From: Jakub Jelinek <jakub@redhat.com>
Date: Sat, 10 Dec 2022 15:50:39 +0000 (+0100)
Subject: ivopts: Fix IP_END handling for asm goto [PR107997]
X-Git-Tag: release-12.2.mpacbti-rel1~69
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=89daf0dd6f1748077c03fbeb27ca5980a0b9abd5;p=thirdparty%2Fgcc.git

ivopts: Fix IP_END handling for asm goto [PR107997]

The following testcase ICEs, because the latch bb ends with
asm goto which has both fallthrough to the header and one or more labels
in the header too.  In that case there is just a single edge out of the
latch block, but still the asm goto is stmt_ends_bb_p statement, yet
ivopts decides to emit an IV bump at the IP_END position and inserts
it into the same bb as the asm goto after it, which then fails verification
(control flow in the middle of bb).

The following patch fixes it by splitting the latch -> header edge in that
case and inserting into the newly created bb, where split_edge ->
redirect_edge_and_branch is able to deal with this case correctly.

2022-12-10  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/107997
	* tree-ssa-loop-ivopts.cc: Include cfganal.h.
	(create_new_iv) <case IP_END>: If ip_end_pos bb is non-empty and ends
	with a stmt which ends bb, instead of adding iv update after it split
	the latch edge and insert iterator into the new latch bb.

	* gcc.c-torture/compile/pr107997.c: New test.

(cherry picked from commit 7676235f690e624b7ed41a22b22ce8ccfac1492f)
---

diff --git a/gcc/testsuite/gcc.c-torture/compile/pr107997.c b/gcc/testsuite/gcc.c-torture/compile/pr107997.c
new file mode 100644
index 000000000000..89e1fd349c3d
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/compile/pr107997.c
@@ -0,0 +1,23 @@
+/* PR tree-optimization/107997 */
+
+int a, b;
+void bar (int);
+int baz (void);
+
+void *
+foo (int x, void *y)
+{
+  asm goto ("" : : "r" (x || !a) : : l);
+l:
+  if (y)
+    return 0;
+  bar (b ? b : x);
+  while (x--)
+    {
+      if (!baz ())
+	baz ();
+      asm goto ("" : : : : l2);
+    l2:;
+    }
+  return y;
+}
diff --git a/gcc/tree-ssa-loop-ivopts.cc b/gcc/tree-ssa-loop-ivopts.cc
index a67f5d549e62..59e8df1b5a9b 100644
--- a/gcc/tree-ssa-loop-ivopts.cc
+++ b/gcc/tree-ssa-loop-ivopts.cc
@@ -131,6 +131,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "builtins.h"
 #include "tree-vectorizer.h"
 #include "dbgcnt.h"
+#include "cfganal.h"
 
 /* For lang_hooks.types.type_for_mode.  */
 #include "langhooks.h"
@@ -7235,6 +7236,12 @@ create_new_iv (struct ivopts_data *data, struct iv_cand *cand)
     case IP_END:
       incr_pos = gsi_last_bb (ip_end_pos (data->current_loop));
       after = true;
+      if (!gsi_end_p (incr_pos) && stmt_ends_bb_p (gsi_stmt (incr_pos)))
+	{
+	  edge e = find_edge (gsi_bb (incr_pos), data->current_loop->header);
+	  incr_pos = gsi_after_labels (split_edge (e));
+	  after = false;
+	}
       break;
 
     case IP_AFTER_USE: