[Bug target/114252] Introducing bswapsi reduces code performance

[gjl at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114252

--- Comment #14 from Georg-Johann Lay <gjl at gcc dot gnu.org> ---
The code in the example is not a perfect bswap, it needs additional shuffling
of bytes.  The tree passes must know that bswap is not a perfect fit.  There
must be *some* criterion that depends on the permutation, and when a bswap is
closer to the bswapped-permutation that a non-bswapped permutation is to the
original one.