+2012-04-29 Marc Glisse <marc.glisse@inria.fr>
+ Paolo Carlini <paolo.carlini@oracle.com>
+
+ PR libstdc++/51795
+ * include/bits/stl_algobase.h (__lg<>(_Size)): Remove.
+ (__lg(int), __lg(unsigned), __lg(long), __lg(unsigned long),
+ __lg(long long), __lg(unsigned long long)): Define constexpr.
+ * include/bits/random.h (_Mod<>): Overcome Schrage's algorithm
+ limitations.
+ (__mod): Adjust.
+ (linear_congruential): Remove FIXME static_assert.
+ * include/bits/random.tcc (_Mod<>): Adjust.
+ * testsuite/26_numerics/random/linear_congruential_engine/operators/
+ 51795.cc: New.
+
2012-04-29 Jonathan Wakely <jwakely.gcc@gmail.com>
* include/std/functional (function::function(F)): LWG 2132: Disable
struct _Shift<_UIntType, __w, true>
{ static const _UIntType __value = _UIntType(1) << __w; };
- template<typename _Tp, _Tp __m, _Tp __a, _Tp __c, bool>
- struct _Mod;
+ template<int __s,
+ int __which = ((__s <= __CHAR_BIT__ * sizeof (int))
+ + (__s <= __CHAR_BIT__ * sizeof (long))
+ + (__s <= __CHAR_BIT__ * sizeof (long long))
+ /* assume long long no bigger than __int128 */
+ + (__s <= 128))>
+ struct _Select_uint_least_t
+ {
+ static_assert(__which < 0, /* needs to be dependent */
+ "sorry, would be too much trouble for a slow result");
+ };
+
+ template<int __s>
+ struct _Select_uint_least_t<__s, 4>
+ { typedef unsigned int type; };
+
+ template<int __s>
+ struct _Select_uint_least_t<__s, 3>
+ { typedef unsigned long type; };
+
+ template<int __s>
+ struct _Select_uint_least_t<__s, 2>
+ { typedef unsigned long long type; };
+
+#ifdef _GLIBCXX_USE_INT128
+ template<int __s>
+ struct _Select_uint_least_t<__s, 1>
+ { typedef unsigned __int128 type; };
+#endif
+
+ // Assume a != 0, a < m, c < m, x < m.
+ template<typename _Tp, _Tp __m, _Tp __a, _Tp __c,
+ bool __big_enough = (!(__m & (__m - 1))
+ || (_Tp(-1) - __c) / __a >= __m - 1),
+ bool __schrage_ok = __m % __a < __m / __a>
+ struct _Mod
+ {
+ typedef typename _Select_uint_least_t<std::__lg(__a)
+ + std::__lg(__m) + 2>::type _Tp2;
+ static _Tp
+ __calc(_Tp __x)
+ { return static_cast<_Tp>((_Tp2(__a) * __x + __c) % __m); }
+ };
+
+ // Schrage.
+ template<typename _Tp, _Tp __m, _Tp __a, _Tp __c>
+ struct _Mod<_Tp, __m, __a, __c, false, true>
+ {
+ static _Tp
+ __calc(_Tp __x);
+ };
+
+ // Special cases:
+ // - for m == 2^n or m == 0, unsigned integer overflow is safe.
+ // - a * (m - 1) + c fits in _Tp, there is no overflow.
+ template<typename _Tp, _Tp __m, _Tp __a, _Tp __c, bool __s>
+ struct _Mod<_Tp, __m, __a, __c, true, __s>
+ {
+ static _Tp
+ __calc(_Tp __x)
+ {
+ _Tp __res = __a * __x + __c;
+ if (__m)
+ __res %= __m;
+ return __res;
+ }
+ };
- // Dispatch based on modulus value to prevent divide-by-zero compile-time
- // errors when m == 0.
template<typename _Tp, _Tp __m, _Tp __a = 1, _Tp __c = 0>
inline _Tp
__mod(_Tp __x)
- { return _Mod<_Tp, __m, __a, __c, __m == 0>::__calc(__x); }
+ { return _Mod<_Tp, __m, __a, __c>::__calc(__x); }
/*
* An adaptor class for converting the output of any Generator into
static_assert(__m == 0u || (__a < __m && __c < __m),
"template argument substituting __m out of bounds");
- // XXX FIXME:
- // _Mod::__calc should handle correctly __m % __a >= __m / __a too.
- static_assert(__m % __a < __m / __a,
- "sorry, not implemented yet: try a smaller 'a' constant");
-
public:
/** The type of the generated random value. */
typedef _UIntType result_type;
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
- // General case for x = (ax + c) mod m -- use Schrage's algorithm to
- // avoid integer overflow.
- //
- // Because a and c are compile-time integral constants the compiler
- // kindly elides any unreachable paths.
+ // General case for x = (ax + c) mod m -- use Schrage's algorithm
+ // to avoid integer overflow.
//
// Preconditions: a > 0, m > 0.
//
- // XXX FIXME: as-is, only works correctly for __m % __a < __m / __a.
- //
- template<typename _Tp, _Tp __m, _Tp __a, _Tp __c, bool>
- struct _Mod
- {
- static _Tp
- __calc(_Tp __x)
- {
- if (__a == 1)
- __x %= __m;
- else
- {
- static const _Tp __q = __m / __a;
- static const _Tp __r = __m % __a;
-
- _Tp __t1 = __a * (__x % __q);
- _Tp __t2 = __r * (__x / __q);
- if (__t1 >= __t2)
- __x = __t1 - __t2;
- else
- __x = __m - __t2 + __t1;
- }
-
- if (__c != 0)
- {
- const _Tp __d = __m - __x;
- if (__d > __c)
- __x += __c;
- else
- __x = __c - __d;
- }
- return __x;
- }
- };
-
- // Special case for m == 0 -- use unsigned integer overflow as modulo
- // operator.
+ // Note: only works correctly for __m % __a < __m / __a.
template<typename _Tp, _Tp __m, _Tp __a, _Tp __c>
- struct _Mod<_Tp, __m, __a, __c, true>
+ _Tp
+ _Mod<_Tp, __m, __a, __c, false, true>::
+ __calc(_Tp __x)
{
- static _Tp
- __calc(_Tp __x)
- { return __a * __x + __c; }
- };
+ if (__a == 1)
+ __x %= __m;
+ else
+ {
+ static const _Tp __q = __m / __a;
+ static const _Tp __r = __m % __a;
+
+ _Tp __t1 = __a * (__x % __q);
+ _Tp __t2 = __r * (__x / __q);
+ if (__t1 >= __t2)
+ __x = __t1 - __t2;
+ else
+ __x = __m - __t2 + __t1;
+ }
+
+ if (__c != 0)
+ {
+ const _Tp __d = __m - __x;
+ if (__d > __c)
+ __x += __c;
+ else
+ __x = __c - __d;
+ }
+ return __x;
+ }
template<typename _InputIterator, typename _OutputIterator,
typename _UnaryOperation>
/// This is a helper function for the sort routines and for random.tcc.
// Precondition: __n > 0.
- template<typename _Size>
- inline _Size
- __lg(_Size __n)
- {
- _Size __k;
- for (__k = 0; __n != 0; __n >>= 1)
- ++__k;
- return __k - 1;
- }
-
- inline int
+ inline _GLIBCXX_CONSTEXPR int
__lg(int __n)
{ return sizeof(int) * __CHAR_BIT__ - 1 - __builtin_clz(__n); }
- inline unsigned
+ inline _GLIBCXX_CONSTEXPR unsigned
__lg(unsigned __n)
{ return sizeof(int) * __CHAR_BIT__ - 1 - __builtin_clz(__n); }
- inline long
+ inline _GLIBCXX_CONSTEXPR long
__lg(long __n)
{ return sizeof(long) * __CHAR_BIT__ - 1 - __builtin_clzl(__n); }
- inline unsigned long
+ inline _GLIBCXX_CONSTEXPR unsigned long
__lg(unsigned long __n)
{ return sizeof(long) * __CHAR_BIT__ - 1 - __builtin_clzl(__n); }
- inline long long
+ inline _GLIBCXX_CONSTEXPR long long
__lg(long long __n)
{ return sizeof(long long) * __CHAR_BIT__ - 1 - __builtin_clzll(__n); }
- inline unsigned long long
+ inline _GLIBCXX_CONSTEXPR unsigned long long
__lg(unsigned long long __n)
{ return sizeof(long long) * __CHAR_BIT__ - 1 - __builtin_clzll(__n); }
--- /dev/null
+// { dg-options "-std=gnu++11" }
+// { dg-require-cstdint "" }
+//
+// Copyright (C) 2012 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+//
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3. If not see
+// <http://www.gnu.org/licenses/>.
+
+// 26.5.3.1 class template linear_congruential_engine [rand.eng.lcong]
+
+#include <random>
+#include <testsuite_hooks.h>
+
+void test01()
+{
+ bool test __attribute__((unused)) = true;
+
+ typedef std::linear_congruential_engine<std::uint64_t, 1103515245ULL,
+ 12345, 2147483648ULL> engine;
+ engine eng(1103527590ULL);
+
+ for (unsigned it = 0; it < 1000; ++it)
+ {
+ std::uint64_t num = eng();
+ VERIFY( (num >= eng.min() && num <= eng.max()) );
+ }
+}
+
+int main()
+{
+ test01();
+ return 0;
+}
projects / thirdparty / gcc.git / commitdiff
