http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55529
--- Comment #4 from Markus Trippelsdorf <markus at trippelsdorf dot de>
2012-11-29 13:16:08 UTC ---
The testcase was derived from the Linux kernel:
CC kernel/rcutree.o
kernel/rcutree.c: In function ‘rcu_init_one’:
kernel/rcutree.c:2850:13: warning: array subscript is above array bounds
[-Warray-bounds]
rsp->level[i] = rsp->level[i - 1] + rsp->levelcnt[i - 1];
^
2849 for (i = 1; i < rcu_num_lvls; i++)
2850 rsp->level[i] = rsp->level[i - 1] + rsp->levelcnt[i - 1];
Where rcu_num_lvls=RCU_NUM_LVLS.
From kernel/rcutree.h:
31 /*
32 * Define shape of hierarchy based on NR_CPUS, CONFIG_RCU_FANOUT, and
33 * CONFIG_RCU_FANOUT_LEAF.
34 * In theory, it should be possible to add more levels straightforwardly.
35 * In practice, this did work well going from three levels to four.
36 * Of course, your mileage may vary.
37 */
38 #define MAX_RCU_LVLS 4
39 #define RCU_FANOUT_1 (CONFIG_RCU_FANOUT_LEAF)
40 #define RCU_FANOUT_2 (RCU_FANOUT_1 * CONFIG_RCU_FANOUT)
41 #define RCU_FANOUT_3 (RCU_FANOUT_2 * CONFIG_RCU_FANOUT)
42 #define RCU_FANOUT_4 (RCU_FANOUT_3 * CONFIG_RCU_FANOUT)
43
44 #if NR_CPUS <= RCU_FANOUT_1
45 # define RCU_NUM_LVLS 1
46 # define NUM_RCU_LVL_0 1
47 # define NUM_RCU_LVL_1 (NR_CPUS)
48 # define NUM_RCU_LVL_2 0
49 # define NUM_RCU_LVL_3 0
50 # define NUM_RCU_LVL_4 0
51 #elif NR_CPUS <= RCU_FANOUT_2
52 # define RCU_NUM_LVLS 2
53 # define NUM_RCU_LVL_0 1
54 # define NUM_RCU_LVL_1 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_1)
55 # define NUM_RCU_LVL_2 (NR_CPUS)
56 # define NUM_RCU_LVL_3 0
57 # define NUM_RCU_LVL_4 0
58 #elif NR_CPUS <= RCU_FANOUT_3
59 # define RCU_NUM_LVLS 3
60 # define NUM_RCU_LVL_0 1
61 # define NUM_RCU_LVL_1 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_2)
62 # define NUM_RCU_LVL_2 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_1)
63 # define NUM_RCU_LVL_3 (NR_CPUS)
64 # define NUM_RCU_LVL_4 0
65 #elif NR_CPUS <= RCU_FANOUT_4
66 # define RCU_NUM_LVLS 4
67 # define NUM_RCU_LVL_0 1
68 # define NUM_RCU_LVL_1 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_3)
69 # define NUM_RCU_LVL_2 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_2)
70 # define NUM_RCU_LVL_3 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_1)
71 # define NUM_RCU_LVL_4 (NR_CPUS)
72 #else
73 # error "CONFIG_RCU_FANOUT insufficient for NR_CPUS"
74 #endif /* #if (NR_CPUS) <= RCU_FANOUT_1 */
