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Re: x86_64: Should the -mavx* options affected __alignof__ (max_align_t)?

On 04/02/2015 09:26 AM, Florian Weimer wrote:
> On 03/23/2015 07:41 PM, Florian Weimer wrote:
>> Ah, I should have looked at what max_align_t actually meant.  With these
>> semantics, the name is a bit confusing.  I agree that requiring 64 byte
>> alignment from malloc does not make much sense.  Thanks.
> Follow-up question: Can malloc return a pointer which is not aligned to
> _Alignof (max_align_t)?


max_align_t is specified in 7.19#2 as "an object type...

As for malloc:

"The pointer returned if the allocation succeeds is suitably aligned
so that it may be assigned to a pointer to any type of object with a
fundamental alignment requirement and then used..."

"A fundamental alignment is represented by an alignment less than or
equal to the greatest alignment supported by the implementation in all
contexts, which is equal to _Alignof (max_align_t)."

So, max_align_t is an object type, and therefore malloc returns a
pointer suitable for max_align_t.


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