[patch/hppa] new in_epilogue_p method

[Randolph Chung <randolph at tausq dot org>]

This patch teaches gdb about the hppa epilogue sequences, and fixes a
bug in software watchpoint handling. It's a bit ugly since there's no
clearly defined way to identify the epilogue... possibly we can do
better than this for dwarf2-enabled targets when we support dwarf2
unwinding ...

i'll give this a few days for comments

btw, now that "read_memory_nobpt" is deprecated, how are we supposed to
get that functionality when there is no "frame"? Do we just call
safe_frame_unwind_memeory with get_current_frame(), noting that the
frame argument to safe_frame_unwind_memory is not actually used?

randolph

2004-12-03  Randolph Chung  <tausq@debian.org>

	* hppa-tdep.c (hppa_in_function_epilogue_p): New function.
	(hppa_gdbarch_init): Set in_epilogue_p method.

Index: hppa-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/hppa-tdep.c,v
retrieving revision 1.184
diff -u -p -r1.184 hppa-tdep.c
--- hppa-tdep.c	3 Dec 2004 23:59:52 -0000	1.184
+++ hppa-tdep.c	4 Dec 2004 00:46:18 -0000
@@ -621,6 +617,44 @@ find_unwind_entry (CORE_ADDR pc)
   return NULL;
 }
 
+/* The epilogue is defined here as the area either on the `bv' instruction 
+   itself or an instruction which destroys the function's stack frame. 
+   
+   We do not assume that the epilogue is at the end of a function as we can
+   also have return sequences in the middle of a function.  */
+static int
+hppa_in_function_epilogue_p (struct gdbarch *gdbarch, CORE_ADDR pc)
+{
+  unsigned long status;
+  unsigned int inst;
+  char buf[4];
+  int off;
+
+  status = deprecated_read_memory_nobpt (pc, buf, 4);
+  if (status != 0)
+    return 0;
+
+  inst = extract_unsigned_integer (buf, 4);
+
+  /* The most common way to perform a stack adjustment ldo X(sp),sp 
+     We are destroying a stack frame if the offset is negative.  */
+  if ((inst & 0xffffc000) == 0x37de0000
+      && hppa_extract_14 (inst) < 0)
+    return 1;
+
+  /* ldw,mb D(sp),X or ldd,mb D(sp),X */
+  if (((inst & 0x0fc010e0) == 0x0fc010e0 
+       || (inst & 0x0fc010e0) == 0x0fc010e0)
+      && hppa_extract_14 (inst) < 0)
+    return 1;
+
+  /* bv %r0(%rp) or bv,n %r0(%rp) */
+  if (inst == 0xe840c000 || inst == 0xe840c002)
+    return 1;
+
+  return 0;
+}
+
 static const unsigned char *
 hppa_breakpoint_from_pc (CORE_ADDR *pc, int *len)
 {
@@ -2529,6 +2535,8 @@ hppa_gdbarch_init (struct gdbarch_info i
   /* The following gdbarch vector elements do not depend on the address
      size, or in any other gdbarch element previously set.  */
   set_gdbarch_skip_prologue (gdbarch, hppa_skip_prologue);
+  set_gdbarch_in_function_epilogue_p (gdbarch,
+				      hppa_in_function_epilogue_p);
   set_gdbarch_inner_than (gdbarch, core_addr_greaterthan);
   set_gdbarch_sp_regnum (gdbarch, HPPA_SP_REGNUM);
   set_gdbarch_fp0_regnum (gdbarch, HPPA_FP0_REGNUM);
-- 
Randolph Chung
Debian GNU/Linux Developer, hppa/ia64 ports
http://www.tausq.org/