X-Git-Url: http://review.tizen.org/git/?a=blobdiff_plain;f=gdb%2Fframe.c;h=5c4217c6d05a1c8ff8d9c3f1e35518bc6e0a8705;hb=ee959deb576c46b85b6174626d700e1393256adf;hp=535a5a6dde26c4001cb7c4737e5c14bb45985b4e;hpb=be2c48b4d50b992ba83bc51f086e316621a03a14;p=platform%2Fupstream%2Fbinutils.git

diff --git a/gdb/frame.c b/gdb/frame.c
index 535a5a6..5c4217c 100644
--- a/gdb/frame.c
+++ b/gdb/frame.c
@@ -1,6 +1,6 @@
 /* Cache and manage frames for GDB, the GNU debugger.
 
-   Copyright (C) 1986-2013 Free Software Foundation, Inc.
+   Copyright (C) 1986-2014 Free Software Foundation, Inc.
 
    This file is part of GDB.
 
@@ -23,8 +23,6 @@
 #include "value.h"
 #include "inferior.h"	/* for inferior_ptid */
 #include "regcache.h"
-#include "gdb_assert.h"
-#include <string.h>
 #include "user-regs.h"
 #include "gdb_obstack.h"
 #include "dummy-frame.h"
@@ -38,15 +36,32 @@
 #include "gdbcmd.h"
 #include "observer.h"
 #include "objfiles.h"
-#include "exceptions.h"
 #include "gdbthread.h"
 #include "block.h"
 #include "inline-frame.h"
 #include "tracepoint.h"
 #include "hashtab.h"
+#include "valprint.h"
 
-static struct frame_info *get_prev_frame_1 (struct frame_info *this_frame);
 static struct frame_info *get_prev_frame_raw (struct frame_info *this_frame);
+static const char *frame_stop_reason_symbol_string (enum unwind_stop_reason reason);
+
+/* Status of some values cached in the frame_info object.  */
+
+enum cached_copy_status
+{
+  /* Value is unknown.  */
+  CC_UNKNOWN,
+
+  /* We have a value.  */
+  CC_VALUE,
+
+  /* Value was not saved.  */
+  CC_NOT_SAVED,
+
+  /* Value is unavailable.  */
+  CC_UNAVAILABLE
+};
 
 /* We keep a cache of stack frames, each of which is a "struct
    frame_info".  The innermost one gets allocated (in
@@ -94,7 +109,7 @@ struct frame_info
 
   /* Cached copy of the previous frame's resume address.  */
   struct {
-    int p;
+    enum cached_copy_status status;
     CORE_ADDR value;
   } prev_pc;
   
@@ -127,6 +142,10 @@ struct frame_info
   /* The reason why we could not set PREV, or UNWIND_NO_REASON if we
      could.  Only valid when PREV_P is set.  */
   enum unwind_stop_reason stop_reason;
+
+  /* A frame specific string describing the STOP_REASON in more detail.
+     Only valid when PREV_P is set, but even then may still be NULL.  */
+  const char *stop_string;
 };
 
 /* A frame stash used to speed up frame lookups.  Create a hash table
@@ -147,10 +166,11 @@ frame_addr_hash (const void *ap)
   const struct frame_id f_id = frame->this_id.value;
   hashval_t hash = 0;
 
-  gdb_assert (f_id.stack_addr_p || f_id.code_addr_p
+  gdb_assert (f_id.stack_status != FID_STACK_INVALID
+	      || f_id.code_addr_p
 	      || f_id.special_addr_p);
 
-  if (f_id.stack_addr_p)
+  if (f_id.stack_status == FID_STACK_VALID)
     hash = iterative_hash (&f_id.stack_addr,
 			   sizeof (f_id.stack_addr), hash);
   if (f_id.code_addr_p)
@@ -188,23 +208,31 @@ frame_stash_create (void)
 			     NULL);
 }
 
-/* Internal function to add a frame to the frame_stash hash table.  Do
-   not store frames below 0 as they may not have any addresses to
-   calculate a hash.  */
+/* Internal function to add a frame to the frame_stash hash table.
+   Returns false if a frame with the same ID was already stashed, true
+   otherwise.  */
 
-static void
+static int
 frame_stash_add (struct frame_info *frame)
 {
-  /* Do not stash frames below level 0.  */
-  if (frame->level >= 0)
-    {
-      struct frame_info **slot;
+  struct frame_info **slot;
 
-      slot = (struct frame_info **) htab_find_slot (frame_stash,
-						    frame,
-						    INSERT);
-      *slot = frame;
-    }
+  /* Do not try to stash the sentinel frame.  */
+  gdb_assert (frame->level >= 0);
+
+  slot = (struct frame_info **) htab_find_slot (frame_stash,
+						frame,
+						INSERT);
+
+  /* If we already have a frame in the stack with the same id, we
+     either have a stack cycle (corrupted stack?), or some bug
+     elsewhere in GDB.  In any case, ignore the duplicate and return
+     an indication to the caller.  */
+  if (*slot != NULL)
+    return 0;
+
+  *slot = frame;
+  return 1;
 }
 
 /* Internal function to search the frame stash for an entry with the
@@ -290,13 +318,23 @@ void
 fprint_frame_id (struct ui_file *file, struct frame_id id)
 {
   fprintf_unfiltered (file, "{");
-  fprint_field (file, "stack", id.stack_addr_p, id.stack_addr);
+
+  if (id.stack_status == FID_STACK_INVALID)
+    fprintf_unfiltered (file, "!stack");
+  else if (id.stack_status == FID_STACK_UNAVAILABLE)
+    fprintf_unfiltered (file, "stack=<unavailable>");
+  else
+    fprintf_unfiltered (file, "stack=%s", hex_string (id.stack_addr));
   fprintf_unfiltered (file, ",");
+
   fprint_field (file, "code", id.code_addr_p, id.code_addr);
   fprintf_unfiltered (file, ",");
+
   fprint_field (file, "special", id.special_addr_p, id.special_addr);
+
   if (id.artificial_depth)
     fprintf_unfiltered (file, ",artificial=%d", id.artificial_depth);
+
   fprintf_unfiltered (file, "}");
 }
 
@@ -356,10 +394,15 @@ fprint_frame (struct ui_file *file, struct frame_info *fi)
     fprintf_unfiltered (file, "<unknown>");
   fprintf_unfiltered (file, ",");
   fprintf_unfiltered (file, "pc=");
-  if (fi->next != NULL && fi->next->prev_pc.p)
-    fprintf_unfiltered (file, "%s", hex_string (fi->next->prev_pc.value));
-  else
+  if (fi->next == NULL || fi->next->prev_pc.status == CC_UNKNOWN)
     fprintf_unfiltered (file, "<unknown>");
+  else if (fi->next->prev_pc.status == CC_VALUE)
+    fprintf_unfiltered (file, "%s",
+			hex_string (fi->next->prev_pc.value));
+  else if (fi->next->prev_pc.status == CC_NOT_SAVED)
+    val_print_not_saved (file);
+  else if (fi->next->prev_pc.status == CC_UNAVAILABLE)
+    val_print_unavailable (file);
   fprintf_unfiltered (file, ",");
   fprintf_unfiltered (file, "id=");
   if (fi->this_id.p)
@@ -382,13 +425,47 @@ fprint_frame (struct ui_file *file, struct frame_info *fi)
 static struct frame_info *
 skip_artificial_frames (struct frame_info *frame)
 {
+  /* Note we use get_prev_frame_always, and not get_prev_frame.  The
+     latter will truncate the frame chain, leading to this function
+     unintentionally returning a null_frame_id (e.g., when the user
+     sets a backtrace limit).  This is safe, because as these frames
+     are made up by GDB, there must be a real frame in the chain
+     below.  */
   while (get_frame_type (frame) == INLINE_FRAME
 	 || get_frame_type (frame) == TAILCALL_FRAME)
-    frame = get_prev_frame (frame);
+    frame = get_prev_frame_always (frame);
 
   return frame;
 }
 
+/* Compute the frame's uniq ID that can be used to, later, re-find the
+   frame.  */
+
+static void
+compute_frame_id (struct frame_info *fi)
+{
+  gdb_assert (!fi->this_id.p);
+
+  if (frame_debug)
+    fprintf_unfiltered (gdb_stdlog, "{ compute_frame_id (fi=%d) ",
+			fi->level);
+  /* Find the unwinder.  */
+  if (fi->unwind == NULL)
+    frame_unwind_find_by_frame (fi, &fi->prologue_cache);
+  /* Find THIS frame's ID.  */
+  /* Default to outermost if no ID is found.  */
+  fi->this_id.value = outer_frame_id;
+  fi->unwind->this_id (fi, &fi->prologue_cache, &fi->this_id.value);
+  gdb_assert (frame_id_p (fi->this_id.value));
+  fi->this_id.p = 1;
+  if (frame_debug)
+    {
+      fprintf_unfiltered (gdb_stdlog, "-> ");
+      fprint_frame_id (gdb_stdlog, fi->this_id.value);
+      fprintf_unfiltered (gdb_stdlog, " }\n");
+    }
+}
+
 /* Return a frame uniq ID that can be used to, later, re-find the
    frame.  */
 
@@ -398,29 +475,7 @@ get_frame_id (struct frame_info *fi)
   if (fi == NULL)
     return null_frame_id;
 
-  if (!fi->this_id.p)
-    {
-      if (frame_debug)
-	fprintf_unfiltered (gdb_stdlog, "{ get_frame_id (fi=%d) ",
-			    fi->level);
-      /* Find the unwinder.  */
-      if (fi->unwind == NULL)
-	frame_unwind_find_by_frame (fi, &fi->prologue_cache);
-      /* Find THIS frame's ID.  */
-      /* Default to outermost if no ID is found.  */
-      fi->this_id.value = outer_frame_id;
-      fi->unwind->this_id (fi, &fi->prologue_cache, &fi->this_id.value);
-      gdb_assert (frame_id_p (fi->this_id.value));
-      fi->this_id.p = 1;
-      if (frame_debug)
-	{
-	  fprintf_unfiltered (gdb_stdlog, "-> ");
-	  fprint_frame_id (gdb_stdlog, fi->this_id.value);
-	  fprintf_unfiltered (gdb_stdlog, " }\n");
-	}
-      frame_stash_add (fi);
-    }
-
+  gdb_assert (fi->this_id.p);
   return fi->this_id.value;
 }
 
@@ -435,13 +490,13 @@ frame_unwind_caller_id (struct frame_info *next_frame)
 {
   struct frame_info *this_frame;
 
-  /* Use get_prev_frame_1, and not get_prev_frame.  The latter will truncate
-     the frame chain, leading to this function unintentionally
-     returning a null_frame_id (e.g., when a caller requests the frame
-     ID of "main()"s caller.  */
+  /* Use get_prev_frame_always, and not get_prev_frame.  The latter
+     will truncate the frame chain, leading to this function
+     unintentionally returning a null_frame_id (e.g., when a caller
+     requests the frame ID of "main()"s caller.  */
 
   next_frame = skip_artificial_frames (next_frame);
-  this_frame = get_prev_frame_1 (next_frame);
+  this_frame = get_prev_frame_always (next_frame);
   if (this_frame)
     return get_frame_id (skip_artificial_frames (this_frame));
   else
@@ -449,7 +504,7 @@ frame_unwind_caller_id (struct frame_info *next_frame)
 }
 
 const struct frame_id null_frame_id; /* All zeros.  */
-const struct frame_id outer_frame_id = { 0, 0, 0, 0, 0, 1, 0 };
+const struct frame_id outer_frame_id = { 0, 0, 0, FID_STACK_INVALID, 0, 1, 0 };
 
 struct frame_id
 frame_id_build_special (CORE_ADDR stack_addr, CORE_ADDR code_addr,
@@ -458,7 +513,36 @@ frame_id_build_special (CORE_ADDR stack_addr, CORE_ADDR code_addr,
   struct frame_id id = null_frame_id;
 
   id.stack_addr = stack_addr;
-  id.stack_addr_p = 1;
+  id.stack_status = FID_STACK_VALID;
+  id.code_addr = code_addr;
+  id.code_addr_p = 1;
+  id.special_addr = special_addr;
+  id.special_addr_p = 1;
+  return id;
+}
+
+/* See frame.h.  */
+
+struct frame_id
+frame_id_build_unavailable_stack (CORE_ADDR code_addr)
+{
+  struct frame_id id = null_frame_id;
+
+  id.stack_status = FID_STACK_UNAVAILABLE;
+  id.code_addr = code_addr;
+  id.code_addr_p = 1;
+  return id;
+}
+
+/* See frame.h.  */
+
+struct frame_id
+frame_id_build_unavailable_stack_special (CORE_ADDR code_addr,
+					  CORE_ADDR special_addr)
+{
+  struct frame_id id = null_frame_id;
+
+  id.stack_status = FID_STACK_UNAVAILABLE;
   id.code_addr = code_addr;
   id.code_addr_p = 1;
   id.special_addr = special_addr;
@@ -472,7 +556,7 @@ frame_id_build (CORE_ADDR stack_addr, CORE_ADDR code_addr)
   struct frame_id id = null_frame_id;
 
   id.stack_addr = stack_addr;
-  id.stack_addr_p = 1;
+  id.stack_status = FID_STACK_VALID;
   id.code_addr = code_addr;
   id.code_addr_p = 1;
   return id;
@@ -484,7 +568,7 @@ frame_id_build_wild (CORE_ADDR stack_addr)
   struct frame_id id = null_frame_id;
 
   id.stack_addr = stack_addr;
-  id.stack_addr_p = 1;
+  id.stack_status = FID_STACK_VALID;
   return id;
 }
 
@@ -494,7 +578,7 @@ frame_id_p (struct frame_id l)
   int p;
 
   /* The frame is valid iff it has a valid stack address.  */
-  p = l.stack_addr_p;
+  p = l.stack_status != FID_STACK_INVALID;
   /* outer_frame_id is also valid.  */
   if (!p && memcmp (&l, &outer_frame_id, sizeof (l)) == 0)
     p = 1;
@@ -521,19 +605,20 @@ frame_id_eq (struct frame_id l, struct frame_id r)
 {
   int eq;
 
-  if (!l.stack_addr_p && l.special_addr_p
-      && !r.stack_addr_p && r.special_addr_p)
+  if (l.stack_status == FID_STACK_INVALID && l.special_addr_p
+      && r.stack_status == FID_STACK_INVALID && r.special_addr_p)
     /* The outermost frame marker is equal to itself.  This is the
        dodgy thing about outer_frame_id, since between execution steps
        we might step into another function - from which we can't
        unwind either.  More thought required to get rid of
        outer_frame_id.  */
     eq = 1;
-  else if (!l.stack_addr_p || !r.stack_addr_p)
+  else if (l.stack_status == FID_STACK_INVALID
+	   || l.stack_status == FID_STACK_INVALID)
     /* Like a NaN, if either ID is invalid, the result is false.
        Note that a frame ID is invalid iff it is the null frame ID.  */
     eq = 0;
-  else if (l.stack_addr != r.stack_addr)
+  else if (l.stack_status != r.stack_status || l.stack_addr != r.stack_addr)
     /* If .stack addresses are different, the frames are different.  */
     eq = 0;
   else if (l.code_addr_p && r.code_addr_p && l.code_addr != r.code_addr)
@@ -600,8 +685,9 @@ frame_id_inner (struct gdbarch *gdbarch, struct frame_id l, struct frame_id r)
 {
   int inner;
 
-  if (!l.stack_addr_p || !r.stack_addr_p)
-    /* Like NaN, any operation involving an invalid ID always fails.  */
+  if (l.stack_status != FID_STACK_VALID || r.stack_status != FID_STACK_VALID)
+    /* Like NaN, any operation involving an invalid ID always fails.
+       Likewise if either ID has an unavailable stack address.  */
     inner = 0;
   else if (l.artificial_depth > r.artificial_depth
 	   && l.stack_addr == r.stack_addr
@@ -610,7 +696,7 @@ frame_id_inner (struct gdbarch *gdbarch, struct frame_id l, struct frame_id r)
 	   && l.special_addr == r.special_addr)
     {
       /* Same function, different inlined functions.  */
-      struct block *lb, *rb;
+      const struct block *lb, *rb;
 
       gdb_assert (l.code_addr_p && r.code_addr_p);
 
@@ -691,10 +777,10 @@ frame_find_by_id (struct frame_id id)
   return NULL;
 }
 
-static int
-frame_unwind_pc_if_available (struct frame_info *this_frame, CORE_ADDR *pc)
+static CORE_ADDR
+frame_unwind_pc (struct frame_info *this_frame)
 {
-  if (!this_frame->prev_pc.p)
+  if (this_frame->prev_pc.status == CC_UNKNOWN)
     {
       if (gdbarch_unwind_pc_p (frame_unwind_arch (this_frame)))
 	{
@@ -724,24 +810,35 @@ frame_unwind_pc_if_available (struct frame_info *this_frame, CORE_ADDR *pc)
 	    {
 	      pc = gdbarch_unwind_pc (prev_gdbarch, this_frame);
 	    }
-	  if (ex.reason < 0 && ex.error == NOT_AVAILABLE_ERROR)
-	    {
-	      this_frame->prev_pc.p = -1;
-
-	      if (frame_debug)
-		fprintf_unfiltered (gdb_stdlog,
-				    "{ frame_unwind_pc (this_frame=%d)"
-				    " -> <unavailable> }\n",
-				    this_frame->level);
-	    }
-	  else if (ex.reason < 0)
+	  if (ex.reason < 0)
 	    {
-	      throw_exception (ex);
+	      if (ex.error == NOT_AVAILABLE_ERROR)
+		{
+		  this_frame->prev_pc.status = CC_UNAVAILABLE;
+
+		  if (frame_debug)
+		    fprintf_unfiltered (gdb_stdlog,
+					"{ frame_unwind_pc (this_frame=%d)"
+					" -> <unavailable> }\n",
+					this_frame->level);
+		}
+	      else if (ex.error == OPTIMIZED_OUT_ERROR)
+		{
+		  this_frame->prev_pc.status = CC_NOT_SAVED;
+
+		  if (frame_debug)
+		    fprintf_unfiltered (gdb_stdlog,
+					"{ frame_unwind_pc (this_frame=%d)"
+					" -> <not saved> }\n",
+					this_frame->level);
+		}
+	      else
+		throw_exception (ex);
 	    }
 	  else
 	    {
 	      this_frame->prev_pc.value = pc;
-	      this_frame->prev_pc.p = 1;
+	      this_frame->prev_pc.status = CC_VALUE;
 	      if (frame_debug)
 		fprintf_unfiltered (gdb_stdlog,
 				    "{ frame_unwind_pc (this_frame=%d) "
@@ -753,27 +850,17 @@ frame_unwind_pc_if_available (struct frame_info *this_frame, CORE_ADDR *pc)
       else
 	internal_error (__FILE__, __LINE__, _("No unwind_pc method"));
     }
-  if (this_frame->prev_pc.p < 0)
-    {
-      *pc = -1;
-      return 0;
-    }
-  else
-    {
-      *pc = this_frame->prev_pc.value;
-      return 1;
-    }
-}
-
-static CORE_ADDR
-frame_unwind_pc (struct frame_info *this_frame)
-{
-  CORE_ADDR pc;
 
-  if (!frame_unwind_pc_if_available (this_frame, &pc))
+  if (this_frame->prev_pc.status == CC_VALUE)
+    return this_frame->prev_pc.value;
+  else if (this_frame->prev_pc.status == CC_UNAVAILABLE)
     throw_error (NOT_AVAILABLE_ERROR, _("PC not available"));
+  else if (this_frame->prev_pc.status == CC_NOT_SAVED)
+    throw_error (OPTIMIZED_OUT_ERROR, _("PC not saved"));
   else
-    return pc;
+    internal_error (__FILE__, __LINE__,
+		    "unexpected prev_pc status: %d",
+		    (int) this_frame->prev_pc.status);
 }
 
 CORE_ADDR
@@ -783,13 +870,6 @@ frame_unwind_caller_pc (struct frame_info *this_frame)
 }
 
 int
-frame_unwind_caller_pc_if_available (struct frame_info *this_frame,
-				     CORE_ADDR *pc)
-{
-  return frame_unwind_pc_if_available (skip_artificial_frames (this_frame), pc);
-}
-
-int
 get_frame_func_if_available (struct frame_info *this_frame, CORE_ADDR *pc)
 {
   struct frame_info *next_frame = this_frame->next;
@@ -877,12 +957,12 @@ frame_pop (struct frame_info *this_frame)
     {
       /* Popping a dummy frame involves restoring more than just registers.
 	 dummy_frame_pop does all the work.  */
-      dummy_frame_pop (get_frame_id (this_frame));
+      dummy_frame_pop (get_frame_id (this_frame), inferior_ptid);
       return;
     }
 
   /* Ensure that we have a frame to pop to.  */
-  prev_frame = get_prev_frame_1 (this_frame);
+  prev_frame = get_prev_frame_always (this_frame);
 
   if (!prev_frame)
     error (_("Cannot pop the initial frame."));
@@ -991,7 +1071,8 @@ frame_unwind_register (struct frame_info *frame, int regnum, gdb_byte *buf)
 			 &lval, &addr, &realnum, buf);
 
   if (optimized)
-    error (_("Register %d was optimized out"), regnum);
+    throw_error (OPTIMIZED_OUT_ERROR,
+		 _("Register %d was not saved"), regnum);
   if (unavailable)
     throw_error (NOT_AVAILABLE_ERROR,
 		 _("Register %d is not available"), regnum);
@@ -1033,7 +1114,10 @@ frame_unwind_register_value (struct frame_info *frame, int regnum)
     {
       fprintf_unfiltered (gdb_stdlog, "->");
       if (value_optimized_out (value))
-	fprintf_unfiltered (gdb_stdlog, " optimized out");
+	{
+	  fprintf_unfiltered (gdb_stdlog, " ");
+	  val_print_optimized_out (value, gdb_stdlog);
+	}
       else
 	{
 	  if (VALUE_LVAL (value) == lval_register)
@@ -1552,7 +1636,7 @@ create_new_frame (CORE_ADDR addr, CORE_ADDR pc)
      very likely to read this, and the corresponding unwinder is
      entitled to rely that the PC doesn't magically change.  */
   fi->next->prev_pc.value = pc;
-  fi->next->prev_pc.p = 1;
+  fi->next->prev_pc.status = CC_VALUE;
 
   /* We currently assume that frame chain's can't cross spaces.  */
   fi->pspace = fi->next->pspace;
@@ -1655,25 +1739,81 @@ frame_register_unwind_location (struct frame_info *this_frame, int regnum,
     }
 }
 
-/* Return a "struct frame_info" corresponding to the frame that called
-   THIS_FRAME.  Returns NULL if there is no such frame.
+/* Called during frame unwinding to remove a previous frame pointer from a
+   frame passed in ARG.  */
 
-   Unlike get_prev_frame, this function always tries to unwind the
-   frame.  */
+static void
+remove_prev_frame (void *arg)
+{
+  struct frame_info *this_frame, *prev_frame;
+
+  this_frame = (struct frame_info *) arg;
+  prev_frame = this_frame->prev;
+  gdb_assert (prev_frame != NULL);
+
+  prev_frame->next = NULL;
+  this_frame->prev = NULL;
+}
+
+/* Get the previous raw frame, and check that it is not identical to
+   same other frame frame already in the chain.  If it is, there is
+   most likely a stack cycle, so we discard it, and mark THIS_FRAME as
+   outermost, with UNWIND_SAME_ID stop reason.  Unlike the other
+   validity tests, that compare THIS_FRAME and the next frame, we do
+   this right after creating the previous frame, to avoid ever ending
+   up with two frames with the same id in the frame chain.  */
 
 static struct frame_info *
-get_prev_frame_1 (struct frame_info *this_frame)
+get_prev_frame_if_no_cycle (struct frame_info *this_frame)
 {
-  struct frame_id this_id;
-  struct gdbarch *gdbarch;
   struct frame_info *prev_frame;
+  struct cleanup *prev_frame_cleanup;
+
+  prev_frame = get_prev_frame_raw (this_frame);
+  if (prev_frame == NULL)
+    return NULL;
+
+  /* The cleanup will remove the previous frame that get_prev_frame_raw
+     linked onto THIS_FRAME.  */
+  prev_frame_cleanup = make_cleanup (remove_prev_frame, this_frame);
+
+  compute_frame_id (prev_frame);
+  if (!frame_stash_add (prev_frame))
+    {
+      /* Another frame with the same id was already in the stash.  We just
+	 detected a cycle.  */
+      if (frame_debug)
+	{
+	  fprintf_unfiltered (gdb_stdlog, "-> ");
+	  fprint_frame (gdb_stdlog, NULL);
+	  fprintf_unfiltered (gdb_stdlog, " // this frame has same ID }\n");
+	}
+      this_frame->stop_reason = UNWIND_SAME_ID;
+      /* Unlink.  */
+      prev_frame->next = NULL;
+      this_frame->prev = NULL;
+      prev_frame = NULL;
+    }
+
+  discard_cleanups (prev_frame_cleanup);
+  return prev_frame;
+}
+
+/* Helper function for get_prev_frame_always, this is called inside a
+   TRY_CATCH block.  Return the frame that called THIS_FRAME or NULL if
+   there is no such frame.  This may throw an exception.  */
+
+static struct frame_info *
+get_prev_frame_always_1 (struct frame_info *this_frame)
+{
+  struct gdbarch *gdbarch;
 
   gdb_assert (this_frame != NULL);
   gdbarch = get_frame_arch (this_frame);
 
   if (frame_debug)
     {
-      fprintf_unfiltered (gdb_stdlog, "{ get_prev_frame_1 (this_frame=");
+      fprintf_unfiltered (gdb_stdlog, "{ get_prev_frame_always (this_frame=");
       if (this_frame != NULL)
 	fprintf_unfiltered (gdb_stdlog, "%d", this_frame->level);
       else
@@ -1709,7 +1849,7 @@ get_prev_frame_1 (struct frame_info *this_frame)
      until we have unwound all the way down to the previous non-inline
      frame.  */
   if (get_frame_type (this_frame) == INLINE_FRAME)
-    return get_prev_frame_raw (this_frame);
+    return get_prev_frame_if_no_cycle (this_frame);
 
   /* Check that this frame is unwindable.  If it isn't, don't try to
      unwind to the prev frame.  */
@@ -1718,21 +1858,16 @@ get_prev_frame_1 (struct frame_info *this_frame)
 				       &this_frame->prologue_cache);
 
   if (this_frame->stop_reason != UNWIND_NO_REASON)
-    return NULL;
-
-  /* Check that this frame's ID was valid.  If it wasn't, don't try to
-     unwind to the prev frame.  Be careful to not apply this test to
-     the sentinel frame.  */
-  this_id = get_frame_id (this_frame);
-  if (this_frame->level >= 0 && frame_id_eq (this_id, outer_frame_id))
     {
       if (frame_debug)
 	{
+	  enum unwind_stop_reason reason = this_frame->stop_reason;
+
 	  fprintf_unfiltered (gdb_stdlog, "-> ");
 	  fprint_frame (gdb_stdlog, NULL);
-	  fprintf_unfiltered (gdb_stdlog, " // this ID is NULL }\n");
+	  fprintf_unfiltered (gdb_stdlog, " // %s }\n",
+			      frame_stop_reason_symbol_string (reason));
 	}
-      this_frame->stop_reason = UNWIND_NULL_ID;
       return NULL;
     }
 
@@ -1742,7 +1877,8 @@ get_prev_frame_1 (struct frame_info *this_frame)
      See the comment at frame_id_inner for details.  */
   if (get_frame_type (this_frame) == NORMAL_FRAME
       && this_frame->next->unwind->type == NORMAL_FRAME
-      && frame_id_inner (get_frame_arch (this_frame->next), this_id,
+      && frame_id_inner (get_frame_arch (this_frame->next),
+			 get_frame_id (this_frame),
 			 get_frame_id (this_frame->next)))
     {
       CORE_ADDR this_pc_in_block;
@@ -1753,7 +1889,7 @@ get_prev_frame_1 (struct frame_info *this_frame)
       this_pc_in_block = get_frame_address_in_block (this_frame);
       morestack_msym = lookup_minimal_symbol_by_pc (this_pc_in_block).minsym;
       if (morestack_msym)
-	morestack_name = SYMBOL_LINKAGE_NAME (morestack_msym);
+	morestack_name = MSYMBOL_LINKAGE_NAME (morestack_msym);
       if (!morestack_name || strcmp (morestack_name, "__morestack") != 0)
 	{
 	  if (frame_debug)
@@ -1815,28 +1951,48 @@ get_prev_frame_1 (struct frame_info *this_frame)
 	}
     }
 
-  prev_frame = get_prev_frame_raw (this_frame);
+  return get_prev_frame_if_no_cycle (this_frame);
+}
 
-  /* Check that this and the prev frame are not identical.  If they
-     are, there is most likely a stack cycle.  Unlike the tests above,
-     we do this right after creating the prev frame, to avoid ever
-     ending up with two frames with the same id in the frame
-     chain.  */
-  if (prev_frame != NULL
-      && frame_id_eq (get_frame_id (prev_frame),
-		      get_frame_id (this_frame)))
+/* Return a "struct frame_info" corresponding to the frame that called
+   THIS_FRAME.  Returns NULL if there is no such frame.
+
+   Unlike get_prev_frame, this function always tries to unwind the
+   frame.  */
+
+struct frame_info *
+get_prev_frame_always (struct frame_info *this_frame)
+{
+  volatile struct gdb_exception ex;
+  struct frame_info *prev_frame = NULL;
+
+  TRY_CATCH (ex, RETURN_MASK_ERROR)
     {
-      if (frame_debug)
+      prev_frame = get_prev_frame_always_1 (this_frame);
+    }
+  if (ex.reason < 0)
+    {
+      if (ex.error == MEMORY_ERROR)
 	{
-	  fprintf_unfiltered (gdb_stdlog, "-> ");
-	  fprint_frame (gdb_stdlog, NULL);
-	  fprintf_unfiltered (gdb_stdlog, " // this frame has same ID }\n");
+	  this_frame->stop_reason = UNWIND_MEMORY_ERROR;
+	  if (ex.message != NULL)
+	    {
+	      char *stop_string;
+	      size_t size;
+
+	      /* The error needs to live as long as the frame does.
+	         Allocate using stack local STOP_STRING then assign the
+	         pointer to the frame, this allows the STOP_STRING on the
+	         frame to be of type 'const char *'.  */
+	      size = strlen (ex.message) + 1;
+	      stop_string = frame_obstack_zalloc (size);
+	      memcpy (stop_string, ex.message, size);
+	      this_frame->stop_string = stop_string;
+	    }
+	  prev_frame = NULL;
 	}
-      this_frame->stop_reason = UNWIND_SAME_ID;
-      /* Unlink.  */
-      prev_frame->next = NULL;
-      this_frame->prev = NULL;
-      return NULL;
+      else
+	throw_exception (ex);
     }
 
   return prev_frame;
@@ -1923,18 +2079,18 @@ frame_debug_got_null_frame (struct frame_info *this_frame,
 static int
 inside_main_func (struct frame_info *this_frame)
 {
-  struct minimal_symbol *msymbol;
+  struct bound_minimal_symbol msymbol;
   CORE_ADDR maddr;
 
   if (symfile_objfile == 0)
     return 0;
   msymbol = lookup_minimal_symbol (main_name (), NULL, symfile_objfile);
-  if (msymbol == NULL)
+  if (msymbol.minsym == NULL)
     return 0;
   /* Make certain that the code, and not descriptor, address is
      returned.  */
   maddr = gdbarch_convert_from_func_ptr_addr (get_frame_arch (this_frame),
-					      SYMBOL_VALUE_ADDRESS (msymbol),
+					      BMSYMBOL_VALUE_ADDRESS (msymbol),
 					      &current_target);
   return maddr == get_frame_func (this_frame);
 }
@@ -2053,7 +2209,7 @@ get_prev_frame (struct frame_info *this_frame)
       return NULL;
     }
 
-  return get_prev_frame_1 (this_frame);
+  return get_prev_frame_always (this_frame);
 }
 
 CORE_ADDR
@@ -2438,20 +2594,17 @@ get_frame_sp (struct frame_info *this_frame)
 enum unwind_stop_reason
 get_frame_unwind_stop_reason (struct frame_info *frame)
 {
-  /* If we haven't tried to unwind past this point yet, then assume
-     that unwinding would succeed.  */
-  if (frame->prev_p == 0)
-    return UNWIND_NO_REASON;
+  /* Fill-in STOP_REASON.  */
+  get_prev_frame_always (frame);
+  gdb_assert (frame->prev_p);
 
-  /* Otherwise, we set a reason when we succeeded (or failed) to
-     unwind.  */
   return frame->stop_reason;
 }
 
 /* Return a string explaining REASON.  */
 
 const char *
-frame_stop_reason_string (enum unwind_stop_reason reason)
+unwind_stop_reason_to_string (enum unwind_stop_reason reason)
 {
   switch (reason)
     {
@@ -2466,6 +2619,39 @@ frame_stop_reason_string (enum unwind_stop_reason reason)
     }
 }
 
+const char *
+frame_stop_reason_string (struct frame_info *fi)
+{
+  gdb_assert (fi->prev_p);
+  gdb_assert (fi->prev == NULL);
+
+  /* Return the specific string if we have one.  */
+  if (fi->stop_string != NULL)
+    return fi->stop_string;
+
+  /* Return the generic string if we have nothing better.  */
+  return unwind_stop_reason_to_string (fi->stop_reason);
+}
+
+/* Return the enum symbol name of REASON as a string, to use in debug
+   output.  */
+
+static const char *
+frame_stop_reason_symbol_string (enum unwind_stop_reason reason)
+{
+  switch (reason)
+    {
+#define SET(name, description) \
+    case name: return #name;
+#include "unwind_stop_reasons.def"
+#undef SET
+
+    default:
+      internal_error (__FILE__, __LINE__,
+		      "Invalid frame stop reason");
+    }
+}
+
 /* Clean up after a failed (wrong unwinder) attempt to unwind past
    FRAME.  */
 
@@ -2518,7 +2704,8 @@ static struct cmd_list_element *show_backtrace_cmdlist;
 static void
 set_backtrace_cmd (char *args, int from_tty)
 {
-  help_list (set_backtrace_cmdlist, "set backtrace ", -1, gdb_stdout);
+  help_list (set_backtrace_cmdlist, "set backtrace ", all_commands,
+	     gdb_stdout);
 }
 
 static void