/* Given FRAME, return the enclosing frame as found in real frames read-in from
inferior memory. Skip any previous frames which were made up by GDB.
- Return the original frame if no immediate previous frames exist. */
+ Return FRAME if FRAME is a non-artificial frame.
+ Return NULL if FRAME is the start of an artificial-only chain. */
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. */
+ sets a backtrace limit).
+
+ Note that for record targets we may get a frame chain that consists
+ of artificial frames only. */
while (get_frame_type (frame) == INLINE_FRAME
|| get_frame_type (frame) == TAILCALL_FRAME)
- frame = get_prev_frame_always (frame);
+ {
+ frame = get_prev_frame_always (frame);
+ if (frame == NULL)
+ break;
+ }
+
+ return frame;
+}
+
+struct frame_info *
+skip_unwritable_frames (struct frame_info *frame)
+{
+ while (gdbarch_code_of_frame_writable (get_frame_arch (frame), frame) == 0)
+ {
+ frame = get_prev_frame (frame);
+ if (frame == NULL)
+ break;
+ }
return frame;
}
skip_tailcall_frames (struct frame_info *frame)
{
while (get_frame_type (frame) == TAILCALL_FRAME)
- frame = get_prev_frame (frame);
+ {
+ /* Note that for record targets we may get a frame chain that consists of
+ tailcall frames only. */
+ frame = get_prev_frame (frame);
+ if (frame == NULL)
+ break;
+ }
return frame;
}
if (fi == NULL)
return null_frame_id;
- gdb_assert (fi->this_id.p);
+ if (!fi->this_id.p)
+ {
+ int stashed;
+
+ /* If we haven't computed the frame id yet, then it must be that
+ this is the current frame. Compute it now, and stash the
+ result. The IDs of other frames are computed as soon as
+ they're created, in order to detect cycles. See
+ get_prev_frame_if_no_cycle. */
+ gdb_assert (fi->level == 0);
+
+ /* Compute. */
+ compute_frame_id (fi);
+
+ /* Since this is the first frame in the chain, this should
+ always succeed. */
+ stashed = frame_stash_add (fi);
+ gdb_assert (stashed);
+ }
+
return fi->this_id.value;
}
requests the frame ID of "main()"s caller. */
next_frame = skip_artificial_frames (next_frame);
+ if (next_frame == NULL)
+ return null_frame_id;
+
this_frame = get_prev_frame_always (next_frame);
if (this_frame)
return get_frame_id (skip_artificial_frames (this_frame));
CORE_ADDR
frame_unwind_caller_pc (struct frame_info *this_frame)
{
- return frame_unwind_pc (skip_artificial_frames (this_frame));
+ this_frame = skip_artificial_frames (this_frame);
+
+ /* We must have a non-artificial frame. The caller is supposed to check
+ the result of frame_unwind_caller_id (), which returns NULL_FRAME_ID
+ in this case. */
+ gdb_assert (this_frame != NULL);
+
+ return frame_unwind_pc (this_frame);
}
int
entering THISFRAME. */
prev_frame = skip_tailcall_frames (prev_frame);
+ if (prev_frame == NULL)
+ error (_("Cannot find the caller frame."));
+
/* Make a copy of all the register values unwound from this frame.
Save them in a scratch buffer so that there isn't a race between
trying to extract the old values from the current regcache while
return data;
}
-/* Return the innermost (currently executing) stack frame. This is
- split into two functions. The function unwind_to_current_frame()
- is wrapped in catch exceptions so that, even when the unwind of the
- sentinel frame fails, the function still returns a stack frame. */
-
-static int
-unwind_to_current_frame (struct ui_out *ui_out, void *args)
-{
- struct frame_info *frame = get_prev_frame ((struct frame_info *) args);
-
- /* A sentinel frame can fail to unwind, e.g., because its PC value
- lands in somewhere like start. */
- if (frame == NULL)
- return 1;
- current_frame = frame;
- return 0;
-}
+static struct frame_info *get_prev_frame_always_1 (struct frame_info *this_frame);
struct frame_info *
get_current_frame (void)
if (current_frame == NULL)
{
+ int stashed;
struct frame_info *sentinel_frame =
create_sentinel_frame (current_program_space, get_current_regcache ());
- if (catch_exceptions (current_uiout, unwind_to_current_frame,
- sentinel_frame, RETURN_MASK_ERROR) != 0)
- {
- /* Oops! Fake a current frame? Is this useful? It has a PC
- of zero, for instance. */
- current_frame = sentinel_frame;
- }
+
+ /* Set the current frame before computing the frame id, to avoid
+ recursion inside compute_frame_id, in case the frame's
+ unwinder decides to do a symbol lookup (which depends on the
+ selected frame's block).
+
+ This call must always succeed. In particular, nothing inside
+ get_prev_frame_always_1 should try to unwind from the
+ sentinel frame, because that could fail/throw, and we always
+ want to leave with the current frame created and linked in --
+ we should never end up with the sentinel frame as outermost
+ frame. */
+ current_frame = get_prev_frame_always_1 (sentinel_frame);
+ gdb_assert (current_frame != NULL);
+
+ /* No need to compute the frame id yet. That'll be done lazily
+ from inside get_frame_id instead. */
}
+
return current_frame;
}
struct cleanup *prev_frame_cleanup;
prev_frame = get_prev_frame_raw (this_frame);
- if (prev_frame == NULL)
- return NULL;
+
+ /* Don't compute the frame id of the current frame yet. Unwinding
+ the sentinel frame can fail (e.g., if the thread is gone and we
+ can't thus read its registers). If we let the cycle detection
+ code below try to compute a frame ID, then an error thrown from
+ within the frame ID computation would result in the sentinel
+ frame as outermost frame, which is bogus. Instead, we'll compute
+ the current frame's ID lazily in get_frame_id. Note that there's
+ no point in doing cycle detection when there's only one frame, so
+ nothing is lost here. */
+ if (prev_frame->level == 0)
+ return prev_frame;
/* The cleanup will remove the previous frame that get_prev_frame_raw
linked onto THIS_FRAME. */
struct gdbarch *
frame_unwind_caller_arch (struct frame_info *next_frame)
{
- return frame_unwind_arch (skip_artificial_frames (next_frame));
+ next_frame = skip_artificial_frames (next_frame);
+
+ /* We must have a non-artificial frame. The caller is supposed to check
+ the result of frame_unwind_caller_id (), which returns NULL_FRAME_ID
+ in this case. */
+ gdb_assert (next_frame != NULL);
+
+ return frame_unwind_arch (next_frame);
}
/* Gets the language of FRAME. */
projects / deliverable / binutils-gdb.git / blobdiff