From 008f8f2ee9bf610485993a17c1c460afb3cadc6c Mon Sep 17 00:00:00 2001
From: Pedro Alves <palves@redhat.com>
Date: Fri, 18 Mar 2011 18:45:30 +0000
Subject: [PATCH] 	gdb/ 	* frame.h
 (frame_unwind_caller_pc_if_available): Declare. 	* frame.c
 (frame_unwind_caller_pc_if_available): New. 	* stack.c (frame_info): Handle
 unavailable PC.

---
 gdb/frame.c             |  7 +++++++
 gdb/frame.h             |  8 ++++++++
 gdb/stack.c             | 22 +++++++++++++++-------
 gdb/testsuite/ChangeLog |  6 ++++++
 4 files changed, 36 insertions(+), 7 deletions(-)

diff --git a/gdb/frame.c b/gdb/frame.c
index 20d8404e984..a817e4d6eb8 100644
--- a/gdb/frame.c
+++ b/gdb/frame.c
@@ -710,6 +710,13 @@ frame_unwind_caller_pc (struct frame_info *this_frame)
   return frame_unwind_pc (skip_inlined_frames (this_frame));
 }
 
+int
+frame_unwind_caller_pc_if_available (struct frame_info *this_frame,
+				     CORE_ADDR *pc)
+{
+  return frame_unwind_pc_if_available (skip_inlined_frames (this_frame), pc);
+}
+
 int
 get_frame_func_if_available (struct frame_info *this_frame, CORE_ADDR *pc)
 {
diff --git a/gdb/frame.h b/gdb/frame.h
index 25f20a944f7..7bc11480afd 100644
--- a/gdb/frame.h
+++ b/gdb/frame.h
@@ -562,6 +562,14 @@ extern void put_frame_register_bytes (struct frame_info *frame, int regnum,
 
 extern CORE_ADDR frame_unwind_caller_pc (struct frame_info *frame);
 
+/* Same as frame_unwind_caller_pc, but returns a boolean indication of
+   whether the caller PC is determinable (when the PC is unavailable,
+   it will not be), instead of possibly throwing an error trying to
+   read unavailable memory or registers.  */
+
+extern int frame_unwind_caller_pc_if_available (struct frame_info *this_frame,
+						CORE_ADDR *pc);
+
 /* Discard the specified frame.  Restoring the registers to the state
    of the caller.  */
 extern void frame_pop (struct frame_info *frame);
diff --git a/gdb/stack.c b/gdb/stack.c
index de204182e7b..dba77d4bf30 100644
--- a/gdb/stack.c
+++ b/gdb/stack.c
@@ -1031,6 +1031,9 @@ frame_info (char *addr_exp, int from_tty)
   int selected_frame_p;
   struct gdbarch *gdbarch;
   struct cleanup *back_to = make_cleanup (null_cleanup, NULL);
+  CORE_ADDR frame_pc;
+  int frame_pc_p;
+  CORE_ADDR caller_pc;
 
   fi = parse_frame_specification_1 (addr_exp, "No stack.", &selected_frame_p);
   gdbarch = get_frame_arch (fi);
@@ -1049,11 +1052,10 @@ frame_info (char *addr_exp, int from_tty)
        get_frame_pc().  */
     pc_regname = "pc";
 
+  frame_pc_p = get_frame_pc_if_available (fi, &frame_pc);
   find_frame_sal (fi, &sal);
   func = get_frame_function (fi);
-  /* FIXME: cagney/2002-11-28: Why bother?  Won't sal.symtab contain
-     the same value?  */
-  s = find_pc_symtab (get_frame_pc (fi));
+  s = sal.symtab;
   if (func)
     {
       funname = SYMBOL_PRINT_NAME (func);
@@ -1074,11 +1076,11 @@ frame_info (char *addr_exp, int from_tty)
 	    }
 	}
     }
-  else
+  else if (frame_pc_p)
     {
       struct minimal_symbol *msymbol;
 
-      msymbol = lookup_minimal_symbol_by_pc (get_frame_pc (fi));
+      msymbol = lookup_minimal_symbol_by_pc (frame_pc);
       if (msymbol != NULL)
 	{
 	  funname = SYMBOL_PRINT_NAME (msymbol);
@@ -1099,7 +1101,10 @@ frame_info (char *addr_exp, int from_tty)
   fputs_filtered (paddress (gdbarch, get_frame_base (fi)), gdb_stdout);
   printf_filtered (":\n");
   printf_filtered (" %s = ", pc_regname);
-  fputs_filtered (paddress (gdbarch, get_frame_pc (fi)), gdb_stdout);
+  if (frame_pc_p)
+    fputs_filtered (paddress (gdbarch, get_frame_pc (fi)), gdb_stdout);
+  else
+    fputs_filtered ("<unavailable>", gdb_stdout);
 
   wrap_here ("   ");
   if (funname)
@@ -1114,7 +1119,10 @@ frame_info (char *addr_exp, int from_tty)
   puts_filtered ("; ");
   wrap_here ("    ");
   printf_filtered ("saved %s ", pc_regname);
-  fputs_filtered (paddress (gdbarch, frame_unwind_caller_pc (fi)), gdb_stdout);
+  if (frame_unwind_caller_pc_if_available (fi, &caller_pc))
+    fputs_filtered (paddress (gdbarch, caller_pc), gdb_stdout);
+  else
+    fputs_filtered ("<unavailable>", gdb_stdout);
   printf_filtered ("\n");
 
   if (calling_frame_info == NULL)
diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index e3b1a8a2930..96e2a9a9566 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2011-03-18  Pedro Alves  <pedro@codesourcery.com>
+
+	* frame.h (frame_unwind_caller_pc_if_available): Declare.
+	* frame.c (frame_unwind_caller_pc_if_available): New.
+	* stack.c (frame_info): Handle unavailable PC.
+
 2011-03-18  Pedro Alves  <pedro@codesourcery.com>
 
 	* frame.c (frame_unwind_pc): Rename to ...
-- 
2.30.2