cmd/compile/internal/gc: unexport and make Hasdefer a bool

Passes go build -a -toolexec 'toolstash -cmp' std cmd.

Change-Id: I804ee4252fa9be78cb277faf7f467e6c9cfdd4a6
Reviewed-on: https://go-review.googlesource.com/14319
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

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

@@ -2399,7 +2399,7 @@ func Ginscall(f *Node, proc int) {
 		if proc == 1 {
 			Ginscall(Newproc, 0)
 		} else {
-			if Hasdefer == 0 {
+			if !hasdefer {
 				Fatalf("hasdefer=0 but has defer")
 			}
 			Ginscall(Deferproc, 0)
@@ -2622,7 +2622,7 @@ func cgen_ret(n *Node) {
 	if n != nil {
 		Genlist(n.List) // copy out args
 	}
-	if Hasdefer != 0 {
+	if hasdefer {
 		Ginscall(Deferreturn, 0)
 	}
 	Genlist(Curfn.Func.Exit)

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

@@ -616,7 +616,7 @@ var blockgen int32 // max block number
 
 var block int32 // current block number
 
-var Hasdefer int // flag that curfn has defer statetment
+var hasdefer bool // flag that curfn has defer statement
 
 var Curfn *Node
 

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

@@ -392,7 +392,7 @@ func compile(fn *Node) {
 		goto ret
 	}
 
-	Hasdefer = 0
+	hasdefer = false
 	walk(Curfn)
 	if nerrors != 0 {
 		goto ret
@@ -487,7 +487,7 @@ func compile(fn *Node) {
 	// TODO: Determine when the final cgen_ret can be omitted. Perhaps always?
 	cgen_ret(nil)
 
-	if Hasdefer != 0 {
+	if hasdefer {
 		// deferreturn pretends to have one uintptr argument.
 		// Reserve space for it so stack scanner is happy.
 		if Maxarg < int64(Widthptr) {

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

@@ -486,7 +486,7 @@ func mkvar(f *Flow, a *obj.Addr) Bits {
 	//
 	// Disable registerization for results if using defer, because the deferred func
 	// might recover and return, causing the current values to be used.
-	if node.Class == PEXTERN || (Hasdefer != 0 && node.Class == PPARAMOUT) {
+	if node.Class == PEXTERN || (hasdefer && node.Class == PPARAMOUT) {
 		v.addr = 1
 	}
 

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

@@ -231,7 +231,7 @@ func walkstmt(np **Node) {
 		walkstmt(&n.Right)
 
 	case ODEFER:
-		Hasdefer = 1
+		hasdefer = true
 		switch n.Left.Op {
 		case OPRINT, OPRINTN:
 			walkprintfunc(&n.Left, &n.Ninit)