[dev.regabi] cmd/compile: rewrite Aux uses of ir.Node to *ir.Name [generated]

Now that the only remaining ir.Node implementation that is stored
(directly) into ssa.Aux, we can rewrite all of the conversions between
ir.Node and ssa.Aux to use *ir.Name instead.

rf doesn't have a way to rewrite the type switch case clauses, so we
just use sed instead. There's only a handful, and they're the only
times that "case ir.Node" appears anyway.

The next CL will move the tag method declarations so that ir.Node no
longer implements ssa.Aux.

Passes buildall w/ toolstash -cmp.

Updates #42982.

[git-generate]
cd src/cmd/compile/internal
sed -i -e 's/case ir.Node/case *ir.Name/' gc/plive.go */ssa.go

cd ssa
rf '
ex . ../gc {
  import "cmd/compile/internal/ir"

  var v *Value
  v.Aux.(ir.Node) -> v.Aux.(*ir.Name)

  var n ir.Node
  var asAux func(Aux)
  strict n        # only match ir.Node-typed expressions; not *ir.Name
  implicit asAux  # match implicit assignments to ssa.Aux
  asAux(n)        -> n.(*ir.Name)
}
'

Change-Id: I3206ef5f12a7cfa37c5fecc67a1ca02ea4d52b32
Reviewed-on: https://go-review.googlesource.com/c/go/+/275789
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>

src/cmd/compile/internal/ssa/regalloc.go

@@ -1249,7 +1249,7 @@ func (s *regAllocState) regalloc(f *Func) {
 					// This forces later liveness analysis to make the
 					// value live at this point.
 					v.SetArg(0, s.makeSpill(a, b))
-				} else if _, ok := a.Aux.(ir.Node); ok && vi.rematerializeable {
+				} else if _, ok := a.Aux.(*ir.Name); ok && vi.rematerializeable {
 					// Rematerializeable value with a gc.Node. This is the address of
 					// a stack object (e.g. an LEAQ). Keep the object live.
 					// Change it to VarLive, which is what plive expects for locals.