[Bug rtl-optimization/79357] Doubling a single complex float gives inefficient code

[glisse at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79357

--- Comment #3 from Marc Glisse <glisse at gcc dot gnu.org> ---
Note that we do not generate better code for
typedef float vec __attribute__((vector_size(8)));
vec g(vec x){return 2*x;}
(we don't consider larger vector modes when lowering/expanding vector
operations, there is already a PR about that)