https://bugs.kde.org/show_bug.cgi?id=424044
Bug ID: 424044
Summary: long double issue: isinf(strtold("+inf", NULL)) != 1
Product: valgrind
Version: unspecified
Platform: unspecified
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: memcheck
Assignee: jsew...@acm.org
Reporter: o...@redislabs.com
Target Milestone: ---
SUMMARY
strtold("+inf",NULL) seems to return a non-inf value.
STEPS TO REPRODUCE
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
int main(int argc, char *argv[])
{
long double x = strtold("+inf", NULL);
fprintf(stderr, "x = %Lf, isinf = %d\n", x, isinf(x));
return 0;
}
OBSERVED RESULT
$ ./a.out
x = inf, isinf = 1
$ valgrind ./a.out
==2890624== Memcheck, a memory error detector
==2890624== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
==2890624== Using Valgrind-3.16.0 and LibVEX; rerun with -h for copyright info
==2890624== Command: ./a.out
==2890624==
x = 11897314953572...., isinf = 0
EXPECTED RESULT
x = inf, isinf = 1
SOFTWARE/OS VERSIONS
Ubuntu 20.04
Linux ip-172-31-20-147 5.4.0-1015-aws #15-Ubuntu SMP Thu Jun 4 22:47:00 UTC
2020 x86_64 x86_64 x86_64 GNU/Linux
valgrind-3.16.0
ADDITIONAL INFORMATION
it seems to depend on the hardware (i didn't collect enough evidence), i
noticed it happens on Xeon, but not on core i7-7700k (both using self built
valgrind-3.16.0 on Ubuntu).
Seen it on both bare metal Xeon (Valgrind-3.15.0) and AWS c5.xlarge VM
(Valgrind-3.16.0), also both with Ubuntu:
processor : 0
vendor_id : GenuineIntel
cpu family : 6
model : 85
model name : Intel(R) Xeon(R) Platinum 8275CL CPU @ 3.00GHz
stepping : 7
microcode : 0x5002f00
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