re PR middle-end/51998 (compiler hangs on self-recursive alias attribute)

	PR middle-end/51998
	* cgraphunit.c (cgraph_analyze_function): Break cyclic aliases.
	* varpool.c (varpool_analyze_pending_decls): Likewise.

	* testsuite/gcc.dg/alias-12.c: New testcase.
	* testsuite/gcc.dg/alias-13.c: New testcase.

Co-Authored-By: Tom de Vries <tom@codesourcery.com>

From-SVN: r183836

6 files changed, 52 insertions, 0 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index c85aa65..9bb5517 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+2012-02-02 Jan Hubicka  <jh@suse.cz>
+	   Tom de Vries  <tom@codesourcery.com>
+
+	PR middle-end/51998
+	* cgraphunit.c (cgraph_analyze_function): Break cyclic aliases.
+	* varpool.c (varpool_analyze_pending_decls): Likewise.
+
 2012-02-02  Sumanth G <sumanth.gundapaneni@kpitcummins.com>
 	    Jayant R Sonar <jayant.sonar@kpitcummins.com>
 
diff --git a/gcc/cgraphunit.c b/gcc/cgraphunit.c
index 8f96d38..ddc0261 100644
--- a/gcc/cgraphunit.c
+++ b/gcc/cgraphunit.c
@@ -836,6 +836,16 @@ cgraph_analyze_function (struct cgraph_node *node)
   if (node->alias && node->thunk.alias)
     {
       struct cgraph_node *tgt = cgraph_get_node (node->thunk.alias);
+      struct cgraph_node *n;
+
+      for (n = tgt; n && n->alias;
+	   n = n->analyzed ? cgraph_alias_aliased_node (n) : NULL)
+	if (n == node)
+	  {
+	    error ("function %q+D part of alias cycle", node->decl);
+	    node->alias = false;
+	    return;
+	  }
       if (!VEC_length (ipa_ref_t, node->ref_list.references))
         ipa_record_reference (node, NULL, tgt, NULL, IPA_REF_ALIAS, NULL);
       if (node->same_body_alias)
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index bad0b70..2e97e5b 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,10 @@
+2012-02-02 Jan Hubicka  <jh@suse.cz>
+	   Tom de Vries  <tom@codesourcery.com>
+
+	PR middle-end/51998
+	* testsuite/gcc.dg/alias-12.c: New testcase.
+	* testsuite/gcc.dg/alias-13.c: New testcase.
+
 2012-02-02  Jakub Jelinek  <jakub@redhat.com>
 
 	PR target/52086
diff --git a/gcc/testsuite/gcc.dg/alias-12.c b/gcc/testsuite/gcc.dg/alias-12.c
new file mode 100644
index 0000000..721716c
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/alias-12.c
@@ -0,0 +1,9 @@
+/* { dg-do compile } */
+/* { dg-require-alias "" } */
+/* { dg-options "-O2" } */
+static void f (void) __attribute__((alias("f"))); // { dg-error "part of alias cycle" "" }
+
+void g ()
+{
+  f ();
+}
diff --git a/gcc/testsuite/gcc.dg/alias-13.c b/gcc/testsuite/gcc.dg/alias-13.c
new file mode 100644
index 0000000..a8390d4
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/alias-13.c
@@ -0,0 +1,9 @@
+/* { dg-do compile } */
+/* { dg-require-alias "" } */
+/* { dg-options "-O2" } */
+static void f (void) __attribute__((alias("g"))); static void g (void) __attribute__((alias("f"))); // { dg-error "part of alias cycle" "" }
+
+void h ()
+{
+  f ();
+}
diff --git a/gcc/varpool.c b/gcc/varpool.c
index e01accb..c2d88c3 100644
--- a/gcc/varpool.c
+++ b/gcc/varpool.c
@@ -477,6 +477,16 @@ varpool_analyze_pending_decls (void)
       if (node->alias && node->alias_of)
 	{
 	  struct varpool_node *tgt = varpool_node (node->alias_of);
+          struct varpool_node *n;
+
+	  for (n = tgt; n && n->alias;
+	       n = n->analyzed ? varpool_alias_aliased_node (n) : NULL)
+	    if (n == node)
+	      {
+		error ("variable %q+D part of alias cycle", node->decl);
+		node->alias = false;
+		continue;
+	      }
 	  if (!VEC_length (ipa_ref_t, node->ref_list.references))
 	    ipa_record_reference (NULL, node, NULL, tgt, IPA_REF_ALIAS, NULL);
 	  /* C++ FE sometimes change linkage flags after producing same body aliases.  */