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Re: gcc3 vs 176.gcc


>>>>> Dale Johannesen writes:

Dale> Could we change the aliasing check as follows?  First check for whether two
Dale> memrefs are accessed off the same register(s); if they are, we know at once
Dale> whether the memrefs interfere or not (depending on the offsets).  Only if
Dale> the result of this check is indeterminate do we look at the aliasing info.

	Trying more ways to notice aliases seems reasonable to me, as long
as it will not create too many false-positives.

Dale> Could we decouple -fstrict-aliasing from -O2?  (Apple may well do this internally
Dale> in any case, since technically incorrect casts like the one above seem to be
Dale> fairly common in existing code.)

	Please see the earlier discussions about -fstrict-aliasing.
Quoting an earlier message:

"-fstrict-aliasing is enabled at -O2 in all snapshots since 2.96, and will
be in 3.0.  It was turned off on the 2.95 branch to give people more time
to fix their code.  It is our understanding that most free software
projects have either fixed their code or wired in a -fno-strict-aliasing
where appropriate."

David


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