re PR c++/58377 (spurious "may be used uninitialized" warning with -Og)

2013-09-11  Richard Biener  <rguenther@suse.de>

	PR middle-end/58377
	* passes.def: Split critical edges before late uninit warning passes.
	* tree-cfg.c (pass_split_crit_edges): Implement clone method.

	* g++.dg/uninit-pred-4.C: New testcase.

From-SVN: r202496

gcc/ChangeLog

+2013-09-11  Richard Biener  <rguenther@suse.de>
+
+	PR middle-end/58377
+	* passes.def: Split critical edges before late uninit warning passes.
+	* tree-cfg.c (pass_split_crit_edges): Implement clone method.
+
 2013-09-11  Jakub Jelinek  <jakub@redhat.com>
 
 	PR tree-optimization/58385

gcc/passes.def

@@ -249,6 +249,9 @@ along with GCC; see the file COPYING3.  If not see
 	 account for the predicates protecting the set and the use of each
 	 variable.  Using a representation like Gated Single Assignment
 	 may help.  */
+      /* Split critical edges before late uninit warning to reduce the
+         number of false positives from it.  */
+      NEXT_PASS (pass_split_crit_edges);
       NEXT_PASS (pass_late_warn_uninitialized);
       NEXT_PASS (pass_dse);
       NEXT_PASS (pass_forwprop);
@@ -282,6 +285,9 @@ along with GCC; see the file COPYING3.  If not see
       /* ???  We do want some kind of loop invariant motion, but we possibly
          need to adjust LIM to be more friendly towards preserving accurate
 	 debug information here.  */
+      /* Split critical edges before late uninit warning to reduce the
+         number of false positives from it.  */
+      NEXT_PASS (pass_split_crit_edges);
       NEXT_PASS (pass_late_warn_uninitialized);
       NEXT_PASS (pass_uncprop);
       NEXT_PASS (pass_local_pure_const);

gcc/testsuite/ChangeLog

+2013-09-11  Richard Biener  <rguenther@suse.de>
+
+	PR middle-end/58377
+	* g++.dg/uninit-pred-4.C: New testcase.
+
 2013-09-11  Jakub Jelinek  <jakub@redhat.com>
 
 	PR tree-optimization/58385

gcc/testsuite/g++.dg/uninit-pred-4.C

+/* { dg-do compile } */
+/* { dg-options "-Wuninitialized -Og" } */
+
+int pop ();
+int pop_first_bucket;
+
+int my_pop ()
+{
+  int out;  // { dg-bogus "uninitialized" "uninitialized variable warning" }
+
+  while (pop_first_bucket)
+    if (pop_first_bucket && (out = pop()))
+      return out;
+
+  return 0;
+}

gcc/tree-cfg.c

@@ -7929,6 +7929,7 @@ public:
   /* opt_pass methods: */
   unsigned int execute () { return split_critical_edges (); }
 
+  opt_pass * clone () { return new pass_split_crit_edges (ctxt_); }
 }; // class pass_split_crit_edges
 
 } // anon namespace