From: Sebastian Huber <sebastian.huber@embedded-brains.de>
To: newlib@sourceware.org
Subject: [PATCH 06/11] To reduce the size of an rb_node, drop the color
Date: Mon, 19 Oct 2020 18:05:19 +0200 [thread overview]
Message-ID: <20201019160522.15408-7-sebastian.huber@embedded-brains.de> (raw)
In-Reply-To: <20201019160522.15408-1-sebastian.huber@embedded-brains.de>
From: dougm <dougm@FreeBSD.org>
field. Set the least significant bit in the pointer to the node from its parent
to indicate that the node is red. Have the tree rotation macros leave the
old-parent/new-child node red and the new-parent/old-child node black.
This change makes RB_LEFT and RB_RIGHT no longer assignable, and
RB_COLOR no longer defined. Any code that modifies the tree or
examines a node color would have to be modified after this change.
Reviewed by: markj
Tested by: pho
Differential Revision: https://reviews.freebsd.org/D25105
---
newlib/libc/include/sys/tree.h | 281 +++++++++++++++++----------------
1 file changed, 143 insertions(+), 138 deletions(-)
diff --git a/newlib/libc/include/sys/tree.h b/newlib/libc/include/sys/tree.h
index 372c001b9..29b731822 100644
--- a/newlib/libc/include/sys/tree.h
+++ b/newlib/libc/include/sys/tree.h
@@ -307,34 +307,31 @@ struct name { \
(root)->rbh_root = NULL; \
} while (/*CONSTCOND*/ 0)
-#define RB_BLACK 0
-#define RB_RED 1
#define RB_ENTRY(type) \
struct { \
struct type *rbe_left; /* left element */ \
struct type *rbe_right; /* right element */ \
struct type *rbe_parent; /* parent element */ \
- int rbe_color; /* node color */ \
}
-#define RB_LEFT(elm, field) (elm)->field.rbe_left
-#define RB_RIGHT(elm, field) (elm)->field.rbe_right
+#define RB_LF(elm, field) (elm)->field.rbe_left
+#define RB_RT(elm, field) (elm)->field.rbe_right
+#define RB_FLIP(elm) (*(__uintptr_t *)&(elm) ^= 1)
+#define RB_FLIP_LF(elm, field) RB_FLIP(RB_LF(elm, field))
+#define RB_FLIP_RT(elm, field) RB_FLIP(RB_RT(elm, field))
+#define RB_ISRED(elm) ((*(__uintptr_t *)&(elm) & 1) != 0)
+#define RB_RED_LF(elm, field) RB_ISRED(RB_LF(elm, field))
+#define RB_RED_RT(elm, field) RB_ISRED(RB_RT(elm, field))
+#define RB_PTR(elm, field) ((__typeof(elm->field.rbe_parent)) \
+ ((__uintptr_t)(elm) & ~(__uintptr_t)1))
+#define RB_LEFT(elm, field) RB_PTR(RB_LF(elm, field), field)
+#define RB_RIGHT(elm, field) RB_PTR(RB_RT(elm, field), field)
#define RB_PARENT(elm, field) (elm)->field.rbe_parent
-#define RB_COLOR(elm, field) (elm)->field.rbe_color
-#define RB_ISRED(elm, field) ((elm) != NULL && RB_COLOR(elm, field) == RB_RED)
#define RB_ROOT(head) (head)->rbh_root
#define RB_EMPTY(head) (RB_ROOT(head) == NULL)
-
-#define RB_SET(elm, parent, field) do { \
- RB_PARENT(elm, field) = parent; \
- RB_LEFT(elm, field) = RB_RIGHT(elm, field) = NULL; \
- RB_COLOR(elm, field) = RB_RED; \
-} while (/*CONSTCOND*/ 0)
-
-#define RB_SET_BLACKRED(black, red, field) do { \
- RB_COLOR(black, field) = RB_BLACK; \
- RB_COLOR(red, field) = RB_RED; \
-} while (/*CONSTCOND*/ 0)
+#define RB_BOOL int
+#define RB_TRUE 1
+#define RB_FALSE 0
/*
* Something to be invoked in a loop at the root of every modified subtree,
@@ -344,37 +341,42 @@ struct { \
#define RB_AUGMENT(x) break
#endif
+/*
+ * Fix pointers to a parent, and from a parent, as part of rotation.
+ */
+#define RB_ROTATE_PARENT(head, elm, tmp, field) do { \
+ if ((RB_PARENT(tmp, field) = RB_PARENT(elm, field)) == NULL) \
+ RB_ROOT(head) = (tmp); \
+ else if ((elm) == RB_LEFT(RB_PARENT(elm, field), field)) \
+ RB_LF(RB_PARENT(elm, field), field) = (tmp); \
+ else \
+ RB_RT(RB_PARENT(elm, field), field) = (tmp); \
+ RB_PARENT(elm, field) = (tmp); \
+} while (/*CONSTCOND*/ 0)
+
+/*
+ * Rotation makes the descending node red, and the ascending
+ * node not-red.
+ */
#define RB_ROTATE_LEFT(head, elm, tmp, field) do { \
(tmp) = RB_RIGHT(elm, field); \
- if ((RB_RIGHT(elm, field) = RB_LEFT(tmp, field)) != NULL) { \
+ if ((RB_RT(elm, field) = RB_LF(tmp, field)) != NULL) { \
RB_PARENT(RB_LEFT(tmp, field), field) = (elm); \
} \
- 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_LEFT(tmp, field) = (elm); \
- RB_PARENT(elm, field) = (tmp); \
+ RB_ROTATE_PARENT(head, elm, tmp, field); \
+ RB_LF(tmp, field) = (elm); \
+ RB_FLIP_LF(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) { \
+ if ((RB_LF(elm, field) = RB_RT(tmp, field)) != NULL) { \
RB_PARENT(RB_RIGHT(tmp, field), field) = (elm); \
} \
- 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_RIGHT(tmp, field) = (elm); \
- RB_PARENT(elm, field) = (tmp); \
+ RB_ROTATE_PARENT(head, elm, tmp, field); \
+ RB_RT(tmp, field) = (elm); \
+ RB_FLIP_RT(tmp, field); \
RB_AUGMENT(elm); \
} while (/*CONSTCOND*/ 0)
@@ -439,110 +441,105 @@ struct { \
attr void \
name##_RB_INSERT_COLOR(struct name *head, struct type *elm) \
{ \
- struct type *parent, *gparent, *tmp; \
- while (RB_ISRED((parent = RB_PARENT(elm, field)), field)) { \
- gparent = RB_PARENT(parent, field); \
- if (parent == RB_LEFT(gparent, field)) { \
- tmp = RB_RIGHT(gparent, field); \
- if (RB_ISRED(tmp, field)) { \
- RB_COLOR(tmp, field) = RB_BLACK; \
- RB_SET_BLACKRED(parent, gparent, field);\
- elm = gparent; \
- continue; \
- } \
+ struct type *gparent, *parent; \
+ while ((parent = RB_PARENT(elm, field)) != NULL) { \
+ if (RB_LEFT(parent, field) == elm) \
+ RB_FLIP_LF(parent, field); \
+ else \
+ RB_FLIP_RT(parent, field); \
+ if ((gparent = RB_PARENT(parent, field)) == NULL) \
+ break; \
+ if (RB_RED_LF(gparent, field) && \
+ RB_RED_RT(gparent, field)) { \
+ RB_FLIP_LF(gparent, field); \
+ RB_FLIP_RT(gparent, field); \
+ elm = gparent; \
+ continue; \
+ } \
+ if (RB_RED_LF(gparent, field) && \
+ parent == RB_LEFT(gparent, field)) { \
if (RB_RIGHT(parent, field) == elm) { \
- RB_ROTATE_LEFT(head, parent, tmp, field);\
- tmp = parent; \
+ RB_ROTATE_LEFT(head, parent, elm, field);\
parent = elm; \
- elm = tmp; \
- } \
- RB_SET_BLACKRED(parent, gparent, field); \
- RB_ROTATE_RIGHT(head, gparent, tmp, field); \
- } else { \
- tmp = RB_LEFT(gparent, field); \
- if (RB_ISRED(tmp, field)) { \
- RB_COLOR(tmp, field) = RB_BLACK; \
- RB_SET_BLACKRED(parent, gparent, field);\
- elm = gparent; \
- continue; \
} \
+ RB_ROTATE_RIGHT(head, gparent, parent, field); \
+ } else if (RB_RED_RT(gparent, field) && \
+ parent == RB_RIGHT(gparent, field)) { \
if (RB_LEFT(parent, field) == elm) { \
- RB_ROTATE_RIGHT(head, parent, tmp, field);\
- tmp = parent; \
+ RB_ROTATE_RIGHT(head, parent, elm, field);\
parent = elm; \
- elm = tmp; \
} \
- RB_SET_BLACKRED(parent, gparent, field); \
- RB_ROTATE_LEFT(head, gparent, tmp, field); \
+ RB_ROTATE_LEFT(head, gparent, parent, field); \
} \
+ break; \
} \
- RB_COLOR(head->rbh_root, field) = RB_BLACK; \
}
#define RB_GENERATE_REMOVE_COLOR(name, type, field, attr) \
attr void \
-name##_RB_REMOVE_COLOR(struct name *head, struct type *parent) \
+name##_RB_REMOVE_COLOR(struct name *head, struct type *elm) \
{ \
- struct type *elm, *tmp; \
- elm = NULL; \
+ struct type *par, *sib, *tmp; \
+ RB_BOOL go_left, left_child, red_par; \
+ left_child = (RB_LEFT(elm, field) == NULL); \
do { \
- if (RB_LEFT(parent, field) == elm) { \
- tmp = RB_RIGHT(parent, field); \
- if (RB_COLOR(tmp, field) == RB_RED) { \
- RB_SET_BLACKRED(tmp, parent, field); \
- RB_ROTATE_LEFT(head, parent, tmp, field);\
- tmp = RB_RIGHT(parent, field); \
+ go_left = left_child; \
+ if (go_left ? \
+ !RB_RED_RT(elm, field) : \
+ !RB_RED_LF(elm, field)) { \
+ par = RB_PARENT(elm, field); \
+ left_child = par != NULL && \
+ RB_LEFT(par, field) == elm; \
+ red_par = left_child ? RB_RED_LF(par, field) : \
+ par == NULL ? RB_TRUE : \
+ RB_RED_RT(par, field); \
+ } \
+ if (go_left) { \
+ if (RB_RED_RT(elm, field)) { \
+ red_par = RB_TRUE; \
+ RB_ROTATE_LEFT(head, elm, par, field); \
} \
- if (RB_ISRED(RB_LEFT(tmp, field), field)) { \
- struct type *oleft; \
- oleft = RB_LEFT(tmp, field); \
- RB_COLOR(oleft, field) = RB_BLACK; \
- RB_COLOR(tmp, field) = RB_RED; \
- RB_ROTATE_RIGHT(head, tmp, oleft, field); \
- tmp = RB_RIGHT(parent, field); \
- } else if (!RB_ISRED(RB_RIGHT(tmp, field), field)) { \
- RB_COLOR(tmp, field) = RB_RED; \
- elm = parent; \
- parent = RB_PARENT(elm, field); \
+ sib = RB_RIGHT(elm, field); \
+ if (RB_RED_LF(sib, field)) { \
+ RB_ROTATE_RIGHT(head, sib, tmp, field); \
+ sib = tmp; \
+ } else if (!RB_RED_RT(sib, field)) { \
+ RB_FLIP_RT(elm, field); \
+ elm = par; \
continue; \
} \
- if (RB_ISRED(RB_RIGHT(tmp, field), field)) \
- RB_COLOR(RB_RIGHT(tmp, field), field) = RB_BLACK; \
- RB_COLOR(tmp, field) = RB_COLOR(parent, field); \
- RB_COLOR(parent, field) = RB_BLACK; \
- RB_ROTATE_LEFT(head, parent, tmp, field); \
- elm = RB_ROOT(head); \
+ if (RB_RED_RT(sib, field)) \
+ RB_FLIP_RT(sib, field); \
+ RB_ROTATE_LEFT(head, elm, sib, field); \
+ RB_FLIP_LF(sib, field); \
break; \
} else { \
- tmp = RB_LEFT(parent, field); \
- if (RB_COLOR(tmp, field) == RB_RED) { \
- RB_SET_BLACKRED(tmp, parent, field); \
- RB_ROTATE_RIGHT(head, parent, tmp, field);\
- tmp = RB_LEFT(parent, field); \
+ if (RB_RED_LF(elm, field)) { \
+ red_par = RB_TRUE; \
+ RB_ROTATE_RIGHT(head, elm, par, field); \
} \
- if (RB_ISRED(RB_RIGHT(tmp, field), field)) { \
- struct type *oright; \
- oright = RB_RIGHT(tmp, field); \
- RB_COLOR(oright, field) = RB_BLACK; \
- RB_COLOR(tmp, field) = RB_RED; \
- RB_ROTATE_LEFT(head, tmp, oright, field); \
- tmp = RB_LEFT(parent, field); \
- } else if (!RB_ISRED(RB_LEFT(tmp, field), field)) { \
- RB_COLOR(tmp, field) = RB_RED; \
- elm = parent; \
- parent = RB_PARENT(elm, field); \
+ sib = RB_LEFT(elm, field); \
+ if (RB_RED_RT(sib, field)) { \
+ RB_ROTATE_LEFT(head, sib, tmp, field); \
+ sib = tmp; \
+ } else if (!RB_RED_LF(sib, field)) { \
+ RB_FLIP_LF(elm, field); \
+ elm = par; \
continue; \
} \
- if (RB_ISRED(RB_LEFT(tmp, field), field)) \
- RB_COLOR(RB_LEFT(tmp, field), field) = RB_BLACK; \
- RB_COLOR(tmp, field) = RB_COLOR(parent, field); \
- RB_COLOR(parent, field) = RB_BLACK; \
- RB_ROTATE_RIGHT(head, parent, tmp, field); \
- elm = RB_ROOT(head); \
+ if (RB_RED_LF(sib, field)) \
+ RB_FLIP_LF(sib, field); \
+ RB_ROTATE_RIGHT(head, elm, sib, field); \
+ RB_FLIP_RT(sib, field); \
break; \
} \
- } while (!RB_ISRED(elm, field) && parent != NULL); \
- RB_COLOR(elm, field) = RB_BLACK; \
+ } while (!red_par); \
+ if (par != NULL && red_par) { \
+ if (left_child) \
+ RB_FLIP_LF(par, field); \
+ else \
+ RB_FLIP_RT(par, field); \
+ } \
}
#define RB_GENERATE_REMOVE(name, type, field, attr) \
@@ -550,12 +547,11 @@ attr struct type * \
name##_RB_REMOVE(struct name *head, struct type *elm) \
{ \
struct type *child, *old, *parent, *parent_old, *right; \
- int color; \
+ RB_BOOL old_red, red; \
\
old = elm; \
parent_old = parent = RB_PARENT(elm, field); \
right = RB_RIGHT(elm, field); \
- color = RB_COLOR(elm, field); \
if (RB_LEFT(elm, field) == NULL) \
elm = child = right; \
else if (right == NULL) \
@@ -563,7 +559,8 @@ name##_RB_REMOVE(struct name *head, struct type *elm) \
else { \
if ((child = RB_LEFT(right, field)) == NULL) { \
child = RB_RIGHT(right, field); \
- RB_RIGHT(old, field) = child; \
+ red = RB_RED_RT(old, field); \
+ RB_RT(old, field) = child; \
parent = elm = right; \
} else { \
do \
@@ -571,23 +568,31 @@ name##_RB_REMOVE(struct name *head, struct type *elm) \
while ((child = RB_LEFT(elm, field)) != NULL); \
child = RB_RIGHT(elm, field); \
parent = RB_PARENT(elm, field); \
- RB_LEFT(parent, field) = child; \
+ red = RB_RED_LF(parent, field); \
+ RB_LF(parent, field) = child; \
RB_PARENT(RB_RIGHT(old, field), field) = elm; \
} \
RB_PARENT(RB_LEFT(old, field), field) = elm; \
- color = RB_COLOR(elm, field); \
elm->field = old->field; \
} \
- if (parent_old == NULL) \
+ 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; \
- if (child != NULL) { \
+ old_red = RB_FALSE; \
+ } else if (RB_LEFT(parent_old, field) == old) { \
+ old_red = RB_RED_LF(parent_old, field); \
+ RB_LF(parent_old, field) = elm; \
+ if (old_red && parent != parent_old) \
+ RB_FLIP_LF(parent_old, field); \
+ } else { \
+ old_red = RB_RED_RT(parent_old, field); \
+ RB_RT(parent_old, field) = elm; \
+ if (old_red && parent != parent_old) \
+ RB_FLIP_RT(parent_old, field); \
+ } \
+ if (child != NULL) \
RB_PARENT(child, field) = parent; \
- RB_COLOR(child, field) = RB_BLACK; \
- } else if (color != RB_RED && parent != NULL) \
+ else if (parent != NULL && \
+ (parent != parent_old ? !red : !old_red)) \
name##_RB_REMOVE_COLOR(head, parent); \
while (parent != NULL) { \
RB_AUGMENT(parent); \
@@ -615,14 +620,14 @@ name##_RB_INSERT(struct name *head, struct type *elm) \
else \
return (tmp); \
} \
- RB_SET(elm, parent, field); \
- if (parent != NULL) { \
- if (comp < 0) \
- RB_LEFT(parent, field) = elm; \
- else \
- RB_RIGHT(parent, field) = elm; \
- } else \
+ RB_PARENT(elm, field) = parent; \
+ RB_LF(elm, field) = RB_RT(elm, field) = NULL; \
+ if (parent == NULL) \
RB_ROOT(head) = elm; \
+ else if (comp < 0) \
+ RB_LF(parent, field) = elm; \
+ else \
+ RB_RT(parent, field) = elm; \
name##_RB_INSERT_COLOR(head, elm); \
while (elm != NULL) { \
RB_AUGMENT(elm); \
--
2.26.2
next prev parent reply other threads:[~2020-10-19 16:05 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-19 16:05 [PATCH 00/11] Synchronize <sys/tree.h> with FreeBSD Sebastian Huber
2020-10-19 16:05 ` [PATCH 01/11] Add RB_REINSERT(3), a low overhead alternative to Sebastian Huber
2020-10-19 16:05 ` [PATCH 02/11] Correct the use of RB_AUGMENT in the RB_TREE Sebastian Huber
2020-10-19 16:05 ` [PATCH 03/11] For the case when RB_REMOVE requires a nontrivial Sebastian Huber
2020-10-19 16:05 ` [PATCH 04/11] RB_REMOVE invokes RB_REMOVE_COLOR either when Sebastian Huber
2020-10-19 16:05 ` [PATCH 05/11] Remove from RB_REMOVE_COLOR some null checks Sebastian Huber
2020-10-19 16:05 ` Sebastian Huber [this message]
2020-10-19 16:05 ` [PATCH 07/11] Restore an RB_COLOR macro, for the benefit of Sebastian Huber
2020-10-19 16:05 ` [PATCH 08/11] Fixup r361997 by balancing parens. Duh Sebastian Huber
2020-10-19 16:05 ` [PATCH 09/11] Linuxkpi uses the rb-tree structures Sebastian Huber
2020-10-26 9:52 ` [PATCH 00/11] Synchronize <sys/tree.h> with FreeBSD Corinna Vinschen
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20201019160522.15408-7-sebastian.huber@embedded-brains.de \
--to=sebastian.huber@embedded-brains.de \
--cc=newlib@sourceware.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).