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Let us focus on the role of PPL for Graphite (which uses the C interface): I believe that this application does not exploit the ability of PPL to continue after an out-of-memory condition or an arithmetic-overflow. If this is true, then any error raised by the PPL would cause an ICE in GCC. If dying with an uncaught exception is considered not significantly worse than dying with an ICE, then there should be no problem. In this hypothesis, the failures you observe are only for test programs that exercise the error-reporting capabilities of the PPL: I would disable just those on the Alpha.
I think that this is the case; I think it's up to the GCC devs to decide whether this is a problem for them or not -- I've added my 2cents to the GCC PR and I'm still hoping for the guys to fix it, even though it is outstanding for quite some time now.
Then the Debian/Alpha users should probably be warned that the PPL package they have does not possess all the properties explained in the PPL documentation, i.e., all the error reporting features are badly broken.
I'll try to make this explicit in the Debian changelog.
Best, Michael