Re: [Qemu-devel] [PATCH v2 1/3] qemu-tls.h: Add abstraction layer for TLS variables

[Paolo Bonzini]

On 10/27/2011 05:15 PM, Peter Maydell wrote:
> > > >>  +#define DEFINE_TLS(type, x)  __thread __typeof__(type) tls__##x
> > >  I assume __typeof__() is a GCCism, indicated by ..._GCC_H, to ensure
> > >  type is actually a valid type?
> Paolo?

No, _GCC_H has nothing to do with GCCisms.  __typeof__ is needed so that 
"type" can be "int[5]":

    __thread __typeof__ (int[5]) foo; /* works */
    __thread int[5] foo; /* fails */

(even without __thread of course).

In fact, it has the opposite side effect: type can be any expression, 
but the assumption is that DEFINE_TLS(123, x) will be caught by review.

Paolo