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Re: [PATCH] Fix aliasing miscompilation
On Tue, Oct 24, 2000 at 11:11:08PM -0700, Mark Mitchell wrote:
> >>>>> "Jakub" == Jakub Jelinek <email@example.com> writes:
> Jakub> If you set it back to -1, it means the restricted pointer
> Jakub> now points to an alias set which is a subset of never used
> Jakub> alias set, so the end result will be that gcc will assume
> Jakub> the restricted pointer cannot ever alias any aggregate of
> Jakub> the type it points to, which is bad.
> I'm sorry; I should have said alias set zero.
> Jakub> So, shouldn't alias.c define a new function which would do
> Jakub> exactly what I did in layout_type and frontends would need
> Jakub> to call this when they are really finished with type
> Jakub> layout?
> I think we already have a means of doing that.
Ok, so should I
1) submit a patch which puts it into alias set zero in layout_type
2) submit a patch which makes sure C finish_structure calls
record_component_aliases and make record_component_aliases be callable
multiple times on the same structure (by doing splay tree lookup if the
subset is already recorded), so that C++ frontend can call it whenever it
adds new fields into the record (once the fields are finished)
> Please look through the previous emails (look for an exchange between
> Kenner and myself) a while back.
I'll search that.