[dev.regabi] cmd/compile: cleanup for concrete types - ssa

An automated rewrite will add concrete type assertions after
a test of n.Op(), when n can be safely type-asserted
(meaning, n is not reassigned a different type, n is not reassigned
and then used outside the scope of the type assertion,
and so on).

This sequence of CLs handles the code that the automated
rewrite does not: adding specific types to function arguments,
adjusting code not to call n.Left() etc when n may have multiple
representations, and so on.

This CL focuses on ssa.go.

Passes buildall w/ toolstash -cmp.

Change-Id: Iefacc7104dd9469e3c574149791ab0bff29f7fee
Reviewed-on: https://go-review.googlesource.com/c/go/+/277923
Trust: Russ Cox <rsc@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

src/cmd/compile/internal/gc/inl.go

@@ -335,7 +335,7 @@ func (v *hairyVisitor) doNode(n ir.Node) error {
 			}
 		}
 
-		if isIntrinsicCall(n) {
+		if isIntrinsicCall(n.(*ir.CallExpr)) {
 			// Treat like any other node.
 			break
 		}
@@ -583,7 +583,7 @@ func inlnode(n ir.Node, maxCost int32, inlMap map[*ir.Func]bool, edit func(ir.No
 		if base.Flag.LowerM > 3 {
 			fmt.Printf("%v:call to func %+v\n", ir.Line(n), n.Left())
 		}
-		if isIntrinsicCall(n) {
+		if isIntrinsicCall(n.(*ir.CallExpr)) {
 			break
 		}
 		if fn := inlCallee(n.Left()); fn != nil && fn.Inl != nil {

src/cmd/compile/internal/gc/phi.go

@@ -254,7 +254,9 @@ func (s *phiState) insertVarPhis(n int, var_ ir.Node, defs []*ssa.Block, typ *ty
 				hasPhi.add(c.ID)
 				v := c.NewValue0I(currentRoot.Pos, ssa.OpPhi, typ, int64(n)) // TODO: line number right?
 				// Note: we store the variable number in the phi's AuxInt field. Used temporarily by phi building.
-				s.s.addNamedValue(var_, v)
+				if var_.Op() == ir.ONAME {
+					s.s.addNamedValue(var_.(*ir.Name), v)
+				}
 				for range c.Preds {
 					v.AddArg(s.placeholder) // Actual args will be filled in by resolveFwdRefs.
 				}
@@ -546,7 +548,9 @@ func (s *simplePhiState) lookupVarOutgoing(b *ssa.Block, t *types.Type, var_ ir.
 	// Generate a FwdRef for the variable and return that.
 	v := b.NewValue0A(line, ssa.OpFwdRef, t, FwdRefAux{N: var_})
 	s.defvars[b.ID][var_] = v
-	s.s.addNamedValue(var_, v)
+	if var_.Op() == ir.ONAME {
+		s.s.addNamedValue(var_.(*ir.Name), v)
+	}
 	s.fwdrefs = append(s.fwdrefs, v)
 	return v
 }

src/cmd/compile/internal/gc/plive.go

@@ -206,8 +206,12 @@ type progeffectscache struct {
 // nor do we care about non-local variables,
 // nor do we care about empty structs (handled by the pointer check),
 // nor do we care about the fake PAUTOHEAP variables.
-func livenessShouldTrack(n ir.Node) bool {
-	return n.Op() == ir.ONAME && (n.Class() == ir.PAUTO || n.Class() == ir.PPARAM || n.Class() == ir.PPARAMOUT) && n.Type().HasPointers()
+func livenessShouldTrack(nn ir.Node) bool {
+	if nn.Op() != ir.ONAME {
+		return false
+	}
+	n := nn.(*ir.Name)
+	return (n.Class() == ir.PAUTO || n.Class() == ir.PPARAM || n.Class() == ir.PPARAMOUT) && n.Type().HasPointers()
 }
 
 // getvariables returns the list of on-stack variables that we need to track
@@ -1165,7 +1169,7 @@ func (lv *Liveness) emit() (argsSym, liveSym *obj.LSym) {
 	// Size args bitmaps to be just large enough to hold the largest pointer.
 	// First, find the largest Xoffset node we care about.
 	// (Nodes without pointers aren't in lv.vars; see livenessShouldTrack.)
-	var maxArgNode ir.Node
+	var maxArgNode *ir.Name
 	for _, n := range lv.vars {
 		switch n.Class() {
 		case ir.PPARAM, ir.PPARAMOUT:

src/cmd/compile/internal/gc/walk.go

@@ -743,7 +743,7 @@ func walkexpr1(n ir.Node, init *ir.Nodes) ir.Node {
 		walkexprlistsafe(n.List().Slice(), init)
 		r = walkexpr(r, init)
 
-		if isIntrinsicCall(r) {
+		if isIntrinsicCall(r.(*ir.CallExpr)) {
 			n.PtrRlist().Set1(r)
 			return n
 		}