GDB: frame: Make VALUEP argument optional in frame_register_unwind

It already accepts a nullptr value and a couple of places were always
calling it that way, so make it possible to omit the argument entirely.

Approved-By: Simon Marchi <simon.marchi@efficios.com>

gdb/frame.c

diff --git a/gdb/frame.c b/gdb/frame.c
index a6900b2..ba4a071 100644
--- a/gdb/frame.c
+++ b/gdb/frame.c
@@ -1447,7 +1447,7 @@ put_frame_register (const frame_info_ptr &next_frame, int regnum,
   gdb_assert (buf.size () == size);
 
   frame_register_unwind (next_frame, regnum, &optim, &unavail, &lval, &addr,
-			 &realnum, nullptr);
+			 &realnum);
   if (optim)
     error (_("Attempt to assign to a register that was not saved."));
   switch (lval)
@@ -2159,7 +2159,7 @@ frame_register_unwind_location (const frame_info_ptr &initial_this_frame,
       int unavailable;
 
       frame_register_unwind (this_frame, regnum, optimizedp, &unavailable,
-			     lvalp, addrp, realnump, NULL);
+			     lvalp, addrp, realnump);
 
       if (*optimizedp)
 	break;

gdb/frame.h

diff --git a/gdb/frame.h b/gdb/frame.h
index 9b41dd9..b265c9b 100644
--- a/gdb/frame.h
+++ b/gdb/frame.h
@@ -685,14 +685,14 @@ const char *unwind_stop_reason_to_string (enum unwind_stop_reason);
 const char *frame_stop_reason_string (const frame_info_ptr &);
 
 /* Unwind the stack frame so that the value of REGNUM, in the previous
-   (up, older) frame is returned.  If VALUEP is NULL, don't
+   (up, older) frame is returned.  If VALUEP is nullptr, don't
    fetch/compute the value.  Instead just return the location of the
    value.  */
 extern void frame_register_unwind (const frame_info_ptr &frame, int regnum,
 				   int *optimizedp, int *unavailablep,
 				   enum lval_type *lvalp,
 				   CORE_ADDR *addrp, int *realnump,
-				   gdb_byte *valuep);
+				   gdb_byte *valuep = nullptr);
 
 /* Fetch a register from this, or unwind a register from the next
    frame.  Note that the get_frame methods are wrappers to

gdb/stack.c

diff --git a/gdb/stack.c b/gdb/stack.c
index 73165c8..2d6712a 100644
--- a/gdb/stack.c
+++ b/gdb/stack.c
@@ -1750,7 +1750,7 @@ info_frame_command_core (const frame_info_ptr &fi, bool selected_frame_p)
 	  /* Find out the location of the saved register without
 	     fetching the corresponding value.  */
 	  frame_register_unwind (fi, i, &optimized, &unavailable,
-				 &lval, &addr, &realnum, NULL);
+				 &lval, &addr, &realnum);
 	  /* For moment, only display registers that were saved on the
 	     stack.  */
 	  if (!optimized && !unavailable && lval == lval_memory)