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 <goldstein.w.n@gmail.com>
Cc: Michel Lespinasse <michel@lespinasse.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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
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)