[Bug target/61837] missed loop invariant expression optimization

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61837

--- Comment #10 from Richard Biener <rguenth at gcc dot gnu.org> ---
Note the unswitching pass has special code to hoist guards of inner loops
steming from loop header copying.  That could possibly be enabled at -O2
since it doesn't come with a size penalty due to loop copying (the code size
issue is the reason we don't unswitch at -O2 - yes, creating non-perfect
nests might be another good reason).