[gcc r13-2537] tree-optimization/106881 - constrain uninit control edge add

[Richard Biener]

https://gcc.gnu.org/g:c8d3b44dfa2851659f966627835497667c5fed6c

commit r13-2537-gc8d3b44dfa2851659f966627835497667c5fed6c
Author: Richard Biener <rguenther@suse.de>
Date:   Thu Sep 8 12:22:26 2022 +0200

    tree-optimization/106881 - constrain uninit control edge add
    
    The following avoids adding fallthru edges to the control chain from
    the post-dominator walk.
    
            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.

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

diff --git a/gcc/gimple-predicate-analysis.cc b/gcc/gimple-predicate-analysis.cc
index f81af2589cd..910ab97a29e 100644
--- a/gcc/gimple-predicate-analysis.cc
+++ b/gcc/gimple-predicate-analysis.cc
@@ -1060,9 +1060,12 @@ 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();
+}