2004-11-08 Andrew Cagney <cagney@gnu.org>

	* sentinel-frame.c (sentinel_frame_prev_pc): New function.
	(sentinel_frame_unwinder): Add the prev_pc method.
	* frame.c (frame_pc_unwind): Use the per-frame pc unwinder when
	available.  Do not handle the sentinel-frame case.
	* frame-unwind.h (frame_prev_register_ftype): Define.
	(struct frame_unwind): Add prev_pc;

4 files changed, 40 insertions, 12 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 552f75d..e5207e7 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,12 @@
+2004-11-08  Andrew Cagney  <cagney@gnu.org>
+
+	* sentinel-frame.c (sentinel_frame_prev_pc): New function.
+	(sentinel_frame_unwinder): Add the prev_pc method.
+	* frame.c (frame_pc_unwind): Use the per-frame pc unwinder when
+	available.  Do not handle the sentinel-frame case.
+	* frame-unwind.h (frame_prev_register_ftype): Define.
+	(struct frame_unwind): Add prev_pc;
+
 2004-11-08  John David Anglin  <dave.anglin@nrc-cnrc.gc.ca>
 
 	* configure.in: Check for ncurses/term.h.
diff --git a/gdb/frame-unwind.h b/gdb/frame-unwind.h
index 12d6dd2..74c0a4a 100644
--- a/gdb/frame-unwind.h
+++ b/gdb/frame-unwind.h
@@ -118,6 +118,14 @@ typedef void (frame_prev_register_ftype) (struct frame_info *next_frame,
 					  CORE_ADDR *addrp,
 					  int *realnump, void *valuep);
 
+/* Assuming the frame chain: (outer) prev <-> this <-> next (inner);
+   use the NEXT frame, and its register unwind method, to return the PREV
+   frame's program-counter.  */
+
+typedef CORE_ADDR (frame_prev_pc_ftype) (struct frame_info *next_frame,
+					 void **this_prologue_cache);
+
+
 struct frame_unwind
 {
   /* The frame's type.  Should this instead be a collection of
@@ -129,6 +137,7 @@ struct frame_unwind
   frame_prev_register_ftype *prev_register;
   const struct frame_data *unwind_data;
   frame_sniffer_ftype *sniffer;
+  frame_prev_pc_ftype *prev_pc;
 };
 
 /* Register a frame unwinder, _prepending_ it to the front of the
diff --git a/gdb/frame.c b/gdb/frame.c
index d9de0e6..61a9520 100644
--- a/gdb/frame.c
+++ b/gdb/frame.c
@@ -390,7 +390,15 @@ frame_pc_unwind (struct frame_info *this_frame)
   if (!this_frame->prev_pc.p)
     {
       CORE_ADDR pc;
-      if (gdbarch_unwind_pc_p (current_gdbarch))
+      if (this_frame->unwind == NULL)
+	this_frame->unwind
+	  = frame_unwind_find_by_frame (this_frame->next,
+					&this_frame->prologue_cache);
+      if (this_frame->unwind->prev_pc != NULL)
+	/* A per-frame unwinder, prefer it.  */
+	pc = this_frame->unwind->prev_pc (this_frame->next,
+					  &this_frame->prologue_cache);
+      else if (gdbarch_unwind_pc_p (current_gdbarch))
 	{
 	  /* The right way.  The `pure' way.  The one true way.  This
 	     method depends solely on the register-unwind code to
@@ -410,17 +418,8 @@ frame_pc_unwind (struct frame_info *this_frame)
 	     different ways that a PC could be unwound.  */
 	  pc = gdbarch_unwind_pc (current_gdbarch, this_frame);
 	}
-      else if (this_frame->level < 0)
-	{
-	  /* FIXME: cagney/2003-03-06: Old code and a sentinel
-             frame.  Do like was always done.  Fetch the PC's value
-             directly from the global registers array (via read_pc).
-             This assumes that this frame belongs to the current
-             global register cache.  The assumption is dangerous.  */
-	  pc = read_pc ();
-	}
       else
-	internal_error (__FILE__, __LINE__, "No gdbarch_unwind_pc method");
+	internal_error (__FILE__, __LINE__, "No unwind_pc method");
       this_frame->prev_pc.value = pc;
       this_frame->prev_pc.p = 1;
       if (frame_debug)
diff --git a/gdb/sentinel-frame.c b/gdb/sentinel-frame.c
index f1e5c7f..b17bc82 100644
--- a/gdb/sentinel-frame.c
+++ b/gdb/sentinel-frame.c
@@ -81,11 +81,22 @@ sentinel_frame_this_id (struct frame_info *next_frame,
   internal_error (__FILE__, __LINE__, "sentinel_frame_this_id called");
 }
 
+static CORE_ADDR
+sentinel_frame_prev_pc (struct frame_info *next_frame,
+			void **this_prologue_cache)
+{
+  struct gdbarch *gdbarch = get_frame_arch (next_frame);
+  return gdbarch_unwind_pc (gdbarch, next_frame);
+}
+
 const struct frame_unwind sentinel_frame_unwinder =
 {
   SENTINEL_FRAME,
   sentinel_frame_this_id,
-  sentinel_frame_prev_register
+  sentinel_frame_prev_register,
+  NULL, /* unwind_data */
+  NULL, /* sniffer */
+  sentinel_frame_prev_pc,
 };
 
 const struct frame_unwind *const sentinel_frame_unwind = &sentinel_frame_unwinder;