commit 6dfd0b7446fce82dba3ae07e24fadb89b9908455
Author: Vladimir Prus <vladimir@codesourcery.com>
Date:   Fri Jan 14 00:10:12 2011 +0300

    Use the right structure and pointer return registers on m68k-elf.
    
    	* m68k-tdep.c (m68k_gdbarch_init): Use A0 for structure
    	returns on ELF targets, A1 otherwise.
    	(m68k_svr4_init_abi): No need to specify %a0 for structure
    	returns here.
    	* m68kbsd-tdep.c (m68kbsd_elf_init_abi): Use A1 for struct return on OpenBSD.

diff --git a/gdb/m68k-tdep.c b/gdb/m68k-tdep.c
index 736bf5b..accffc8 100644
--- a/gdb/m68k-tdep.c
+++ b/gdb/m68k-tdep.c
@@ -1114,8 +1114,7 @@ m68k_svr4_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
   /* SVR4 uses a different calling convention.  */
   set_gdbarch_return_value (gdbarch, m68k_svr4_return_value);
 
-  /* SVR4 uses %a0 instead of %a1.  */
-  tdep->struct_value_regnum = M68K_A0_REGNUM;
+  tdep->ptr_value_regnum = M68K_A0_REGNUM;
 
   tdep->ptr_value_regnum = M68K_A0_REGNUM;
 }
@@ -1291,7 +1290,16 @@ m68k_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
   /* Function call & return.  */
   set_gdbarch_push_dummy_call (gdbarch, m68k_push_dummy_call);
   set_gdbarch_return_value (gdbarch, m68k_return_value);
+  tdep->struct_return = reg_struct_return;
 
+  /* These register numbers may be overridden by an OSABI
+     sniffer.  */
+  if (info.abfd == NULL)
+    tdep->struct_value_regnum = M68K_A0_REGNUM;
+  else if (bfd_get_flavour (info.abfd) == bfd_target_elf_flavour)
+    tdep->struct_value_regnum = M68K_A0_REGNUM;
+  else
+    tdep->struct_value_regnum = M68K_A1_REGNUM;
   tdep->ptr_value_regnum = M68K_D0_REGNUM;
 
   /* Disassembler.  */
@@ -1303,8 +1311,6 @@ m68k_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
 #else
   tdep->jb_pc = -1;
 #endif
-  tdep->struct_value_regnum = M68K_A1_REGNUM;
-  tdep->struct_return = reg_struct_return;
 
   /* Frame unwinder.  */
   set_gdbarch_dummy_id (gdbarch, m68k_dummy_id);
diff --git a/gdb/m68kbsd-tdep.c b/gdb/m68kbsd-tdep.c
index 3b5f5e0..f5bfa1a 100644
--- a/gdb/m68kbsd-tdep.c
+++ b/gdb/m68kbsd-tdep.c
@@ -234,6 +234,15 @@ m68kbsd_elf_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
   /* NetBSD ELF uses SVR4-style shared libraries.  */
   set_solib_svr4_fetch_link_map_offsets
     (gdbarch, svr4_ilp32_fetch_link_map_offsets);
+
+  /* OpenBSD uses %a1to return structures.  */
+  if (info.abfd)
+    {
+      enum gdb_osabi osabi = gdbarch_lookup_osabi (info.abfd);
+
+      if (osabi == GDB_OSABI_OPENBSD_ELF)
+	tdep->struct_value_regnum = M68K_A1_REGNUM;
+    }
 }