[C++11][4.9] Add missing REDUC_PLUS_EXPR case to potential_constant_expression_1.

[Marc Glisse]

On Thu, 14 Mar 2013, Jakub Jelinek wrote:

> I wonder if it wouldn't be better to fold the target builtins only later on
> (e.g. guard the folding with cfun && gimple_in_ssa_p (cfun) (or if we have
> any predicate that is set starting with gimplification or so)).
> Having all the FEs have to deal with myriads of weird tree codes etc. isn't
> IMHO desirable.

Wouldn't that prevent from using those builtins in constant expressions? 
That seems undesirable. Maybe an alternative could be to push some of the 
functionality from potential_constant_expression_1 to the middle-end?

-- 
Marc Glisse