2010-10-25  Jie Zhang  <jie@codesourcery.com>

	Issue #9812

	Backport from mainline:

	gcc/
	2010-10-25  Jie Zhang  <jie@codesourcery.com>
	* combine.c (try_combine): If insns need to be kept around,
	check that they can be copied in the merged instruction.

	gcc/testsuite/
	2010-10-25  Jie Zhang  <jie@codesourcery.com>
	* g++.dg/opt/combine.c: New test.

=== modified file 'gcc/combine.c'
--- old/gcc/combine.c	2010-09-20 22:37:32 +0000
+++ new/gcc/combine.c	2010-11-04 12:39:28 +0000
@@ -2809,6 +2809,17 @@
     = i1 && ! (i1_feeds_i3 ? dead_or_set_p (i3, i1dest)
 	       : (dead_or_set_p (i3, i1dest) || dead_or_set_p (i2, i1dest)));
 
+  /* We are about to copy insns for the case where they need to be kept
+     around.  Check that they can be copied in the merged instruction.  */
+
+  if (targetm.cannot_copy_insn_p
+      && ((added_sets_2 && targetm.cannot_copy_insn_p (i2))
+	  || (i1 && added_sets_1 && targetm.cannot_copy_insn_p (i1))))
+    {
+      undo_all ();
+      return 0;
+    }
+
   /* If the set in I2 needs to be kept around, we must make a copy of
      PATTERN (I2), so that when we substitute I1SRC for I1DEST in
      PATTERN (I2), we are only substituting for the original I1DEST, not into

=== added file 'gcc/testsuite/g++.dg/opt/combine.C'
--- old/gcc/testsuite/g++.dg/opt/combine.C	1970-01-01 00:00:00 +0000
+++ new/gcc/testsuite/g++.dg/opt/combine.C	2010-11-04 12:39:28 +0000
@@ -0,0 +1,72 @@
+// { dg-do assemble { target fpic } }
+// { dg-options "-O2 -fweb -fPIC -fvisibility=hidden" }
+
+class QBasicAtomicInt
+{
+public:
+  volatile int _q_value;
+  inline operator int () const {return _q_value;}
+};
+class QVariant;
+class QScriptContext;
+class QScriptEngine;
+class QScriptValue
+{
+public:
+  QVariant toVariant () const;
+};
+class QScriptDebuggerBackendPrivate
+{
+  static QScriptValue trace (QScriptContext *context);
+};
+template <typename T> struct QMetaTypeId { };
+template <typename T> struct QMetaTypeId2
+{
+  static inline int qt_metatype_id ()
+  {
+    return QMetaTypeId<T>::qt_metatype_id () ;
+  }
+};
+template <typename T> inline int qMetaTypeId (T * = 0)
+{
+  return QMetaTypeId2<T>::qt_metatype_id () ;
+}
+class QVariant { };
+template<typename T> inline T qvariant_cast (const QVariant &v)
+{
+  const int vid = qMetaTypeId<T> ((0)) ;
+};
+class QScriptContext
+{
+public: 
+  QScriptValue callee () const;
+};
+class QScriptEngine  
+{
+public:
+  static bool convertV2 (const QScriptValue &value , int type , void *ptr) ;
+};
+inline bool qscriptvalue_cast_helper (const QScriptValue &value , int type , void *ptr)
+{
+  return QScriptEngine::convertV2 (value, type, ptr) ;
+}
+template<typename T> T qscriptvalue_cast (const QScriptValue &value)
+{
+  T t;
+  const int id = qMetaTypeId<T> () ;
+  if ( qscriptvalue_cast_helper (value, id, &t))
+    return qvariant_cast<T> (value.toVariant ()) ;
+}
+template <> struct QMetaTypeId< QScriptDebuggerBackendPrivate* >
+{
+  static int qt_metatype_id ()
+  {
+    static QBasicAtomicInt metatype_id = { (0) };
+    return metatype_id;
+  }
+};
+QScriptValue QScriptDebuggerBackendPrivate::trace (QScriptContext *context)
+{
+  QScriptValue data = context->callee () ;
+  QScriptDebuggerBackendPrivate *self = qscriptvalue_cast<QScriptDebuggerBackendPrivate*> (data) ;
+}