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Re: Non-call exceptions versus cse
- From: Richard Henderson <rth at redhat dot com>
- To: Andrew Haley <aph at redhat dot com>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Tue, 19 Nov 2002 15:55:18 -0800
- Subject: Re: Non-call exceptions versus cse
- References: <200211191621.gAJGLTs10581@cuddles.cambridge.redhat.com>
On Tue, Nov 19, 2002 at 04:21:29PM +0000, Andrew Haley wrote:
> Consider this code fragment:
>
> int nn = 0;
> try
> {
> int tmp = foo->bar;
> nn = tmp;
> }
> ...
>
> When using non-call exceptions, this may not be changed to
>
> int nn = 0;
> try
> {
> nn = foo->bar;
> }
Huh?
I don't see that these two are going to be any different at all.
The value must be loaded from foo->bar before it can be stored
in nn. This is true even if you have mem->mem moves, since the
source might cause a normal page fault as well.
Please explain the problem you're actaully seeing in more detail.
r~