cmd/compile: minor init handling cleanup

Place comments correctly.
Simplify control flow.
Reduce variable scope.

Passes toolstash-check.

Change-Id: Iea47ed3502c15491c2ca6db8149fe0949b8849aa
Reviewed-on: https://go-review.googlesource.com/38914
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/cmd/compile/internal/gc/init.go

@@ -17,35 +17,15 @@ func renameinit() *Sym {
 	return lookupN("init.", renameinit_initgen)
 }
 
-// hand-craft the following initialization code
-//      var initdone· uint8                             (1)
-//      func init() {                                   (2)
-//              if initdone· > 1 {                      (3)
-//                      return                          (3a)
-//              }
-//              if initdone· == 1 {                     (4)
-//                      throw()                         (4a)
-//              }
-//              initdone· = 1                           (5)
-//              // over all matching imported symbols
-//                      <pkg>.init()                    (6)
-//              { <init stmts> }                        (7)
-//              init.<n>() // if any                    (8)
-//              initdone· = 2                           (9)
-//              return                                  (10)
-//      }
+// anyinit reports whether there any interesting init statements.
 func anyinit(n []*Node) bool {
-	// are there any interesting init statements
 	for _, ln := range n {
 		switch ln.Op {
 		case ODCLFUNC, ODCLCONST, ODCLTYPE, OEMPTY:
-			break
-
 		case OAS:
-			if isblank(ln.Left) && candiscard(ln.Right) {
-				break
+			if !isblank(ln.Left) || !candiscard(ln.Right) {
+				return true
 			}
-			fallthrough
 		default:
 			return true
 		}
@@ -57,9 +37,7 @@ func anyinit(n []*Node) bool {
 	}
 
 	// is there an explicit init function
-	s := lookup("init.1")
-
-	if s.Def != nil {
+	if s := lookup("init.1"); s.Def != nil {
 		return true
 	}
 
@@ -74,6 +52,24 @@ func anyinit(n []*Node) bool {
 	return false
 }
 
+// fninit hand-crafts package initialization code.
+//
+//      var initdone· uint8                             (1)
+//      func init() {                                   (2)
+//              if initdone· > 1 {                      (3)
+//                      return                          (3a)
+//              }
+//              if initdone· == 1 {                     (4)
+//                      throw()                         (4a)
+//              }
+//              initdone· = 1                           (5)
+//              // over all matching imported symbols
+//                      <pkg>.init()                    (6)
+//              { <init stmts> }                        (7)
+//              init.<n>() // if any                    (8)
+//              initdone· = 2                           (9)
+//              return                                  (10)
+//      }
 func fninit(n []*Node) {
 	lineno = autogeneratedPos
 	nf := initfix(n)