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Re: Ada front-end depends on signed overflow
> > Right, the code generated by the front end is not pretty either, but at
> > least the front-end knows what it is doing Ada-wise. -ftrapv is so dumb
> > at the moment that it emits checks for virtually anything.
>
> No, it just emits it for signed operations.
Of course, it is not so dumb as to blatantly violate its specification.
> If we use -ftrapv, then we have to make sure that operations labeled by the
> front end as not requiring an overflow check are transformed into unsigned
> operations by gigi.
I think it would be dangerous to take that path.
> I don't see that's so terrible, the jmp will be free in practice anyway
> so I don't think you will find this slows things down.
You missed the point; the overflow check has been optimized away by one of the
RTL optimization passes.
--
Eric Botcazou