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| author | Richard Biener <rguenther@suse.de> | 2021-05-10 11:37:27 +0200 |
|---|---|---|
| committer | Richard Biener <rguenther@suse.de> | 2021-05-10 13:05:58 +0200 |
| commit | 60af2db18013a0339302928ba98fee893ccc1957 (patch) | |
| tree | 88a9e0c0e46e838e441917a516385ce5a032ff33 /gcc/tree-loop-distribution.c | |
| parent | cc1d563887b1fe3183a21572b2ea63466b2bfa3a (diff) | |
| download | gcc-60af2db18013a0339302928ba98fee893ccc1957.zip gcc-60af2db18013a0339302928ba98fee893ccc1957.tar.gz gcc-60af2db18013a0339302928ba98fee893ccc1957.tar.bz2 | |
tree-optimization/100492 - avoid irreducible regions in loop distribution
When we distribute away a condition we rely on the ability to
change it to either 1 != 0 or 0 != 0 depending on the direction
of the exit branch in the respective loop. But when the loop
contains an irreducible sub-region then for the conditions inside
this this fails and can lead to infinite loops being generated.
Avoid distibuting loops with irreducible sub-regions.
2021-05-10 Richard Biener <rguenther@suse.de>
PR tree-optimization/100492
* tree-loop-distribution.c (find_seed_stmts_for_distribution):
Find nothing when the loop contains an irreducible region.
* gcc.dg/torture/pr100492.c: New testcase.
Diffstat (limited to 'gcc/tree-loop-distribution.c')
| -rw-r--r-- | gcc/tree-loop-distribution.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/gcc/tree-loop-distribution.c b/gcc/tree-loop-distribution.c index 8b91a30..65aa1df 100644 --- a/gcc/tree-loop-distribution.c +++ b/gcc/tree-loop-distribution.c @@ -3203,6 +3203,16 @@ find_seed_stmts_for_distribution (class loop *loop, vec<gimple *> *work_list) /* Initialize the worklist with stmts we seed the partitions with. */ for (unsigned i = 0; i < loop->num_nodes; ++i) { + /* In irreducible sub-regions we don't know how to redirect + conditions, so fail. See PR100492. */ + if (bbs[i]->flags & BB_IRREDUCIBLE_LOOP) + { + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "loop %d contains an irreducible region.\n", + loop->num); + work_list->truncate (0); + break; + } for (gphi_iterator gsi = gsi_start_phis (bbs[i]); !gsi_end_p (gsi); gsi_next (&gsi)) { |