Proposed Target Macro for Java Front-end: MODIFY_JNI_METHOD_CALL

[Ranjit Mathew <rmathew at hotmail dot com>]

Hi,

    I would like to propose a new target macro 'MODIFY_JNI_METHOD_CALL'
to allow targets like Cygwin and MinGW to modify the call generated
by the GCC Java front-end to invoke a JNI (Java Native Interface)
method.

For background information on the need for such a macro, please
see the thread starting from this message:

    http://gcc.gnu.org/ml/gcc/2002-11/msg00734.html

The following proposed patch to "gcc/doc/tm.texi" explains this
macro in more detail:
------------------------------- 8< -----------------------------------
--- gcc/doc/tm.texi	2002-12-05 05:00:30.000000000 +0530
+++ gcc/doc/tm.texi	2002-12-05 07:03:16.000000000 +0530
@@ -9141,4 +9141,20 @@
 lists.

+@findex MODIFY_JNI_METHOD_CALL
+@item MODIFY_JNI_METHOD_CALL (@var{mdecl})
+Define this macro to a C expression representing a variant of
+the method call @var{mdecl}, if Java Native Interface (JNI) methods
+must be invoked differently than other methods on your target
+machine. For example, on 32-bit Windows, JNI methods must be invoked
+using the @code{stdcall} calling convention and this macro
+could then be defined as this expression:
+
+@smallexample
+build_type_attribute_variant (@var{mdecl},
+                              build_tree_list
+                              (get_identifier ("stdcall"),
+                               NULL))
+@end smallexample
+
 @end table
------------------------------- 8< -----------------------------------

The following proposed patch would make the Java front-end use this
macro:
------------------------------- 8< -----------------------------------
--- gcc/java/expr.c	2002-12-05 07:12:31.000000000 +0530
+++ gcc/java/expr.c	2002-12-05 07:15:34.000000000 +0530
@@ -2266,7 +2266,11 @@
 		 tree_cons (NULL_TREE, build_utf8_ref (tem), lookup_arg));

-  jni_func_type
-    = build_pointer_type (build_function_type (TREE_TYPE (TREE_TYPE 
(method)),
-					       arg_types));
+  tem = build_function_type (TREE_TYPE (TREE_TYPE (method)), arg_types);
+
+  #ifdef MODIFY_JNI_METHOD_CALL
+  tem = MODIFY_JNI_METHOD_CALL (tem);
+  #endif
+
+  jni_func_type = build_pointer_type (tem);

   jnifunc = build (COND_EXPR, ptr_type_node,
------------------------------- 8< -----------------------------------

Finally, the following proposed patch will make the Cygwin/MinGW targets
define this macro appropriately (mingw32.h #include-s cygwin.h):
------------------------------- 8< -----------------------------------
--- gcc/config/i386/cygwin.h	2002-12-05 07:19:36.000000000 +0530
+++ gcc/config/i386/cygwin.h	2002-12-05 07:23:10.000000000 +0530
@@ -398,4 +398,12 @@
      }

+/* Java Native Interface (JNI) methods on Win32 are invoked using
+   the stdcall calling convention */
+#undef MODIFY_JNI_METHOD_CALL
+#define MODIFY_JNI_METHOD_CALL(MDECL) \
+  build_type_attribute_variant ((MDECL), build_tree_list \
+                                         (get_identifier ("stdcall"), \
+                                          NULL))
+
 /* External function declarations.  */
------------------------------- 8< -----------------------------------

Does this look all right? If it does, I can submit it as patches
to the gcc-patches, mingw-patches and java-patches mailing lists.

I am sorry if this is not the right way to propose a new target
macro.

Sincerely Yours,
Ranjit.

--
Ranjit Mathew        Email: rmathew AT hotmail DOT com
Bangalore,
INDIA.               Web: http://ranjitmathew.tripod.com/