Commit b0687c11 authored by Noah Goldstein's avatar Noah Goldstein Committed by Andrew Morton

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.comSigned-off-by: default avatarNoah Goldstein <goldstein.w.n@gmail.com>
Cc: Michel Lespinasse <michel@lespinasse.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 1be2edb2
...@@ -156,13 +156,13 @@ RB_DECLARE_CALLBACKS(RBSTATIC, RBNAME, \ ...@@ -156,13 +156,13 @@ RB_DECLARE_CALLBACKS(RBSTATIC, RBNAME, \
static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p) 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, static inline void rb_set_parent_color(struct rb_node *rb,
struct rb_node *p, int color) 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 static inline void
......
...@@ -58,7 +58,7 @@ ...@@ -58,7 +58,7 @@
static inline void rb_set_black(struct rb_node *rb) 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) static inline struct rb_node *rb_red_parent(struct rb_node *red)
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment