Patch: RFA: versioning gcj classes

[Tom Tromey <tromey at redhat dot com>]

This is a slightly revised (function name change) version of a patch I
sent last week concerning versioning gcj-compiled classes.  See the
original thread:

    http://gcc.gnu.org/ml/java-patches/2005-q1/msg00082.html

I've now run this through the test suite, in addition to the tests
mentioned in my earlier post.

Ok?

Tom

Index: gcc/java/ChangeLog
from  Tom Tromey  <tromey@redhat.com>

	* java-tree.h (gcj_abi_version): Declare.
	* class.c (make_class_data): Push gcj_abi_version into "next"
	field.
	* decl.c (gcj_abi_version): New global.
	(parse_version): New function.
	(java_init_decl_processing): Call it.
	Include version.h.
	(GCJ_BINARYCOMPAT_ADDITION): New define.

Index: gcc/java/class.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/java/class.c,v
retrieving revision 1.219
diff -u -r1.219 class.c
--- gcc/java/class.c 13 Dec 2004 06:57:13 -0000 1.219
+++ gcc/java/class.c 20 Jan 2005 00:05:29 -0000
@@ -1,5 +1,5 @@
 /* Functions related to building classes and their related objects.
-   Copyright (C) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004
+   Copyright (C) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005
    Free Software Foundation, Inc.
 
 This file is part of GCC.
@@ -1741,7 +1741,7 @@
   FINISH_RECORD_CONSTRUCTOR (temp);
   START_RECORD_CONSTRUCTOR (cons, class_type_node);
   PUSH_SUPER_VALUE (cons, temp);
-  PUSH_FIELD_VALUE (cons, "next", null_pointer_node);
+  PUSH_FIELD_VALUE (cons, "next", gcj_abi_version);
   PUSH_FIELD_VALUE (cons, "name", build_utf8_ref (DECL_NAME (type_decl)));
   PUSH_FIELD_VALUE (cons, "accflags",
 		    build_int_cst (NULL_TREE,
Index: gcc/java/decl.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/java/decl.c,v
retrieving revision 1.206
diff -u -r1.206 decl.c
--- gcc/java/decl.c 27 Nov 2004 20:48:16 -0000 1.206
+++ gcc/java/decl.c 20 Jan 2005 00:05:30 -0000
@@ -1,6 +1,6 @@
 /* Process declarations and variables for the GNU compiler for the
    Java(TM) language.
-   Copyright (C) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004
+   Copyright (C) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005
    Free Software Foundation, Inc.
 
 This file is part of GCC.
@@ -47,6 +47,7 @@
 #include "cgraph.h"
 #include "tree-inline.h"
 #include "target.h"
+#include "version.h"
 
 #if defined (DEBUG_JAVA_BINDING_LEVELS)
 extern void indent (void);
@@ -58,6 +59,13 @@
 static struct binding_level *make_binding_level (void);
 static tree create_primitive_vtable (const char *);
 static tree check_local_unnamed_variable (tree, tree, tree);
+static void parse_version (void);
+
+/* Used when computing the ABI version.  */
+#define GCJ_BINARYCOMPAT_ADDITION 5
+
+/* The ABI version number.  */
+tree gcj_abi_version;
 
 /* Name of the Cloneable class.  */
 tree java_lang_cloneable_identifier_node;
@@ -559,6 +567,48 @@
   return t;
 }
 
+/* Parse the version string and compute the ABI version number.  */
+static void
+parse_version (void)
+{
+  const char *p = version_string;
+  unsigned int major = 0, minor = 0;
+  unsigned int abi_version;
+
+  /* Skip leading junk.  */
+  while (*p && !ISDIGIT (*p))
+    ++p;
+  gcc_assert (*p);
+
+  /* Extract major version.  */
+  while (ISDIGIT (*p))
+    {
+      major = major * 10 + *p - '0';
+      ++p;
+    }
+
+  gcc_assert (*p == '.' || ISDIGIT (p[1]));
+  ++p;
+
+  /* Extract minor version.  */
+  while (ISDIGIT (*p))
+    {
+      minor = minor * 10 + *p - '0';
+      ++p;
+    }
+
+  /* Implicit in this computation is the idea that we won't break the
+     old-style binary ABI in a minor release.  */
+  abi_version = 10000 * major + 10 * minor;
+  /* It is helpful to distinguish BC ABI from ordinary ABI at this
+     level, since at some point we will recognize a variety of BC ABIs
+     (objects generated by different version of gcj), but will
+     probably always require strict matching for ordinary ABI.  */
+  if (flag_indirect_dispatch)
+    abi_version += GCJ_BINARYCOMPAT_ADDITION;
+
+  gcj_abi_version = build_int_cstu (ptr_type_node, abi_version);
+}
 
 void
 java_init_decl_processing (void)
@@ -1100,6 +1150,8 @@
 #if 0
   soft_fmodf_node = built_in_decls[BUILT_IN_FMODF];
 #endif
+
+  parse_version ();
 }
 
 
Index: gcc/java/java-tree.h
===================================================================
RCS file: /cvs/gcc/gcc/gcc/java/java-tree.h,v
retrieving revision 1.224
diff -u -r1.224 java-tree.h
--- gcc/java/java-tree.h 6 Dec 2004 15:32:37 -0000 1.224
+++ gcc/java/java-tree.h 20 Jan 2005 00:05:31 -0000
@@ -1,6 +1,6 @@
 /* Definitions for parsing and type checking for the GNU compiler for
    the Java(TM) language.
-   Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004
+   Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005
    Free Software Foundation, Inc.
 
 This file is part of GCC.
@@ -274,6 +274,7 @@
 
 extern GTY(()) tree java_lang_cloneable_identifier_node;
 extern GTY(()) tree java_io_serializable_identifier_node;
+extern GTY(()) tree gcj_abi_version;
 
 enum java_tree_index
 {
Index: libjava/ChangeLog
from  Tom Tromey  <tromey@redhat.com>

	* java/lang/Class.h (next): Updated documentation.
	* java/lang/natClassLoader.cc (_Jv_RegisterClasses): Use
	_Jv_CheckABIVersion.
	(_Jv_RegisterClasses_Counted): Likewise.
	(_Jv_RegisterClassHookDefault): Fix starting condition of
	duplicate-checking loop.
	* include/jvm.h (GCJ_VERSION): New define.
	(GCJ_BINARYCOMPAT_ADDITION): Likewise.
	(_Jv_CheckABIVersion): New function.

Index: libjava/include/jvm.h
===================================================================
RCS file: /cvs/gcc/gcc/libjava/include/jvm.h,v
retrieving revision 1.74
diff -u -r1.74 jvm.h
--- libjava/include/jvm.h 14 Jan 2005 07:36:27 -0000 1.74
+++ libjava/include/jvm.h 20 Jan 2005 00:05:42 -0000
@@ -566,4 +566,19 @@
 
 extern void _Jv_RegisterBootstrapPackages ();
 
+
+// This is used to find ABI versions we recognize.
+#define GCJ_VERSION (__GNUC__ * 10000 + __GNUC_MINOR__ * 10)
+#define GCJ_BINARYCOMPAT_ADDITION 5
+
+inline bool
+_Jv_CheckABIVersion (unsigned long value)
+{
+  // For this release, recognize just our defined C++ ABI and our
+  // defined BC ABI.  (In the future we may recognize past BC ABIs as
+  // well.)
+  return (value == GCJ_VERSION
+	  || value == (GCJ_VERSION + GCJ_BINARYCOMPAT_ADDITION));
+}
+
 #endif /* __JAVA_JVM_H__ */
Index: libjava/java/lang/Class.h
===================================================================
RCS file: /cvs/gcc/gcc/libjava/java/lang/Class.h,v
retrieving revision 1.75
diff -u -r1.75 Class.h
--- libjava/java/lang/Class.h 10 Jan 2005 19:39:25 -0000 1.75
+++ libjava/java/lang/Class.h 20 Jan 2005 00:05:42 -0000
@@ -488,7 +488,9 @@
 
   friend void ::_Jv_sharedlib_register_hook (jclass klass);
 
-  // Chain for class pool.
+  // Chain for class pool.  This also doubles as the ABI version
+  // number.  It is only used for this purpose at class registration
+  // time, and only for precompiled classes.
   jclass next;
   // Name of class.
   _Jv_Utf8Const *name;
Index: libjava/java/lang/natClassLoader.cc
===================================================================
RCS file: /cvs/gcc/gcc/libjava/java/lang/natClassLoader.cc,v
retrieving revision 1.74
diff -u -r1.74 natClassLoader.cc
--- libjava/java/lang/natClassLoader.cc 10 Jan 2005 19:39:26 -0000 1.74
+++ libjava/java/lang/natClassLoader.cc 20 Jan 2005 00:05:43 -0000
@@ -122,7 +122,8 @@
     {
       jclass klass = *classes;
 
-      (*_Jv_RegisterClassHook) (klass);
+      if (_Jv_CheckABIVersion ((unsigned long) klass->next))
+	(*_Jv_RegisterClassHook) (klass);
     }
 }
 
@@ -135,7 +136,8 @@
     {
       jclass klass = classes[i];
 
-      (*_Jv_RegisterClassHook) (klass);
+      if (_Jv_CheckABIVersion ((unsigned long) klass->next))
+	(*_Jv_RegisterClassHook) (klass);
     }
 }
 
@@ -144,12 +146,10 @@
 {
   jint hash = HASH_UTF (klass->name);
 
-  // The BC ABI makes this check unnecessary: we always resolve all
-  // data references via the appropriate class loader, so the kludge
-  // that required this check has gone.
   // If the class is already registered, don't re-register it.
-  jclass check_class = klass->next;
-  while (check_class != NULL)
+  for (jclass check_class = loaded_classes[hash];
+       check_class != NULL;
+       check_class = check_class->next)
     {
       if (check_class == klass)
 	{
@@ -170,8 +170,6 @@
 	      throw new java::lang::VirtualMachineError (str);
 	    }
 	}
-
-      check_class = check_class->next;
     }
 
   // FIXME: this is really bogus!