https://bugs.kde.org/show_bug.cgi?id=414870
Bug ID: 414870
Summary: std::frexp(long double) broken under valgrind.
Product: valgrind
Version: 3.15 SVN
Platform: Other
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: memcheck
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---
SUMMARY
The invariants of std::frexp(long double) are broken when the argument is >
DOUBLE_MAX on Ubuntu 19.10, but not on Ubuntu 18.04.
STEPS TO REPRODUCE
Compile the following program with g++ -g:
#include <cmath>
#include <limits>
int main()
{
long double f = std::numeric_limits<double>::max();
int e;
assert(std::frexp(f, &e) < 1); // passes
f *= 2;
if(!std::isinf(f)) // passes, f is still finite
assert(std::frexp(f, &e) < 1); // fails
return 0;
}
Then run valgrind ./a.out
OBSERVED RESULT
==3249== Memcheck, a memory error detector
==3249== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
==3249== Using Valgrind-3.15.0 and LibVEX; rerun with -h for copyright info
==3249== Command: ./a.out
==3249==
a.out: boost/t.cpp:12: int main(): Assertion `std::frexp(f, &e) < 1' failed.
==3249==
==3249== Process terminating with default action of signal 6 (SIGABRT)
==3249== at 0x4BDD3EB: raise (raise.c:51)
==3249== by 0x4BBC898: abort (abort.c:79)
==3249== by 0x4BBC768: __assert_fail_base.cold (assert.c:92)
==3249== by 0x4BCE005: __assert_fail (assert.c:101)
==3249== by 0x109284: main (t.cpp:12)
==3249==
==3249== HEAP SUMMARY:
==3249== in use at exit: 0 bytes in 0 blocks
==3249== total heap usage: 3 allocs, 3 frees, 72,882 bytes allocated
==3249==
==3249== All heap blocks were freed -- no leaks are possible
==3249==
==3249== For lists of detected and suppressed errors, rerun with: -s
==3249== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)
Aborted (core dumped)
EXPECTED RESULT
There is no assert when running outside valgrind, or on ubuntu-18 (not sure
which valgrind version is installed there).
This is a reduced test case from a Boost.Multiprecision bug report:
https://github.com/boostorg/multiprecision/issues/174
SOFTWARE/OS VERSIONS
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