Re: [PATCH][2.6.6-rc3] gcc-3.4.0 fixes

[Andreas Schwab]

William Lee Irwin III <wli@xxxxxxxxxxxxxx> writes:

> On Tue, Jun 01, 2004 at 04:52:59PM +0200, Mikael Pettersson wrote:
>> You're assuming pointers have uniform representation.
>> C makes no such guarantees, and machines _have_ had
>> different types of representations in the past.
>> Some not-so-obsolete 64-bit machines in effect use fat
>> representations for pointers to functions (descriptors),
>> but they usually cheat and use pointers to the descriptors
>> instead. However, a C implementation could legally
>> represent a function pointer as a 128-bit value, while
>> data pointers remain 64 bits.
>
> IIRC for all types foo, sizeof(foo *) <= sizeof(void *), no?

No.  There is no implied relation between data pointers and function
pointers.  The only requirement is that all _function_ pointers smell
alike, because you can convert any function pointer to any other function
pointer and back without losing information.  There is no dedicated
generic function pointer type, any one can function as one.

Andreas.

-- 
Andreas Schwab, SuSE Labs, schwab@xxxxxxx
SuSE Linux AG, Maxfeldstraße 5, 90409 Nürnberg, Germany
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