[patch/rfc] Add frame_read_signed/unsigned_register()

[Andrew Cagney <ac131313@redhat.com>]

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> Hmm,
> 
> (I think I might split this in two)
> 
> The attached adds the methods:
> 
> +extern void frame_read_signed_register (struct frame_info *frame,
> +                                       int regnum, LONGEST *val);
> +extern void frame_read_unsigned_register (struct frame_info *frame,
> +                                         int regnum, ULONGEST *val);
> 
> These correspond to the frame_unwind_XXXX methods() except that they return the value of a register in THIS frame rather than the value of the register in the PREVIOUS frame.
> 
> They are simply convenience functions to make it easier to obtain a specified frame's register value.
> 
> Thoughts?

I've checked in the attatched.  The additional comment and assertion 
should address the questions DanielJ raised.

Andrew


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2002-10-31  Andrew Cagney  <cagney@redhat.com>

	* frame.c (frame_read_unsigned_register): New function.
	(frame_read_signed_register): New function.
	* frame.h (frame_read_unsigned_register): Declare.
	(frame_read_signed_register): Declare.

Index: frame.c
===================================================================
RCS file: /cvs/src/src/gdb/frame.c,v
retrieving revision 1.18
diff -u -r1.18 frame.c
--- frame.c	25 Sep 2002 20:30:37 -0000	1.18
+++ frame.c	31 Oct 2002 19:53:11 -0000
@@ -153,6 +153,40 @@
 }
 
 void
+frame_read_unsigned_register (struct frame_info *frame, int regnum,
+			      ULONGEST *val)
+{
+  /* NOTE: cagney/2002-10-31: There is a bit of dogma here - there is
+     always a frame.  Both this, and the equivalent
+     frame_read_signed_register() function, can only be called with a
+     valid frame.  If, for some reason, this function is called
+     without a frame then the problem isn't here, but rather in the
+     caller.  It should of first created a frame and then passed that
+     in.  */
+  /* NOTE: cagney/2002-10-31: As a side bar, keep in mind that the
+     ``current_frame'' should not be treated as a special case.  While
+     ``get_next_frame (current_frame) == NULL'' currently holds, it
+     should, as far as possible, not be relied upon.  In the future,
+     ``get_next_frame (current_frame)'' may instead simply return a
+     normal frame object that simply always gets register values from
+     the register cache.  Consequently, frame code should try to avoid
+     tests like ``if get_next_frame() == NULL'' and instead just rely
+     on recursive frame calls (like the below code) when manipulating
+     a frame chain.  */
+  gdb_assert (frame != NULL);
+  frame_unwind_unsigned_register (get_next_frame (frame), regnum, val);
+}
+
+void
+frame_read_signed_register (struct frame_info *frame, int regnum,
+			    LONGEST *val)
+{
+  /* See note in frame_read_unsigned_register().  */
+  gdb_assert (frame != NULL);
+  frame_unwind_signed_register (get_next_frame (frame), regnum, val);
+}
+
+void
 generic_unwind_get_saved_register (char *raw_buffer,
 				   int *optimizedp,
 				   CORE_ADDR *addrp,
Index: frame.h
===================================================================
RCS file: /cvs/src/src/gdb/frame.h,v
retrieving revision 1.26
diff -u -r1.26 frame.h
--- frame.h	2 Oct 2002 21:33:58 -0000	1.26
+++ frame.h	31 Oct 2002 19:53:11 -0000
@@ -366,6 +366,16 @@
 extern int frame_register_read (struct frame_info *frame, int regnum,
 				void *buf);
 
+/* Return the value of register REGNUM that belongs to FRAME.  The
+   value is obtained by unwinding the register from the next / more
+   inner frame.  */
+/* NOTE: cagney/2002-09-13: Return void as one day these functions may
+   be changed to return an indication that the read succeeded.  */
+extern void frame_read_signed_register (struct frame_info *frame,
+					int regnum, LONGEST *val);
+extern void frame_read_unsigned_register (struct frame_info *frame,
+					  int regnum, ULONGEST *val);
+
 /* Map between a frame register number and its name.  A frame register
    space is a superset of the cooked register space --- it also
    includes builtin registers.  */