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Re: [vtab (and trunk?)] fix fallout from SSA-coalescing user variables
On 10/13/07, Alexandre Oliva <aoliva@redhat.com> wrote:
> > On Oct 11, 2007, "Richard Guenther" <richard.guenther@gmail.com> wrote:
> >> The extra checking triggers PR33735.
>
> > Thanks. This is an interesting testcase. It is a variant of the
> > problem H-P had reported, but I hadn't realized there was a lingering
> > bug then.
>
> So the patch below reverts the work around for H-P's testcase, and
> fixes the problem explained below.
>
> > The problem is that an exception thrown during stack unwinding is
> > supposed to call terminate(), but AFAICT, when we inline the dtor of
> > temporaries (other than the exception object) in the throw expression
> > itself, calls that are brought in as part of the destructor get EH
> > edges as if they were before the throw expression, escaping the
> > requirement to call terminate in case they throw.
>
> > Now, since there aren't edges from the original dtor call to enclosing
> > catch or clean-up points, when we look for such edges at the time of
> > adjusting the PHI nodes, we don't find them. Oops.
>
> The patch below recognizes an ERT_ALLOWED_EXCEPTIONS EH region with an
> empty type list and prevents the enclosing try block from being
> regarded as reachable from within. With it, both testcases compile
> correctly.
>
> libstdc++ builds with it; starting bootstrap and regtesting on
> x86_64-linux-gnu right now. Ok to install?
This is ok.
Thanks,
Richard.