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Re: [PATCH] Handle ObjC OPS in eval.c



Michael Snyder wrote:
Adam Fedor wrote:

2003-01-02  Adam Fedor  <fedor@gnu.org>

       * Makefile.in (eval.o): Add $(objc_lang_h)
       * eval.c (evaluate_subexp_standard): Handle ObjC ops.
       * valops.c (find_function_addr): Make non-static.
       * value.h (find_function_addr): Declare.

Adam, this is OK in principal, assuming that the objc code
such as value_nsstring is being unconditionally built now.
A few remarks:

I havne't been able to resolve the problem you had with the last part of the patch, but here is an updated patch with the other changes.

2003-02-12  Adam Fedor  <fedor@gnu.org>

	* Makefile.in (eval.o): Add $(objc_lang_h)
	* eval.c (evaluate_subexp_standard): Handle ObjC ops.
	* valops.c (find_function_addr): Make non-static.
	* value.h (find_function_addr): Declare.

Index: Makefile.in
===================================================================
RCS file: /cvs/src/src/gdb/Makefile.in,v
retrieving revision 1.329
diff -u -p -r1.329 Makefile.in
--- Makefile.in	11 Feb 2003 16:11:16 -0000	1.329
+++ Makefile.in	13 Feb 2003 02:46:43 -0000
@@ -1641,7 +1642,7 @@ elfread.o: elfread.c $(defs_h) $(bfd_h) 
 environ.o: environ.c $(defs_h) $(environ_h) $(gdb_string_h)
 eval.o: eval.c $(defs_h) $(gdb_string_h) $(symtab_h) $(gdbtypes_h) \
 	$(value_h) $(expression_h) $(target_h) $(frame_h) $(language_h) \
-	$(f_lang_h) $(cp_abi_h)
+	$(f_lang_h) $(cp_abi_h) $(objc_lang_h)
 event-loop.o: event-loop.c $(defs_h) $(event_loop_h) $(event_top_h) \
 	$(gdb_string_h)
 event-top.o: event-top.c $(defs_h) $(top_h) $(inferior_h) $(target_h) \
Index: eval.c
===================================================================
RCS file: /cvs/src/src/gdb/eval.c,v
retrieving revision 1.27
diff -u -p -r1.27 eval.c
--- eval.c	14 Jan 2003 00:49:03 -0000	1.27
+++ eval.c	13 Feb 2003 02:46:44 -0000
@@ -31,6 +31,7 @@
 #include "frame.h"
 #include "language.h"		/* For CAST_IS_CONVERSION */
 #include "f-lang.h"		/* for array bound stuff */
+#include "objc-lang.h"
 #include "cp-abi.h"
 
 /* Defined in symtab.c */
@@ -471,6 +472,15 @@ evaluate_subexp_standard (struct type *e
 	goto nosideret;
       return value_string (&exp->elts[pc + 2].string, tem);
 
+    case OP_OBJC_NSSTRING:		/* Objective C Foundation Class NSString constant.  */
+      tem = longest_to_int (exp->elts[pc + 1].longconst);
+      (*pos) += 3 + BYTES_TO_EXP_ELEM (tem + 1);
+      if (noside == EVAL_SKIP)
+	{
+	  goto nosideret;
+	}
+      return (struct value *) value_nsstring (&exp->elts[pc + 2].string, tem + 1);
+
     case OP_BITSTRING:
       tem = longest_to_int (exp->elts[pc + 1].longconst);
       (*pos)
@@ -667,6 +677,295 @@ evaluate_subexp_standard (struct type *e
 	  return arg2;
 	}
 
+    case OP_OBJC_SELECTOR:
+      {				/* Objective C @selector operator.  */
+	char *sel = &exp->elts[pc + 2].string;
+	int len = longest_to_int (exp->elts[pc + 1].longconst);
+
+	(*pos) += 3 + BYTES_TO_EXP_ELEM (len + 1);
+	if (noside == EVAL_SKIP)
+	  goto nosideret;
+
+	if (sel[len] != 0)
+	  sel[len] = 0;		/* Make sure it's terminated.  */
+	return value_from_longest (lookup_pointer_type (builtin_type_void),
+				   lookup_child_selector (sel));
+      }
+
+    case OP_OBJC_MSGCALL:
+      {				/* Objective C message (method) call.  */
+
+	static unsigned long responds_selector = 0;
+	static unsigned long method_selector = 0;
+	static unsigned int selector_generation = 0;
+
+	unsigned long selector = 0;
+
+	int using_gcc = 0;
+	int struct_return = 0;
+	int sub_no_side = 0;
+
+	static struct value *msg_send = NULL;
+	static struct value *msg_send_stret = NULL;
+	static struct value *msg_send_typed = NULL;
+	static int gnu_runtime = 0;
+
+	struct value *target = NULL;
+	struct value *method = NULL;
+	struct value *called_method = NULL; 
+
+	struct type *selector_type = NULL;
+
+	struct value *ret = NULL;
+	struct symbol *sym = NULL;
+	CORE_ADDR addr = 0;
+
+	selector = exp->elts[pc + 1].longconst;
+	nargs = exp->elts[pc + 2].longconst;
+	argvec = (struct value **) alloca (sizeof (struct value *) 
+					   * (nargs + 5));
+
+	(*pos) += 3;
+
+	selector_type = lookup_pointer_type (builtin_type_void);
+	sub_no_side = (noside == EVAL_AVOID_SIDE_EFFECTS) 
+	  ? EVAL_NORMAL : noside;
+
+	target = evaluate_subexp (selector_type, exp, pos, sub_no_side);
+
+	if (value_as_long (target) == 0)
+ 	  return value_from_longest (builtin_type_long, 0);
+	
+	if (lookup_minimal_symbol ("objc_msg_lookup", 0, 0))
+	  gnu_runtime = 1;
+	
+	if (gnu_runtime)
+	  {
+	    msg_send = find_function_in_inferior ("objc_msg_lookup");
+	    msg_send_stret = find_function_in_inferior ("objc_msg_lookup");
+	    msg_send_typed = find_function_in_inferior ("objc_msg_lookup");
+	  }
+	else
+	  {
+	    msg_send = find_function_in_inferior ("objc_msgSend");
+	    msg_send_stret = find_function_in_inferior ("objc_msgSend_stret");
+	    msg_send_typed = find_function_in_inferior ("objc_msgSend");
+	  }
+
+	/* Verify target responds to method selector.  Must also
+	   account for new (NSObject) and old (Object) worlds. */
+
+	responds_selector = lookup_child_selector ("respondsToSelector:");
+	if (responds_selector == 0)
+	  responds_selector = lookup_child_selector ("respondsTo:");
+	
+	if (responds_selector == 0)
+	  error ("no 'respondsTo:' or 'respondsToSelector:' method");
+	
+	if (gnu_runtime)
+	  {
+	    method_selector = lookup_child_selector ("methodFor:");
+	    if (method_selector == 0)
+	      method_selector = lookup_child_selector ("methodForSelector:");
+	  }
+	else
+	  {
+	    method_selector = lookup_child_selector ("methodForSelector:");
+	    if (method_selector == 0)
+	      method_selector = lookup_child_selector ("methodFor:");
+	  }
+	
+	if (method_selector == 0)
+	  error ("no 'methodFor:' or 'methodForSelector:' method");
+
+	/* Call "respondsToSelector:" method, to make sure that the
+	 target class implements the user's desired method
+	 selector. */
+
+	argvec[0] = msg_send_typed;
+	argvec[1] = target;
+	argvec[2] = value_from_longest (builtin_type_long, responds_selector);
+	argvec[3] = value_from_longest (builtin_type_long, selector);
+	argvec[4] = 0;
+
+	ret = call_function_by_hand (argvec[0], 3, argvec + 1);
+	if (gnu_runtime)
+	  {
+	    /* Function objc_msg_lookup returns a pointer.  */
+	    argvec[0] = ret;
+	    ret = call_function_by_hand (argvec[0], 3, argvec + 1);
+	  }
+	if (value_as_long (ret) == 0)
+	  error ("Target does not respond to this message selector.");
+
+	/* Call "methodForSelector:" method, to get the address of a
+	   function method that implements this selector for this
+	   class.  If we can find a symbol at that address, then we
+	   know the return type, parameter types etc.  (that's a good
+	   thing). */
+
+	argvec[0] = msg_send_typed;
+	argvec[1] = target;
+	argvec[2] = value_from_longest (builtin_type_long, method_selector);
+	argvec[3] = value_from_longest (builtin_type_long, selector);
+	argvec[4] = 0;
+
+	ret = call_function_by_hand (argvec[0], 3, argvec + 1);
+	if (gnu_runtime)
+	  {
+	    argvec[0] = ret;
+	    ret = call_function_by_hand (argvec[0], 3, argvec + 1);
+	  }
+
+	/* ret should now be the selector.  */
+
+	addr = value_as_long (ret);
+	if (addr)
+	  {
+	    /* Is it a high_level symbol?  */
+
+#if 0
+	    /* Was defined only for HPPA architectures. Commented out
+	       since we cannot verify that this works anymore.  Anyone
+	       experiencing problems on HPPA machines can check this
+	       for validity.  */
+	    CORE_ADDR tmp;
+	    /* Code and comment lifted from hppa-tdep.c.
+	       Unfortunately there is no builtin function to do
+	       this.  */
+	    /* If bit 30 (counting from the left) is on, then addr
+	       is the address of the PLT entry for this function,
+	       not the address of the function itself.  Bit 31 has
+	       meaning too, but only for MPE.  */
+	    if (addr & 0x2)
+	      addr = (CORE_ADDR) read_memory_unsigned_integer (addr & ~0x3, 4);
+	    if (tmp = skip_trampoline_code (addr, 0))
+	      addr = tmp;
+#endif
+
+	    sym = find_pc_function (addr);
+	    if (sym != NULL) 
+	      method = value_of_variable (sym, 0);
+	  }
+
+	/* If we found a method with symbol information, check to see
+           if it returns a struct.  Otherwise assume it doesn't.  */
+
+	if (method)
+	  {
+	    struct block *b;
+	    CORE_ADDR funaddr;
+	    struct type *value_type;
+
+	    funaddr = find_function_addr (method, &value_type);
+
+	    b = block_for_pc (funaddr);
+
+	    /* If compiled without -g, assume GCC 2.  */
+	    using_gcc = (b == NULL ? 2 : BLOCK_GCC_COMPILED (b));
+
+	    CHECK_TYPEDEF (value_type);
+	  
+	    if ((value_type == NULL) 
+		|| (TYPE_CODE(value_type) == TYPE_CODE_ERROR))
+	      {
+		if (expect_type != NULL)
+		  value_type = expect_type;
+	      }
+
+	    struct_return = using_struct_return (method, funaddr, value_type, using_gcc);
+	  }
+	else if (expect_type != NULL)
+	  {
+	    struct_return = using_struct_return (NULL, addr, check_typedef (expect_type), using_gcc);
+	  }
+	
+	/* Found a function symbol.  Now we will substitute its
+	   value in place of the message dispatcher (obj_msgSend),
+	   so that we call the method directly instead of thru
+	   the dispatcher.  The main reason for doing this is that
+	   we can now evaluate the return value and parameter values
+	   according to their known data types, in case we need to
+	   do things like promotion, dereferencing, special handling
+	   of structs and doubles, etc.
+	  
+	   We want to use the type signature of 'method', but still
+	   jump to objc_msgSend() or objc_msgSend_stret() to better
+	   mimic the behavior of the runtime.  */
+	
+	if (method)
+	  {
+	    if (TYPE_CODE (VALUE_TYPE (method)) != TYPE_CODE_FUNC)
+	      error ("method address has symbol information with non-function type; skipping");
+	    if (struct_return)
+	      VALUE_ADDRESS (method) = value_as_address (msg_send_stret);
+	    else
+	      VALUE_ADDRESS (method) = value_as_address (msg_send);
+	    called_method = method;
+	  }
+	else
+	  {
+	    if (struct_return)
+	      called_method = msg_send_stret;
+	    else
+	      called_method = msg_send;
+	  }
+
+	if (noside == EVAL_SKIP)
+	  goto nosideret;
+
+	if (noside == EVAL_AVOID_SIDE_EFFECTS)
+	  {
+	    /* If the return type doesn't look like a function type,
+	       call an error.  This can happen if somebody tries to
+	       turn a variable into a function call. This is here
+	       because people often want to call, eg, strcmp, which
+	       gdb doesn't know is a function.  If gdb isn't asked for
+	       it's opinion (ie. through "whatis"), it won't offer
+	       it. */
+
+	    struct type *type = VALUE_TYPE (called_method);
+	    if (type && TYPE_CODE (type) == TYPE_CODE_PTR)
+	      type = TYPE_TARGET_TYPE (type);
+	    type = TYPE_TARGET_TYPE (type);
+
+	    if (type)
+	    {
+	      if ((TYPE_CODE (type) == TYPE_CODE_ERROR) && expect_type)
+		return allocate_value (expect_type);
+	      else
+		return allocate_value (type);
+	    }
+	    else
+	      error ("Expression of type other than \"method returning ...\" used as a method");
+	  }
+
+	/* Now depending on whether we found a symbol for the method,
+	   we will either call the runtime dispatcher or the method
+	   directly.  */
+
+	argvec[0] = called_method;
+	argvec[1] = target;
+	argvec[2] = value_from_longest (builtin_type_long, selector);
+	/* User-supplied arguments.  */
+	for (tem = 0; tem < nargs; tem++)
+	  argvec[tem + 3] = evaluate_subexp_with_coercion (exp, pos, noside);
+	argvec[tem + 3] = 0;
+
+	if (gnu_runtime && (method != NULL))
+	  {
+	    ret = call_function_by_hand (argvec[0], nargs + 2, argvec + 1);
+	    /* Function objc_msg_lookup returns a pointer.  */
+	    argvec[0] = ret;
+	    ret = call_function_by_hand (argvec[0], nargs + 2, argvec + 1);
+	  }
+	else
+	  ret = call_function_by_hand (argvec[0], nargs + 2, argvec + 1);
+
+	return ret;
+      }
+      break;
+
     case OP_FUNCALL:
       (*pos) += 2;
       op = exp->elts[*pos].opcode;
@@ -1748,6 +2047,10 @@ evaluate_subexp_standard (struct type *e
     case OP_THIS:
       (*pos) += 1;
       return value_of_this (1);
+
+    case OP_OBJC_SELF:
+      (*pos) += 1;
+      return value_of_local ("self", 1);
 
     case OP_TYPE:
       error ("Attempt to use a type name as an expression");
Index: valops.c
===================================================================
RCS file: /cvs/src/src/gdb/valops.c,v
retrieving revision 1.89
diff -u -p -r1.89 valops.c
--- valops.c	30 Jan 2003 16:44:20 -0000	1.89
+++ valops.c	13 Feb 2003 02:46:52 -0000
@@ -48,7 +48,6 @@ extern int overload_debug;
 static int typecmp (int staticp, int varargs, int nargs,
 		    struct field t1[], struct value *t2[]);
 
-static CORE_ADDR find_function_addr (struct value *, struct type **);
 static struct value *value_arg_coerce (struct value *, struct type *, int);
 
 
@@ -1172,7 +1171,7 @@ value_arg_coerce (struct value *arg, str
 /* Determine a function's address and its return type from its value.
    Calls error() if the function is not valid for calling.  */
 
-static CORE_ADDR
+CORE_ADDR
 find_function_addr (struct value *function, struct type **retval_type)
 {
   register struct type *ftype = check_typedef (VALUE_TYPE (function));
Index: value.h
===================================================================
RCS file: /cvs/src/src/gdb/value.h,v
retrieving revision 1.41
diff -u -p -r1.41 value.h
--- value.h	19 Jan 2003 04:06:46 -0000	1.41
+++ value.h	13 Feb 2003 02:46:52 -0000
@@ -563,6 +563,8 @@ extern CORE_ADDR default_push_arguments 
 					 CORE_ADDR sp, int struct_return,
 					 CORE_ADDR struct_addr);
 
+extern CORE_ADDR find_function_addr (struct value *, struct type **);
+
 extern struct value *value_of_local (const char *name, int complain);
 
 #endif /* !defined (VALUE_H) */

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