[PATCH] Modernize VAX target; return values

[Mark Kettenis <kettenis at chello dot nl>]

This revamps the return value support.  Writing this also revealed a
bug in the call dummy stuff where I implemented the VAX VMS way of
return structures instead of the VAX Unix way, so this patch fixes
that too.

No deprecated stuff anymore in vax-tdep.c :-).

Committed,

Mark


Index: ChangeLog
from  Mark Kettenis  <kettenis@gnu.org>
 
	* vax-tdep.h (vax_regnum): Add VAX_R0_REGNUM and VAX_R1_REGNUM.
	* vax-tdep.c (vax_store_arguments): Remove struct_return and
	struct_addr arguments.  Don't push return value address.
	(vax_push_dummy_call): Don't pass STRUCT_RETURN and STRUCT_ADDR as
	arguments to vax_store_arguments.  Store return value address in
	R1.
	(vax_store_struct_return, vax_extract_return_value)
	(vax_store_return_value): Remove functions.
	(vax_return_value): New function.
	(vax_gdbarch_init): Set return value.  Don't set
	deprecated_store_struct_return, deprecated_extract_struct_return
	and deprecated_store_return_value.

Index: vax-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/vax-tdep.c,v
retrieving revision 1.73
diff -u -p -r1.73 vax-tdep.c
--- vax-tdep.c 14 Apr 2004 10:58:39 -0000 1.73
+++ vax-tdep.c 14 Apr 2004 17:44:43 -0000
@@ -66,10 +66,13 @@ vax_register_type (struct gdbarch *gdbar
 }
 
 
+/* The VAX Unix calling convention uses R1 to pass a structure return
+   value address instead of passing it as a first (hidden) argument as
+   the VMS calling convention suggests.  */
+
 static CORE_ADDR
 vax_store_arguments (struct regcache *regcache, int nargs,
-		     struct value **args, CORE_ADDR sp,
-		     int struct_return, CORE_ADDR struct_addr)
+		     struct value **args, CORE_ADDR sp)
 {
   char buf[4];
   int count = 0;
@@ -88,15 +91,6 @@ vax_store_arguments (struct regcache *re
       write_memory (sp, VALUE_CONTENTS_ALL (args[i]), len);
     }
 
-  /* Push value address.  */
-  if (struct_return)
-    {
-      sp -= 4;
-      count++;
-      store_unsigned_integer (buf, 4, struct_addr);
-      write_memory (sp, buf, 4);
-    }
-
   /* Push argument count.  */
   sp -= 4;
   store_unsigned_integer (buf, 4, count);
@@ -119,8 +113,11 @@ vax_push_dummy_call (struct gdbarch *gdb
   char buf[4];
 
   /* Set up the function arguments.  */
-  sp = vax_store_arguments (regcache, nargs, args, sp,
-			    struct_return, struct_addr);
+  sp = vax_store_arguments (regcache, nargs, args, sp);
+
+  /* Store return value address.  */
+  if (struct_return)
+    regcache_cooked_write_unsigned (regcache, VAX_R1_REGNUM, struct_addr);
 
   /* Store return address in the PC slot.  */
   sp -= 4;
@@ -164,22 +161,37 @@ vax_unwind_dummy_id (struct gdbarch *gdb
 }
 
 
-static void
-vax_store_struct_return (CORE_ADDR addr, CORE_ADDR sp)
-{
-  write_register (1, addr);
-}
+static enum return_value_convention
+vax_return_value (struct gdbarch *gdbarch, struct type *type,
+		  struct regcache *regcache, void *readbuf,
+		  const void *writebuf)
+{
+  int len = TYPE_LENGTH (type);
+  char buf[8];
+
+  if (TYPE_CODE (type) == TYPE_CODE_STRUCT
+      || TYPE_CODE (type) == TYPE_CODE_STRUCT
+      || TYPE_CODE (type) == TYPE_CODE_ARRAY)
+    return RETURN_VALUE_STRUCT_CONVENTION;
 
-static void
-vax_extract_return_value (struct type *valtype, char *regbuf, char *valbuf)
-{
-  memcpy (valbuf, regbuf + DEPRECATED_REGISTER_BYTE (0), TYPE_LENGTH (valtype));
-}
+  if (readbuf)
+    {
+      /* Read the contents of R0 and (if necessary) R1.  */
+      regcache_cooked_read (regcache, VAX_R0_REGNUM, buf);
+      if (len > 4)
+	regcache_cooked_read (regcache, VAX_R1_REGNUM, buf + 4);
+      memcpy (readbuf, buf, len);
+    }
+  if (writebuf)
+    {
+      /* Read the contents to R0 and (if necessary) R1.  */
+      memcpy (buf, writebuf, len);
+      regcache_cooked_write (regcache, VAX_R0_REGNUM, buf);
+      if (len > 4)
+	regcache_cooked_write (regcache, VAX_R1_REGNUM, buf + 4);
+    }
 
-static void
-vax_store_return_value (struct type *valtype, char *valbuf)
-{
-  deprecated_write_register_bytes (0, valbuf, TYPE_LENGTH (valtype));
+  return RETURN_VALUE_REGISTER_CONVENTION;
 }
 
 
@@ -426,9 +438,7 @@ vax_gdbarch_init (struct gdbarch_info in
   set_gdbarch_inner_than (gdbarch, core_addr_lessthan);
 
   /* Return value info */
-  set_gdbarch_deprecated_store_struct_return (gdbarch, vax_store_struct_return);
-  set_gdbarch_deprecated_extract_return_value (gdbarch, vax_extract_return_value);
-  set_gdbarch_deprecated_store_return_value (gdbarch, vax_store_return_value);
+  set_gdbarch_return_value (gdbarch, vax_return_value);
 
   /* Call dummy code.  */
   set_gdbarch_push_dummy_call (gdbarch, vax_push_dummy_call);
Index: vax-tdep.h
===================================================================
RCS file: /cvs/src/src/gdb/vax-tdep.h,v
retrieving revision 1.6
diff -u -p -r1.6 vax-tdep.h
--- vax-tdep.h 12 Apr 2004 16:49:35 -0000 1.6
+++ vax-tdep.h 14 Apr 2004 17:44:43 -0000
@@ -26,6 +26,8 @@
 
 enum vax_regnum
 {
+  VAX_R0_REGNUM,
+  VAX_R1_REGNUM,
   VAX_AP_REGNUM = 12,		/* Argument pointer on user stack.  */
   VAX_FP_REGNUM,		/* Address of executing stack frame.  */
   VAX_SP_REGNUM,		/* Address of top of stack.  */