[ppc64-linux]: register CONVERT_FROM_FUNC_PTR_ADDR method

[Jim Blandy <jimb@redhat.com>]

2003-06-11  Jim Blandy  <jimb@redhat.com>

	* ppc-linux-tdep.c (ppc64_linux_convert_from_func_ptr_addr): New
	function.
	(ppc_linux_init_abi): Register it as the
	CONVERT_FROM_FUNC_PTR_ADDR method under the PPC64 Linux ABI.

Index: gdb/ppc-linux-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/ppc-linux-tdep.c,v
retrieving revision 1.28.8.14
diff -c -r1.28.8.14 ppc-linux-tdep.c
*** gdb/ppc-linux-tdep.c	11 Jun 2003 06:46:17 -0000	1.28.8.14
--- gdb/ppc-linux-tdep.c	11 Jun 2003 08:48:28 -0000
***************
*** 894,899 ****
--- 894,932 ----
  }
  
  
+ /* Support for CONVERT_FROM_FUNC_PTR_ADDR(ADDR).
+ 
+    Usually a function pointer's representation is simply the address
+    of the function. On the RS/6000 however, a function pointer is
+    represented by a pointer to a TOC entry. This TOC entry contains
+    three words, the first word is the address of the function, the
+    second word is the TOC pointer (r2), and the third word is the
+    static chain value.  Throughout GDB it is currently assumed that a
+    function pointer contains the address of the function, which is not
+    easy to fix.  In addition, the conversion of a function address to
+    a function pointer would require allocation of a TOC entry in the
+    inferior's memory space, with all its drawbacks.  To be able to
+    call C++ virtual methods in the inferior (which are called via
+    function pointers), find_function_addr uses this function to get the
+    function address from a function pointer.  */
+ 
+ /* Return real function address if ADDR (a function pointer) is in the data
+    space and is therefore a special function pointer.  */
+ 
+ static CORE_ADDR
+ ppc64_linux_convert_from_func_ptr_addr (CORE_ADDR addr)
+ {
+   struct obj_section *s;
+ 
+   s = find_pc_section (addr);
+   if (s && s->the_bfd_section->flags & SEC_CODE)
+     return addr;
+ 
+   /* ADDR is in the data space, so it's a special function pointer. */
+   return ppc64_desc_entry_point (addr);
+ }
+ 
+ 
  /* On 64-bit PowerPC Linux, the ELF header's e_entry field is the
     address of a function descriptor for the entry point function, not
     the actual entry point itself.  So to find the actual address at
***************
*** 1028,1033 ****
--- 1061,1071 ----
    if (tdep->wordsize == 8)
      {
        set_gdbarch_long_double_bit (gdbarch, 16 * TARGET_CHAR_BIT);
+ 
+       /* Handle PPC64 Linux function pointers (which are really
+          function descriptors).  */
+       set_gdbarch_convert_from_func_ptr_addr
+         (gdbarch, ppc64_linux_convert_from_func_ptr_addr);
  
        set_gdbarch_call_dummy_address (gdbarch, ppc64_call_dummy_address);