[Bug tree-optimization/90917] Propagate constants into loads if dominated by str(n)cmp/memcmp

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90917

--- Comment #3 from Martin Sebor <msebor at gcc dot gnu.org> ---
The solution for pr83431 doesn't handle the case in comment #2 but hopefully a
future improvement (in GCC 11) will.