cmd/5g, cmd/6g, cmd/8g, cmd/9g: clear Addr parameter in sudoaddable

The Addr might be a stack variable with uninitialized fields.

Fixes #9777.

Change-Id: I799786e3d8b2e17e069725bc66a076cf9ca11f93
Signed-off-by: Shenghou Ma <minux@golang.org>
Reviewed-on: https://go-review.googlesource.com/3932Reviewed-by: Dave Cheney <dave@cheney.net>
Reviewed-by: Keith Randall <khr@golang.org>

src/cmd/5g/gsubr.c

@@ -1812,6 +1812,8 @@ sudoaddable(int as, Node *n, Addr *a, int *w)
 	if(n->type == T)
 		return 0;
 
+	memset(a, 0, sizeof *a);
+
 	switch(n->op) {
 	case OLITERAL:
 		if(!isconst(n, CTINT))

src/cmd/6g/gsubr.c

@@ -1966,6 +1966,8 @@ sudoaddable(int as, Node *n, Addr *a)
 	if(n->type == T)
 		return 0;
 
+	memset(a, 0, sizeof *a);
+
 	switch(n->op) {
 	case OLITERAL:
 		if(!isconst(n, CTINT))

src/cmd/8g/gsubr.c

@@ -2398,7 +2398,7 @@ sudoaddable(int as, Node *n, Addr *a)
 {
 	USED(as);
 	USED(n);
-	USED(a);
 
+	memset(a, 0, sizeof *a);
 	return 0;
 }

src/cmd/9g/gsubr.c

@@ -1700,6 +1700,7 @@ int
 sudoaddable(int as, Node *n, Addr *a)
 {
 	// TODO(minux)
-	USED(as); USED(n); USED(a);
+	USED(as); USED(n);
+	memset(a, 0, sizeof *a);
 	return 0;
 }