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| author | Jonathan Wakely <jwakely@redhat.com> | 2017-03-28 17:09:49 +0100 |
|---|---|---|
| committer | Jonathan Wakely <redi@gcc.gnu.org> | 2017-03-28 17:09:49 +0100 |
| commit | 92d85953a54ab7bf45f49e35cae98253eaf00752 (patch) | |
| tree | a616fc03fc91a88ce7eb94224dcc0d097b87b25f | |
| parent | 9d384e80bda2cf905cd550c8908494210ae11c15 (diff) | |
| download | gcc-92d85953a54ab7bf45f49e35cae98253eaf00752.zip gcc-92d85953a54ab7bf45f49e35cae98253eaf00752.tar.gz gcc-92d85953a54ab7bf45f49e35cae98253eaf00752.tar.bz2 | |
PR libstdc++/80137 use std::nextafter instead of looping
PR libstdc++/80137
* include/bits/random.tcc (generate_canonical): Use std::nextafter
or numeric_limits::epsilon() to reduce out-of-range values.
* testsuite/26_numerics/random/uniform_real_distribution/operators/
64351.cc: Verify complexity requirement is met.
From-SVN: r246542
| -rw-r--r-- | libstdc++-v3/ChangeLog | 6 | ||||
| -rw-r--r-- | libstdc++-v3/include/bits/random.tcc | 25 | ||||
| -rw-r--r-- | libstdc++-v3/testsuite/26_numerics/random/uniform_real_distribution/operators/64351.cc | 16 |
3 files changed, 33 insertions, 14 deletions
diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog index cc7c3fb..b4f7e2b 100644 --- a/libstdc++-v3/ChangeLog +++ b/libstdc++-v3/ChangeLog @@ -1,5 +1,11 @@ 2017-03-28 Jonathan Wakely <jwakely@redhat.com> + PR libstdc++/80137 + * include/bits/random.tcc (generate_canonical): Use std::nextafter + or numeric_limits::epsilon() to reduce out-of-range values. + * testsuite/26_numerics/random/uniform_real_distribution/operators/ + 64351.cc: Verify complexity requirement is met. + * doc/xml/manual/abi.xml: Add xml:id anchor. * doc/xml/manual/using.xml (manual.intro.using.macros): Document _GLIBCXX_RELEASE. Link to new anchor for __GLIBCXX__ notes. diff --git a/libstdc++-v3/include/bits/random.tcc b/libstdc++-v3/include/bits/random.tcc index 2d5582a..df05ebe 100644 --- a/libstdc++-v3/include/bits/random.tcc +++ b/libstdc++-v3/include/bits/random.tcc @@ -3323,18 +3323,23 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION const size_t __m = std::max<size_t>(1UL, (__b + __log2r - 1UL) / __log2r); _RealType __ret; - do + _RealType __sum = _RealType(0); + _RealType __tmp = _RealType(1); + for (size_t __k = __m; __k != 0; --__k) { - _RealType __sum = _RealType(0); - _RealType __tmp = _RealType(1); - for (size_t __k = __m; __k != 0; --__k) - { - __sum += _RealType(__urng() - __urng.min()) * __tmp; - __tmp *= __r; - } - __ret = __sum / __tmp; + __sum += _RealType(__urng() - __urng.min()) * __tmp; + __tmp *= __r; + } + __ret = __sum / __tmp; + if (__builtin_expect(__ret >= _RealType(1), 0)) + { +#if _GLIBCXX_USE_C99_MATH_TR1 + __ret = std::nextafter(_RealType(1), _RealType(0)); +#else + __ret = _RealType(1) + - std::numeric_limits<_RealType>::epsilon() / _RealType(2); +#endif } - while (__builtin_expect(__ret >= _RealType(1), 0)); return __ret; } diff --git a/libstdc++-v3/testsuite/26_numerics/random/uniform_real_distribution/operators/64351.cc b/libstdc++-v3/testsuite/26_numerics/random/uniform_real_distribution/operators/64351.cc index ddb67e8..229fe9c 100644 --- a/libstdc++-v3/testsuite/26_numerics/random/uniform_real_distribution/operators/64351.cc +++ b/libstdc++-v3/testsuite/26_numerics/random/uniform_real_distribution/operators/64351.cc @@ -42,10 +42,18 @@ test02() std::mt19937 rng(8890); std::seed_seq sequence{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}; rng.seed(sequence); - rng.discard(12 * 629143 + 6); - float n = - std::generate_canonical<float, std::numeric_limits<float>::digits>(rng); - VERIFY( n != 1.f ); + rng.discard(12 * 629143); + std::mt19937 rng2{rng}; + for (int i = 0; i < 20; ++i) + { + float n = + std::generate_canonical<float, std::numeric_limits<float>::digits>(rng); + VERIFY( n != 1.f ); + + // PR libstdc++/80137 + rng2.discard(1); + VERIFY( rng == rng2 ); + } } int |