Re: [PATCH] PR fortran/83998 -- fix dot_product on 0-sized arrays

[Steve Kargl <sgk@troutmask.apl.washington.edu>]

On Thu, Jan 25, 2018 at 11:07:04AM -0800, Steve Kargl wrote:
> On Thu, Jan 25, 2018 at 07:58:22PM +0100, Thomas Koenig wrote:
> > Hi Steve,
> > 
> > thanks for your explanations.
> > 
> > The patch is OK for trunk. Thanks a lot!
> > 
> 
> Upon even further reading, the code segment with temp might
> be needed.  If one looks in compute_dot_product(), one finds
> 
>   result = gfc_get_constant_expr (matrix_a->ts.type, matrix_a->ts.kind,
> 				  &matrix_a->where);
>   init_result_expr (result, 0, NULL);
>  
> which sets the type of result to matrix_a, unconditionally.
> We may however still benefit from mixed-mode math during
> the summation because we have
> 
> 	    result = gfc_add (result, gfc_multiply (c, gfc_copy_expr (b)));
> 
> and both gfc_add and gfc_multiply should do mixed-mode math.
> 
> I'll check before I commit.

This code confirms proper handling of mixed-mode math.
   program p
   integer, parameter :: a(2) = [1, 2]
   real, parameter :: b(2) = [1., 2.]
   real c
   c = dot_product(a,b)
   print *, c
   end

-- 
Steve