A combiner type optimization is causing a failure

[Paolo Bonzini]

> My question is that, IMO the test is checking overflow behaviour. Is
> it right to have such a test ?

Would you care to prepare a patch that moved it under gcc.dg, adding a { 
dg-options "-O2 -fno-strict-overflow" } marker (or maybe "-O2 
-fno-wrapv")?  But your optimization should also be conditional on 
whether strict overflow behavior is requested.

Paolo