This is the mail archive of the mailing list for the GCC project.

Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: Question about building hash values from pointers

Kai Tietz wrote:

> Andrew Haley <> wrote on 30.05.2008 11:45:50:
>> Kai Tietz wrote:
>>> as I noticed, most hash value calculations are trying to use pointer 
>>> values for building the value and assume that a long/unsigned long 
> scalar 
>>> is wide enough for a pointer. This is at least for w64 target not 
> true. So 
>>> I want to know, if it would be good to introduce an gcc specific type 
> for 
>>> those kind of casts, or to use ssize_t/size_t.?
>> Why would it matter?  Are there any circumstances is which not using the
>> upper part of an address will reduce performance or break something?
> First of all it matters about warnings. The native build of w64 gcc is 
> full of 'cast from pointer to integer of different size. The second, IMHO 
> the more important reason, is that a general type to express a host 
> pointer scalar size would prevent such bugs as in PR/36386.

If what Andrew Pinski says is true, this is not a bug at all.  Not
that I'm against fixing warnings, of course; using long where size_t is
meant is probably a hangover from the days when gcc had to compile on
non-ISO C.

You can't use ssize_t, though, as it's nonstandard.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]