This revision was automatically updated to reflect the committed changes.
Closed by commit rCXX339969: [libc++] Use correct rand.eng.mers all-zeroes seed
sequence fallback (authored by hubert.reinterpretcast, committed by ).
Changed prior to commit:
https://reviews.llvm.org/D50736?vs=160923&id=161145#toc
Repository:
rCXX libc++
https://reviews.llvm.org/D50736
Files:
include/random
test/std/numerics/rand/rand.eng/rand.eng.mers/ctor_sseq_all_zero.pass.cpp
Index: include/random
===================================================================
--- include/random
+++ include/random
@@ -2337,7 +2337,7 @@
for (size_t __i = 1; __i < __n; ++__i)
if (__x_[__i] != 0)
return;
- __x_[0] = _Max;
+ __x_[0] = result_type(1) << (__w - 1);
}
}
@@ -2363,7 +2363,7 @@
for (size_t __i = 1; __i < __n; ++__i)
if (__x_[__i] != 0)
return;
- __x_[0] = _Max;
+ __x_[0] = result_type(1) << (__w - 1);
}
}
Index: test/std/numerics/rand/rand.eng/rand.eng.mers/ctor_sseq_all_zero.pass.cpp
===================================================================
--- test/std/numerics/rand/rand.eng/rand.eng.mers/ctor_sseq_all_zero.pass.cpp
+++ test/std/numerics/rand/rand.eng/rand.eng.mers/ctor_sseq_all_zero.pass.cpp
@@ -0,0 +1,81 @@
+//===----------------------------------------------------------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <random>
+
+// template <class UIntType, size_t w, size_t n, size_t m, size_t r,
+// UIntType a, size_t u, UIntType d, size_t s,
+// UIntType b, size_t t,
+// UIntType c, size_t l, UIntType f>
+// class mersenne_twister_engine;
+
+// template <class Sseq> explicit mersenne_twister_engine(Sseq &q);
+//
+// [ ... ] Finally, if the most significant $w-r$ bits of $X_{-n}$ are zero,
+// and if each of the other resulting $X_i$ is $0$, changes $X_{-n}$ to
+// $ 2^{w-1} $.
+
+#include <random>
+
+#include <algorithm>
+#include <cassert>
+#include <cstddef>
+#if TEST_STD_VER >= 11
+#include <initializer_list>
+#endif
+
+struct all_zero_seed_seq {
+ typedef unsigned int result_type;
+
+ all_zero_seed_seq() {}
+
+ template <typename InputIterator>
+ all_zero_seed_seq(InputIterator, InputIterator) {}
+#if TEST_STD_VER >= 11
+ all_zero_seed_seq(std::initializer_list<result_type>) {}
+#endif
+
+ template <typename RandomAccessIterator>
+ void generate(RandomAccessIterator rb, RandomAccessIterator re) {
+ std::fill(rb, re, 0u);
+ }
+
+ std::size_t size() const { return 0u; }
+ template <typename OutputIterator> void param(OutputIterator) const {}
+};
+
+template <typename result_type, std::size_t word_size>
+void test(void) {
+ const std::size_t state_size = 1u;
+ const std::size_t shift_size = 1u;
+ const std::size_t tempering_l = word_size;
+
+ all_zero_seed_seq q;
+ std::mersenne_twister_engine<result_type, word_size, state_size,
+ shift_size,
+ 0u,
+ 0x0,
+ 0u, 0x0, 0u, 0x0, 0u, 0x0,
+ tempering_l,
+ 0u>
+ e(q);
+
+ const result_type Xneg1 = result_type(1) << (word_size - 1);
+ const result_type Y = Xneg1;
+ const result_type X0 = Xneg1 ^ (Y >> 1);
+ assert(e() == X0);
+}
+
+int main() {
+ // Test for k == 1: word_size <= 32.
+ test<unsigned short, 3u>();
+
+ // Test for k == 2: (32 < word_size <= 64).
+ test<unsigned long long, 33u>();
+}
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