http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53695
--- Comment #7 from Steven Bosscher <steven at gcc dot gnu.org> 2012-08-22
20:13:32 UTC ---
Before tracer we have this CFG:
ENTRY
|
V
|
2(0)
|
|
V
| (a)
| +-<-+
V / |
| / / (a)
3(1)->-4(1)-->--5(1)-+
/\ |
/ +-----<------+
/
|
V(a)
|
6(0)
|
EXIT
and (BASIC_BLOCK(3)->flags & IRREDUCIBLE_LOOP) is true. The IRREDUCIBLE_LOOP
flags appear to be out-of-date because the flag is not set on BASIC_BLOCK(4)
but it's set on all edges out of it so that's good enough.
Tracer goes to work on this and finds the following traces:
Trace seed 4 [10000],4 [10000],3 [6667] forward 2 [6667],3 [6667],4 [10000]
Duplicated 3 as 7 [6667]
covered now 66.7
Trace seed 6 [3333] forward 6 [3333]
covered now 100.0
The resulting flow graph was already shown in comment #6, but now with the
basic block numbers before the CFG is cleaned up:
ENTRY
|
V
|
2(0)
|
|
V
|
7(0)
|
\
\
\
\
\
\
+-->--+ | +--<---+
| \ V / |
| \ | / |
+-3(1)-<-4(1)->-5(1)-+
(a) | (a)
|
|(a)
|
6(0)
|
EXIT
