Re: Libm core dump with SIGILL

[Greg Stark <stark%mit.edu@localhost>]

On Fri, Aug 21, 2015 at 2:24 PM, Johnny Billquist <bqt%update.uu.se@localhost> wrote:
>>
>> SIGILL is a compiler bug (if the implementation of exp() is in C) or a
>> programmer error (if it's in assembler).
>
>
> We should check this. There is trickery going on with VAX FP, in order to
> somewhat achieve some of the similar properties of IEEE FP. I know that have
> bitten me in the past, and it might even be needed to check in gcc itself,
> as the actual libraries might not even be invoked.


Sorry, I should have included the versions of things

This is on a freshly installed NetBSD 6.1.5 on simh from a recently
checked out git tree:

simh# uname -a
NetBSD simh 6.1.5 NetBSD 6.1.5 (GENERIC) vax

simh# gcc --version
gcc (GCC) 4.1.3 20080704 prerelease (NetBSD nb3 20111107)

$ ./vax -h
MicroVAX 3900 simulator V4.0-0 Beta        git commit id: f3af74e4

The backtrace is actually a bit deeper than just exp()

#0  0x7f7b6984 in infnan (34) from /usr/lib/libm.so.0
#1  0x7f7b6810 in scalb (16512, 1179648, 17406, 0) from /usr/lib/libm.so.0
#2  0x7f7b66df in exp (255017904, 735823842) from /usr/lib/libm.so.0

-- 
greg