[tree-ssa] Fix variables getting out of their scope
law@redhat.com
law@redhat.com
Wed Aug 20 22:53:00 GMT 2003
In message <20030820223318.GA26494@atrey.karlin.mff.cuni.cz>, Zdenek Dvorak wri
tes:
>Hello,
>copy propagation may replace set to j with i, thus moving it out of its
>scope. Given that we may (??? not really sure whether we do it) assign
>the same stack slot to i, j and bla, this would cause a misscompilation.
Everything which goes into a stack slot (as opposed to be assigned a
pseudo register) should be marked as addressable -- which should in turn
prevent the object from being used for copy propagation. ie, it should
be a non-issue.
>2) That cursed extension:
>
>{
> int z = ...;
>
> {
> int array[z];
> }
>}
>
>Not really sure whether the process you describe is able to handle this.
>But we probably should lower this anyway.
It's standard for C99, so we shouldn't continue to think about VLAs
as extensions, but as first class features we need to support.
[ And I'm as guily as the next person in looking at VLAs as extensions..... ]
Jeff
>
>Zdenek
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