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Re: [PATCH][4.3] Deprecate -ftrapv
Richard Guenther wrote:
The tree optimizers do not recognize +-* of singed integers as
possibly trapping which causes functions to become const/pure that
should not and causes 'dead' code to be removed that should not.
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.
I fully agree that claiming things work when they don't is bad -- we
don't want to lie to the users! But, is the failure mode that we issue
run-time errors when we shouldn't, or that we don't issue run-time
errors when we should? The latter is much less severe than the former.
I guess you've withdrawn the deprecation request, so maybe this is
something of a moot point now? I certainly agree that we shouldn't let
a non-working feature stand in the way of improvements in 4.4.
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