cmd/compile/internal/typecheck: simplify DeclFunc

This CL reworks DeclFunc so that we no longer need to internally
create an ir.FuncType. The next CL will remove ir.FuncType entirely.

Change-Id: I1c02b1b0c35221f2448d6d3ab35cb327a2da40e4
Reviewed-on: https://go-review.googlesource.com/c/go/+/403935
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: David Chase <drchase@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

src/cmd/compile/internal/typecheck/dcl.go

@@ -22,7 +22,18 @@ func DeclFunc(sym *types.Sym, recv *ir.Field, params, results []*ir.Field) *ir.F
 	fn.Nname.Func = fn
 	fn.Nname.Defn = fn
 	ir.MarkFunc(fn.Nname)
-	StartFuncBody(fn, recv, params, results)
+	StartFuncBody(fn)
+
+	var recv1 *types.Field
+	if recv != nil {
+		recv1 = declareParam(ir.PPARAM, -1, recv)
+	}
+
+	typ := types.NewSignature(types.LocalPkg, recv1, nil, declareParams(ir.PPARAM, params), declareParams(ir.PPARAMOUT, results))
+	checkdupfields("argument", typ.Recvs().FieldSlice(), typ.Params().FieldSlice(), typ.Results().FieldSlice())
+	fn.Nname.SetType(typ)
+	fn.Nname.SetTypecheck(1)
+
 	return fn
 }
 
@@ -91,20 +102,13 @@ func Export(n *ir.Name) {
 // and declare the arguments.
 // called in extern-declaration context
 // returns in auto-declaration context.
-func StartFuncBody(fn *ir.Func, recv *ir.Field, params, results []*ir.Field) {
+func StartFuncBody(fn *ir.Func) {
 	// change the declaration context from extern to auto
 	funcStack = append(funcStack, funcStackEnt{ir.CurFunc, DeclContext})
 	ir.CurFunc = fn
 	DeclContext = ir.PAUTO
 
 	types.Markdcl()
-
-	tfn := ir.NewFuncType(base.Pos, recv, params, results)
-	funcargs(tfn)
-
-	tfn = tcFuncType(tfn)
-	fn.Nname.SetType(tfn.Type())
-	fn.Nname.SetTypecheck(1)
 }
 
 // finish the body.
@@ -190,46 +194,44 @@ type funcStackEnt struct {
 	dclcontext ir.Class
 }
 
-func funcarg(n *ir.Field, ctxt ir.Class) {
-	if n.Sym == nil {
-		return
+func declareParams(ctxt ir.Class, l []*ir.Field) []*types.Field {
+	fields := make([]*types.Field, len(l))
+	for i, n := range l {
+		fields[i] = declareParam(ctxt, i, n)
 	}
-
-	name := ir.NewNameAt(n.Pos, n.Sym)
-	n.Decl = name
-	Declare(name, ctxt)
+	return fields
 }
 
-func funcargs(nt *ir.FuncType) {
-	if nt.Op() != ir.OTFUNC {
-		base.Fatalf("funcargs %v", nt.Op())
-	}
+func declareParam(ctxt ir.Class, i int, param *ir.Field) *types.Field {
+	f := types.NewField(param.Pos, param.Sym, param.Type)
+	f.SetIsDDD(param.IsDDD)
 
-	// declare the receiver and in arguments.
-	if nt.Recv != nil {
-		funcarg(nt.Recv, ir.PPARAM)
-	}
-	for _, n := range nt.Params {
-		funcarg(n, ir.PPARAM)
-	}
-
-	// declare the out arguments.
-	for i, n := range nt.Results {
-		if n.Sym == nil {
+	sym := param.Sym
+	if ctxt == ir.PPARAMOUT {
+		if sym == nil {
 			// Name so that escape analysis can track it. ~r stands for 'result'.
-			n.Sym = LookupNum("~r", i)
-		} else if n.Sym.IsBlank() {
+			sym = LookupNum("~r", i)
+		} else if sym.IsBlank() {
 			// Give it a name so we can assign to it during return. ~b stands for 'blank'.
 			// The name must be different from ~r above because if you have
 			//	func f() (_ int)
 			//	func g() int
 			// f is allowed to use a plain 'return' with no arguments, while g is not.
 			// So the two cases must be distinguished.
-			n.Sym = LookupNum("~b", i)
+			sym = LookupNum("~b", i)
 		}
-
-		funcarg(n, ir.PPARAMOUT)
 	}
+
+	if sym != nil {
+		name := ir.NewNameAt(param.Pos, sym)
+		name.SetType(f.Type)
+		name.SetTypecheck(1)
+		Declare(name, ctxt)
+
+		f.Nname = name
+	}
+
+	return f
 }
 
 func Temp(t *types.Type) *ir.Name {

src/cmd/compile/internal/typecheck/type.go

@@ -3,56 +3,3 @@
 // license that can be found in the LICENSE file.
 
 package typecheck
-
-import (
-	"cmd/compile/internal/base"
-	"cmd/compile/internal/ir"
-	"cmd/compile/internal/types"
-)
-
-// tcFuncType typechecks an OTFUNC node.
-func tcFuncType(n *ir.FuncType) *ir.FuncType {
-	misc := func(f *types.Field, nf *ir.Field) {
-		f.SetIsDDD(nf.IsDDD)
-		if nf.Decl != nil {
-			nf.Decl.SetType(f.Type)
-			f.Nname = nf.Decl
-		}
-	}
-
-	lno := base.Pos
-
-	var recv *types.Field
-	if n.Recv != nil {
-		recv = tcField(n.Recv, misc)
-	}
-
-	t := types.NewSignature(types.LocalPkg, recv, nil, tcFields(n.Params, misc), tcFields(n.Results, misc))
-	checkdupfields("argument", t.Recvs().FieldSlice(), t.Params().FieldSlice(), t.Results().FieldSlice())
-
-	base.Pos = lno
-
-	n.SetOTYPE(t)
-	return n
-}
-
-// tcField typechecks a generic Field.
-// misc can be provided to handle specialized typechecking.
-func tcField(n *ir.Field, misc func(*types.Field, *ir.Field)) *types.Field {
-	base.Pos = n.Pos
-	f := types.NewField(n.Pos, n.Sym, n.Type)
-	if misc != nil {
-		misc(f, n)
-	}
-	return f
-}
-
-// tcFields typechecks a slice of generic Fields.
-// misc can be provided to handle specialized typechecking.
-func tcFields(l []*ir.Field, misc func(*types.Field, *ir.Field)) []*types.Field {
-	fields := make([]*types.Field, len(l))
-	for i, n := range l {
-		fields[i] = tcField(n, misc)
-	}
-	return fields
-}

src/cmd/compile/internal/typecheck/typecheck.go

@@ -473,10 +473,6 @@ func typecheck1(n ir.Node, top int) ir.Node {
 	case ir.OTYPE:
 		return n
 
-	case ir.OTFUNC:
-		n := n.(*ir.FuncType)
-		return tcFuncType(n)
-
 	// type or expr
 	case ir.ODEREF:
 		n := n.(*ir.StarExpr)