https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87008
--- Comment #11 from Marc Glisse <glisse at gcc dot gnu.org> ---
The original testcase also shows a small, unrelated regression: DSE3 used to be
able to remove the initialization of sum to 0 when there were 2 statements
(setting each element to 0). Now that we vectorize so that sum is initialized
with { 0.0, 0.0 } in a single statement, DSE doesn't manage anymore, it doesn't
see that the 2 writes together cover the whole thing. Probably if we improved
the vectorizer to vectorize this loop (I think the blocker is that we go from
{x,y} to {x+y,x+y}), it would manage again.
