6837094: False positive for "meet not symmetric" failure

Summary: Have the meet not symmetric check recursively do the interface-vs-oop check on array subtypes.
Reviewed-by: jrose
Contributed-by: rasbold@google.com

src/share/vm/opto/type.cpp

@@ -487,6 +487,23 @@ bool Type::is_nan()    const {
   return false;
 }
 
+//----------------------interface_vs_oop---------------------------------------
+#ifdef ASSERT
+bool Type::interface_vs_oop(const Type *t) const {
+  bool result = false;
+
+  const TypeInstPtr* this_inst = this->isa_instptr();
+  const TypeInstPtr*    t_inst =    t->isa_instptr();
+  if( this_inst && this_inst->is_loaded() && t_inst && t_inst->is_loaded() ) {
+    bool this_interface = this_inst->klass()->is_interface();
+    bool    t_interface =    t_inst->klass()->is_interface();
+    result = this_interface ^ t_interface;
+  }
+
+  return result;
+}
+#endif
+
 //------------------------------meet-------------------------------------------
 // Compute the MEET of two types.  NOT virtual.  It enforces that meet is
 // commutative and the lattice is symmetric.
@@ -507,16 +524,8 @@ const Type *Type::meet( const Type *t ) const {
   // Interface meet Oop is Not Symmetric:
   // Interface:AnyNull meet Oop:AnyNull == Interface:AnyNull
   // Interface:NotNull meet Oop:NotNull == java/lang/Object:NotNull
-  const TypeInstPtr* this_inst = this->isa_instptr();
-  const TypeInstPtr*    t_inst =    t->isa_instptr();
-  bool interface_vs_oop = false;
-  if( this_inst && this_inst->is_loaded() && t_inst && t_inst->is_loaded() ) {
-    bool this_interface = this_inst->klass()->is_interface();
-    bool    t_interface =    t_inst->klass()->is_interface();
-    interface_vs_oop = this_interface ^ t_interface;
-  }
 
-  if( !interface_vs_oop && (t2t != t->_dual || t2this != _dual) ) {
+  if( !interface_vs_oop(t) && (t2t != t->_dual || t2this != _dual) ) {
     tty->print_cr("=== Meet Not Symmetric ===");
     tty->print("t   =                   ");         t->dump(); tty->cr();
     tty->print("this=                   ");            dump(); tty->cr();
@@ -1800,6 +1809,17 @@ int TypeAry::hash(void) const {
   return (intptr_t)_elem + (intptr_t)_size;
 }
 
+//----------------------interface_vs_oop---------------------------------------
+#ifdef ASSERT
+bool TypeAry::interface_vs_oop(const Type *t) const {
+  const TypeAry* t_ary = t->is_ary();
+  if (t_ary) {
+    return _elem->interface_vs_oop(t_ary->_elem);
+  }
+  return false;
+}
+#endif
+
 //------------------------------dump2------------------------------------------
 #ifndef PRODUCT
 void TypeAry::dump2( Dict &d, uint depth, outputStream *st ) const {
@@ -3389,6 +3409,17 @@ const Type *TypeAryPtr::xdual() const {
   return new TypeAryPtr( dual_ptr(), _const_oop, _ary->dual()->is_ary(),_klass, _klass_is_exact, dual_offset(), dual_instance_id() );
 }
 
+//----------------------interface_vs_oop---------------------------------------
+#ifdef ASSERT
+bool TypeAryPtr::interface_vs_oop(const Type *t) const {
+  const TypeAryPtr* t_aryptr = t->isa_aryptr();
+  if (t_aryptr) {
+    return _ary->interface_vs_oop(t_aryptr->_ary);
+  }
+  return false;
+}
+#endif
+
 //------------------------------dump2------------------------------------------
 #ifndef PRODUCT
 void TypeAryPtr::dump2( Dict &d, uint depth, outputStream *st ) const {

src/share/vm/opto/type.hpp

@@ -190,6 +190,11 @@ public:
   // Currently, it also works around limitations involving interface types.
   virtual const Type *filter( const Type *kills ) const;
 
+#ifdef ASSERT
+  // One type is interface, the other is oop
+  virtual bool interface_vs_oop(const Type *t) const;
+#endif
+
   // Returns true if this pointer points at memory which contains a
   // compressed oop references.
   bool is_ptr_to_narrowoop() const;
@@ -546,6 +551,10 @@ public:
   virtual const Type *xmeet( const Type *t ) const;
   virtual const Type *xdual() const;    // Compute dual right now.
   bool ary_must_be_exact() const;  // true if arrays of such are never generic
+#ifdef ASSERT
+  // One type is interface, the other is oop
+  virtual bool interface_vs_oop(const Type *t) const;
+#endif
 #ifndef PRODUCT
   virtual void dump2( Dict &d, uint, outputStream *st  ) const; // Specialized per-Type dumping
 #endif
@@ -867,6 +876,10 @@ public:
   }
   static const TypeAryPtr *_array_body_type[T_CONFLICT+1];
   // sharpen the type of an int which is used as an array size
+#ifdef ASSERT
+  // One type is interface, the other is oop
+  virtual bool interface_vs_oop(const Type *t) const;
+#endif
 #ifndef PRODUCT
   virtual void dump2( Dict &d, uint depth, outputStream *st ) const; // Specialized per-Type dumping
 #endif

test/compiler/6837094/Test.java

+/*
+ * Copyright 2009 Sun Microsystems, Inc.  All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ */
+
+/**
+ * @test
+ * @bug 6837094
+ * @summary False positive for "meet not symmetric" failure
+ *
+ * @run main/othervm -Xbatch -XX:CompileOnly=Test.collectIs,Test$Factory$1.getArray,Test$Factory$2.getArray Test
+ */
+
+import java.util.Set;
+import java.util.HashSet;
+
+public class Test {
+
+  private interface Factory<M extends Interface> {
+    Factory<Child0> Zero = new Factory<Child0>() {
+      public Child0[] getArray() { return new Child0[1]; }
+    };
+
+    Factory<Child1> One = new Factory<Child1>() {
+      public Child1[] getArray() { return new Child1[1]; }
+    };
+
+    M[] getArray();
+  }
+
+  /**
+   * C2 asserts when compiling this method. Bimorphic inlining happens at
+   * getArray call site. A Phi in the catch block tries to join the meet type
+   * from he inline site (Parent[]) with the type expected by CI (Interface[]).
+   *
+   * C2 throws an assert when it doesn't need to.
+   */
+  private static <I extends Interface> void collectIs(
+      Factory<I> factory, Set<Interface> s) {
+    for (I i : factory.getArray()) {
+      try {
+        s.add(i);
+      } catch (Exception e) {
+      }
+    }
+  }
+
+  static public void main(String argv[]) {
+    Set<Interface> s = new HashSet();
+
+    for (int i = 0; i < 25000; i++) {
+      collectIs(Factory.Zero, s);
+      collectIs(Factory.One, s);
+    }
+  }
+}
+
+/**
+ * Establish necessary class hierarchy
+ */
+
+interface Interface {
+}
+
+class Parent {
+}
+
+class Child0 extends Parent implements Interface {
+}
+
+class Child1 extends Parent implements Interface {
+}
+
+class Child2 extends Parent implements Interface {
+}