The compiler is also smart enough to recognize that this is redundant.
The resulting code on amd64 is basically equivalent (slightly different
register allocation and instruction scheduling).
ok?
Index: uvm/uvm_amap.c
===================================================================
RCS file: /cvs/src/sys/uvm/uvm_amap.c,v
retrieving revision 1.61
diff -u -p -r1.61 uvm_amap.c
--- uvm/uvm_amap.c 15 Mar 2016 18:16:21 -0000 1.61
+++ uvm/uvm_amap.c 16 Mar 2016 16:33:52 -0000
@@ -917,10 +917,6 @@ amap_swap_off(int startslot, int endslot
LIST_INSERT_BEFORE(am, &marker_prev, am_list);
LIST_INSERT_AFTER(am, &marker_next, am_list);
- if (am->am_nused <= 0) {
- goto next;
- }
-
for (i = 0; i < am->am_nused; i++) {
int slot;
int swslot;
@@ -950,7 +946,6 @@ amap_swap_off(int startslot, int endslot
i = 0;
}
-next:
KASSERT(LIST_NEXT(&marker_prev, am_list) == &marker_next ||
LIST_NEXT(LIST_NEXT(&marker_prev, am_list), am_list) ==
&marker_next);
