[PATCH] [Annotalysis] Change to get_virtual_function_decl

[Delesley Hutchins]

This patch modifies the behavior of cp_get_virtual_function_decl in
gcc/cp/class.c so that it returns NULL if the function declaration
cannot be found.  The previous behavior was to fail with a
segmentation fault.  The method-not-found case may occur when
Annotalysis uses the function to look up a method, in cases where the
static type cannot be accurately determined.

Bootstrapped and passed GCC regression testsuite on x86_64-unknown-linux-gnu.

Okay for branches/annotalysis and google/main?

 -DeLesley


2011-07-06   DeLesley Hutchins  <deles...@google.com>
       * cp_get_virtual_function_decl.c (handle_call_gs): Changes
       function to return null if the method cannot be found.
       * thread_annot_lock-79.C: Additional annotalysis test cases


Index: gcc/cp/class.c
===================================================================
--- gcc/cp/class.c      (revision 175718)
+++ gcc/cp/class.c      (working copy)
@@ -8391,13 +8391,17 @@ cp_get_virtual_function_decl (tree ref, tree known
   HOST_WIDE_INT i = 0;
   tree v = BINFO_VIRTUALS (TYPE_BINFO (known_type));
   tree fndecl;
-
-  while (i != index)
+
+  while (v && i != index)
     {
       i += (TARGET_VTABLE_USES_DESCRIPTORS
            ? TARGET_VTABLE_USES_DESCRIPTORS : 1);
       v = TREE_CHAIN (v);
     }
+
+  /* Return null if the method is not found.  */
+  if (!v)
+    return NULL_TREE;

   fndecl = BV_FN (v);

Index: gcc/testsuite/g++.dg/thread-ann/thread_annot_lock-79.C
===================================================================
--- gcc/testsuite/g++.dg/thread-ann/thread_annot_lock-79.C      (revision 
175719)
+++ gcc/testsuite/g++.dg/thread-ann/thread_annot_lock-79.C      (working copy)
@@ -5,8 +5,20 @@

 #include "thread_annot_common.h"

-class Foo {
+class FooBase1 {
 public:
+  int dummy;
+};
+
+
+class FooBase2 : public FooBase1 {
+public:
+  virtual ~FooBase2();
+};
+
+
+class Foo : public FooBase2 {
+public:
   Mutex m;

   Foo();
@@ -39,6 +51,18 @@ void foo1(void* ptr)
   reinterpret_cast<Foo*>(ptr)->doSomething();
 }

+// downcast from structure type with no virtuals
+void foo1(FooBase1* ptr)
+{
+  reinterpret_cast<Foo*>(ptr)->doSomething();
+}
+
+// downcast from structure type with virtuals
+void foo1(FooBase2* ptr)
+{
+  reinterpret_cast<Foo*>(ptr)->doSomething();
+}
+
 // C-style cast
 void foo2(int* buf)
 {