[Bug middle-end/101197] __builtin_memmove does not perform constant optimizations

[tnfchris at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101197

Tamar Christina <tnfchris at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
              Build|x86_64-linux-gnu            |x86_64-linux-gnu,
                   |                            |aarch64-linux-gnu
             Target|x86_64-linux-gnu            |x86_64-linux-gnu,
                   |                            |aarch64-linux-gnu
               Host|x86_64-linux-gnu            |x86_64-linux-gnu,
                   |                            |aarch64-linux-gnu
                 CC|                            |tnfchris at gcc dot gnu.org
           See Also|                            |https://gcc.gnu.org/bugzill
                   |                            |a/show_bug.cgi?id=90262

--- Comment #5 from Tamar Christina <tnfchris at gcc dot gnu.org> ---
Clang seems to also be able to do better alias analysis here and transform
memmove to memcpy if it can prove the pointers don't overlap in the copy
region.

This seems to give GCC about a 30% loss compared to clang in some widely used
open source compression library.