[dev.regabi] cmd/compile: remove Func.ClosureEnter

We can easily compute this on demand.

Passes toolstash -cmp.

Change-Id: I433d8adb2b1615ae05b2764e69904369a59542c5
Reviewed-on: https://go-review.googlesource.com/c/go/+/280994
Trust: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>

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

@@ -75,13 +75,6 @@ type Func struct {
 	// Byval set if they're captured by value.
 	ClosureVars []*Name
 
-	// ClosureEnter holds the expressions that the enclosing function
-	// will use to initialize the closure's free variables. These
-	// correspond one-to-one with the variables in ClosureVars, and will
-	// be either an ONAME node (if the variable is captured by value) or
-	// an OADDR-of-ONAME node (if not).
-	ClosureEnter Nodes
-
 	// Parents records the parent scope of each scope within a
 	// function. The root scope (0) has no parent, so the i'th
 	// scope's parent is stored at Parents[i-1].

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

@@ -20,7 +20,7 @@ func TestSizeof(t *testing.T) {
 		_32bit uintptr     // size on 32bit platforms
 		_64bit uintptr     // size on 64bit platforms
 	}{
-		{Func{}, 196, 344},
+		{Func{}, 184, 320},
 		{Name{}, 124, 216},
 	}
 

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

@@ -122,20 +122,17 @@ func CaptureVars(fn *ir.Func) {
 		}
 		out = append(out, v)
 
-		// type check the & of closed variables outside the closure,
+		// type check closed variables outside the closure,
 		// so that the outer frame also grabs them and knows they escape.
-		types.CalcSize(v.Type())
+		Expr(v.Outer)
 
-		var outer ir.Node
-		outer = v.Outer
 		outermost := v.Defn.(*ir.Name)
 
 		// out parameters will be assigned to implicitly upon return.
-		if outermost.Class_ != ir.PPARAMOUT && !outermost.Addrtaken() && !outermost.Assigned() && v.Type().Width <= 128 {
+		if outermost.Class_ != ir.PPARAMOUT && !outermost.Addrtaken() && !outermost.Assigned() && v.Type().Size() <= 128 {
 			v.SetByval(true)
 		} else {
 			outermost.SetAddrtaken(true)
-			outer = NodAddr(outer)
 		}
 
 		if base.Flag.LowerM > 1 {
@@ -147,11 +144,8 @@ func CaptureVars(fn *ir.Func) {
 			if v.Byval() {
 				how = "value"
 			}
-			base.WarnfAt(v.Pos(), "%v capturing by %s: %v (addr=%v assign=%v width=%d)", name, how, v.Sym(), outermost.Addrtaken(), outermost.Assigned(), int32(v.Type().Width))
+			base.WarnfAt(v.Pos(), "%v capturing by %s: %v (addr=%v assign=%v width=%d)", name, how, v.Sym(), outermost.Addrtaken(), outermost.Assigned(), v.Type().Size())
 		}
-
-		outer = Expr(outer)
-		fn.ClosureEnter.Append(outer)
 	}
 
 	fn.ClosureVars = out

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

@@ -131,7 +131,7 @@ func walkClosure(clo *ir.ClosureExpr, init *ir.Nodes) ir.Node {
 
 	clos := ir.NewCompLitExpr(base.Pos, ir.OCOMPLIT, ir.TypeNode(typ).(ir.Ntype), nil)
 	clos.SetEsc(clo.Esc())
-	clos.List.Set(append([]ir.Node{ir.NewUnaryExpr(base.Pos, ir.OCFUNC, fn.Nname)}, fn.ClosureEnter...))
+	clos.List.Set(append([]ir.Node{ir.NewUnaryExpr(base.Pos, ir.OCFUNC, fn.Nname)}, closureArgs(clo)...))
 
 	addr := typecheck.NodAddr(clos)
 	addr.SetEsc(clo.Esc())
@@ -151,6 +151,26 @@ func walkClosure(clo *ir.ClosureExpr, init *ir.Nodes) ir.Node {
 	return walkExpr(cfn, init)
 }
 
+// closureArgs returns a slice of expressions that an be used to
+// initialize the given closure's free variables. These correspond
+// one-to-one with the variables in clo.Func.ClosureVars, and will be
+// either an ONAME node (if the variable is captured by value) or an
+// OADDR-of-ONAME node (if not).
+func closureArgs(clo *ir.ClosureExpr) []ir.Node {
+	fn := clo.Func
+
+	args := make([]ir.Node, len(fn.ClosureVars))
+	for i, v := range fn.ClosureVars {
+		var outer ir.Node
+		outer = v.Outer
+		if !v.Byval() {
+			outer = typecheck.NodAddrAt(fn.Pos(), outer)
+		}
+		args[i] = typecheck.Expr(outer)
+	}
+	return args
+}
+
 func walkCallPart(n *ir.SelectorExpr, init *ir.Nodes) ir.Node {
 	// Create closure in the form of a composite literal.
 	// For x.M with receiver (x) type T, the generated code looks like:

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

@@ -498,8 +498,7 @@ func walkCall(n *ir.CallExpr, init *ir.Nodes) ir.Node {
 
 		// Prepend captured variables to argument list.
 		clo := n.X.(*ir.ClosureExpr)
-		n.Args.Prepend(clo.Func.ClosureEnter...)
-		clo.Func.ClosureEnter.Set(nil)
+		n.Args.Prepend(closureArgs(clo)...)
 
 		// Replace OCLOSURE with ONAME/PFUNC.
 		n.X = clo.Func.Nname