[gcc r13-4594] ivopts: Fix IP_END handling for asm goto [PR107997]

[Jakub Jelinek <jakub@gcc.gnu.org>]

https://gcc.gnu.org/g:7676235f690e624b7ed41a22b22ce8ccfac1492f

commit r13-4594-g7676235f690e624b7ed41a22b22ce8ccfac1492f
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Sat Dec 10 16:50:39 2022 +0100

    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.

Diff:
---
 gcc/testsuite/gcc.c-torture/compile/pr107997.c | 23 +++++++++++++++++++++++
 gcc/tree-ssa-loop-ivopts.cc                    |  7 +++++++
 2 files changed, 30 insertions(+)

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 00000000000..89e1fd349c3
--- /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 5b9044fc3f3..ebd4aecce37 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: