RE: [PATCH] x86/fpu: use __alignof__ to avoid UB in TYPE_ALIGN

[David Laight]

From: YingChi Long
> Sent: 26 September 2022 14:18
> 
> Seems GCC __alignof__ is not evaluated to the minimum alignment of some
> TYPE, and depends on fields of the struct.
> 
>  > Notably I think 'long long' has 4 byte alignment on i386 and some other
>  > 32bit archs.
> 
> C11 _Alignof matches in the case (see godbolt link below). How about
> switch to _Alignof?

__alignof__() returns the preferred alignment, not the minimal one.
So one i386 it returns 8 for 'long long' rather than 4.

Using alignof(struct{long long x;}) does give the required 4.
(as does _Alignof()).

See https://godbolt.org/z/13xTYYd11

	David

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