cmd/compile: add ir.ContainsClosure

And use it to unify all codes that need parent/closure checking.

Change-Id: I0b0aa1b007598668dff2c4bee31e21f0fb3830ce
Reviewed-on: https://go-review.googlesource.com/c/go/+/650315
Auto-Submit: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: David Chase <drchase@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>

1 files changed, 15 insertions, 0 deletions

diff --git a/src/cmd/compile/internal/ir/func.go b/src/cmd/compile/internal/ir/func.go
index 6354da3556..668537c90e 100644
--- a/src/cmd/compile/internal/ir/func.go
+++ b/src/cmd/compile/internal/ir/func.go
@@ -627,3 +627,18 @@ func (fn *Func) DeclareParams(setNname bool) {
 	declareParams(params, PPARAM, "~p", 0)
 	declareParams(results, PPARAMOUT, "~r", len(params))
 }
+
+// ContainsClosure reports whether c is a closure contained within f.
+func ContainsClosure(f, c *Func) bool {
+	// Common cases.
+	if f == c || c.OClosure == nil {
+		return false
+	}
+
+	for p := c.ClosureParent; p != nil; p = p.ClosureParent {
+		if p == f {
+			return true
+		}
+	}
+	return false
+}