On Mon, Jul 20, 2026 at 2:02 PM Tomasz Kaminski <[email protected]> wrote:
> > > On Mon, Jul 20, 2026 at 1:45 PM Jonathan Wakely <[email protected]> > wrote: > >> On Tue, 02 Jun 2026 at 16:01 +0200, Tomasz Kamiński wrote: >> >This patch splits implementation of generate_cannonical_any, into tree >> >> "canonical" >> "three" >> >> >different path depending on bits generated (R), required bits of entropy >> >(b), and value k such that R^k > 2^d > R^(k-1): >> >* log2(R) >= d: single call of generator is sufficient (k = 1), >> > and computation can be performed in the generator value type (_UIntR) >> >* bit_width(R^k) <= 128: computation can be performed using type >> > __detail::_Select_uint_least_t; previous implementation is reused >> >* bit_width(R^k) > 128: the computations required may overflow 128 bit; >> > such generators were previously unsupported, as illustrated by >> > r17-507-g5d17eec7d83445 >> > >> >This patch implements the support for the last branch, by observing >> >that while it is possible for computation to overflow 128 the sum: >> > sum_[0, k) urng() * R^i >> >The values of sum, such that (sum / x * 2^d) > 1, are rejected, and >> >any value (sum / x) > 2^d can be rejected. As 2^d is guaranteed to fit >> >in 128 integer, we can use above to reject the value, before overflow >> >will occur. >> > >> >Firstly, we know that for l = k-1, the value R^l < 2^d, and >> >sum_[0, l) urng() * R^i <= R^l (because urng() is alwayus < R), >> >> "always" >> >> >always fit in 128bit integer. We compute tha valuet (__lsum) using >> >> "value" >> >> >normal loop. >> > >> >This leaves us with final iteration of multiplying __kth * R^l, >> >where __kth is result of invocation of urng. In that case we >> >compute the bitwidth (__abits) of value that can be multiplied >> >by _R^l without overflow 128bit integer. The __kth * R^l is >> >performed by multiplying the loop of __abits of __kth in >> >loop where: >> >* __sumx (initially __lsum / __x) is the current value of sum / x >> >* __remx (initially 2^d - __sumx) is the value that we can still >> > add before overflowing (shifted with each iteration) >> >* __modx (initially __modx % __x) are corrected reminders >> >In each iteration the lowest __kth bits are multiplied with _Rl (__val), >> >scaled (__valx) and checked against __rem. When fits the __sumx, __modx >> >and __remx are updated, and both values of __remx and __kth are shifted >> >right by __abits. >> > >> >If the multiplication finished without overflow (__kth is zero), >> > we handle the collected reminders (__modx), and compute the __ret value. >> >> "remainders" (and there seems to be a stray space at the start of the >> line) >> >> >The value greater or equal 1 (e.g. due floating point aproximation), are >> >> "approximation" >> >> >still rejected. >> > >> >Similar approach is applied when computing x = R^k / 2^d. >> >Again while R^k will overflow 128 bits, we know that x < R (so fits >> >in 64bits), as R^l < 2^d < R^k, then x < R. We again compute >> >R * R^l / 2^d, by splitting the value of R into __abits chunks (_pR). >> >For result of chunks multipliations (_pRk), the bits (_xp) remaining >> >> "multiplications" >> >> >after division by __shift (starts from __d and reduces by __abits), >> >are collected into cumulative value of __x. While the lower bits >> >are preserved for later iteration (__pRk). >> > >> > PR libstdc++/119739 >> > >> >libstdc++-v3/ChangeLog: >> > >> > * include/bits/random.tcc (__generate_canonical_any): >> > Rewrite to support more cases. >> > * >> testsuite/26_numerics/random/uniform_real_distribution/operators/gencanon.cc: >> > Add test for previously unsupported generator. >> > * >> testsuite/26_numerics/random/uniform_real_distribution/operators/gencanon_eng.cc: >> > Add test for previously unsuported-generator ranges. >> > * >> testsuite/26_numerics/random/uniform_real_distribution/operators/gencanon_eng_neg.cc: >> > Moved (now-supported) generator test to gencanon_eng.cc, and >> removed >> > the file. >> >--- >> >Tested on x86_64-linux. Also tested a modified version, with __bits <= >> 128 >> >branch being removed and __abits hardoced to 10. This confirms that new >> >implementation gives the same output as existing one. >> > >> >OK for trunk? >> > >> > libstdc++-v3/include/bits/random.tcc | 169 +++++++++++++++--- >> > .../operators/gencanon.cc | 96 ++++++++++ >> > .../operators/gencanon_eng.cc | 63 +++++++ >> > .../operators/gencanon_eng_neg.cc | 89 --------- >> > 4 files changed, 300 insertions(+), 117 deletions(-) >> > delete mode 100644 >> libstdc++-v3/testsuite/26_numerics/random/uniform_real_distribution/operators/gencanon_eng_neg.cc >> > >> >diff --git a/libstdc++-v3/include/bits/random.tcc >> b/libstdc++-v3/include/bits/random.tcc >> >index a8fab79961d..aa1f4a83a66 100644 >> >--- a/libstdc++-v3/include/bits/random.tcc >> >+++ b/libstdc++-v3/include/bits/random.tcc >> >@@ -242,7 +242,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION >> > constexpr size_t >> > mersenne_twister_engine<_UIntType, __w, __n, __m, __r, __a, __u, >> __d, >> > __s, __b, __t, __c, __l, __f>::tempering_u; >> >- >> >+ >> > template<typename _UIntType, >> > size_t __w, size_t __n, size_t __m, size_t __r, >> > _UIntType __a, size_t __u, _UIntType __d, size_t __s, >> >@@ -3753,38 +3753,151 @@ namespace __detail >> > constexpr unsigned __log2R >> > = sizeof(_UIntR) * __CHAR_BIT__ - __builtin_clzg(__R) - 1; >> > // We overstimate number of required bits, by computing >> >- // r such that l * log2(R) >= d, so: >> >- // R^l >= (2 ^ log2(R)) ^ l == 2 ^ (log2(r) * l) >= 2^d >> >- // And then requiring l * bit_width(R) bits. >> >- constexpr unsigned __l = (__d + __log2R - 1) / __log2R; >> >- constexpr unsigned __bits = (__log2R + 1) * __l; >> >- using _UInt = typename >> __detail::_Select_uint_least_t<__bits>::type; >> >- >> >- _GLIBCXX_GEN_CANON_CONST _UInt __rd = _UInt(1) << __d; >> >- _GLIBCXX_GEN_CANON_CONST auto __logRrd = __gen_canon_log(__rd, >> __R); >> >- _GLIBCXX_GEN_CANON_CONST unsigned __k >> >- = __logRrd.__floor_log + (__rd > __logRrd.__floor_pow); >> >- >> >- _GLIBCXX_GEN_CANON_CONST _UInt __Rk >> >- = (__k > __logRrd.__floor_log) >> >- ? _UInt(__logRrd.__floor_pow) * _UInt(__R) >> >- : _UInt(__logRrd.__floor_pow); >> >- _GLIBCXX_GEN_CANON_CONST _UInt __x = __Rk / __rd; >> >+ // r such that m * log2(R) >= d, so: >> >+ // R^m >= (2 ^ log2(R)) ^ m == 2 ^ (log2(r) * m) >= 2^d >> >+ // And then requiring m * bit_width(R) bits. >> >+ constexpr unsigned __m = (__d + __log2R - 1) / __log2R; >> >+ constexpr unsigned __bits = (__log2R + 1) * __m; >> >+ if constexpr (__log2R >= __d) >> >+ { >> >+ // range already provide required number of bits, >> >+ // so in this case __k == 1, and single call to generator >> >+ // is sufficient. Futhermore 2^d fits in _UIntR >> >+ constexpr _UIntR __rd = _UIntR(1) << __d; >> >+ constexpr _UIntR __x = __R >> __d; >> > >> >- while (true) >> >+ while (true) >> >+ { >> >+ _UIntR __val(__urng() - _Urbg::min()); >> >+ const _RealT __ret = _RealT(__val / __x) / _RealT(__rd); >> >+ if (__ret < _RealT(1.0)) >> >+ return __ret; >> >+ } >> >+ } >> >+ // generator call produce less bits than __d, but R^k > rd fits >> >> s/less/fewer/ >> >> >+ // into 128 bits. >> >+ else if constexpr (__bits <= 128) >> > { >> >- _UInt __Ri{1}; >> >- _UInt __sum(__urng() - _Urbg::min()); >> >- for (int __i = __k - 1; __i > 0; --__i) >> >+ using _UInt = typename >> __detail::_Select_uint_least_t<__bits>::type; >> >+ >> >+ _GLIBCXX_GEN_CANON_CONST _UInt __rd = _UInt(1) << __d; >> >+ _GLIBCXX_GEN_CANON_CONST auto __logRrd = __gen_canon_log(__rd, >> __R); >> >+ // __rd is power of two, and __R is not so __floor_pow is never >> >+ // equal to __rd. >> >+ _GLIBCXX_GEN_CANON_CONST unsigned __k = __logRrd.__floor_log + >> 1; >> >+ _GLIBCXX_GEN_CANON_CONST _UInt __Rk = __logRrd.__floor_pow * >> _UInt(__R); >> >+ // x = floor(R^k / 2^d) = R^k >> d; >> >+ _GLIBCXX_GEN_CANON_CONST _UInt __x = __Rk >> __d; >> >+ >> >+ while (true) >> > { >> >- __Ri *= _UInt(__R); >> >- __sum += _UInt(__urng() - _Urbg::min()) * __Ri; >> >+ _UInt __Ri{1}; >> >+ _UInt __sum(__urng() - _Urbg::min()); >> >+ for (int __i = __k - 1; __i > 0; --__i) >> >+ { >> >+ __Ri *= __R; >> >+ __sum += __Ri * _UIntR(__urng() - _Urbg::min()); >> >+ } >> >+ const _RealT __ret = _RealT(__sum / __x) / _RealT(__rd); >> >+ if (__ret < _RealT(1.0)) >> >+ return __ret; >> > } >> >- const _RealT __ret = _RealT(__sum / __x) / _RealT(__rd); >> >- if (__ret < _RealT(1.0)) >> >- return __ret; >> > } >> >-#undef _GLIBCXX_GEN_CANON_CONST >> >+ else >> >+ { >> >+#pragma GCC diagnostic ignored "-Wshift-count-overflow" // we shift by >> 64bits >> >> There's no push/pop around this pragma, but why is it here at all? >> > We are inside push/pop for if constexpr, so I didn't think I needed to add > a new set. > > >> Doesn't this warning indicate undefined behaviour, so we don't want to >> just suppress it? >> > As far as I recall, I thought this is UB caused by compiler, but that was > 6 months ago, > I mean to say that this was false-positive and warning only appeared in when _GLIBCXX_GEN_CANON_CONST does not expand to `constexpr`. But will double check. > Let me double check to be certain. > >> >> >+ static_assert(__log2R < 64, "Only generators emitting >> up to 64 bits are supported"); >> >+ using _UInt = typename >> __detail::_Select_uint_least_t<128>::type; >> >+ using _UInt64 = typename >> __detail::_Select_uint_least_t<64>::type; >> >+ >> >+ _GLIBCXX_GEN_CANON_CONST _UInt __rd = _UInt(1) << __d; >> >+ _GLIBCXX_GEN_CANON_CONST auto __logRrd = __gen_canon_log(__rd, >> __R); >> >+ // __rd is power of two, and __R is not so __floor_pow is never >> >+ // equal to __rd, and l == k - 1 >> >+ _GLIBCXX_GEN_CANON_CONST unsigned __l = __logRrd.__floor_log; >> >+ _GLIBCXX_GEN_CANON_CONST _UInt __Rl = __logRrd.__floor_pow; >> >+ >> >+ // __abits is maximum bit width of the value, that can >> >+ // be multiplied by R^l without overflowing 128 bit integer >> >+ // TODO: use bit_width(_Rl) >> >+ _GLIBCXX_GEN_CANON_CONST unsigned __bwRl = (__log2R + 1) * __l; >> >+ // For __R close to power of two, the actual __k may be smaller >> than __m, >> >+ // and will use less than 128bits. >> >+ _GLIBCXX_GEN_CANON_CONST unsigned __abits = __bwRl > 64 ? 128 - >> __bwRl : 64; >> >+ _GLIBCXX_GEN_CANON_CONST _UInt64 __amask >> >+ = (__abits == 64) ? ~_UInt64(0) : (_UInt64(1) << __abits) - >> 1; >> >+ >> >+ // Compute __x = _Rk / __rd (_Rk >> __d), by spliting _R into >> chunks >> >+ // (_pR) of __abits, so their multiplication does not overflow >> 128 bits. >> >+ // __x fits in 64bits, becuse __R^l < __rd < __R^k, thus __x < >> _R >> >+ _UInt64 __x(0), __pR(__R); _UInt __pRk(0); >> >+ for (unsigned __shift = __d; __pR; __shift -= __abits) >> >+ { >> >+ __pRk += __Rl * (__pR & __amask); >> >+ __pR >>= __abits; >> >+ >> >+ _UInt __xp(__pRk >> __shift); >> >+ __x += _UInt64(__xp); >> >+ __pRk -= (__xp << __shift); >> >+ __pRk >>= __abits; >> >+ } >> >+ >> >+ while (true) >> >+ { >> >+ // Compute sum of __urng() * R^i for i in range [0, l). >> >+ // The values is smaller than R^l which is smaller than >> >> "value" >> >> >+ // __rd so fits into 128 bit integer. >> >+ _UInt __Ri{1}; >> >+ _UInt __lsum(__urng() - _Urbg::min()); >> >+ for (int __i = __l - 1; __i > 0; --__i) >> >+ { >> >+ __Ri *= _UInt64(__R); >> >+ __lsum += __Ri * _UInt64(__urng() - _Urbg::min()); >> >+ } >> >+ >> >+ // The last iteration __urng() * R^k may overflow 128bit >> >+ // integer. We use the fact that we reject __sum / __x >= >> __rd, >> >+ // and split __urng() value into chunks of __abits, so their >> >+ // products with R^l does not overflow 128bit. These product >> >> "products" >> >> >+ // are then multiplied by 2^__shift, scaled by __x and >> added into >> >+ // the __sumx, until they value is smaller than remaining >> value >> >> "the value" or "their value"? >> >> >+ // __rem [(__rd - __sumx) * 2^__shift], or whole value was >> >+ // multiplied (__kth is zero). The reminder of division by >> >> "remainder" >> >> >+ // __x are accumulated into __modx value, and handled later. >> >+ // In consequence this guarantees that __sumx never exceeded >> >> "exceeds" >> >> >+ // __rd value, and thus does not overflow 128 bit integer. >> >+ _UInt __sumx = __lsum / __x, __modx = __lsum % __x; >> >+ _UInt __remx = __rd - __sumx; >> >+ _UInt64 __kth(__urng() - _Urbg::min()); >> >+ for (unsigned __shift = 0; __kth; __shift += __abits) >> >+ { >> >+ const _UInt __val = __Rl * (__kth & __amask); >> >+ const _UInt __valx = __val / __x; >> >+ if (__valx > __remx) >> >+ break; >> >+ __kth >>= __abits; >> >+ >> >+ __sumx += (__valx << __shift); >> >+ __modx += ((__val % __x) << __shift); >> >+ >> >+ __remx -= __valx; >> >+ __remx >>= __abits; >> >+ } >> >+ if (__kth) // __sum / __x > _rd after adding __kth iteration >> >+ continue; >> >+ >> >+ // Handle accumulated reminders >> >> "remainders" >> >> >+ const _UInt __valx = __modx / __x; >> >+ if (__valx > __rd - __sumx) // avoids overflow >> >+ continue; >> >+ >> >+ __sumx += __valx; >> >+ const _RealT __ret = _RealT(__sumx) / _RealT(__rd); >> >+ if (__ret < _RealT(1.0)) >> >+ return __ret; >> >+ } >> >+ } >> >+#undef _GLIBCXX_GEN_CANON_CONST >> > } >> > >> > #if !defined(_GLIBCXX_GENERATE_CANONICAL_STRICT) >> >diff --git >> a/libstdc++-v3/testsuite/26_numerics/random/uniform_real_distribution/operators/gencanon.cc >> b/libstdc++-v3/testsuite/26_numerics/random/uniform_real_distribution/operators/gencanon.cc >> >index ae93ec13b7a..4da53e9d4f2 100644 >> >--- >> a/libstdc++-v3/testsuite/26_numerics/random/uniform_real_distribution/operators/gencanon.cc >> >+++ >> b/libstdc++-v3/testsuite/26_numerics/random/uniform_real_distribution/operators/gencanon.cc >> >@@ -234,6 +234,98 @@ test_2p31m1(const std::mt19937& rng) >> > } >> > } >> > >> >+template<std::uint64_t Max, typename Under = std::mt19937_64> >> >+struct trimmed_engine >> >+{ >> >+ using result_type = std::uint64_t; >> >+ >> >+ static constexpr >> >+ result_type min() >> >+ { return result_type(0); } >> >+ >> >+ static constexpr >> >+ result_type max() >> >+ { return result_type(Max); } >> >+ >> >+ trimmed_engine() : dist(min(), max()) >> >+ {} >> >+ >> >+ trimmed_engine(const Under& gen) >> >+ : under(gen), dist(min(), max()) >> >+ {} >> >+ >> >+ result_type operator()() >> >+ { return dist(under); } >> >+ >> >+ void discard(std::size_t n) >> >+ { >> >+ for (size_t i = 0; i < n; ++i) >> >+ (void)dist(under); >> >+ } >> >+ >> >+ friend bool >> >+ operator==(const trimmed_engine& lhs, const trimmed_engine& rhs) >> >+ { return lhs.under == rhs.under; } >> >+ >> >+private: >> >+ Under under; >> >+ std::uniform_int_distribution<result_type> dist; >> >+}; >> >+ >> >+// Uses a generate that emits range of size 2^55+2. >> >> "generator" >> >> >+// To produce 128bit IEE float, we need 3 calls to above generator, >> that can >> >+// produce value that have 155 bits, and uses separate path. >> >+template <typename T> >> >+void >> >+test_2p55p1(const std::mt19937& rng) >> >+{ >> >+ if (!std::numeric_limits<T>::is_iec559) >> >+ return; >> >+ >> >+ constexpr size_t mantissa = std::numeric_limits<T>::digits; >> >+ constexpr size_t call_per_elem = (mantissa / 55) + 1; >> >+ const trimmed_engine<(1ULL << 55) + 1ULL, std::mt19937> lrng{rng}; >> >+ >> >+ int deviation = 0, max = 0, rms = 0, zeros = 0; >> >+ int skips = run_generator<T, -1u, call_per_elem, 1u> >> >+ (lrng, deviation, max, rms, zeros); >> >+ >> >+ switch (mantissa) >> >+ { >> >+ case 24: // ieee32 >> >+ VERIFY(skips == 0); >> >+ VERIFY(deviation == 7682); >> >+ VERIFY(max == 295); >> >+ VERIFY(rms == 971); >> >+ VERIFY(zeros == 0); >> >+ break; >> >+ case 53: // ieee64 >> >+ VERIFY(skips == 0); >> >+ VERIFY(deviation == 7682); >> >+ VERIFY(max == 295); >> >+ VERIFY(rms == 971); >> >+ VERIFY(zeros == 0); >> >+ break; >> >+ case 64: // ieee80 >> >+ VERIFY(skips == 0); >> >+ VERIFY(deviation == 6788); >> >+ VERIFY(max == 248); >> >+ VERIFY(rms == 854); >> >+ VERIFY(zeros == 0); >> >+ break; >> >+ case 113: // ieee128 >> >+ VERIFY(skips == 0); >> >+ VERIFY(deviation == 8222); >> >+ VERIFY(max == 257); >> >+ VERIFY(rms == 999); >> >+ VERIFY(zeros == 0); >> >+ break; >> >+ default: >> >+ VERIFY(false); >> >+ break; >> >+ } >> >+} >> >+ >> > int main() >> > { >> > std::mt19937 rng(8890); >> >@@ -244,20 +336,24 @@ int main() >> > test_2p32<float>(rng); >> > test_10p6<float>(rng); >> > test_2p31m1<float>(rng); >> >+ test_2p55p1<float>(rng); >> > >> > test_2p32<double>(rng); >> > test_10p6<double>(rng); >> > test_2p31m1<double>(rng); >> >+ test_2p55p1<double>(rng); >> > >> > test_2p32<long double>(rng); >> > test_10p6<long double>(rng); >> > test_2p31m1<long double>(rng); >> >+ test_2p55p1<long double>(rng); >> > >> > #ifndef _GLIBCXX_GENERATE_CANONICAL_STRICT >> > # ifdef __SIZEOF_FLOAT128__ >> > test_2p32<__float128>(rng); >> > test_10p6<__float128>(rng); >> > test_2p31m1<__float128>(rng); >> >+ test_2p55p1<__float128>(rng); >> > # endif >> > #endif >> > } >> >diff --git >> a/libstdc++-v3/testsuite/26_numerics/random/uniform_real_distribution/operators/gencanon_eng.cc >> b/libstdc++-v3/testsuite/26_numerics/random/uniform_real_distribution/operators/gencanon_eng.cc >> >index 662e3568a30..f586ebc7d17 100644 >> >--- >> a/libstdc++-v3/testsuite/26_numerics/random/uniform_real_distribution/operators/gencanon_eng.cc >> >+++ >> b/libstdc++-v3/testsuite/26_numerics/random/uniform_real_distribution/operators/gencanon_eng.cc >> >@@ -10,6 +10,40 @@ test_engine() >> > (void)std::generate_canonical<_Real, size_t(-1)>(__engine); >> > } >> > >> >+template<std::uint64_t Max, typename Under = std::mt19937_64> >> >+struct trimmed_engine >> >+{ >> >+ using result_type = std::uint64_t; >> >+ >> >+ static constexpr >> >+ result_type min() >> >+ { return result_type(0); } >> >+ >> >+ static constexpr >> >+ result_type max() >> >+ { return result_type(Max); } >> >+ >> >+ trimmed_engine() : dist(min(), max()) >> >+ {} >> >+ >> >+ result_type operator()() >> >+ { return dist(under); } >> >+ >> >+private: >> >+ Under under; >> >+ std::uniform_int_distribution<result_type> dist; >> >+}; >> >+ >> >+template<typename Real, size_t Bits> >> >+void >> >+test_bits() >> >+{ >> >+ trimmed_engine<(std::uint64_t(1) << Bits) - 1> pow2_engine; >> >+ (void)std::generate_canonical<Real, -1u>(pow2_engine); >> >+ trimmed_engine<(std::uint64_t(1) << Bits) - 2> non_pow2_engine; >> >+ (void)std::generate_canonical<Real, -1u>(non_pow2_engine); >> >+} >> >+ >> > template<typename _Real> >> > void >> > test_all_engines() >> >@@ -29,6 +63,35 @@ test_all_engines() >> > test_engine<_Real, std::philox4x32>(); >> > test_engine<_Real, std::philox4x64>(); >> > #endif >> >+ >> >+ // For 128bit floating points, generator emitting a range, which size >> is >> >+ // not power of two, but of width of B bits, such that for any N: >> >+ // N * B < 113 (bits in ieee128) >> >+ // (N+1) * B > 128 >> >+ // use >128bits patch, as they would otherwise require integer with >> more >> >+ // than 128 bits. >> >+ // N == 3: B in [43, 57) >> >+ test_bits<_Real, 42>(); // 3 calls >> >+ test_bits<_Real, 43>(); // 3 calls, >128bits path >> >+ test_bits<_Real, 56>(); // 3 calls, >128bits path >> >+ test_bits<_Real, 57>(); // 2 calls >> >+ >> >+ // N == 4: B in [33, 38) >> >+ test_bits<_Real, 32>(); // 4 calls >> >+ test_bits<_Real, 33>(); // 4 calls, >128bits path >> >+ test_bits<_Real, 37>(); // 4 calls, >128bits path >> >+ test_bits<_Real, 38>(); // 3 calls >> >+ >> >+ // N == 5: B in [26, 29) >> >+ test_bits<_Real, 25>(); // 5 calls >> >+ test_bits<_Real, 26>(); // 5 calls, >128bits path >> >+ test_bits<_Real, 28>(); // 5 calls, >128bits path >> >+ test_bits<_Real, 29>(); // 4 calls >> >+ >> >+ // N == 6: B == 22 >> >+ test_bits<_Real, 21>(); // 6 calls >> >+ test_bits<_Real, 22>(); // 6 calls, >128bits path >> >+ test_bits<_Real, 23>(); // 5 calls >> > } >> > >> > int main() >> >diff --git >> a/libstdc++-v3/testsuite/26_numerics/random/uniform_real_distribution/operators/gencanon_eng_neg.cc >> b/libstdc++-v3/testsuite/26_numerics/random/uniform_real_distribution/operators/gencanon_eng_neg.cc >> >deleted file mode 100644 >> >index e3b4540bf2b..00000000000 >> >--- >> a/libstdc++-v3/testsuite/26_numerics/random/uniform_real_distribution/operators/gencanon_eng_neg.cc >> >+++ /dev/null >> >@@ -1,89 +0,0 @@ >> >-// { dg-do compile { target { c++11 } } } >> >-// { dg-require-effective-target __float128 } >> >-// { dg-require-effective-target base_quadfloat_support } >> >-// { dg-add-options __float128 } >> >- >> >-#include <random> >> >-#include <cstdint> >> >- >> >-template<std::uint64_t Max, typename Under = std::mt19937_64> >> >-struct trimmed_engine >> >-{ >> >- using result_type = std::uint64_t; >> >- >> >- static constexpr >> >- result_type min() >> >- { return result_type(0); } >> >- >> >- static constexpr >> >- result_type max() >> >- { return result_type(Max); } >> >- >> >- trimmed_engine() : dist(min(), max()) >> >- {} >> >- >> >- result_type operator()() >> >- { return dist(under); } >> >- >> >-private: >> >- Under under; >> >- std::uniform_int_distribution<result_type> dist; >> >-}; >> >- >> >-template<typename Real, size_t Bits> >> >-void >> >-test_non_pow2() >> >-{ >> >- trimmed_engine<(std::uint64_t(1) << Bits) - 2> non_pow2_engine; >> >- (void)std::generate_canonical<Real, -1u>(non_pow2_engine); >> >-} >> >- >> >-template<typename Real, size_t Bits> >> >-void >> >-test_pow2() >> >-{ >> >- trimmed_engine<(std::uint64_t(1) << Bits) - 1> pow2_engine; >> >- (void)std::generate_canonical<Real, -1u>(pow2_engine); >> >-} >> >- >> >-int main() >> >-{ >> >- // For 128bit floating points, generator emitting a range, which size >> is >> >- // not power of two, but of width of B bits, such that for any N: >> >- // N * B < 113 (bits in ieee128) >> >- // (N+1) * B > 128 >> >- // are not supported, as they would require integer with more than >> 127 bits. >> >- >> >- // N == 3: B in [43, 57) >> >- test_non_pow2<__float128, 42>(); // 3 calls >> >- test_non_pow2<__float128, 43>(); // { dg-error "from here" } >> >- test_non_pow2<__float128, 56>(); // { dg-error "from here" } >> >- test_non_pow2<__float128, 57>(); // 2 calls >> >- test_pow2<__float128, 43>(); >> >- test_pow2<__float128, 56>(); >> >- >> >- // N == 4: B in [33, 38) >> >- test_non_pow2<__float128, 32>(); // 4 calls >> >- test_non_pow2<__float128, 33>(); // { dg-error "from here" } >> >- test_non_pow2<__float128, 37>(); // { dg-error "from here" } >> >- test_non_pow2<__float128, 38>(); // 3 calls >> >- test_pow2<__float128, 33>(); >> >- test_pow2<__float128, 37>(); >> >- >> >- // N == 5: B in [26, 29) >> >- test_non_pow2<__float128, 25>(); // 5 calls >> >- test_non_pow2<__float128, 26>(); // { dg-error "from here" } >> >- test_non_pow2<__float128, 28>(); // { dg-error "from here" } >> >- test_non_pow2<__float128, 29>(); // 4 calls >> >- test_pow2<__float128, 26>(); >> >- test_pow2<__float128, 28>(); >> >- >> >- // N == 6: B == 22 >> >- test_non_pow2<__float128, 21>(); // 6 calls >> >- test_non_pow2<__float128, 22>(); // { dg-error "from here" } >> >- test_non_pow2<__float128, 23>(); // 5 calls >> >- test_pow2<__float128, 22>(); >> >-} >> >- >> >-// { dg-prune-output "no type named 'type' in 'struct >> std::__detail::_Select_uint_least_t" } >> >-// { dg-prune-output "static assertion failed: sorry, would be too much >> trouble for a slow result" } >> >-- >> >2.54.0 >> > >> > >> >>
