diff options
Diffstat (limited to 'gcc/testsuite/gcc.dg/tree-ssa/ssa-dom-thread-6.c')
| -rw-r--r-- | gcc/testsuite/gcc.dg/tree-ssa/ssa-dom-thread-6.c | 38 |
1 files changed, 36 insertions, 2 deletions
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/ssa-dom-thread-6.c b/gcc/testsuite/gcc.dg/tree-ssa/ssa-dom-thread-6.c index 551fbac..16a9ef4 100644 --- a/gcc/testsuite/gcc.dg/tree-ssa/ssa-dom-thread-6.c +++ b/gcc/testsuite/gcc.dg/tree-ssa/ssa-dom-thread-6.c @@ -1,7 +1,41 @@ /* { dg-do compile } */ /* { dg-options "-O2 -fdump-tree-thread1-details -fdump-tree-thread2-details" } */ -/* { dg-final { scan-tree-dump-times "FSM" 3 "thread1" } } */ -/* { dg-final { scan-tree-dump-times "FSM" 5 "thread2" } } */ + +/* All the threads in the thread1 dump start on a X->BB12 edge, as can + be seen in the dump: + + Registering FSM jump thread: (x, 12) incoming edge; ... + etc + etc + + Before the new evrp, we were threading paths that started at the + following edges: + + Registering FSM jump thread: (10, 12) incoming edge + Registering FSM jump thread: (6, 12) incoming edge + Registering FSM jump thread: (9, 12) incoming edge + + This was because the PHI at BB12 had constant values coming in from + BB10, BB6, and BB9: + + # state_10 = PHI <state_11(7), 0(10), state_11(5), 1(6), state_11(8), 2(9), state_11(11)> + + Now with the new evrp, we get: + + # state_10 = PHI <0(7), 0(10), state_11(5), 1(6), 0(8), 2(9), 1(11)> + + Thus, we have 3 more paths that are known to be constant and can be + threaded. Which means that by the second threading pass, we can + only find one profitable path. + + For the record, all these extra constants are better paths coming + out of switches. For example: + + SWITCH_BB -> BBx -> BBy -> BBz -> PHI + + We now know the value of the switch index at PHI. */ +/* { dg-final { scan-tree-dump-times "FSM" 6 "thread1" } } */ +/* { dg-final { scan-tree-dump-times "FSM" 1 "thread2" } } */ int sum0, sum1, sum2, sum3; int foo (char *s, char **ret) |