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Re: how well does gcc support type-specific pointer formats?

On Wed, Sep 30, 2015 at 11:23 AM, Mikael Pettersson
<> wrote:
> Does gcc allow backends to have a say in how pointers are represented
> (bits beyond the address), what happens in conversions between pointer
> types, and what happens in conversions between pointers and uintptr_t?
> The target in question has:
> - one pointer format and set of load/store instructions for pointers to int/long
> - another format and set of load/store instructions for pointers to char
> - pointers to short use a third format in general, but can use the int/long
>   format IF you know which half of the word you're going to access
> What mechanisms, if any, are present in gcc to deal with this?

Basically none.  The only thing I could imagine you could use is have
the pointer
formats be different address-spaces.  The target controls how to
convert pointers
from/to different address-spaces.  I am not aware of specialities for
or int-to-pointer conversion though - IIRC they simply use
bit-identical conversions
(thus subregs if the modes differ).

But who would design this kind of weird architecture and think he could get
away with that easily?


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