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Re: [PATCH][4.3] Deprecate -ftrapv
On Fri, 29 Feb 2008, Mark Mitchell wrote:
> Thanks for the explanations. It seems like tree-ssa should in theory make it
> easier to implement this; for example, at the point of gimplification one
> could insert checks, and then just let everything else do its thing. I don't
> see how libcalls and such would matter in that scheme. I'm not denying that
> this is a project, though.
Obviously you need to keep the functions in libgcc in any event for the
sake of old object code (just as we keep __eprintf there), even if you
make GCC generate inline code rather than libcalls or remove the option
entirely.
You also need to deal with fold, which will optimize away potentially
trapping computations with -ftrapv and runs before gimplification
(possibly in association with making fold run at gimplification time and
not before).
--
Joseph S. Myers
joseph@codesourcery.com