From b0687c1119b4e8c88a651b6e876b7eae28d076e3 Mon Sep 17 00:00:00 2001 From: Noah Goldstein Date: Tue, 4 Apr 2023 17:13:51 -0500 Subject: [PATCH] lib/rbtree: use '+' instead of '|' for setting color. This has a slight benefit for x86 and has no effect on other targets. The benefit to x86 is it change the codegen for setting a node to block from `mov %r0, %r1; or $RB_BLACK, %r1` to `lea RB_BLACK(%r0), %r1` which saves an instructions. In all other cases it just replace ALU with ALU (or -> and) which perform the same on all machines I am aware of. Total instructions in rbtree.o: Before - 802 After - 782 so it saves about 20 `mov` instructions. Link: https://lkml.kernel.org/r/20230404221350.3806566-1-goldstein.w.n@gmail.com Signed-off-by: Noah Goldstein Cc: Michel Lespinasse Signed-off-by: Andrew Morton --- include/linux/rbtree_augmented.h | 4 ++-- lib/rbtree.c | 2 +- 2 files changed, 3 insertions(+), 3 deletions(-) diff --git a/include/linux/rbtree_augmented.h b/include/linux/rbtree_augmented.h index d1c53e9d8c75..7ee7ed5de722 100644 --- a/include/linux/rbtree_augmented.h +++ b/include/linux/rbtree_augmented.h @@ -156,13 +156,13 @@ RB_DECLARE_CALLBACKS(RBSTATIC, RBNAME, \ static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p) { - rb->__rb_parent_color = rb_color(rb) | (unsigned long)p; + rb->__rb_parent_color = rb_color(rb) + (unsigned long)p; } static inline void rb_set_parent_color(struct rb_node *rb, struct rb_node *p, int color) { - rb->__rb_parent_color = (unsigned long)p | color; + rb->__rb_parent_color = (unsigned long)p + color; } static inline void diff --git a/lib/rbtree.c b/lib/rbtree.c index c4ac5c2421f2..5114eda6309c 100644 --- a/lib/rbtree.c +++ b/lib/rbtree.c @@ -58,7 +58,7 @@ static inline void rb_set_black(struct rb_node *rb) { - rb->__rb_parent_color |= RB_BLACK; + rb->__rb_parent_color += RB_BLACK; } static inline struct rb_node *rb_red_parent(struct rb_node *red)