[Bug rtl-optimization/92712] [8/9/10 Regression] Performance regression with assumed values

[glisse at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92712

--- Comment #5 from Marc Glisse <glisse at gcc dot gnu.org> ---
a*x+x -> (a+1)*x is unsafe (a=INT_MAX, x=0), but there are cases where we could
prove that it is safe, in particular when a is actually b-1 (more generally for
a*x+b*x when we can prove (with VRP?) that a+b cannot overflow).

Also, enabling -fwrapv for the last few gimple passes would help.