Re: PATCH for loop.c, SIGFPE with bad integer operands on host (linux-)ix86

[Andrew Haley <aph@pasanda.cygnus.co.uk>]

> Date: Tue, 03 Aug 1999 18:09:31 -0600
> From: Jeffrey A Law <law@cygnus.com>
> 
>   In message <Pine.BSF.4.10.9908031834570.14732-100000@dair.pair.com>you write:
>   > There's a (well-known?) problem with integer arithmetic on
>   > (linux-)ix86 platforms:  Doing signed integer modulus or
>   > division on (0x80000000 / -1) or (0x80000000 % -1) gives a
>   > SIGFPE.  This is ix86-specific, and maybe possible to work
>   > around in the right interrupt handler in the kernel for
>   > those who know that stuff.  This happens on linux 2.0.30
>   > with a PPro as well as on linux 2.2.1 with a PII, and
>   > probably on non-linux systems as well; I believe cygwin b20.1
>   > has the same problem.
> The kernel trap handlers need to be fixed.

Well, maybe.  However, efficient Java implementation requires
language-specific handling of this case.  Other programming languages
may also require handlers, for all I know.  It would be a Bad Thing if
the kernel were to fail to send SIGFPE to a running Java application,
as we'd have to put a test around every divide instruction.

I suggest that gcc should not try to do a signed integer division in
this case as the result isn't portably defined.

Andrew.