* Integral type with sizeof(T) == 1 and distinct aliasing class
@ 2012-05-20 9:45 Florian Weimer
2012-05-21 4:06 ` Ian Lance Taylor
0 siblings, 1 reply; 4+ messages in thread
From: Florian Weimer @ 2012-05-20 9:45 UTC (permalink / raw)
To: gcc-help
Is there a type which is basically an (unsigned) char, but with the
additional feature that a pointer derived from it wouldn't alias with
basically anything?
This type would be handy for optimizing marshaling code.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Integral type with sizeof(T) == 1 and distinct aliasing class
2012-05-20 9:45 Integral type with sizeof(T) == 1 and distinct aliasing class Florian Weimer
@ 2012-05-21 4:06 ` Ian Lance Taylor
2012-05-25 20:01 ` Florian Weimer
0 siblings, 1 reply; 4+ messages in thread
From: Ian Lance Taylor @ 2012-05-21 4:06 UTC (permalink / raw)
To: Florian Weimer; +Cc: gcc-help
Florian Weimer <fw@deneb.enyo.de> writes:
> Is there a type which is basically an (unsigned) char, but with the
> additional feature that a pointer derived from it wouldn't alias with
> basically anything?
>
> This type would be handy for optimizing marshaling code.
There is no such type. However, use of the restrict qualifier should
achieve a similar effect.
Ian
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Integral type with sizeof(T) == 1 and distinct aliasing class
2012-05-21 4:06 ` Ian Lance Taylor
@ 2012-05-25 20:01 ` Florian Weimer
2012-05-25 20:41 ` Gabriel Dos Reis
0 siblings, 1 reply; 4+ messages in thread
From: Florian Weimer @ 2012-05-25 20:01 UTC (permalink / raw)
To: Ian Lance Taylor; +Cc: gcc-help
* Ian Lance Taylor:
> Florian Weimer <fw@deneb.enyo.de> writes:
>
>> Is there a type which is basically an (unsigned) char, but with the
>> additional feature that a pointer derived from it wouldn't alias with
>> basically anything?
>>
>> This type would be handy for optimizing marshaling code.
>
> There is no such type. However, use of the restrict qualifier should
> achieve a similar effect.
It turns out that I can't get GCC to eliminate redundant bounds
checks, no matter what the type is. I guess I have to do this in a
library after all, using template metaprogramming.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Integral type with sizeof(T) == 1 and distinct aliasing class
2012-05-25 20:01 ` Florian Weimer
@ 2012-05-25 20:41 ` Gabriel Dos Reis
0 siblings, 0 replies; 4+ messages in thread
From: Gabriel Dos Reis @ 2012-05-25 20:41 UTC (permalink / raw)
To: Florian Weimer; +Cc: Ian Lance Taylor, gcc-help
On Fri, May 25, 2012 at 3:01 PM, Florian Weimer <fw@deneb.enyo.de> wrote:
> * Ian Lance Taylor:
>
>> Florian Weimer <fw@deneb.enyo.de> writes:
>>
>>> Is there a type which is basically an (unsigned) char, but with the
>>> additional feature that a pointer derived from it wouldn't alias with
>>> basically anything?
>>>
>>> This type would be handy for optimizing marshaling code.
>>
>> There is no such type. However, use of the restrict qualifier should
>> achieve a similar effect.
>
> It turns out that I can't get GCC to eliminate redundant bounds
> checks, no matter what the type is. I guess I have to do this in a
> library after all, using template metaprogramming.
is it possible to use one of those GCC type mode extensions to
typedef int with mode saying it has 8-bit and use that?
-- Gaby
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2012-05-25 20:41 UTC | newest]
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2012-05-20 9:45 Integral type with sizeof(T) == 1 and distinct aliasing class Florian Weimer
2012-05-21 4:06 ` Ian Lance Taylor
2012-05-25 20:01 ` Florian Weimer
2012-05-25 20:41 ` Gabriel Dos Reis
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