cmd/compile/internal/ssa: fix PPC64 merging of (AND (S[RL]Dconst ...)
CL 622236 forgot to check the mask was also a 32 bit rotate mask. Add
a modified version of isPPC64WordRotateMask which valids the mask is
contiguous and fits inside a uint32.
I don't this is possible when merging SRDconst, the first check should
always reject such combines. But, be extra careful and do it there
too.
Fixes #73153
Change-Id: Ie95f74ec5e7d89dc761511126db814f886a7a435
Reviewed-on: https://go-review.googlesource.com/c/go/+/679775
Auto-Submit: Keith Randall <khr@golang.org> Reviewed-by: Jayanth Krishnamurthy <jayanth.krishnamurthy@ibm.com> Reviewed-by: Keith Randall <khr@google.com> Reviewed-by: Cherry Mui <cherryyz@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Keith Randall <khr@golang.org>