[newlib-cygwin] Define RB_SET_PARENT to do all assignments

[newlib-cygwin] Define RB_SET_PARENT to do all assignments

[Sebastian Huber]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=17b7dfc0b55a0668178cdc18aa14e0221468b2bc

commit 17b7dfc0b55a0668178cdc18aa14e0221468b2bc
Author: dougm <dougm@FreeBSD.org>
Date:   Tue Jun 23 20:02:55 2020 +0000

    Define RB_SET_PARENT to do all assignments
    
    to rb parent pointers. Define RB_SWAP_CHILD to replace the child of a parent
    with its twin, and use it in 4 places. Use RB_SET in rb_link_node to remove the
    only linuxkpi reference to color, and then drop color- and parent-related
    definitions that are defined and used only in rbtree.h.
    
    This is intended to be entirely cosmetic, with no impact on program
    behavior, and leave RB_PARENT and RB_SET_PARENT as the only ways to
    read and write rb parent pointers.
    
    Reviewed by:    markj, kib
    Tested by:      pho
    Differential Revision:  https://reviews.freebsd.org/D25264

Diff:
---
 newlib/libc/include/sys/tree.h | 58 ++++++++++++++++++++----------------------
 1 file changed, 28 insertions(+), 30 deletions(-)

diff --git a/newlib/libc/include/sys/tree.h b/newlib/libc/include/sys/tree.h
index 2e1cc1eda..2af77a499 100644
--- a/newlib/libc/include/sys/tree.h
+++ b/newlib/libc/include/sys/tree.h
@@ -325,8 +325,12 @@ struct {								\
 #define RB_ROOT(head)			(head)->rbh_root
 #define RB_EMPTY(head)			(RB_ROOT(head) == NULL)
 
+#define RB_SET_PARENT(dst, src, field) do {				\
+	RB_PARENT(dst, field) = src;					\
+} while (/*CONSTCOND*/ 0)
+
 #define RB_SET(elm, parent, field) do {					\
-	RB_PARENT(elm, field) = parent;					\
+	RB_SET_PARENT(elm, parent, field);				\
 	RB_LEFT(elm, field) = RB_RIGHT(elm, field) = NULL;		\
 	RB_COLOR(elm, field) = RB_RED;					\
 } while (/*CONSTCOND*/ 0)
@@ -344,37 +348,36 @@ struct {								\
 #define RB_AUGMENT(x)	break
 #endif
 
+#define RB_SWAP_CHILD(head, out, in, field) do {			\
+	if (RB_PARENT(out, field) == NULL)				\
+		RB_ROOT(head) = (in);					\
+	else if ((out) == RB_LEFT(RB_PARENT(out, field), field))	\
+		RB_LEFT(RB_PARENT(out, field), field) = (in);		\
+	else								\
+		RB_RIGHT(RB_PARENT(out, field), field) = (in);		\
+} while (/*CONSTCOND*/ 0)
+
 #define RB_ROTATE_LEFT(head, elm, tmp, field) do {			\
 	(tmp) = RB_RIGHT(elm, field);					\
 	if ((RB_RIGHT(elm, field) = RB_LEFT(tmp, field)) != NULL) {	\
-		RB_PARENT(RB_LEFT(tmp, field), field) = (elm);		\
+		RB_SET_PARENT(RB_RIGHT(elm, field), elm, field);	\
 	}								\
-	if ((RB_PARENT(tmp, field) = RB_PARENT(elm, field)) != NULL) {	\
-		if ((elm) == RB_LEFT(RB_PARENT(elm, field), field))	\
-			RB_LEFT(RB_PARENT(elm, field), field) = (tmp);	\
-		else							\
-			RB_RIGHT(RB_PARENT(elm, field), field) = (tmp);	\
-	} else								\
-		(head)->rbh_root = (tmp);				\
+	RB_SET_PARENT(tmp, RB_PARENT(elm, field), field);		\
+	RB_SWAP_CHILD(head, elm, tmp, field);				\
 	RB_LEFT(tmp, field) = (elm);					\
-	RB_PARENT(elm, field) = (tmp);					\
+	RB_SET_PARENT(elm, tmp, field);					\
 	RB_AUGMENT(elm);						\
 } while (/*CONSTCOND*/ 0)
 
 #define RB_ROTATE_RIGHT(head, elm, tmp, field) do {			\
 	(tmp) = RB_LEFT(elm, field);					\
 	if ((RB_LEFT(elm, field) = RB_RIGHT(tmp, field)) != NULL) {	\
-		RB_PARENT(RB_RIGHT(tmp, field), field) = (elm);		\
+		RB_SET_PARENT(RB_LEFT(elm, field), elm, field);		\
 	}								\
-	if ((RB_PARENT(tmp, field) = RB_PARENT(elm, field)) != NULL) {	\
-		if ((elm) == RB_LEFT(RB_PARENT(elm, field), field))	\
-			RB_LEFT(RB_PARENT(elm, field), field) = (tmp);	\
-		else							\
-			RB_RIGHT(RB_PARENT(elm, field), field) = (tmp);	\
-	} else								\
-		(head)->rbh_root = (tmp);				\
+	RB_SET_PARENT(tmp, RB_PARENT(elm, field), field);		\
+	RB_SWAP_CHILD(head, elm, tmp, field);				\
 	RB_RIGHT(tmp, field) = (elm);					\
-	RB_PARENT(elm, field) = (tmp);					\
+	RB_SET_PARENT(elm, tmp, field);					\
 	RB_AUGMENT(elm);						\
 } while (/*CONSTCOND*/ 0)
 
@@ -545,11 +548,11 @@ name##_RB_REMOVE_COLOR(struct name *head, struct type *parent)		\
 attr struct type *							\
 name##_RB_REMOVE(struct name *head, struct type *elm)			\
 {									\
-	struct type *child, *old, *parent, *parent_old, *right;		\
+	struct type *child, *old, *parent, *right;			\
 	int color;							\
 									\
 	old = elm;							\
-	parent_old = parent = RB_PARENT(elm, field);			\
+	parent = RB_PARENT(elm, field);					\
 	right = RB_RIGHT(elm, field);					\
 	color = RB_COLOR(elm, field);					\
 	if (RB_LEFT(elm, field) == NULL)				\
@@ -568,20 +571,15 @@ name##_RB_REMOVE(struct name *head, struct type *elm)			\
 			child = RB_RIGHT(elm, field);			\
 			parent = RB_PARENT(elm, field);			\
 			RB_LEFT(parent, field) = child;			\
-			RB_PARENT(RB_RIGHT(old, field), field) = elm;	\
+			RB_SET_PARENT(RB_RIGHT(old, field), elm, field); \
 		}							\
-		RB_PARENT(RB_LEFT(old, field), field) = elm;		\
+		RB_SET_PARENT(RB_LEFT(old, field), elm, field);		\
 		color = RB_COLOR(elm, field);				\
 		elm->field = old->field;				\
 	}								\
-	if (parent_old == NULL)						\
-		RB_ROOT(head) = elm;					\
-	else if (RB_LEFT(parent_old, field) == old)			\
-		RB_LEFT(parent_old, field) = elm;			\
-	else								\
-		RB_RIGHT(parent_old, field) = elm;			\
+	RB_SWAP_CHILD(head, old, elm, field);				\
 	if (child != NULL) {						\
-		RB_PARENT(child, field) = parent;			\
+		RB_SET_PARENT(child, parent, field);			\
 		RB_COLOR(child, field) = RB_BLACK;			\
 	} else if (color != RB_RED && parent != NULL)			\
 		name##_RB_REMOVE_COLOR(head, parent);			\