Re: m68k-elf return value registers

[Vladimir Prus <vladimir at codesourcery dot com>]

On Tuesday, January 25, 2011 19:49:15 Vladimir Prus wrote:

> How about this split:
> 
> - Register used to return structures
> - Logic used to decide whether a structure is returned in register
> - Adjusting register used for returning pointers

Here's a patch to adjust the register for returning pointers.
Comments? Note that I still not able to test on classic m68k,
therefore eye inspection or testing there would be still required.

Thanks,


-- 
Vladimir Prus
Mentor Graphics
+7 (812) 677-68-40

commit 607918e383bd3ba7f84ce5f3a1255da5ac5ee401
Author: Vladimir Prus <vladimir@codesourcery.com>
Date:   Tue Apr 26 15:31:18 2011 +0400

    Make pointer return value be right on bare metal.
    
    	* m68k-tdep.h (struct gdbarch_tdep): New field
    	ptr_value_regnum.
    	* m68k-tdep.c (m68k_svr4_extract_return_value): Use
    	tdep->ptr_value_regnum.
    	(m68k_svr4_store_return_value): Likewise.
    	(m68k_svr4_init_abi): Set ptr_value_regnum to %a0.
    	(m68k_gdbarch_init): Set ptr_value_regnum to %d0.
    	* m68kbsd-tdep.c (m68kbsd_aout_init_abi): Set ptr_value_regnum
    	to %a0.

diff --git a/gdb/m68k-tdep.c b/gdb/m68k-tdep.c
index 6d7a824..c6ae36d 100644
--- a/gdb/m68k-tdep.c
+++ b/gdb/m68k-tdep.c
@@ -329,7 +329,7 @@ m68k_svr4_extract_return_value (struct type *type, struct regcache *regcache,
       convert_typed_floating (buf, fpreg_type, valbuf, type);
     }
   else if (TYPE_CODE (type) == TYPE_CODE_PTR && len == 4)
-    regcache_raw_read (regcache, M68K_A0_REGNUM, valbuf);
+    regcache_raw_read (regcache, tdep->ptr_value_regnum, valbuf);
   else
     m68k_extract_return_value (type, regcache, valbuf);
 }
@@ -371,10 +371,7 @@ m68k_svr4_store_return_value (struct type *type, struct regcache *regcache,
       regcache_raw_write (regcache, M68K_FP0_REGNUM, buf);
     }
   else if (TYPE_CODE (type) == TYPE_CODE_PTR && len == 4)
-    {
-      regcache_raw_write (regcache, M68K_A0_REGNUM, valbuf);
-      regcache_raw_write (regcache, M68K_D0_REGNUM, valbuf);
-    }
+    regcache_raw_write (regcache, tdep->ptr_value_regnum, valbuf);
   else
     m68k_store_return_value (type, regcache, valbuf);
 }
@@ -1065,6 +1062,8 @@ m68k_svr4_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 
   /* SVR4 uses %a0 instead of %a1.  */
   tdep->struct_value_regnum = M68K_A0_REGNUM;
+
+  tdep->ptr_value_regnum = M68K_A0_REGNUM;
 }
 
 
@@ -1239,6 +1238,7 @@ m68k_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
   set_gdbarch_push_dummy_call (gdbarch, m68k_push_dummy_call);
   set_gdbarch_return_value (gdbarch, m68k_return_value);
 
+  tdep->ptr_value_regnum = M68K_D0_REGNUM;
 
   /* Disassembler.  */
   set_gdbarch_print_insn (gdbarch, print_insn_m68k);
diff --git a/gdb/m68k-tdep.h b/gdb/m68k-tdep.h
index 596a8cb..3ea7f24 100644
--- a/gdb/m68k-tdep.h
+++ b/gdb/m68k-tdep.h
@@ -83,6 +83,9 @@ struct gdbarch_tdep
   /* Convention for returning structures.  */
   enum struct_return struct_return;
 
+  /* Register in which pointers are returned.  */
+  int ptr_value_regnum;
+
   /* Convention for returning floats.  zero in int regs, non-zero in float.  */
   int float_return;
 
diff --git a/gdb/m68kbsd-tdep.c b/gdb/m68kbsd-tdep.c
index 81e34e9..3b5f5e0 100644
--- a/gdb/m68kbsd-tdep.c
+++ b/gdb/m68kbsd-tdep.c
@@ -213,11 +213,12 @@ m68kbsd_aout_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
   m68kbsd_init_abi (info, gdbarch);
 
   tdep->struct_return = reg_struct_return;
+  tdep->ptr_value_regnum = M68K_A0_REGNUM;
 
   tramp_frame_prepend_unwinder (gdbarch, &m68kobsd_sigtramp);
 }
 
-/* NetBSD ELF.  */
+/* OpenBSD and NetBSD ELF.  */
 
 static void
 m68kbsd_elf_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)