Re: [PATCH 7/8] add the thrd_xxxxxx functions

[Alexander Monakov <amonakov@ispras.ru>]

On Sun, 31 Aug 2014, Jens Gustedt wrote:
> > > @@ -234,7 +253,10 @@ static int __pthread_create(pthread_t *restrict res, const pthread_attr_t *restr
> > >  	new->canary = self->canary;
> > >  
> > >  	a_inc(&libc.threads_minus_1);
> > > -	ret = __clone(start, stack, flags, new, &new->tid, TP_ADJ(new), &new->tid);
> > > +	if (c11)
> > > +		ret = __clone(start_c11, stack, flags, new, &new->tid, TP_ADJ(new), &new->tid);
> > > +	else
> > > +		ret = __clone(start, stack, flags, new, &new->tid, TP_ADJ(new), &new->tid);
> > 
> > Couldn't this be "c11 ? start_c11 : start" to avoid duplicating the
> > rest of the call?
> 
> I think that the ternary expression together with the other
> parenthesized paramenter and the length of the line would make the
> line barely readable.
> 
> This are some of the pivots lines of the implementation, I'd rather
> have them stick out.
> 
> Also the assembler that is produced should be identical.

It probably won't be with GCC.  Try:

echo 'int g(int); int f(int y){if (y) return g(0); else return g(1);}' |
  gcc -xc - -S -o- -O

And try varying optimization levels.  With gcc-4.8 on x86-64 I get two calls
except with -Os, and even with -Os it's worse than with a ternary operator.

Alexander