cmd/compile: allow inlining labeled for-statement and switch-statement

After CL 349012 and CL 350911, we can fully handle these
labeled statements, so we can allow them when inlining.

Updates #14768

Change-Id: I0ab3fd3f8d7436b49b1aedd946516b33c63f5747
Reviewed-on: https://go-review.googlesource.com/c/go/+/355497
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Dan Scales <danscales@google.com>
Reviewed-by: David Chase <drchase@google.com>
Trust: Dan Scales <danscales@google.com>

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

@@ -390,27 +390,6 @@ func (v *hairyVisitor) doNode(n ir.Node) bool {
 		// These nodes don't produce code; omit from inlining budget.
 		return false
 
-	case ir.OFOR, ir.OFORUNTIL:
-		n := n.(*ir.ForStmt)
-		if n.Label != nil {
-			v.reason = "labeled control"
-			return true
-		}
-	case ir.OSWITCH:
-		n := n.(*ir.SwitchStmt)
-		if n.Label != nil {
-			v.reason = "labeled control"
-			return true
-		}
-	// case ir.ORANGE, ir.OSELECT in "unhandled" above
-
-	case ir.OBREAK, ir.OCONTINUE:
-		n := n.(*ir.BranchStmt)
-		if n.Label != nil {
-			// Should have short-circuited due to labeled control error above.
-			base.Fatalf("unexpected labeled break/continue: %v", n)
-		}
-
 	case ir.OIF:
 		n := n.(*ir.IfStmt)
 		if ir.IsConst(n.Cond, constant.Bool) {

test/inline.go

@@ -135,8 +135,7 @@ func s1(x int) int { // ERROR "can inline s1"
 	return foo() // ERROR "inlining call to s1.func1"
 }
 
-// can't currently inline functions with a break statement
+func switchBreak(x, y int) int { // ERROR "can inline switchBreak"
-func switchBreak(x, y int) int {
 	var n int
 	switch x {
 	case 0:
@@ -218,8 +217,7 @@ func for1(fn func() bool) { // ERROR "can inline for1" "fn does not escape"
 	}
 }
 
-// BAD: for2 should be inlineable too.
+func for2(fn func() bool) { // ERROR "can inline for2" "fn does not escape"
-func for2(fn func() bool) { // ERROR "fn does not escape"
 Loop:
 	for {
 		if fn() {