Hi.
The PR is about a verification error where we have a FALLTHRU edge that
contains barrier instruction. The instruction is created during bbpart pass
in add_labels_and_missing_jumps (emit_barrier_after_bb). At that time, the
basic blocks live in a different partition (hot,cold). Later then the edge
is redirected and the basic blocks are in a same partition. The code in
cfg_layout_redirect_edge_and_branch correctly sets FALLTHRU flag, but forgets
to remove the created barrier.
The problem is seen during build of Firefox with LTO+PGO in one LTRANS unit.
Patch can bootstrap on x86_64-linux-gnu and survives regression tests.
Ready to be installed?
Thanks,
Martin
gcc/ChangeLog:
2019-01-23 Martin Liska <mli...@suse.cz>
PR lto/88858
* cfgrtl.c (cfg_layout_redirect_edge_and_branch): When BB_FOOTER
contains a BARRIER and we're removing a crossing jump, remove
the barrier.
---
gcc/cfgrtl.c | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)
diff --git a/gcc/cfgrtl.c b/gcc/cfgrtl.c
index 172bdf585d0..5dd316efb63 100644
--- a/gcc/cfgrtl.c
+++ b/gcc/cfgrtl.c
@@ -4396,6 +4396,25 @@ cfg_layout_redirect_edge_and_branch (edge e, basic_block dest)
"Removing crossing jump while redirecting edge form %i to %i\n",
e->src->index, dest->index);
delete_insn (BB_END (src));
+
+ /* Unlink a BARRIER that can be still in BB_FOOTER. */
+ rtx_insn *insn = BB_FOOTER (src);
+ while (insn != NULL_RTX && !BARRIER_P (insn))
+ insn = NEXT_INSN (insn);
+
+ if (insn != NULL_RTX)
+ {
+ if (insn == BB_FOOTER (src))
+ BB_FOOTER (src) = NULL;
+ else
+ {
+ if (PREV_INSN (insn))
+ SET_NEXT_INSN (PREV_INSN (insn)) = NEXT_INSN (insn);
+ if (NEXT_INSN (insn))
+ SET_PREV_INSN (NEXT_INSN (insn)) = PREV_INSN (insn);
+ }
+ }
+
e->flags |= EDGE_FALLTHRU;
}
