re PR ipa/60965 (IPA: Devirtualization versus placement new)

	PR ipa/60965
	* ipa-devirt.c (get_class_context): Allow POD to change to non-POD.
	* g++.dg/ipa/devirt-32.C: New testcase.

From-SVN: r210086

gcc/ChangeLog

+2014-05-05  Jan Hubicka  <hubicka@ucw.cz>
+
+	PR ipa/60965
+	* ipa-devirt.c (get_class_context): Allow POD to change to non-POD.
+
 2014-05-05  Radovan Obradovic  <robradovic@mips.com>
             Tom de Vries  <tom@codesourcery.com>
 

gcc/ipa-devirt.c

@@ -1137,6 +1137,17 @@ give_up:
   context->outer_type = expected_type;
   context->offset = 0;
   context->maybe_derived_type = true;
+  context->maybe_in_construction = true;
+  /* POD can be changed to an instance of a polymorphic type by
+     placement new.  Here we play safe and assume that any
+     non-polymorphic type is POD.  */
+  if ((TREE_CODE (type) != RECORD_TYPE
+       || !TYPE_BINFO (type)
+       || !polymorphic_type_binfo_p (TYPE_BINFO (type)))
+      && (TREE_CODE (TYPE_SIZE (type)) != INTEGER_CST
+	  || (offset + tree_to_uhwi (TYPE_SIZE (expected_type)) <=
+	      tree_to_uhwi (TYPE_SIZE (type)))))
+    return true;
   return false;
 }
 

gcc/testsuite/ChangeLog

+2014-05-05  Jan Hubicka  <hubicka@ucw.cz>
+
+	PR ipa/60965
+	* g++.dg/ipa/devirt-32.C: New testcase.
+
 2014-05-05  Richard Biener  <rguenther@suse.de>
 
 	PR middle-end/61010

gcc/testsuite/g++.dg/ipa/devirt-32.C

+/* { dg-options "-O2 -std=c++11 -fdump-ipa-inline"  } */
+#include <new>
+
+class EmbeddedObject {
+public:
+  virtual int val() { return 2; }
+};
+
+class Container {
+  alignas(EmbeddedObject) char buffer[sizeof(EmbeddedObject)];
+public:
+  EmbeddedObject *obj() { return (EmbeddedObject*)buffer; }
+  Container() { new (buffer) EmbeddedObject(); }
+};
+
+Container o;
+
+int main()
+{
+  __builtin_printf("%d\n", o.obj()->val());
+}
+/* { dg-final { scan-ipa-dump-not "__builtin_unreachable"  "inline"  } } */
+/* { dg-final { cleanup-ipa-dump "inline" } } */