Loop optimizers expect to be able to insert on the preheader
edge w/o splitting it thus avoid ending up with a preheader
that enters the loop via an EH edge (or an abnormal edge).
Bootstrapped on x86_64-unknown-linux-gnu, testing in progress.
Richard.
2020-05-06 Richard Biener <rguent...@suse.de>
PR middle-end/94964
* cfgloopmanip.c (create_preheader): Require non-complex
preheader edge for CP_SIMPLE_PREHEADERS.
---
gcc/cfgloopmanip.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/gcc/cfgloopmanip.c b/gcc/cfgloopmanip.c
index 50c7267ec49..73134a20e33 100644
--- a/gcc/cfgloopmanip.c
+++ b/gcc/cfgloopmanip.c
@@ -1506,9 +1506,10 @@ create_preheader (class loop *loop, int flags)
else
{
/* If we want simple preheaders, also force the preheader to have
- just a single successor. */
+ just a single successor and a normal edge. */
if ((flags & CP_SIMPLE_PREHEADERS)
- && !single_succ_p (single_entry->src))
+ && ((single_entry->flags & EDGE_COMPLEX)
+ || !single_succ_p (single_entry->src)))
need_forwarder_block = true;
/* If we want fallthru preheaders, also create forwarder block when
preheader ends with a jump or has predecessors from loop. */
--
2.25.1
