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Check existence of BSD random before use.

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`TensorRandom` currently relies on BSD `random()`, which is not always
available.  The [linux manpage](https://man7.org/linux/man-pages/man3/srandom.3.html)
gives the glibc condition:
```
_XOPEN_SOURCE >= 500
               || /* Glibc since 2.19: */ _DEFAULT_SOURCE
	       || /* Glibc <= 2.19: */ _SVID_SOURCE ||  _BSD_SOURCE
```
In particular, this was failing to compile for MinGW via msys2. If not
available, we fall back to using `rand()`.
This commit is contained in:
Antonio Sanchez 2021-04-21 11:03:23 -07:00 committed by Rasmus Munk Larsen
parent d213a0bcea
commit 045c0609b5
1 changed files with 20 additions and 14 deletions
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34
unsupported/Eigen/CXX11/src/Tensor/TensorRandom.h
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@ -34,9 +34,9 @@ EIGEN_DEVICE_FUNC uint64_t get_random_seed() {
// we try to generate seeds faster than the clock resolution.
// We need 2 random values since the generator only generate 16 bits at
// a time (https://msdn.microsoft.com/en-us/library/398ax69y.aspx)
int rnd1 = ::rand();
int rnd2 = ::rand();
uint64_t rnd = (rnd1 | rnd2 << 16) ^ time;
unsigned rnd1 = static_cast<unsigned>(::rand());
unsigned rnd2 = static_cast<unsigned>(::rand());
uint64_t rnd = (rnd1 ^ (rnd2 << 16)) ^ time;
return rnd;
#elif defined __APPLE__
@ -45,23 +45,29 @@ EIGEN_DEVICE_FUNC uint64_t get_random_seed() {
uint64_t rnd = ::random() ^ mach_absolute_time();
return rnd;
#elif defined __native_client__
// Same approach as for win32, except using clock_gettime
timespec ts;
clock_gettime(CLOCK_REALTIME, &ts);
int rnd1 = ::rand();
int rnd2 = ::rand();
uint64_t rnd = (rnd1 | rnd2 << 16) ^ ts.tv_nsec;
return rnd;
#else
// Augment the current time with pseudo random number generation
// to ensure that we get different seeds if we try to generate seeds
// faster than the clock resolution.
timespec ts;
clock_gettime(CLOCK_REALTIME, &ts);
uint64_t rnd = ::random() ^ ts.tv_nsec;
return rnd;
// Check for BSD random().
#if EIGEN_COMP_GNUC && (\
defined(_XOPEN_SOURCE) && _XOPEN_SOURCE >= 500 \
|| /* Glibc since 2.19: */ (defined(_DEFAULT_SOURCE) && _DEFAULT_SOURCE) \
|| /* Glibc <= 2.19: */ (defined(_SVID_SOURCE) && _SVID_SOURCE) \
|| (defined(_BSD_SOURCE) && _BSD_SOURCE) \
)
uint64_t rnd = ::random();
#else
// Build random from rand()
unsigned rnd1 = static_cast<unsigned>(::rand());
unsigned rnd2 = static_cast<unsigned>(::rand());
uint64_t rnd = (rnd1 ^ (rnd2 << 16));
#endif
return rnd ^ ts.tv_nsec;
#endif
}