[dev.regabi] cmd/compile: remove ONEWOBJ

After CL 283233, SSA can now handle new(typ) without the frontend to
generate the type address, so we can remove ONEWOBJ in favor of ONEW
only.

This is also not save for toolstash, the same reason with CL 284115.

Change-Id: Ie03ea36b3b6f95fc7ce080376c6f7afc402d51a3
Reviewed-on: https://go-review.googlesource.com/c/go/+/284117
Trust: Cuong Manh Le <[email protected]>
Run-TryBot: Cuong Manh Le <[email protected]>
TryBot-Result: Go Bot <[email protected]>
Reviewed-by: Matthew Dempsky <[email protected]>

Author: cuonglm

src/cmd/compile/internal/ir/expr.go

@@ -657,7 +657,7 @@ func (n *UnaryExpr) SetOp(op Op) {
 	case OBITNOT, ONEG, ONOT, OPLUS, ORECV,
 		OALIGNOF, OCAP, OCLOSE, OIMAG, OLEN, ONEW,
 		OOFFSETOF, OPANIC, OREAL, OSIZEOF,
-		OCHECKNIL, OCFUNC, OIDATA, OITAB, ONEWOBJ, OSPTR, OVARDEF, OVARKILL, OVARLIVE:
+		OCHECKNIL, OCFUNC, OIDATA, OITAB, OSPTR, OVARDEF, OVARKILL, OVARLIVE:
 		n.op = op
 	}
 }

src/cmd/compile/internal/ir/node.go

@@ -216,7 +216,6 @@ const (
 	OAND         // Left & Right
 	OANDNOT      // Left &^ Right
 	ONEW         // new(Left); corresponds to calls to new in source code
-	ONEWOBJ      // runtime.newobject(n.Type); introduced by walk; Left is type descriptor
 	ONOT         // !Left
 	OBITNOT      // ^Left
 	OPLUS        // +Left

src/cmd/compile/internal/ir/op_string.go

@@ -3034,7 +3034,7 @@ func (s *state) expr(n ir.Node) *ssa.Value {
 		}
 		return s.zeroVal(n.Type())
 
-	case ir.ONEWOBJ:
+	case ir.ONEW:
 		n := n.(*ir.UnaryExpr)
 		return s.newObject(n.Type().Elem())
 

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

@@ -501,18 +501,21 @@ func walkMakeSliceCopy(n *ir.MakeExpr, init *ir.Nodes) ir.Node {
 
 // walkNew walks an ONEW node.
 func walkNew(n *ir.UnaryExpr, init *ir.Nodes) ir.Node {
-	if n.Type().Elem().NotInHeap() {
+	t := n.Type().Elem()
+	if t.NotInHeap() {
 		base.Errorf("%v can't be allocated in Go; it is incomplete (or unallocatable)", n.Type().Elem())
 	}
 	if n.Esc() == ir.EscNone {
-		if n.Type().Elem().Width >= ir.MaxImplicitStackVarSize {
+		if t.Size() >= ir.MaxImplicitStackVarSize {
 			base.Fatalf("large ONEW with EscNone: %v", n)
 		}
-		r := typecheck.Temp(n.Type().Elem())
+		r := typecheck.Temp(t)
 		init.Append(typecheck.Stmt(ir.NewAssignStmt(base.Pos, r, nil))) // zero temp
 		return typecheck.Expr(typecheck.NodAddr(r))
 	}
-	return callnew(n.Type().Elem())
+	types.CalcSize(t)
+	n.MarkNonNil()
+	return n
 }
 
 // generate code for print
@@ -678,15 +681,6 @@ func badtype(op ir.Op, tl, tr *types.Type) {
 	base.Errorf("illegal types for operand: %v%s", op, s)
 }
 
-func callnew(t *types.Type) ir.Node {
-	types.CalcSize(t)
-	n := ir.NewUnaryExpr(base.Pos, ir.ONEWOBJ, reflectdata.TypePtr(t))
-	n.SetType(types.NewPtr(t))
-	n.SetTypecheck(1)
-	n.MarkNonNil()
-	return n
-}
-
 func writebarrierfn(name string, l *types.Type, r *types.Type) ir.Node {
 	fn := typecheck.LookupRuntime(name)
 	fn = typecheck.SubstArgTypes(fn, l, r)

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

@@ -248,7 +248,11 @@ func walkStringToBytes(n *ir.ConvExpr, init *ir.Nodes) ir.Node {
 		if n.Esc() == ir.EscNone && len(sc) <= int(ir.MaxImplicitStackVarSize) {
 			a = typecheck.NodAddr(typecheck.Temp(t))
 		} else {
-			a = callnew(t)
+			types.CalcSize(t)
+			a = ir.NewUnaryExpr(base.Pos, ir.ONEW, nil)
+			a.SetType(types.NewPtr(t))
+			a.SetTypecheck(1)
+			a.MarkNonNil()
 		}
 		p := typecheck.Temp(t.PtrTo()) // *[n]byte
 		init.Append(typecheck.Stmt(ir.NewAssignStmt(base.Pos, p, a)))

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

@@ -84,7 +84,7 @@ func walkExpr1(n ir.Node, init *ir.Nodes) ir.Node {
 		base.Fatalf("walkexpr: switch 1 unknown op %+v", n.Op())
 		panic("unreachable")
 
-	case ir.ONONAME, ir.OGETG, ir.ONEWOBJ:
+	case ir.ONONAME, ir.OGETG:
 		return n
 
 	case ir.OTYPE, ir.ONAME, ir.OLITERAL, ir.ONIL, ir.ONAMEOFFSET:

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

@@ -358,7 +358,7 @@ func calcHasCall(n ir.Node) bool {
 	case ir.OBITNOT, ir.ONOT, ir.OPLUS, ir.ORECV,
 		ir.OALIGNOF, ir.OCAP, ir.OCLOSE, ir.OIMAG, ir.OLEN, ir.ONEW,
 		ir.OOFFSETOF, ir.OPANIC, ir.OREAL, ir.OSIZEOF,
-		ir.OCHECKNIL, ir.OCFUNC, ir.OIDATA, ir.OITAB, ir.ONEWOBJ, ir.OSPTR, ir.OVARDEF, ir.OVARKILL, ir.OVARLIVE:
+		ir.OCHECKNIL, ir.OCFUNC, ir.OIDATA, ir.OITAB, ir.OSPTR, ir.OVARDEF, ir.OVARKILL, ir.OVARLIVE:
 		n := n.(*ir.UnaryExpr)
 		return n.X.HasCall()
 	case ir.ODOT, ir.ODOTMETH, ir.ODOTINTER: