Re: [Qemu-devel] [PATCH][SPARC] Full implementation of IEEE exceptions

[Aurelien Jarno]

On Fri, Apr 06, 2007 at 08:22:21AM +0200, Blue Swirl wrote:
> >The attached patch fully implements IEEE exceptions on the SPARC target.
> 
> Nice work, thank you. Do you know of any code that uses the exceptions?

I guess no code is using IEEE exceptions to generate a trap, because 
defining a signal handler for SIGFPE is highly non-standard. However a 
few programs are querying FSR to check the AEXC flags after a sequence 
of floating point instructions. This is the case for example of the SUN 
Java J2RE.

> The flags enabling exceptions could be recorded to TB flags so that the 
> check code is generated only when needed, see cpu-exec.c:180.

Well I doubt it is possible, because check_ieee_exceptions() generates a
trap if the TEM flags in the FSR register are set, but also update the 
AEXC flag in FSR. I even doubt lazy FSR is possible here, because it 
accumulates the exceptions of all floating points instructions since 
those flags are cleared.

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