Re: [PATCH v3 RESEND] aarch64: express sqxtun and friends as us_truncate of smax

[Dominic P]

Ping.  v3 makes us_truncate of an smax the RTL the sqxtun, sqshrun and
sqrshrun patterns match, as asked; the note under the --- says why the
simplify-rtx rule would be dead code today, and I will add it if you still
want it.  Applies to trunk 2cb78d1a0e5 and re-tested there alone under
qemu-aarch64 (aarch64.exp, advsimd-intrinsics.exp, vect.exp): only its own
test moves, and the match-sat-alu.pd tests of 20 September pass either way.
OK for trunk?