https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81897
--- Comment #15 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
The problem is in the:
@@ -671,11 +669,9 @@
e = one_cd_chain[j];
guard_bb = e->src;
gsi = gsi_last_bb (guard_bb);
- if (gsi_end_p (gsi))
- {
- has_valid_pred = false;
- break;
- }
+ /* Ignore empty BBs as they're basically forwarder blocks. */
+ if (empty_block_p (guard_bb) && single_succ_p (guard_bb))
+ continue;
cond_stmt = gsi_stmt (gsi);
if (is_gimple_call (cond_stmt) && EDGE_COUNT (e->src->succs) >= 2)
/* Ignore EH edge. Can add assertion on the other edge's flag. */
hunk. When guard_bb is a bb that contains one or more PHIs, but no other
statements, then gsi_stmt (gsi) returns NULL and is_gimple_call will ICE on it.
So, something like:
--- gcc/tree-ssa-uninit.c.jj 2018-01-07 20:28:14.894731685 +0100
+++ gcc/tree-ssa-uninit.c 2018-01-08 09:48:11.327325457 +0100
@@ -672,6 +672,11 @@ convert_control_dep_chain_into_preds (ve
/* Ignore empty BBs as they're basically forwarder blocks. */
if (empty_block_p (guard_bb) && single_succ_p (guard_bb))
continue;
+ if (gsi_end_p (gsi))
+ {
+ has_valid_pred = false;
+ break;
+ }
cond_stmt = gsi_stmt (gsi);
if (is_gimple_call (cond_stmt) && EDGE_COUNT (e->src->succs) >= 2)
/* Ignore EH edge. Can add assertion on the other edge's flag. */
ought to fix it. Also note that for -fcompare-debug, the guard_bb could
contain just one or more PHIs and one or more debug stmts and nothing else, in
that case gsi_last_bb returns an iterator with the debug stmt, so cond_stmt
will be a DEBUG_STMT etc. in current code and will do has_valid_pred = false;
break;
PHIs have non-trivial effect though, so not really sure we can ignore them, but
I could be wrong. If we ignore them, we'd need to use gsi_last_nondebug_bb
though.
