Re: Crashes in x86_64 math functions

[PaweÅ Sikora <pluto at agmk dot net>]

On Tuesday 10 of January 2012 17:38:05 Allan McRae wrote:

> I have not been able to debug this further yet due to a combined lack of
> time and ability...

Hi,

attached testcase (compiled with: gcc -Wall t.c -g2 -o t -fno-builtin -lm)
runs on glibc-2.14.1/valgrind without errors but on glibc-2.15 the valgrind reports:

$ valgrind ./t                                  
==4233== Memcheck, a memory error detector
==4233== Copyright (C) 2002-2011, and GNU GPL'd, by Julian Seward et al.
==4233== Using Valgrind-3.7.0 and LibVEX; rerun with -h for copyright info
==4233== Command: ./t
==4233==
==4233== Conditional jump or move depends on uninitialised value(s)
==4233==    at 0x40174B6: index (strchr.S:56)
==4233==    by 0x4007862: expand_dynamic_string_token (dl-load.c:431)
==4233==    by 0x400812F: _dl_map_object (dl-load.c:2281)
==4233==    by 0x400185D: map_doit (rtld.c:632)
==4233==    by 0x400E2F5: _dl_catch_error (dl-error.c:178)
==4233==    by 0x4000F0A: do_preload (rtld.c:821)
==4233==    by 0x400487E: dl_main (rtld.c:1714)
==4233==    by 0x4014576: _dl_sysdep_start (dl-sysdep.c:244)
==4233==    by 0x4004EED: _dl_start (rtld.c:337)
==4233==    by 0x4001687: ??? (in /lib64/ld-2.15.so)
==4233==
==4233== Conditional jump or move depends on uninitialised value(s)
==4233==    at 0x40174BB: index (strchr.S:59)
==4233==    by 0x4007862: expand_dynamic_string_token (dl-load.c:431)
==4233==    by 0x400812F: _dl_map_object (dl-load.c:2281)
==4233==    by 0x400185D: map_doit (rtld.c:632)
==4233==    by 0x400E2F5: _dl_catch_error (dl-error.c:178)
==4233==    by 0x4000F0A: do_preload (rtld.c:821)
==4233==    by 0x400487E: dl_main (rtld.c:1714)
==4233==    by 0x4014576: _dl_sysdep_start (dl-sysdep.c:244)
==4233==    by 0x4004EED: _dl_start (rtld.c:337)
==4233==    by 0x4001687: ??? (in /lib64/ld-2.15.so)


i have an intel-i7-2630QM mobile cpu (family: 0x06, model: 0x2a) with avx.

BR,
PaweÅ.

#include <math.h>
int main()
{
	volatile double d = tan( M_PI / 4 );
	return d == 1.0;
}