Fix bug in random.
Test: ./run_test.py --bitness 32
Test: ./run_test.py --bitness 64
Test: ./run_test.py --bitness 64 --host
Bug: https://bugs.chromium.org/p/chromium/issues/detail?id=994957
Bug: http://b/139690488
Change-Id: I71708114d7fc8ed90c30b4d32b01d3f3aef7600b
(cherry picked from commit a1d1caa3d831030ce802ed335a9743180911d553)
(cherry picked from commit 819e8133bd777d2270ba19d54fd8fa8ac933a417)
diff --git a/include/random b/include/random
index 724bd0f..9b29e14 100644
--- a/include/random
+++ b/include/random
@@ -4593,7 +4593,10 @@
template<class _IntType>
poisson_distribution<_IntType>::param_type::param_type(double __mean)
- : __mean_(__mean)
+ // According to the standard `inf` is a valid input, but it causes the
+ // distribution to hang, so we replace it with the maximum representable
+ // mean.
+ : __mean_(isinf(__mean) ? numeric_limits<double>::max() : __mean)
{
if (__mean_ < 10)
{
@@ -4611,7 +4614,7 @@
{
__s_ = _VSTD::sqrt(__mean_);
__d_ = 6 * __mean_ * __mean_;
- __l_ = static_cast<result_type>(__mean_ - 1.1484);
+ __l_ = std::trunc(__mean_ - 1.1484);
__omega_ = .3989423 / __s_;
double __b1_ = .4166667E-1 / __mean_;
double __b2_ = .3 * __b1_ * __b1_;
@@ -4628,12 +4631,12 @@
_IntType
poisson_distribution<_IntType>::operator()(_URNG& __urng, const param_type& __pr)
{
- result_type __x;
+ double __tx;
uniform_real_distribution<double> __urd;
if (__pr.__mean_ < 10)
{
- __x = 0;
- for (double __p = __urd(__urng); __p > __pr.__l_; ++__x)
+ __tx = 0;
+ for (double __p = __urd(__urng); __p > __pr.__l_; ++__tx)
__p *= __urd(__urng);
}
else
@@ -4643,19 +4646,19 @@
double __u;
if (__g > 0)
{
- __x = static_cast<result_type>(__g);
- if (__x >= __pr.__l_)
- return __x;
- __difmuk = __pr.__mean_ - __x;
+ __tx = std::trunc(__g);
+ if (__tx >= __pr.__l_)
+ return std::__clamp_to_integral<result_type>(__tx);
+ __difmuk = __pr.__mean_ - __tx;
__u = __urd(__urng);
if (__pr.__d_ * __u >= __difmuk * __difmuk * __difmuk)
- return __x;
+ return std::__clamp_to_integral<result_type>(__tx);
}
exponential_distribution<double> __edist;
for (bool __using_exp_dist = false; true; __using_exp_dist = true)
{
double __e;
- if (__using_exp_dist || __g < 0)
+ if (__using_exp_dist || __g <= 0)
{
double __t;
do
@@ -4665,31 +4668,31 @@
__u += __u - 1;
__t = 1.8 + (__u < 0 ? -__e : __e);
} while (__t <= -.6744);
- __x = __pr.__mean_ + __pr.__s_ * __t;
- __difmuk = __pr.__mean_ - __x;
+ __tx = std::trunc(__pr.__mean_ + __pr.__s_ * __t);
+ __difmuk = __pr.__mean_ - __tx;
__using_exp_dist = true;
}
double __px;
double __py;
- if (__x < 10)
+ if (__tx < 10 && __tx >= 0)
{
const double __fac[] = {1, 1, 2, 6, 24, 120, 720, 5040,
40320, 362880};
__px = -__pr.__mean_;
- __py = _VSTD::pow(__pr.__mean_, (double)__x) / __fac[__x];
+ __py = _VSTD::pow(__pr.__mean_, (double)__tx) / __fac[static_cast<int>(__tx)];
}
else
{
- double __del = .8333333E-1 / __x;
+ double __del = .8333333E-1 / __tx;
__del -= 4.8 * __del * __del * __del;
- double __v = __difmuk / __x;
+ double __v = __difmuk / __tx;
if (_VSTD::abs(__v) > 0.25)
- __px = __x * _VSTD::log(1 + __v) - __difmuk - __del;
+ __px = __tx * _VSTD::log(1 + __v) - __difmuk - __del;
else
- __px = __x * __v * __v * (((((((.1250060 * __v + -.1384794) *
+ __px = __tx * __v * __v * (((((((.1250060 * __v + -.1384794) *
__v + .1421878) * __v + -.1661269) * __v + .2000118) *
__v + -.2500068) * __v + .3333333) * __v + -.5) - __del;
- __py = .3989423 / _VSTD::sqrt(__x);
+ __py = .3989423 / _VSTD::sqrt(__tx);
}
double __r = (0.5 - __difmuk) / __pr.__s_;
double __r2 = __r * __r;
@@ -4709,7 +4712,7 @@
}
}
}
- return __x;
+ return std::__clamp_to_integral<result_type>(__tx);
}
template <class _CharT, class _Traits, class _IntType>
diff --git a/test/std/numerics/rand/rand.dis/rand.dist.bern/rand.dist.bern.geo/eval.pass.cpp b/test/std/numerics/rand/rand.dis/rand.dist.bern/rand.dist.bern.geo/eval.pass.cpp
index 6e6072a..3c726a1 100644
--- a/test/std/numerics/rand/rand.dis/rand.dist.bern/rand.dist.bern.geo/eval.pass.cpp
+++ b/test/std/numerics/rand/rand.dis/rand.dist.bern/rand.dist.bern.geo/eval.pass.cpp
@@ -29,6 +29,20 @@
return x * x;
}
+struct Eng : std::mt19937 {
+ using Base = std::mt19937;
+ using Base::Base;
+};
+
+void test_small_inputs() {
+ Eng engine;
+ std::geometric_distribution<std::int16_t> distribution(5.45361e-311);
+ for (auto i=0; i < 1000; ++i) {
+ volatile auto res = distribution(engine);
+ ((void)res);
+ }
+}
+
void
test1()
{
@@ -295,4 +309,5 @@
test4();
test5();
test6();
+ test_small_inputs();
}
diff --git a/test/std/numerics/rand/rand.dis/rand.dist.pois/rand.dist.pois.poisson/eval.pass.cpp b/test/std/numerics/rand/rand.dis/rand.dist.pois/rand.dist.pois.poisson/eval.pass.cpp
index 12fcfa3..e7127d7 100644
--- a/test/std/numerics/rand/rand.dis/rand.dist.pois/rand.dist.pois.poisson/eval.pass.cpp
+++ b/test/std/numerics/rand/rand.dis/rand.dist.pois/rand.dist.pois.poisson/eval.pass.cpp
@@ -29,6 +29,68 @@
return x * x;
}
+void test_bad_ranges() {
+ // Test cases where the mean is around the largest representable integer for
+ // `result_type`. These cases don't generate valid poisson distributions, but
+ // at least they don't blow up.
+ std::mt19937 eng;
+
+ {
+ std::poisson_distribution<std::int16_t> distribution(32710.9);
+ for (int i=0; i < 1000; ++i) {
+ volatile std::int16_t res = distribution(eng);
+ ((void)res);
+ }
+ }
+ {
+ std::poisson_distribution<std::int16_t> distribution(std::numeric_limits<std::int16_t>::max());
+ for (int i=0; i < 1000; ++i) {
+ volatile std::int16_t res = distribution(eng);
+ ((void)res);
+ }
+ }
+ {
+ std::poisson_distribution<std::int16_t> distribution(
+ static_cast<double>(std::numeric_limits<std::int16_t>::max()) + 10);
+ for (int i=0; i < 1000; ++i) {
+ volatile std::int16_t res = distribution(eng);
+ ((void)res);
+ }
+ }
+ {
+ std::poisson_distribution<std::int16_t> distribution(
+ static_cast<double>(std::numeric_limits<std::int16_t>::max()) * 2);
+ for (int i=0; i < 1000; ++i) {
+ volatile std::int16_t res = distribution(eng);
+ ((void)res);
+ }
+ }
+ {
+ // We convert `INF` to `DBL_MAX` otherwise the distribution will hang.
+ std::poisson_distribution<std::int16_t> distribution(std::numeric_limits<double>::infinity());
+ for (int i=0; i < 1000; ++i) {
+ volatile std::int16_t res = distribution(eng);
+ ((void)res);
+ }
+ }
+ {
+ std::poisson_distribution<std::int16_t> distribution(0);
+ for (int i=0; i < 1000; ++i) {
+ volatile std::int16_t res = distribution(eng);
+ ((void)res);
+ }
+ }
+ {
+ // We convert `INF` to `DBL_MAX` otherwise the distribution will hang.
+ std::poisson_distribution<std::int16_t> distribution(-100);
+ for (int i=0; i < 1000; ++i) {
+ volatile std::int16_t res = distribution(eng);
+ ((void)res);
+ }
+ }
+}
+
+
int main()
{
{
@@ -148,4 +210,6 @@
assert(std::abs((skew - x_skew) / x_skew) < 0.01);
assert(std::abs((kurtosis - x_kurtosis) / x_kurtosis) < 0.01);
}
+
+ test_bad_ranges();
}
