[Bug target/95784] Failure to optimize usage of __builtin_add_overflow with return statement properly

[gabravier at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95784

--- Comment #3 from Gabriel Ravier <gabravier at gmail dot com> ---
The most important problem here is really that all the computations for r8d are
dependant on each other, too, the sal+sar+and chain all depend on the previous
operation, the LLVM version seems much better for OOO than the GCC version.