[Linux-ia64] Port of the posix timers to IA64

[Linux-ia64] Port of the posix timers to IA64

[Eric Piel]

Hello David,

I'm working on the port of the posix timers to IA64. The first (over 4)
part has just been integrated in the linus tree (2.5.63) so I think you
can find interest in my work. 
Even if it's supposed to be portable accross platforms, due to some mix
between long and int, it doesn't run correctly on IA64. 

Here comes my question, I'm still newbie to kernel hacking and IA64
compilation and I don't know how I should handle some troubles with
longs. In the code I have some cases like this one:

long v;
:
:
if ( v >= (1 << 56)){
:
}

It seems very strange for me that when compiling this part gcc considers
that eveything must be converted to int. I have to write 1UL instead of
1 in order to obtain the correct behaviour of the code. I guess you've
already come along with such problem.
So, first, do you think it's a bug in gcc? Second should I convert every
1's I see by 1UL's (there are only few but sounds so strange)?

Thanks
Eric

Re: [Linux-ia64] Port of the posix timers to IA64

[Andreas Schwab]

Eric Piel <Eric.Piel@Bull.Net> writes:

|> Hello David,
|> 
|> I'm working on the port of the posix timers to IA64. The first (over 4)
|> part has just been integrated in the linus tree (2.5.63) so I think you
|> can find interest in my work. 
|> Even if it's supposed to be portable accross platforms, due to some mix
|> between long and int, it doesn't run correctly on IA64. 
|> 
|> Here comes my question, I'm still newbie to kernel hacking and IA64
|> compilation and I don't know how I should handle some troubles with
|> longs. In the code I have some cases like this one:
|> 
|> long v;
|> :
|> :
|> if ( v >= (1 << 56)){
|> :
|> }
|> 
|> It seems very strange for me that when compiling this part gcc considers
|> that eveything must be converted to int. I have to write 1UL instead of
|> 1 in order to obtain the correct behaviour of the code. I guess you've
|> already come along with such problem.

That's how C is working.  A type of an expression is determined
independent of the context, so the type of 1 is always int.  And shifting
by more than the width of the type is an undefined operation.

Andreas.

-- 
Andreas Schwab, SuSE Labs, schwab@suse.de
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