[PATCH] tree-optimization/106881 - constrain uninit control edge add

[Richard Biener via Gcc-patches]

The following avoids adding fallthru edges to the control chain from
the post-dominator walk.

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

        PR tree-optimization/106881
        * gimple-predicate-analysis.cc (compute_control_dep_chain_pdom):
        Add only non-fallthru edges and avoid the same set of edges
        as the caller does.

        * gcc.dg/uninit-pr106881.c: New testcase.
---
 gcc/gimple-predicate-analysis.cc       |  9 ++++++---
 gcc/testsuite/gcc.dg/uninit-pr106881.c | 16 ++++++++++++++++
 2 files changed, 22 insertions(+), 3 deletions(-)
 create mode 100644 gcc/testsuite/gcc.dg/uninit-pr106881.c

diff --git a/gcc/gimple-predicate-analysis.cc b/gcc/gimple-predicate-analysis.cc
index b03b42e029e..8b7f49903c3 100644
--- a/gcc/gimple-predicate-analysis.cc
+++ b/gcc/gimple-predicate-analysis.cc
@@ -1065,9 +1065,12 @@ compute_control_dep_chain_pdom (basic_block cd_bb, 
const_basic_block dep_bb,
         gcc.dg/unninit-pred-12.c and PR106754.  */
       if (single_pred_p (cd_bb))
        {
-         edge e2 = find_edge (prev_cd_bb, cd_bb);
-         gcc_assert (e2);
-         cur_cd_chain.safe_push (e2);
+         edge e2 = single_pred_edge (cd_bb);
+         gcc_assert (e2->src == prev_cd_bb);
+         /* But avoid adding fallthru or abnormal edges.  */
+         if (!(e2->flags & (EDGE_FAKE | EDGE_ABNORMAL | EDGE_DFS_BACK))
+             && !single_succ_p (prev_cd_bb))
+           cur_cd_chain.safe_push (e2);
        }
     }
   return found_cd_chain;
diff --git a/gcc/testsuite/gcc.dg/uninit-pr106881.c 
b/gcc/testsuite/gcc.dg/uninit-pr106881.c
new file mode 100644
index 00000000000..343b13ed73d
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/uninit-pr106881.c
@@ -0,0 +1,16 @@
+/* { dg-do compile } */
+/* { dg-options "-O -fexceptions -Wuninitialized" } */
+
+void l_free (void *);
+char *l_settings_get_string ();
+void eap_append_secret ();
+inline void auto_free(void *a) {
+  void **p = a;
+  l_free(*p); /* { dg-warning "uninitialized" } */
+}
+void eap_gtc_check_settings() {
+  char *identity __attribute__((cleanup(auto_free)));
+  char password __attribute__((cleanup(auto_free)));
+  identity = l_settings_get_string();
+  eap_append_secret();
+}
-- 
2.35.3