https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92924
--- Comment #18 from Martin Liška <marxin at gcc dot gnu.org> ---
I've got more detailed stats for current GCC master with 4 TOPN counters
(default) and 8 TOPN counters:
$ gcov-dump-analysis.py gcc-4 4
== Stats for gcc-4 ==
stats for indirect_call:
total: 9210 freq: 5945890924
not executed at all: 6248
invalid: 669 (7.26%) freq:2216493157 (37.28%)
only one target: 1788 (19.41%) freq:2259048939 (37.99%)
useful values (with not one target):
0 values: 23 times (0.25%) freq: 48188389 (0.81%)
1 values: 271 times (2.94%) freq: 1144170389 (19.24%)
2 values: 179 times (1.94%) freq: 200108367 (3.37%)
3 values: 32 times (0.35%) freq: 77881683 (1.31%)
4 values: 0 times (0.00%) freq: 0 (0.00%)
Top 10 invalid counters:
freq: 10.18%: [605586849, 0, -1, 0, 0, 0, 0, 0, 0]
freq: 5.45%: [324297046, 0, -1, 0, 0, 0, 0, 0, 0]
freq: 2.91%: [173094875, 0, -1, 0, 0, 0, 0, 0, 0]
freq: 1.71%: [101484459, 0, -1, 0, 0, 0, 0, 0, 0]
freq: 1.35%: [80265242, 0, -1, 0, 0, 0, 0, 0, 0]
freq: 0.94%: [55609315, 0, -1, 0, 0, 0, 0, 0, 0]
freq: 0.93%: [55570274, 0, -1, 0, 0, 0, 0, 0, 0]
freq: 0.93%: [55570274, 0, -1, 0, 0, 0, 0, 0, 0]
freq: 0.83%: [49637863, 0, -1, 0, 0, 0, 0, 0, 0]
freq: 0.83%: [49463167, 0, -1, 0, 0, 0, 0, 0, 0]
stats for topn:
total: 1513 freq: 1760102743
not executed at all: 1028
invalid: 192 (12.69%) freq:1012619038 (57.53%)
only one target: 147 (9.72%) freq:362167225 (20.58%)
useful values (with not one target):
0 values: 9 times (0.59%) freq: 4449793 (0.25%)
1 values: 80 times (5.29%) freq: 287605028 (16.34%)
2 values: 50 times (3.30%) freq: 91203061 (5.18%)
3 values: 7 times (0.46%) freq: 2058598 (0.12%)
4 values: 0 times (0.00%) freq: 0 (0.00%)
Top 10 invalid counters:
freq: 27.71%: [487664454, 0, -1, 0, 0, 0, 0, 0, 0]
freq: 3.84%: [67602541, 0, -1, 0, 0, 0, 0, 0, 0]
freq: 3.35%: [58977259, 0, -1, 0, 0, 0, 0, 168, 10778]
freq: 2.49%: [43823851, 0, -1, 0, 0, 0, 0, 0, 0]
freq: 2.41%: [42335473, 0, -1, 0, 0, 0, 0, 0, 0]
freq: 1.31%: [23140803, 0, -1, 0, 0, 0, 0, 0, 0]
freq: 1.27%: [22339515, 0, -1, 0, 0, 0, 0, 0, 0]
freq: 1.06%: [18680508, 0, -1, 0, 0, 0, 0, 0, 0]
freq: 1.05%: [18468596, 0, -1, 0, 0, 0, 0, 0, 0]
freq: 0.97%: [17042811, 0, -1, 0, 0, 8, 8986, 0, 0]
$ gcov-dump-analysis.py gcc-8 8
== Stats for gcc-8 ==
stats for indirect_call:
total: 9210 freq: 5945896994
not executed at all: 6248
invalid: 86 (0.93%) freq:1411998192 (23.75%)
only one target: 1788 (19.41%) freq:2259051432 (37.99%)
useful values (with not one target):
0 values: 1 times (0.01%) freq: 23730 (0.00%)
1 values: 213 times (2.31%) freq: 1069863050 (17.99%)
2 values: 234 times (2.54%) freq: 559000644 (9.40%)
3 values: 253 times (2.75%) freq: 566516561 (9.53%)
4 values: 282 times (3.06%) freq: 68094936 (1.15%)
5 values: 99 times (1.07%) freq: 10628476 (0.18%)
6 values: 6 times (0.07%) freq: 719973 (0.01%)
7 values: 0 times (0.00%) freq: 0 (0.00%)
8 values: 0 times (0.00%) freq: 0 (0.00%)
Top 10 invalid counters:
freq: 10.18%: [605586911, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 723230572,
84092, 1139593113, 84612]
freq: 5.45%: [324297850, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
freq: 2.91%: [173094959, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
freq: 1.35%: [80265372, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
freq: 0.83%: [49637931, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
freq: 0.39%: [22933816, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
freq: 0.30%: [17614204, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
freq: 0.24%: [13977669, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
freq: 0.23%: [13907686, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
freq: 0.21%: [12233528, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
stats for topn:
total: 1513 freq: 1760099471
not executed at all: 1028
invalid: 133 (8.79%) freq:888710548 (50.49%)
only one target: 147 (9.72%) freq:362167643 (20.58%)
useful values (with not one target):
0 values: 8 times (0.53%) freq: 23626986 (1.34%)
1 values: 72 times (4.76%) freq: 171882763 (9.77%)
2 values: 74 times (4.89%) freq: 243855009 (13.85%)
3 values: 34 times (2.25%) freq: 44981550 (2.56%)
4 values: 13 times (0.86%) freq: 24863705 (1.41%)
5 values: 2 times (0.13%) freq: 287 (0.00%)
6 values: 1 times (0.07%) freq: 10 (0.00%)
7 values: 1 times (0.07%) freq: 10970 (0.00%)
8 values: 0 times (0.00%) freq: 0 (0.00%)
Top 10 invalid counters:
freq: 27.71%: [487664555, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 40, 75356, 64,
99276, 0, 0]
freq: 3.84%: [67601993, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
freq: 3.35%: [58977256, 0, -1, 0, 0, 0, 0, 32, 6857, 0, 0, 0, 0, 0, 0, 168,
23937]
freq: 2.49%: [43823851, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
freq: 2.41%: [42335497, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
freq: 1.31%: [23140803, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
freq: 1.27%: [22338585, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
freq: 1.05%: [18468605, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
freq: 0.97%: [17042805, 0, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 8, 18248, 0, 0]
freq: 0.62%: [10938516, 168, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
So the frequency of invalid goes down 37.28% -> 23.75% (57.53% -> 50.49%
respectively).
Looking at the biggest invalid offenders for 8 counters:
ggc_internal_cleared_alloc (size_t size, void (*<Tf1>) (void *) f, size_t s,
size_t n)
{
...
memset (buf_7, 0, size_2(D));
Top N value counter all: 487664555, values: [0:-1], [0:0], [0:0], [0:0], [0:0],
[40:75356], [64:99276], [0:0].
}
walk_tree_1 (union tree_node * * tp, union tree_node * (*walk_tree_fn) (union
tree_node * *, int *, void *) func, void * data, struct hash_set * pset, union
tree_node * (*walk_tree_lh) (union tree_node * *, int *, union tree_node *
(*<T4bb8>) (union tree_node * *, int *, void *), void *, struct hash_set *) lh)
{
...
result_157 = func_154(D) (tp_118, &walk_subtrees, data_155(D));
Indirect call counter all: 605586911, values: [0:-1], [0:0], [0:0], [0:0],
[0:0], [0:0], [723230572:84092], [1139593113:84612].
...
}
note_pattern_stores (const struct rtx_def * x, void (*<T54f2>) (struct rtx_def
*, const struct rtx_def *, void *) fun, void * data)
{
...
fun_30(D) (dest_12, x_17, data_31(D));
Indirect call counter all: 324297850, values: [0:-1], [0:0], [0:0], [0:0],
[0:0], [0:0], [0:0], [0:0].
...
}
All these seem to me situations where we have very many different values that
we track.
