Re: [tree-ssa] Implement non-call exceptions

[Richard Henderson <rth at redhat dot com>]

On Thu, Dec 04, 2003 at 11:00:48AM +0000, Andrew Haley wrote:
> Maybe I'll have a look at the mainline code to find out why it behaves
> differently.

That would be good, because IIRC division is handled specially
in this case by optabs.c.

> I guess it depends on the language.  What language throws exceptions
> on floating-point execptions?  Ada?  Perhaps it should be a langhook.

It's more than throwing.  Look at the rtl may_trap_p.  It is true
for anything that could *fault*.  It's probably a mistake to have
a function whose name implies the same test but behaves differently.

At present we don't have any tree-level optimizations that move
code places that they wouldn't have been executed before, but that
could change in the future.

Anyway, in theory one could use -fnon-call-exceptions in C++ and
throw floating point exceptions yourself, assuming you installed
a handler similar to what libjava implements.  I would expect it
to work.

A language hook might be a reasonable idea, but that would have
to go into tree_could_throw_p, rather than tree_could_trap_p.


r~