/MathAlgorithms.h"
 #include "mozilla/MemoryReporting.h"
 #include <algorithm>  // for std::max
 #include <fcntl.h>
 #ifdef XP_UNIX
 # include <unistd.h>
 #endif
 #include "jsapi.h"
 #include "jsatom.h"
 #include "jscntxt.h"
 #include "jscompartment.h"
 #include "jslibmath.h"
 #include "jstypes.h"
 #include "prmjtime.h"
 #include "jsobjinlines.h"
 using namespace js;
 using mozilla::Abs;
 using mozilla::NumberEqualsInt32;
 using mozilla::NumberIsInt32;
 using mozilla::ExponentComponent;
 using mozilla::FloatingPoint;
 using mozilla::IsFinite;
 using mozilla::IsInfinite;
 using mozilla::IsNaN;
 using mozilla::IsNegative;
 using mozilla::IsNegativeZero;
 using mozilla::PositiveInfinity;
 using mozilla::NegativeInfinity;
 using JS::ToNumber;
 using JS::GenericNaN;
 static const JSConstDoubleSpec math_constants[] = {
     {M_E,       "E",            0, {0,0,0}},
     {M_LOG2E,   "LOG2E",        0, {0,0,0}},
     {M_LOG10E,  "LOG10E",       0, {0,0,0}},
     {M_LN2,     "LN2",          0, {0,0,0}},
     {M_LN10,    "LN10",         0, {0,0,0}},
     {M_PI,      "PI",           0, {0,0,0}},
     {M_SQRT2,   "SQRT2",        0, {0,0,0}},
     {M_SQRT1_2, "SQRT1_2",      0, {0,0,0}},
     {0,0,0,{0,0,0}}
 };
 MathCache::MathCache() {
     memset(table, 0, sizeof(table));
     /* See comments in lookup(). */
     JS_ASSERT(IsNegativeZero(-0.0));
     JS_ASSERT(!IsNegativeZero(+0.0));
     JS_ASSERT(hash(-0.0) != hash(+0.0));
 }
 size_t
 MathCache::sizeOfIncludingThis(mozilla::MallocSizeOf mallocSizeOf)
 {
     return mallocSizeOf(this);
 }
 const Class js::MathClass = {
     js_Math_str,
     JSCLASS_HAS_CACHED_PROTO(JSProto_Math),
     JS_PropertyStub,         /* addProperty */
     JS_DeletePropertyStub,   /* delProperty */
     JS_PropertyStub,         /* getProperty */
     JS_StrictPropertyStub,   /* setProperty */
     JS_EnumerateStub,
     JS_ResolveStub,
     JS_ConvertStub
 };
 bool
 js_math_abs(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     if (args.length() == 0) {
         args.rval().setNaN();
         return true;
     }
     double x;
     if (!ToNumber(cx, args[0], &x))
         return false;
     double z = Abs(x);
     args.rval().setNumber(z);
     return true;
 }
 #if defined(SOLARIS) && defined(__GNUC__)
 #define ACOS_IF_OUT_OF_RANGE(x) if (x < -1 || 1 < x) return GenericNaN();
 #else
 #define ACOS_IF_OUT_OF_RANGE(x)
 #endif
 double
 js::math_acos_impl(MathCache *cache, double x)
 {
     ACOS_IF_OUT_OF_RANGE(x);
     return cache->lookup(acos, x);
 }
 double
 js::math_acos_uncached(double x)
 {
     ACOS_IF_OUT_OF_RANGE(x);
     return acos(x);
 }
 #undef ACOS_IF_OUT_OF_RANGE
 bool
 js::math_acos(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     if (args.length() == 0) {
         args.rval().setNaN();
         return true;
     }
     double x;
     if (!ToNumber(cx, args[0], &x))
         return false;
     MathCache *mathCache = cx->runtime()->getMathCache(cx);
     if (!mathCache)
         return false;
     double z = math_acos_impl(mathCache, x);
     args.rval().setDouble(z);
     return true;
 }
 #if defined(SOLARIS) && defined(__GNUC__)
 #define ASIN_IF_OUT_OF_RANGE(x) if (x < -1 || 1 < x) return GenericNaN();
 #else
 #define ASIN_IF_OUT_OF_RANGE(x)
 #endif
 double
 js::math_asin_impl(MathCache *cache, double x)
 {
     ASIN_IF_OUT_OF_RANGE(x);
     return cache->lookup(asin, x);
 }
 double
 js::math_asin_uncached(double x)
 {
     ASIN_IF_OUT_OF_RANGE(x);
     return asin(x);
 }
 #undef ASIN_IF_OUT_OF_RANGE
 bool
 js::math_asin(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     if (args.length() == 0) {
         args.rval().setNaN();
         return true;
     }
     double x;
     if (!ToNumber(cx, args[0], &x))
         return false;
     MathCache *mathCache = cx->runtime()->getMathCache(cx);
     if (!mathCache)
         return false;
     double z = math_asin_impl(mathCache, x);
     args.rval().setDouble(z);
     return true;
 }
 double
 js::math_atan_impl(MathCache *cache, double x)
 {
     return cache->lookup(atan, x);
 }
 double
 js::math_atan_uncached(double x)
 {
     return atan(x);
 }
 bool
 js::math_atan(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     if (args.length() == 0) {
         args.rval().setNaN();
         return true;
     }
     double x;
     if (!ToNumber(cx, args[0], &x))
         return false;
     MathCache *mathCache = cx->runtime()->getMathCache(cx);
     if (!mathCache)
         return false;
     double z = math_atan_impl(mathCache, x);
     args.rval().setDouble(z);
     return true;
 }
 double
 js::ecmaAtan2(double y, double x)
 {
 #if defined(_MSC_VER)
     /*
      * MSVC's atan2 does not yield the result demanded by ECMA when both x
      * and y are infinite.
      * - The result is a multiple of pi/4.
      * - The sign of y determines the sign of the result.
      * - The sign of x determines the multiplicator, 1 or 3.
      */
     if (IsInfinite(y) && IsInfinite(x)) {
         double z = js_copysign(M_PI / 4, y);
         if (x < 0)
             z *= 3;
         return z;
     }
 #endif
 #if defined(SOLARIS) && defined(__GNUC__)
     if (y == 0) {
         if (IsNegativeZero(x))
             return js_copysign(M_PI, y);
         if (x == 0)
             return y;
     }
 #endif
     return atan2(y, x);
 }
 bool
 js::math_atan2(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     double y;
     if (!ToNumber(cx, args.get(0), &y))
         return false;
     double x;
     if (!ToNumber(cx, args.get(1), &x))
         return false;
     double z = ecmaAtan2(y, x);
     args.rval().setDouble(z);
     return true;
 }
 double
 js::math_ceil_impl(double x)
 {
 #ifdef __APPLE__
     if (x < 0 && x > -1.0)
         return js_copysign(0, -1);
 #endif
     return ceil(x);
 }
 bool
 js::math_ceil(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     if (args.length() == 0) {
         args.rval().setNaN();
         return true;
     }
     double x;
     if (!ToNumber(cx, args[0], &x))
         return false;
     double z = math_ceil_impl(x);
     args.rval().setNumber(z);
     return true;
 }
 bool
 js::math_clz32(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     if (args.length() == 0) {
         args.rval().setInt32(32);
         return true;
     }
     uint32_t n;
     if (!ToUint32(cx, args[0], &n))
         return false;
     if (n == 0) {
         args.rval().setInt32(32);
         return true;
     }
     args.rval().setInt32(mozilla::CountLeadingZeroes32(n));
     return true;
 }
 double
 js::math_cos_impl(MathCache *cache, double x)
 {
     return cache->lookup(cos, x);
 }
 double
 js::math_cos_uncached(double x)
 {
     return cos(x);
 }
 bool
 js::math_cos(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     if (args.length() == 0) {
         args.rval().setNaN();
         return true;
     }
     double x;
     if (!ToNumber(cx, args[0], &x))
         return false;
     MathCache *mathCache = cx->runtime()->getMathCache(cx);
     if (!mathCache)
         return false;
     double z = math_cos_impl(mathCache, x);
     args.rval().setDouble(z);
     return true;
 }
 #ifdef _WIN32
 #define EXP_IF_OUT_OF_RANGE(x)                  \
     if (!IsNaN(x)) {                            \
         if (x == PositiveInfinity<double>())    \
             return PositiveInfinity<double>();  \
         if (x == NegativeInfinity<double>())    \
             return 0.0;                         \
     }
 #else
 #define EXP_IF_OUT_OF_RANGE(x)
 #endif
 double
 js::math_exp_impl(MathCache *cache, double x)
 {
     EXP_IF_OUT_OF_RANGE(x);
     return cache->lookup(exp, x);
 }
 double
 js::math_exp_uncached(double x)
 {
     EXP_IF_OUT_OF_RANGE(x);
     return exp(x);
 }
 #undef EXP_IF_OUT_OF_RANGE
 bool
 js::math_exp(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     if (args.length() == 0) {
         args.rval().setNaN();
         return true;
     }
     double x;
     if (!ToNumber(cx, args[0], &x))
         return false;
     MathCache *mathCache = cx->runtime()->getMathCache(cx);
     if (!mathCache)
         return false;
     double z = math_exp_impl(mathCache, x);
     args.rval().setNumber(z);
     return true;
 }
 double
 js::math_floor_impl(double x)
 {
     return floor(x);
 }
 bool
 js::math_floor(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     if (args.length() == 0) {
         args.rval().setNaN();
         return true;
     }
     double x;
     if (!ToNumber(cx, args[0], &x))
         return false;
     double z = math_floor_impl(x);
     args.rval().setNumber(z);
     return true;
 }
 bool
 js::math_imul(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     uint32_t a = 0, b = 0;
     if (args.hasDefined(0) && !ToUint32(cx, args[0], &a))
         return false;
     if (args.hasDefined(1) && !ToUint32(cx, args[1], &b))
         return false;
     uint32_t product = a * b;
     args.rval().setInt32(product > INT32_MAX
                          ? int32_t(INT32_MIN + (product - INT32_MAX - 1))
                          : int32_t(product));
     return true;
 }
 // Implements Math.fround (20.2.2.16) up to step 3
 bool
 js::RoundFloat32(JSContext *cx, Handle<Value> v, float *out)
 {
     double d;
     bool success = ToNumber(cx, v, &d);
     *out = static_cast<float>(d);
     return success;
 }
 bool
 js::math_fround(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     if (args.length() == 0) {
         args.rval().setNaN();
         return true;
     }
     float f;
     if (!RoundFloat32(cx, args[0], &f))
         return false;
     args.rval().setDouble(static_cast<double>(f));
     return true;
 }
 #if defined(SOLARIS) && defined(__GNUC__)
 #define LOG_IF_OUT_OF_RANGE(x) if (x < 0) return GenericNaN();
 #else
 #define LOG_IF_OUT_OF_RANGE(x)
 #endif
 double
 js::math_log_impl(MathCache *cache, double x)
 {
     LOG_IF_OUT_OF_RANGE(x);
     return cache->lookup(log, x);
 }
 double
 js::math_log_uncached(double x)
 {
     LOG_IF_OUT_OF_RANGE(x);
     return log(x);
 }
 #undef LOG_IF_OUT_OF_RANGE
 bool
 js::math_log(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     if (args.length() == 0) {
         args.rval().setNaN();
         return true;
     }
     double x;
     if (!ToNumber(cx, args[0], &x))
         return false;
     MathCache *mathCache = cx->runtime()->getMathCache(cx);
     if (!mathCache)
         return false;
     double z = math_log_impl(mathCache, x);
     args.rval().setNumber(z);
     return true;
 }
 bool
 js_math_max(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     double maxval = NegativeInfinity<double>();
     for (unsigned i = 0; i < args.length(); i++) {
         double x;
         if (!ToNumber(cx, args[i], &x))
             return false;
         // Math.max(num, NaN) => NaN, Math.max(-0, +0) => +0
         if (x > maxval || IsNaN(x) || (x == maxval && IsNegative(maxval)))
             maxval = x;
     }
     args.rval().setNumber(maxval);
     return true;
 }
 bool
 js_math_min(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     double minval = PositiveInfinity<double>();
     for (unsigned i = 0; i < args.length(); i++) {
         double x;
         if (!ToNumber(cx, args[i], &x))
             return false;
         // Math.min(num, NaN) => NaN, Math.min(-0, +0) => -0
         if (x < minval || IsNaN(x) || (x == minval && IsNegativeZero(x)))
             minval = x;
     }
     args.rval().setNumber(minval);
     return true;
 }
 // Disable PGO for Math.pow() and related functions (see bug 791214).
 #if defined(_MSC_VER)
 # pragma optimize("g", off)
 #endif
 double
 js::powi(double x, int y)
 {
     unsigned n = (y < 0) ? -y : y;
     double m = x;
     double p = 1;
     while (true) {
         if ((n & 1) != 0) p *= m;
         n >>= 1;
         if (n == 0) {
             if (y < 0) {
                 // Unfortunately, we have to be careful when p has reached
                 // infinity in the computation, because sometimes the higher
                 // internal precision in the pow() implementation would have
                 // given us a finite p. This happens very rarely.
                 double result = 1.0 / p;
                 return (result == 0 && IsInfinite(p))
                        ? pow(x, static_cast<double>(y))  // Avoid pow(double, int).
                        : result;
             }
             return p;
         }
         m *= m;
     }
 }
 #if defined(_MSC_VER)
 # pragma optimize("", on)
 #endif
 // Disable PGO for Math.pow() and related functions (see bug 791214).
 #if defined(_MSC_VER)
 # pragma optimize("g", off)
 #endif
 double
 js::ecmaPow(double x, double y)
 {
     /*
      * Use powi if the exponent is an integer-valued double. We don't have to
      * check for NaN since a comparison with NaN is always false.
      */
     int32_t yi;
     if (NumberEqualsInt32(y, &yi))
         return powi(x, yi);
     /*
      * Because C99 and ECMA specify different behavior for pow(),
      * we need to wrap the libm call to make it ECMA compliant.
      */
     if (!IsFinite(y) && (x == 1.0 || x == -1.0))
         return GenericNaN();
     /* pow(x, +-0) is always 1, even for x = NaN (MSVC gets this wrong). */
     if (y == 0)
         return 1;
     /*
      * Special case for square roots. Note that pow(x, 0.5) != sqrt(x)
      * when x = -0.0, so we have to guard for this.
      */
     if (IsFinite(x) && x != 0.0) {
         if (y == 0.5)
             return sqrt(x);
         if (y == -0.5)
             return 1.0 / sqrt(x);
     }
     return pow(x, y);
 }
 #if defined(_MSC_VER)
 # pragma optimize("", on)
 #endif
 // Disable PGO for Math.pow() and related functions (see bug 791214).
 #if defined(_MSC_VER)
 # pragma optimize("g", off)
 #endif
 bool
 js_math_pow(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     double x;
     if (!ToNumber(cx, args.get(0), &x))
         return false;
     double y;
     if (!ToNumber(cx, args.get(1), &y))
         return false;
     double z = ecmaPow(x, y);
     args.rval().setNumber(z);
     return true;
 }
 #if defined(_MSC_VER)
 # pragma optimize("", on)
 #endif
 static uint64_t
 random_generateSeed()
 {
     union {
         uint8_t     u8[8];
         uint32_t    u32[2];
         uint64_t    u64;
     } seed;
     seed.u64 = 0;
 #if defined(XP_WIN)
     /*
      * Our PRNG only uses 48 bits, so calling rand_s() twice to get 64 bits is
      * probably overkill.
      */
     rand_s(&seed.u32[0]);
 #elif defined(XP_UNIX)
     /*
      * In the unlikely event we can't read /dev/urandom, there's not much we can
      * do, so just mix in the fd error code and the current time.
      */
     int fd = open("/dev/urandom", O_RDONLY);
     MOZ_ASSERT(fd >= 0, "Can't open /dev/urandom");
     if (fd >= 0) {
         read(fd, seed.u8, mozilla::ArrayLength(seed.u8));
         close(fd);
     }
     seed.u32[0] ^= fd;
 #else
 # error "Platform needs to implement random_generateSeed()"
 #endif
     seed.u32[1] ^= PRMJ_Now();
     return seed.u64;
 }
 static const uint64_t RNG_MULTIPLIER = 0x5DEECE66DLL;
 static const uint64_t RNG_ADDEND = 0xBLL;
 static const uint64_t RNG_MASK = (1LL << 48) - 1;
 static const double RNG_DSCALE = double(1LL << 53);
 /*
  * Math.random() support, lifted from java.util.Random.java.
  */
 static void
 random_initState(uint64_t *rngState)
 {
     /* Our PRNG only uses 48 bits, so squeeze our entropy into those bits. */
     uint64_t seed = random_generateSeed();
     seed ^= (seed >> 16);
     *rngState = (seed ^ RNG_MULTIPLIER) & RNG_MASK;
 }
 uint64_t
 random_next(uint64_t *rngState, int bits)
 {
     MOZ_ASSERT((*rngState & 0xffff000000000000ULL) == 0, "Bad rngState");
     MOZ_ASSERT(bits > 0 && bits <= 48, "bits is out of range");
     if (*rngState == 0) {
         random_initState(rngState);
     }
     uint64_t nextstate = *rngState * RNG_MULTIPLIER;
     nextstate += RNG_ADDEND;
     nextstate &= RNG_MASK;
     *rngState = nextstate;
     return nextstate >> (48 - bits);
 }
 static inline double
 random_nextDouble(JSContext *cx)
 {
     uint64_t *rng = &cx->compartment()->rngState;
     return double((random_next(rng, 26) << 27) + random_next(rng, 27)) / RNG_DSCALE;
 }
 double
 math_random_no_outparam(JSContext *cx)
 {
     /* Calculate random without memory traffic, for use in the JITs. */
     return random_nextDouble(cx);
 }
 bool
 js_math_random(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     double z = random_nextDouble(cx);
     args.rval().setDouble(z);
     return true;
 }
 double
 js::math_round_impl(double x)
 {
     int32_t ignored;
     if (NumberIsInt32(x, &ignored))
         return x;
     /* Some numbers are so big that adding 0.5 would give the wrong number. */
     if (ExponentComponent(x) >= int_fast16_t(FloatingPoint<double>::ExponentShift))
         return x;
     return js_copysign(floor(x + 0.5), x);
 }
 float
 js::math_roundf_impl(float x)
 {
     int32_t ignored;
     if (NumberIsInt32(x, &ignored))
         return x;
     /* Some numbers are so big that adding 0.5 would give the wrong number. */
     if (ExponentComponent(x) >= int_fast16_t(FloatingPoint<float>::ExponentShift))
         return x;
     return js_copysign(floorf(x + 0.5f), x);
 }
 bool /* ES5 15.8.2.15. */
 js::math_round(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     if (args.length() == 0) {
         args.rval().setNaN();
         return true;
     }
     double x;
     if (!ToNumber(cx, args[0], &x))
         return false;
     double z = math_round_impl(x);
     args.rval().setNumber(z);
     return true;
 }
 double
 js::math_sin_impl(MathCache *cache, double x)
 {
     return cache->lookup(sin, x);
 }
 double
 js::math_sin_uncached(double x)
 {
     return sin(x);
 }
 bool
 js::math_sin(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     if (args.length() == 0) {
         args.rval().setNaN();
         return true;
     }
     double x;
     if (!ToNumber(cx, args[0], &x))
         return false;
     MathCache *mathCache = cx->runtime()->getMathCache(cx);
     if (!mathCache)
         return false;
     double z = math_sin_impl(mathCache, x);
     args.rval().setDouble(z);
     return true;
 }
 bool
 js_math_sqrt(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     if (args.length() == 0) {
         args.rval().setNaN();
         return true;
     }
     double x;
     if (!ToNumber(cx, args[0], &x))
         return false;
     MathCache *mathCache = cx->runtime()->getMathCache(cx);
     if (!mathCache)
         return false;
     double z = mathCache->lookup(sqrt, x);
     args.rval().setDouble(z);
     return true;
 }
 double
 js::math_tan_impl(MathCache *cache, double x)
 {
     return cache->lookup(tan, x);
 }
 double
 js::math_tan_uncached(double x)
 {
     return tan(x);
 }
 bool
 js::math_tan(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     if (args.length() == 0) {
         args.rval().setNaN();
         return true;
     }
     double x;
     if (!ToNumber(cx, args[0], &x))
         return false;
     MathCache *mathCache = cx->runtime()->getMathCache(cx);
     if (!mathCache)
         return false;
     double z = math_tan_impl(mathCache, x);
     args.rval().setDouble(z);
     return true;
 }
 typedef double (*UnaryMathFunctionType)(MathCache *cache, double);
 template <UnaryMathFunctionType F>
 static bool math_function(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     if (args.length() == 0) {
         args.rval().setNumber(GenericNaN());
         return true;
     }
     double x;
     if (!ToNumber(cx, args[0], &x))
         return false;
     MathCache *mathCache = cx->runtime()->getMathCache(cx);
     if (!mathCache)
         return false;
     double z = F(mathCache, x);
     args.rval().setNumber(z);
     return true;
 }
 double
 js::math_log10_impl(MathCache *cache, double x)
 {
     return cache->lookup(log10, x);
 }
 double
 js::math_log10_uncached(double x)
 {
     return log10(x);
 }
 bool
 js::math_log10(JSContext *cx, unsigned argc, Value *vp)
 {
     return math_function<math_log10_impl>(cx, argc, vp);
 }
 #if !HAVE_LOG2
 double log2(double x)
 {
     return log(x) / M_LN2;
 }
 #endif
 double
 js::math_log2_impl(MathCache *cache, double x)
 {
     return cache->lookup(log2, x);
 }
 double
 js::math_log2_uncached(double x)
 {
     return log2(x);
 }
 bool
 js::math_log2(JSContext *cx, unsigned argc, Value *vp)
 {
     return math_function<math_log2_impl>(cx, argc, vp);
 }
 #if !HAVE_LOG1P
 double log1p(double x)
 {
     if (fabs(x) < 1e-4) {
         /*
          * Use Taylor approx. log(1 + x) = x - x^2 / 2 + x^3 / 3 - x^4 / 4 with error x^5 / 5
          * Since |x| < 10^-4, |x|^5 < 10^-20, relative error less than 10^-16
          */
         double z = -(x * x * x * x) / 4 + (x * x * x) / 3 - (x * x) / 2 + x;
         return z;
     } else {
         /* For other large enough values of x use direct computation */
         return log(1.0 + x);
     }
 }
 #endif
 #ifdef __APPLE__
 // Ensure that log1p(-0) is -0.
 #define LOG1P_IF_OUT_OF_RANGE(x) if (x == 0) return x;
 #else
 #define LOG1P_IF_OUT_OF_RANGE(x)
 #endif
 double
 js::math_log1p_impl(MathCache *cache, double x)
 {
     LOG1P_IF_OUT_OF_RANGE(x);
     return cache->lookup(log1p, x);
 }
 double
 js::math_log1p_uncached(double x)
 {
     LOG1P_IF_OUT_OF_RANGE(x);
     return log1p(x);
 }
 #undef LOG1P_IF_OUT_OF_RANGE
 bool
 js::math_log1p(JSContext *cx, unsigned argc, Value *vp)
 {
     return math_function<math_log1p_impl>(cx, argc, vp);
 }
 #if !HAVE_EXPM1
 double expm1(double x)
 {
     /* Special handling for -0 */
     if (x == 0.0)
         return x;
     if (fabs(x) < 1e-5) {
         /*
          * Use Taylor approx. exp(x) - 1 = x + x^2 / 2 + x^3 / 6 with error x^4 / 24
          * Since |x| < 10^-5, |x|^4 < 10^-20, relative error less than 10^-15
          */
         double z = (x * x * x) / 6 + (x * x) / 2 + x;
         return z;
     } else {
         /* For other large enough values of x use direct computation */
         return exp(x) - 1.0;
     }
 }
 #endif
 double
 js::math_expm1_impl(MathCache *cache, double x)
 {
     return cache->lookup(expm1, x);
 }
 double
 js::math_expm1_uncached(double x)
 {
     return expm1(x);
 }
 bool
 js::math_expm1(JSContext *cx, unsigned argc, Value *vp)
 {
     return math_function<math_expm1_impl>(cx, argc, vp);
 }
 #if !HAVE_SQRT1PM1
 /* This algorithm computes sqrt(1+x)-1 for small x */
 double sqrt1pm1(double x)
 {
     if (fabs(x) > 0.75)
         return sqrt(1 + x) - 1;
     return expm1(log1p(x) / 2);
 }
 #endif
 double
 js::math_cosh_impl(MathCache *cache, double x)
 {
     return cache->lookup(cosh, x);
 }
 double
 js::math_cosh_uncached(double x)
 {
     return cosh(x);
 }
 bool
 js::math_cosh(JSContext *cx, unsigned argc, Value *vp)
 {
     return math_function<math_cosh_impl>(cx, argc, vp);
 }
 double
 js::math_sinh_impl(MathCache *cache, double x)
 {
     return cache->lookup(sinh, x);
 }
 double
 js::math_sinh_uncached(double x)
 {
     return sinh(x);
 }
 bool
 js::math_sinh(JSContext *cx, unsigned argc, Value *vp)
 {
     return math_function<math_sinh_impl>(cx, argc, vp);
 }
 double
 js::math_tanh_impl(MathCache *cache, double x)
 {
     return cache->lookup(tanh, x);
 }
 double
 js::math_tanh_uncached(double x)
 {
     return tanh(x);
 }
 bool
 js::math_tanh(JSContext *cx, unsigned argc, Value *vp)
 {
     return math_function<math_tanh_impl>(cx, argc, vp);
 }
 #if !HAVE_ACOSH
 double acosh(double x)
 {
     const double SQUARE_ROOT_EPSILON = sqrt(std::numeric_limits<double>::epsilon());
     if ((x - 1) >= SQUARE_ROOT_EPSILON) {
         if (x > 1 / SQUARE_ROOT_EPSILON) {
             /*
              * http://functions.wolfram.com/ElementaryFunctions/ArcCosh/06/01/06/01/0001/
              * approximation by laurent series in 1/x at 0+ order from -1 to 0
              */
             return log(x) + M_LN2;
         } else if (x < 1.5) {
             // This is just a rearrangement of the standard form below
             // devised to minimize loss of precision when x ~ 1:
             double y = x - 1;
             return log1p(y + sqrt(y * y + 2 * y));
         } else {
             // http://functions.wolfram.com/ElementaryFunctions/ArcCosh/02/
             return log(x + sqrt(x * x - 1));
         }
     } else {
         // see http://functions.wolfram.com/ElementaryFunctions/ArcCosh/06/01/04/01/0001/
         double y = x - 1;
         // approximation by taylor series in y at 0 up to order 2.
         // If x is less than 1, sqrt(2 * y) is NaN and the result is NaN.
         return sqrt(2 * y) * (1 - y / 12 + 3 * y * y / 160);
     }
 }
 #endif
 double
 js::math_acosh_impl(MathCache *cache, double x)
 {
     return cache->lookup(acosh, x);
 }
 double
 js::math_acosh_uncached(double x)
 {
     return acosh(x);
 }
 bool
 js::math_acosh(JSContext *cx, unsigned argc, Value *vp)
 {
     return math_function<math_acosh_impl>(cx, argc, vp);
 }
 #if !HAVE_ASINH
 // Bug 899712 - gcc incorrectly rewrites -asinh(-x) to asinh(x) when overriding
 // asinh.
 static double my_asinh(double x)
 {
     const double SQUARE_ROOT_EPSILON = sqrt(std::numeric_limits<double>::epsilon());
     const double FOURTH_ROOT_EPSILON = sqrt(SQUARE_ROOT_EPSILON);
     if (x >= FOURTH_ROOT_EPSILON) {
         if (x > 1 / SQUARE_ROOT_EPSILON)
             // http://functions.wolfram.com/ElementaryFunctions/ArcSinh/06/01/06/01/0001/
             // approximation by laurent series in 1/x at 0+ order from -1 to 1
             return M_LN2 + log(x) + 1 / (4 * x * x);
         else if (x < 0.5)
             return log1p(x + sqrt1pm1(x * x));
         else
             return log(x + sqrt(x * x + 1));
     } else if (x <= -FOURTH_ROOT_EPSILON) {
         return -my_asinh(-x);
     } else {
         // http://functions.wolfram.com/ElementaryFunctions/ArcSinh/06/01/03/01/0001/
         // approximation by taylor series in x at 0 up to order 2
         double result = x;
         if (fabs(x) >= SQUARE_ROOT_EPSILON) {
             double x3 = x * x * x;
             // approximation by taylor series in x at 0 up to order 4
             result -= x3 / 6;
         }
         return result;
     }
 }
 #endif
 double
 js::math_asinh_impl(MathCache *cache, double x)
 {
 #ifdef HAVE_ASINH
     return cache->lookup(asinh, x);
 #else
     return cache->lookup(my_asinh, x);
 #endif
 }
 double
 js::math_asinh_uncached(double x)
 {
 #ifdef HAVE_ASINH
     return asinh(x);
 #else
     return my_asinh(x);
 #endif
 }
 bool
 js::math_asinh(JSContext *cx, unsigned argc, Value *vp)
 {
     return math_function<math_asinh_impl>(cx, argc, vp);
 }
 #if !HAVE_ATANH
 double atanh(double x)
 {
     const double EPSILON = std::numeric_limits<double>::epsilon();
     const double SQUARE_ROOT_EPSILON = sqrt(EPSILON);
     const double FOURTH_ROOT_EPSILON = sqrt(SQUARE_ROOT_EPSILON);
     if (fabs(x) >= FOURTH_ROOT_EPSILON) {
         // http://functions.wolfram.com/ElementaryFunctions/ArcTanh/02/
         if (fabs(x) < 0.5)
             return (log1p(x) - log1p(-x)) / 2;
         return log((1 + x) / (1 - x)) / 2;
     } else {
         // http://functions.wolfram.com/ElementaryFunctions/ArcTanh/06/01/03/01/
         // approximation by taylor series in x at 0 up to order 2
         double result = x;
         if (fabs(x) >= SQUARE_ROOT_EPSILON) {
             double x3 = x * x * x;
             result += x3 / 3;
         }
         return result;
     }
 }
 #endif
 double
 js::math_atanh_impl(MathCache *cache, double x)
 {
     return cache->lookup(atanh, x);
 }
 double
 js::math_atanh_uncached(double x)
 {
     return atanh(x);
 }
 bool
 js::math_atanh(JSContext *cx, unsigned argc, Value *vp)
 {
     return math_function<math_atanh_impl>(cx, argc, vp);
 }
 /* Consistency wrapper for platform deviations in hypot() */
 double
 js::ecmaHypot(double x, double y)
 {
 #ifdef XP_WIN
     /*
      * Workaround MS hypot bug, where hypot(Infinity, NaN or Math.MIN_VALUE)
      * is NaN, not Infinity.
      */
     if (mozilla::IsInfinite(x) || mozilla::IsInfinite(y)) {
         return mozilla::PositiveInfinity<double>();
     }
 #endif
     return hypot(x, y);
 }
 bool
 js::math_hypot(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     // IonMonkey calls the system hypot function directly if two arguments are
     // given. Do that here as well to get the same results.
     if (args.length() == 2) {
         double x, y;
         if (!ToNumber(cx, args[0], &x))
             return false;
         if (!ToNumber(cx, args[1], &y))
             return false;
         double result = ecmaHypot(x, y);
         args.rval().setNumber(result);
         return true;
     }
     bool isInfinite = false;
     bool isNaN = false;
     double scale = 0;
     double sumsq = 1;
     for (unsigned i = 0; i < args.length(); i++) {
         double x;
         if (!ToNumber(cx, args[i], &x))
             return false;
         isInfinite |= mozilla::IsInfinite(x);
         isNaN |= mozilla::IsNaN(x);
         double xabs = mozilla::Abs(x);
         if (scale < xabs) {
             sumsq = 1 + sumsq * (scale / xabs) * (scale / xabs);
             scale = xabs;
         } else if (scale != 0) {
             sumsq += (xabs / scale) * (xabs / scale);
         }
     }
     double result = isInfinite ? PositiveInfinity<double>() :
                     isNaN ? GenericNaN() :
                     scale * sqrt(sumsq);
     args.rval().setNumber(result);
     return true;
 }
 #if !HAVE_TRUNC
 double trunc(double x)
 {
     return x > 0 ? floor(x) : ceil(x);
 }
 #endif
 double
 js::math_trunc_impl(MathCache *cache, double x)
 {
     return cache->lookup(trunc, x);
 }
 double
 js::math_trunc_uncached(double x)
 {
     return trunc(x);
 }
 bool
 js::math_trunc(JSContext *cx, unsigned argc, Value *vp)
 {
     return math_function<math_trunc_impl>(cx, argc, vp);
 }
 static double sign(double x)
 {
     if (mozilla::IsNaN(x))
         return GenericNaN();
     return x == 0 ? x : x < 0 ? -1 : 1;
 }
 double
 js::math_sign_impl(MathCache *cache, double x)
 {
     return cache->lookup(sign, x);
 }
 double
 js::math_sign_uncached(double x)
 {
     return sign(x);
 }
 bool
 js::math_sign(JSContext *cx, unsigned argc, Value *vp)
 {
     return math_function<math_sign_impl>(cx, argc, vp);
 }
 #if !HAVE_CBRT
 double cbrt(double x)
 {
     if (x > 0) {
         return pow(x, 1.0 / 3.0);
     } else if (x == 0) {
         return x;
     } else {
         return -pow(-x, 1.0 / 3.0);
     }
 }
 #endif
 double
 js::math_cbrt_impl(MathCache *cache, double x)
 {
     return cache->lookup(cbrt, x);
 }
 double
 js::math_cbrt_uncached(double x)
 {
     return cbrt(x);
 }
 bool
 js::math_cbrt(JSContext *cx, unsigned argc, Value *vp)
 {
     return math_function<math_cbrt_impl>(cx, argc, vp);
 }
 #if JS_HAS_TOSOURCE
 static bool
 math_toSource(JSContext *cx, unsigned argc, Value *vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     args.rval().setString(cx->names().Math);
     return true;
 }
 #endif
 static const JSFunctionSpec math_static_methods[] = {
 #if JS_HAS_TOSOURCE
     JS_FN(js_toSource_str,  math_toSource,        0, 0),
 #endif
     JS_FN("abs",            js_math_abs,          1, 0),
     JS_FN("acos",           math_acos,            1, 0),
     JS_FN("asin",           math_asin,            1, 0),
     JS_FN("atan",           math_atan,            1, 0),
     JS_FN("atan2",          math_atan2,           2, 0),
     JS_FN("ceil",           math_ceil,            1, 0),
     JS_FN("clz32",          math_clz32,           1, 0),
     JS_FN("cos",            math_cos,             1, 0),
     JS_FN("exp",            math_exp,             1, 0),
     JS_FN("floor",          math_floor,           1, 0),
     JS_FN("imul",           math_imul,            2, 0),
     JS_FN("fround",         math_fround,          1, 0),
     JS_FN("log",            math_log,             1, 0),
     JS_FN("max",            js_math_max,          2, 0),
     JS_FN("min",            js_math_min,          2, 0),
     JS_FN("pow",            js_math_pow,          2, 0),
     JS_FN("random",         js_math_random,       0, 0),
     JS_FN("round",          math_round,           1, 0),
     JS_FN("sin",            math_sin,             1, 0),
     JS_FN("sqrt",           js_math_sqrt,         1, 0),
     JS_FN("tan",            math_tan,             1, 0),
     JS_FN("log10",          math_log10,           1, 0),
     JS_FN("log2",           math_log2,            1, 0),
     JS_FN("log1p",          math_log1p,           1, 0),
     JS_FN("expm1",          math_expm1,           1, 0),
     JS_FN("cosh",           math_cosh,            1, 0),
     JS_FN("sinh",           math_sinh,            1, 0),
     JS_FN("tanh",           math_tanh,            1, 0),
     JS_FN("acosh",          math_acosh,           1, 0),
     JS_FN("asinh",          math_asinh,           1, 0),
     JS_FN("atanh",          math_atanh,           1, 0),
     JS_FN("hypot",          math_hypot,           2, 0),
     JS_FN("trunc",          math_trunc,           1, 0),
     JS_FN("sign",           math_sign,            1, 0),
     JS_FN("cbrt",           math_cbrt,            1, 0),
     JS_FS_END
 };
 JSObject *
 js_InitMathClass(JSContext *cx, HandleObject obj)
 {
     RootedObject proto(cx, obj->as<GlobalObject>().getOrCreateObjectPrototype(cx));
     if (!proto)
         return nullptr;
     RootedObject Math(cx, NewObjectWithGivenProto(cx, &MathClass, proto, obj, SingletonObject));
     if (!Math)
         return nullptr;
     if (!JS_DefineProperty(cx, obj, js_Math_str, Math, 0,
                            JS_PropertyStub, JS_StrictPropertyStub))
     {
         return nullptr;
     }
     if (!JS_DefineFunctions(cx, Math, math_static_methods))
         return nullptr;
     if (!JS_DefineConstDoubles(cx, Math, math_constants))
         return nullptr;
     obj->as<GlobalObject>().setConstructor(JSProto_Math, ObjectValue(*Math));
     return Math;
 }

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js/src/jsmath.cpp