[PATCH] tree-optimization/106422 - verify block copying in forward threading

[Richard Biener via Gcc-patches]

The forward threader failed to check whether it can actually duplicate
blocks.  The following adds this in a similar place the backwards threader
performs this check.

Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed.

        PR tree-optimization/106422
        * tree-ssa-threadupdate.cc (fwd_jt_path_registry::update_cfg):
        Check whether we can copy thread blocks and cancel the thread if not.

        * gcc.dg/torture/pr106422.c: New testcase.
---
 gcc/testsuite/gcc.dg/torture/pr106422.c | 14 ++++++++++++++
 gcc/tree-ssa-threadupdate.cc            |  4 +++-
 2 files changed, 17 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/gcc.dg/torture/pr106422.c

diff --git a/gcc/testsuite/gcc.dg/torture/pr106422.c 
b/gcc/testsuite/gcc.dg/torture/pr106422.c
new file mode 100644
index 00000000000..a2cef1aecb6
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr106422.c
@@ -0,0 +1,14 @@
+/* { dg-do compile } */
+
+void vfork() __attribute__((__leaf__));
+void semanage_reload_policy(char *arg, void cb(void))
+{
+  if (!arg)
+    {
+      cb();
+      return;
+    }
+  vfork();
+  if (arg)
+    __builtin_free(arg);
+}
diff --git a/gcc/tree-ssa-threadupdate.cc b/gcc/tree-ssa-threadupdate.cc
index f901c7759e3..0f2b319d44a 100644
--- a/gcc/tree-ssa-threadupdate.cc
+++ b/gcc/tree-ssa-threadupdate.cc
@@ -2678,7 +2678,9 @@ fwd_jt_path_registry::update_cfg (bool 
may_peel_loop_headers)
        for (j = 0; j < path->length (); j++)
          {
            edge e = (*path)[j]->e;
-           if (m_removed_edges->find_slot (e, NO_INSERT))
+           if (m_removed_edges->find_slot (e, NO_INSERT)
+               || ((*path)[j]->type == EDGE_COPY_SRC_BLOCK
+                   && !can_duplicate_block_p (e->src)))
              break;
          }
 
-- 
2.35.3