[Bug middle-end/115551] [missed optimization] "c1 << (a + c2)" not optimized into "(c1 << c2) << a"

[rguenth at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115551

--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
all same for right-shifts (both logical and arithmetic).

Note that 1 << (a + 5) might be cheaper than (1<<5) << a due to constraints
on immediates but for GIMPLE the latter is definitely more canonical.