The multiplication (4 * _M_t * __1p) can wraparound to zero if _M_t is
unsigned and 4 * _M_t wraps to zero. The third operand has type double,
so do the second multiplication first, so that we aren't multiplying
integers.
libstdc++-v3/ChangeLog:
PR libstdc++/114359
* include/bits/random.tcc (binomial_distribution::param_type):
Ensure arithmetic is done as type double.
* testsuite/26_numerics/random/binomial_distribution/114359.cc: New test.
(cherry picked from commit 07e03761a7)
I implemented the resolution of LWG 3809 in r13-4364-ga64775a0edd469 but
it was recently noted in the MSVC STL github repo that the change causes
possible truncation for 64-bit seeds. Whether the truncation occurs (and
to what value) depends on the width of uint_least32_t which is not
portable, so the output of the PRNG for 64-bit seed values is no longer
the same as in C++20, and no longer portable across platforms.
That new issue was filed as LWG 4014. I proposed a new change which
reduces the seed by the LCG's modulus before the conversion to
uint_least32_t. This ensures that 64-bit seed values are consistently
reduced by the modulus before any truncation. This removes the
platform-dependent behaviour and restores the old behaviour for
std::subtract_with_carry_engine specializations using a 64-bit result
type (such as std::ranlux48_base).
libstdc++-v3/ChangeLog:
PR libstdc++/107466
* include/bits/random.tcc (subtract_with_carry_engine::seed):
Implement proposed resolution of LWG 4014.
* testsuite/26_numerics/random/pr60037-neg.cc: Adjust dg-error
line number.
* testsuite/26_numerics/random/subtract_with_carry_engine/cons/lwg3809.cc:
Check for expected result of 64-bit engine with seed that
doesn't fit in 32-bits.
(cherry picked from commit c224dec0e7)
This implements the proposed resolution of LWG 3809, so that
std::subtract_with_carry_engine can be used with a 16-bit result_type.
Currently this produces a narrowing error when instantiating the
std::linear_congruential_engine to create the initial state. It also
truncates the default_seed constant when passing it as a result_type
argument.
Change the type of the constant to uint_least32_t and pass 0u when the
default_seed should be used.
libstdc++-v3/ChangeLog:
PR libstdc++/107466
* include/bits/random.h (subtract_with_carry_engine): Use 32-bit
type for default seed. Use 0u as default argument for
subtract_with_carry_engine(result_type) constructor and
seed(result_type) member function.
* include/bits/random.tcc (subtract_with_carry_engine): Use
32-bit type for default seed and engine used for initial state.
* testsuite/26_numerics/random/subtract_with_carry_engine/cons/lwg3809.cc:
New test.
This fixes a regression in std::normal_distribution deserialization that
caused the object to be left unchanged if the __state_avail value read
from the stream was false.
libstdc++-v3/ChangeLog:
PR libstdc++/105502
* include/bits/random.tcc
(operator>>(basic_istream<C,T>&, normal_distribution<R>&)):
Update state when __state_avail is false.
* testsuite/26_numerics/random/normal_distribution/operators/serialize.cc:
Check that deserialized object equals serialized one.
When std::seed_seq is constructed from random access iterators we can
detect the internal vector size in O(1). Reserving memory for elements
in such cases may avoid multiple memory allocations.
Signed-off-by: Jonathan Wakely <jwakely@redhat.com>
libstdc++-v3/ChangeLog:
* include/bits/random.tcc (seed_seq::seed_seq): Reserve capacity
if distance is O(1).
* testsuite/26_numerics/random/pr60037-neg.cc: Adjust dg-error
line number.
Co-authored-by: Jonathan Wakely <jwakely@redhat.com>
In C++17 the out-of-class definitions for static constexpr variables are
redundant, because they are implicitly inline. This change avoids
"redundant redeclaration" warnings from -Wsystem-headers -Wdeprecated.
Signed-off-by: Jonathan Wakely <jwakely@redhat.com>
libstdc++-v3/ChangeLog:
* include/bits/random.tcc (linear_congruential_engine): Do not
define static constexpr members when they are implicitly inline.
* include/std/ratio (ratio, __ratio_multiply, __ratio_divide)
(__ratio_add, __ratio_subtract): Likewise.
* include/std/type_traits (integral_constant): Likewise.
* testsuite/26_numerics/random/pr60037-neg.cc: Adjust dg-error
line number.
This defines some new Doxygen groups for C++17 variable templates and
for the contents of <experimental/type_traits>. By documenting the group
as a whole and adding each template to a group we don't need to document
them individually.
Also mark more internals with "@cond undocumented" so that Doxygen
ignores them by default. Also make Doxygen process <experimental/simd>.
For some reason, many of the class templates in <type_traits> do not
appear in the "Metaprogramming" group. For example, add_cv,
remove_extent, and all the is_xxx_constructible and is_xxx_assignable
traits. For some reason, Doxygen doesn't include them in the group,
despite doing it correctly for other traits in the same header.
Signed-off-by: Jonathan Wakely <jwakely@redhat.com>
libstdc++-v3/ChangeLog:
PR libstdc++/101258
* doc/doxygen/user.cfg.in (INPUT): Add <experimental/simd>.
(COLS_IN_ALPHA_INDEX): Remove obsolete tag.
(PREDEFINED): Add/fix some more macros that need to be expanded.
* include/bits/random.h: Stop Doxygen from documenting internal
implementation details.
* include/bits/random.tcc: Likewise.
* include/bits/this_thread_sleep.h: Fix @file name.
* include/experimental/bits/simd.h: Add to Doxygen group. Do not
document internal implementation details.
* include/experimental/bits/simd_detail.h: Do not document
internal implementation details.
* include/experimental/simd: Define Doxygen groups.
* include/experimental/type_traits: Improve documentation for
the header file. Define groups. Use @since commands.
* include/std/scoped_allocator (scoped_allocator_adaptor): Move
declaration before undocumented region.
* include/std/type_traits (true_type, false_type): Use using
declaration instead of typedef.
(is_invocable_v, is_nothrow_invocable_v, is_invocable_r_v)
(is_nothrow_invocable_r_v): Move definitions next to other C++17
variable templates.
Do not document internal implementation details. Move misplaced
group-end command. Define group for variable templates.
* include/std/variant: Do not document internal implementation
details.
* testsuite/26_numerics/random/pr60037-neg.cc: Adjust dg-error
line number.
Since C++17 the static members of the random number engines are
implicitly inline, so don't need definitions.
Signed-off-by: Jonathan Wakely <jwakely@redhat.com>
libstdc++-v3/ChangeLog:
* include/bits/random.tcc [__cpp_inline_variables]: Remove
redundant definitions of static constexpr member variables.
* testsuite/26_numerics/random/pr60037-neg.cc: Adjust dg-error
line number.
This ensures that the std::seed_seq initializer-list constructor will
not be used for list-initialization unless the initializers in the list
are integers. This allows list-initialization syntax to be used with a
pair of pointers and for that to use the appropriate constructor.
Signed-off-by: Jonathan Wakely <jwakely@redhat.com>
libstdc++-v3/ChangeLog:
* include/bits/random.h (seed_seq): Constrain initializer-list
constructor.
* include/bits/random.tcc (seed_seq): Add template parameter.
* testsuite/26_numerics/random/seed_seq/cons/default.cc: Check
for noexcept.
* testsuite/26_numerics/random/seed_seq/cons/initlist.cc: Check
constraints.
The transition algorithm for std::shuffle_order_engine uses long double
to ensure that the value (max() - min() + 1) can be accurately
represented, to avoid bias in the shuffling. However, when the base
engine's range is small enough we can avoid slower long double
arithmetic by using double. For example, long double is unnecessary for
any base engine returning 32-bit values.
This makes std::knuth_b::operator() about 15% faster on x86_64, and
probably even more on targets where long double uses soft-float.
libstdc++-v3/ChangeLog:
* include/bits/random.h (independent_bit_engine): Fix typo
in comment.
(shuffle_order_engine): Fix incorrect description in comment.
* include/bits/random.tcc (__representable_as_double
(__p1_representable_as_double): New helper functions.
(shuffle_order_engine::operator()): Use double for calculation
if (max() - min() + 1) is representable as double.
* testsuite/26_numerics/random/pr60037-neg.cc: Adjust dg-error
line number.
This ensures that intermediate results are done in uint32_t values,
meeting the requirement for operations to be done modulo 2^32.
If the target doesn't define __UINT32_TYPE__ then substitute uint32_t
with a class type that uses uint_least32_t and masks the value to
UINT32_MAX.
I've also split the first loop that goes from k=0 to k<m into three
loops, for k=0, [1,s] and [s+1,m). This avoids branching for those three
cases in the body of the loop, and also avoids the concerns in PR 94823
regarding the k-1 index when k==0.
libstdc++-v3/ChangeLog:
PR libstdc++/97311
* include/bits/random.tcc (seed_seq::generate): Use uint32_t for
calculations. Also split the first loop into three loops to
avoid branching on k on every iteration, resolving PR 94823.
* testsuite/26_numerics/random/seed_seq/97311.cc: New test.
* testsuite/26_numerics/random/pr60037-neg.cc: Adjust dg-erro
line number.
These three distributions all require 0 < S where S is the sum of the
weights. When the sum is zero there's an undefined FP division by zero.
Add assertions to help users diagnose the problem.
libstdc++-v3/ChangeLog:
PR libstdc++/82584
* include/bits/random.tcc
(discrete_distribution::param_type::_M_initialize)
(piecewise_constant_distribution::param_type::_M_initialize)
(piecewise_linear_distribution::param_type::_M_initialize):
Add assertions for positive sums..
* testsuite/26_numerics/random/pr60037-neg.cc: Adjust dg-error
line.
The deserialization functions for random number distributions fail to
check the stream state before using the extracted values. In some cases
this leads to using indeterminate values to resize a vector, and then
filling that vector with indeterminate values.
No values that affect control flow should be used without checking that a
good value was read from the stream.
Additionally, where reasonable to do so, defer modifying any state in
the distribution until all values have been successfully read, to avoid
modifying some of the distribution's parameters and leaving others
unchanged.
PR libstdc++/93205
* include/bits/random.h (operator>>): Check stream operation succeeds.
* include/bits/random.tcc (operator<<): Remove redundant __ostream_type
typedefs.
(operator>>): Remove redundant __istream_type typedefs. Check stream
operations succeed.
(__extract_params): New function to fill a vector from a stream.
* testsuite/26_numerics/random/pr60037-neg.cc: Adjust dg-error line.
From-SVN: r280061
Constrain constructors and member functions of random number engines so
that functions taking seed sequences can only be called with types that
meet the seed sequence requirements.
PR libstdc++/85749
* include/bits/random.h (__detail::__is_seed_seq): New SFINAE helper.
(linear_congruential_engine, mersenne_twister_engine)
(subtract_with_carry_engine, discard_block_engine)
(independent_bits_engine, shuffle_order_engine): Use __is_seed_seq to
constrain function templates taking seed sequences.
* include/bits/random.tcc (linear_congruential_engine::seed(_Sseq&))
(mersenne_twister_engine::seed(_Sseq&))
(subtract_with_carry_engine::seed(_Sseq&)): Change return types to
match declarations.
* include/ext/random (simd_fast_mersenne_twister_engine): Use
__is_seed_seq to constrain function templates taking seed sequences.
* include/ext/random.tcc (simd_fast_mersenne_twister_engine::seed):
Change return type to match declaration.
* testsuite/26_numerics/random/discard_block_engine/cons/seed_seq2.cc:
New.
* testsuite/26_numerics/random/independent_bits_engine/cons/
seed_seq2.cc: New.
* testsuite/26_numerics/random/linear_congruential_engine/cons/
seed_seq2.cc: New.
* testsuite/26_numerics/random/mersenne_twister_engine/cons/
seed_seq2.cc: New.
* testsuite/26_numerics/random/pr60037-neg.cc: Adjust dg-error lineno.
* testsuite/26_numerics/random/shuffle_order_engine/cons/seed_seq2.cc:
New.
* testsuite/26_numerics/random/subtract_with_carry_engine/cons/
seed_seq2.cc: New.
* testsuite/ext/random/simd_fast_mersenne_twister_engine/cons/
seed_seq2.cc: New.
From-SVN: r260263
2018-05-07 Edward Smith-Rowland <3dw4rd@verizon.net>
Moar PR libstdc++/80506
* include/bits/random.tcc (gamma_distribution::__generate_impl()):
Fix magic number used in loop condition.
Actually put the file in.
Don't know what my problem is today...
From-SVN: r260008
2015-08-26 Edward Smith-Rowland <3dw4rd@verizon.net>
Jonathan Wakely <jwakely@redhat.com>
PR libstdc++/64351
PR libstdc++/63176
* include/bits/random.tcc (generate_canonical): Loop until we get a
result less than one.
* testsuite/26_numerics/random/uniform_real_distribution/operators/
64351.cc: New.
Co-Authored-By: Jonathan Wakely <jwakely@redhat.com>
From-SVN: r227233
2014-07-29 Ed Smith-Rowland <3dw4rd@verizon.net>
PR libstdc++/60037 - SIGFPE in std::generate_canonical<unsigned int...>
* include/bits/random.h (_Adaptor): static_assert for non floating-point
result type.
* include/bits/random.tcc (generate_canonical): Ditto.
* include/ext/random.tcc (hypergeometric_distribution::operator()):
Use double as a rng result type.
* testsuite/26_numerics/random/pr60037-neg.cc: New.
* testsuite/ext/random/hypergeometric_distribution/pr60037.cc: New.
From-SVN: r213207
* include/bits/random.h (mersenne_twister_engine): Don't inline
discard here. New member function _M_gen_rand.
* include/bits/random.tcc (mersenne_twister_engine<>::_M_gen_rand):
New function. Extracted from operator().
(mersenne_twister_engine<>::discard): New implementation which
skips in large steps.
(mersenne_twister_engine<>::operator()): Use _M_gen_rand.
From-SVN: r190711
Jonathan Wakely