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Re: tree-ssa: a weird (mis)optimization
- From: Richard Henderson <rth at redhat dot com>
- To: Andrew Haley <aph at redhat dot com>
- Cc: Geert Bosch <bosch at adacore dot com>, gcc at gcc dot gnu dot org
- Date: Wed, 1 Dec 2004 09:19:34 -0800
- Subject: Re: tree-ssa: a weird (mis)optimization
- References: <16812.39590.439732.460777@cuddles.cambridge.redhat.com> <08C7A98A-42FB-11D9-91E1-000A959A128E@adacore.com> <16812.47260.320238.536151@cuddles.cambridge.redhat.com> <20041130224704.GA4960@redhat.com> <16813.39257.780795.560709@cuddles.cambridge.redhat.com>
On Wed, Dec 01, 2004 at 10:13:45AM +0000, Andrew Haley wrote:
> Let me put it this way: a trapping instruction has an abnormal edge in
> the CFG, so why would it get deleted?
Well, for one, I didn't think things worked this way. It doesn't
make a whole lot of sense to me. We work hard to *get rid* of
instructions that trap, and to remove the associated abnormal edges.
I still think that the Java front end should be doing something in
order to indicate that these loads should not be removed, beyond
just marking them as trapping -- or rather, not marking them as not
trapping. Otherwise -fnon-call-exceptions will suddenly generate
*significantly* worse code for everyone else.
r~