Date: Thu, 21 May 2020 05:34:02 +0000 (UTC) From: Doug Moore <dougm@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r361324 - head/sys/sys Message-ID: <202005210534.04L5Y2VB001034@repo.freebsd.org>
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Author: dougm Date: Thu May 21 05:34:02 2020 New Revision: 361324 URL: https://svnweb.freebsd.org/changeset/base/361324 Log: For the case when RB_REMOVE requires a nontrivial search to find the node to replace the one being removed, restructure to first remove the replacement node and correct the parent pointers around it, and then let the all-cases code at the end deal with the parent of the deleted node, making it point to the replacement node. This removes one or two conditional branches. Reviewed by: markj Tested by: pho Differential Revision: https://reviews.freebsd.org/D24845 Modified: head/sys/sys/tree.h Modified: head/sys/sys/tree.h ============================================================================== --- head/sys/sys/tree.h Thu May 21 05:02:58 2020 (r361323) +++ head/sys/sys/tree.h Thu May 21 05:34:02 2020 (r361324) @@ -562,48 +562,44 @@ name##_RB_REMOVE_COLOR(struct name *head, struct type attr struct type * \ name##_RB_REMOVE(struct name *head, struct type *elm) \ { \ - struct type *child, *parent, *old = elm; \ + struct type *child, *parent, *parent_old, *old = elm; \ int color; \ - if (RB_LEFT(elm, field) == NULL) \ - child = RB_RIGHT(elm, field); \ - else if (RB_RIGHT(elm, field) == NULL) \ - child = RB_LEFT(elm, field); \ - else { \ + parent_old = parent = RB_PARENT(elm, field); \ + color = RB_COLOR(elm, field); \ + if (RB_LEFT(elm, field) == NULL) { \ + elm = child = RB_RIGHT(elm, field); \ + if (elm != NULL) \ + RB_PARENT(elm, field) = parent; \ + } else if (RB_RIGHT(elm, field) == NULL) { \ + elm = child = RB_LEFT(elm, field); \ + RB_PARENT(elm, field) = parent; \ + } else { \ elm = RB_RIGHT(old, field); \ if ((child = RB_LEFT(elm, field)) == NULL) { \ child = RB_RIGHT(elm, field); \ RB_RIGHT(old, field) = child; \ - RB_PARENT(elm, field) = elm; \ + parent = elm; \ } else { \ do \ elm = child; \ while ((child = RB_LEFT(elm, field)) != NULL); \ child = RB_RIGHT(elm, field); \ + parent = RB_PARENT(elm, field); \ + RB_LEFT(parent, field) = child; \ + if (child != NULL) \ + RB_PARENT(child, field) = parent; \ RB_PARENT(RB_RIGHT(old, field), field) = elm; \ } \ RB_PARENT(RB_LEFT(old, field), field) = elm; \ - parent = RB_PARENT(old, field); \ - if (parent != NULL) { \ - if (RB_LEFT(parent, field) == old) \ - RB_LEFT(parent, field) = elm; \ - else \ - RB_RIGHT(parent, field) = elm; \ - } else \ - RB_ROOT(head) = elm; \ + color = RB_COLOR(elm, field); \ + elm->field = old->field; \ } \ - parent = RB_PARENT(elm, field); \ - color = RB_COLOR(elm, field); \ - if (child != NULL) \ - RB_PARENT(child, field) = parent; \ - if (parent != NULL) { \ - if (RB_LEFT(parent, field) == elm) \ - RB_LEFT(parent, field) = child; \ - else \ - RB_RIGHT(parent, field) = child; \ - } else \ - RB_ROOT(head) = child; \ - if (elm != old) \ - (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; \ if (color == RB_BLACK) \ name##_RB_REMOVE_COLOR(head, parent, child); \ while (parent != NULL) { \
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