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

[glisse at gcc dot gnu.org]

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

--- Comment #25 from Marc Glisse <glisse at gcc dot gnu.org> ---
(In reply to Feng Xue from comment #24)
> Another point: if B+-C can be folded to an existing gimple value, we might
> deduce B+-C does not overflow?

We can deduce that loading this value that represents B+-C does not overflow at
runtime (since we aren't computing anything, just copying some other value),
but not that the operation B+-C would not overflow if it was actually
evaluated. So it could help a bit sometimes. We still need to ensure that the
multiplication by A does not overflow though.