Re: New flag: TREE_THIS_NOTRAP

[Richard Henderson <rth at redhat dot com>]

On Fri, Jun 11, 2004 at 08:44:22PM +0100, Andrew Haley wrote:
> It has to be doesn't it?  The trapping in
> 
>    *exp
> 
> is a property of exp, not a property of *.  If someone attaches
> another INDIRECT_REF to exp, it will not be marked as NOTRAP.

Yes, but if someone copies exp to a compiler temporary,
we'll also lose the NOTRAP.  Something that is exceedingly
likely to occur when we go into and out of SSA form.

The INDIRECT_REF is more stable than the pointer in this.

Probably it would best be associated with the type of exp.
That's the property that should be reliably propagated 
during these transformations.  (There is a question of
whether tree_ssa_useless_type_conversion would discard
a type change between T* and T* nothrow, however.)


r~