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Re: C provenance semantics proposal
Am Mittwoch, den 24.04.2019, 21:30 +0200 schrieb Philipp Klaus Krause:
> Am 24.04.19 um 20:41 schrieb Jeff Law:
> > > > > 4.) Compilers make sure that exposed objects never
> > > > > are allocated next to each other (as Jens proposed).
> > > >
> > > > Ugh. Not sure how you enforce that. Consider that the compiler may
> > > > ultimately have no control over layout of data in static storage.
> > >
> > > Make everything 1 byte larger.
> >
> > Not a bad idea. I suspect the embedded folks would go bananas though.
> >
>
> Some of the systems the Small Device C compiler targets have just 60 B
> of RAM. And we are curetnly considering adding support for a multicore
> microcontroller, of which also variants with just 60 B of RAM exist.
> But even for the other architectures supported in SDCC, where devices
> tend to have much bigger RAM, in the range of 128B to even a few KB,
> wasting memory like that is not acceptable.
It would not be a requirement, you could always do the pointer
comparison at run-time or write a smarter compiler which not
only uses provenance for optimization but also takes
neighborhood relationships into accout.
Martin