[PATCH] TARGET_ADJUST_BREAKPOINT_ADDRESS - patch 4 of 4

[Kevin Buettner <kevinb at redhat dot com>]

Below is patch 4 of 4 of my current TARGET_ADJUST_BREAKPOINT_ADDRESS
patch set.  To better understand what this is all about, see patch 3
at:

    http://sources.redhat.com/ml/gdb-patches/2003-10/msg00073.html

I'll commit this patch sometime after patch 1 is committed.  (In order
to actually be used, it depends on patch 3, but no harm will occur if
it goes in before patch 3.)

	* frv-tdep.c (frv_target_adjust_breakpoint_address): New function.
	(frv_gdbarch_init): Initialize TARGET_ADJUST_BREAKPOINT_ADDRESS
	method.

Index: frv-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/frv-tdep.c,v
retrieving revision 1.53
diff -u -p -r1.53 frv-tdep.c
--- frv-tdep.c	19 Sep 2003 16:22:38 -0000	1.53
+++ frv-tdep.c	3 Oct 2003 23:38:25 -0000
@@ -37,6 +37,7 @@ static gdbarch_init_ftype frv_gdbarch_in
 
 static gdbarch_register_name_ftype frv_register_name;
 static gdbarch_breakpoint_from_pc_ftype frv_breakpoint_from_pc;
+static gdbarch_target_adjust_breakpoint_address_ftype frv_target_adjust_breakpoint_address;
 static gdbarch_skip_prologue_ftype frv_skip_prologue;
 static gdbarch_deprecated_extract_return_value_ftype frv_extract_return_value;
 static gdbarch_deprecated_extract_struct_value_address_ftype frv_extract_struct_value_address;
@@ -272,6 +273,42 @@ frv_breakpoint_from_pc (CORE_ADDR *pcptr
 }
 
 
+static CORE_ADDR
+frv_target_adjust_breakpoint_address (CORE_ADDR bpaddr)
+{
+  int count = 8;
+  CORE_ADDR addr = bpaddr - 4;
+  CORE_ADDR func_start = get_pc_function_start (bpaddr);
+
+  /* Find the end of the previous packing sequence.  This will be indicated
+     by either attempting to access some inaccessible memory or by finding
+     an instruction word whose packing bit is set to one. */
+  while (count-- > 0 && addr >= func_start)
+    {
+      int status;
+      char instr[4];
+
+      status = read_memory_nobpt (addr, instr, sizeof instr);
+
+      if (status != 0)
+	break;
+
+      /* This is a big endian architecture, so byte zero will have most
+         significant byte.  The most significant bit of this byte is the
+         packing bit.  */
+      if (instr[0] & 0x80)
+	break;
+
+      addr -= 4;
+    }
+
+  if (count > 0)
+    bpaddr = addr + 4;
+
+  return bpaddr;
+}
+
+
 /* Return true if REG is a caller-saves ("scratch") register,
    false otherwise.  */
 static int
@@ -1114,6 +1151,7 @@ frv_gdbarch_init (struct gdbarch_info in
 
   set_gdbarch_skip_prologue (gdbarch, frv_skip_prologue);
   set_gdbarch_breakpoint_from_pc (gdbarch, frv_breakpoint_from_pc);
+  set_gdbarch_target_adjust_breakpoint_address (gdbarch, frv_target_adjust_breakpoint_address);
 
   set_gdbarch_frame_args_skip (gdbarch, 0);
   set_gdbarch_frameless_function_invocation (gdbarch, frv_frameless_function_invocation);