Re: [boost] [atomic] unconditional cmpxchg8b support

Subject: Re: [boost] [atomic] unconditional cmpxchg8b support
From: Tim Blechmann (tim_at_[hidden])
Date: 2012-10-23 08:28:46

>>>> however on debian for example, the compiler defaults to generate code
>>>> for i486. cmpxchg8b has been introduced with the p5 architecture,
>>>> though, so compiling without specifying a -march flag won't generate the
>>>> instruction.
>>>
>>> GCC will not let you use instructions outside of the target architecture.
>>
>> fyi, boost.atomic is using inline assembly
> 
> While inline assembly may allow to circumvent that restriction, I do not 
> think it is a good idea to force a design that requires their usage.

in a perfect world, we would not need boost.atomic, as all compilers,
standard libraries would be c++11 compliant.

helge might want to comment about his decision to use inline assembly,
but iirc, gcc did not provide good support for atomic builtins until 4.4
or so ... so portability would be a reason