[Bug middle-end/66313] Unsafe factorization of a*b+a*c

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66313

--- Comment #5 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
I think I'll restrict the computation in unsigned only for
TYPE_OVERFLOW_SANITIZED, otherwise we fail to optimize important stuff :/ (e.g.
tree-ssa/pr23294.c).