diff options
Diffstat (limited to 'gdb/frame.c')
| -rw-r--r-- | gdb/frame.c | 117 |
1 files changed, 93 insertions, 24 deletions
diff --git a/gdb/frame.c b/gdb/frame.c index 15168fb..bb835e2 100644 --- a/gdb/frame.c +++ b/gdb/frame.c @@ -317,17 +317,15 @@ frame_stash_invalidate (void) /* See frame.h */ scoped_restore_selected_frame::scoped_restore_selected_frame () { - m_fid = get_frame_id (get_selected_frame (NULL)); + m_lang = current_language->la_language; + save_selected_frame (&m_fid, &m_level); } /* See frame.h */ scoped_restore_selected_frame::~scoped_restore_selected_frame () { - frame_info *frame = frame_find_by_id (m_fid); - if (frame == NULL) - warning (_("Unable to restore previously selected frame.")); - else - select_frame (frame); + restore_selected_frame (m_fid, m_level); + set_language (m_lang); } /* Flag to control debugging. */ @@ -1685,10 +1683,63 @@ get_current_frame (void) } /* The "selected" stack frame is used by default for local and arg - access. May be zero, for no selected frame. */ - + access. + + The "single source of truth" for the selected frame is the + SELECTED_FRAME_ID / SELECTED_FRAME_LEVEL pair. + + Frame IDs can be saved/restored across reinitializing the frame + cache, while frame_info pointers can't (frame_info objects are + invalidated). If we know the corresponding frame_info object, it + is cached in SELECTED_FRAME. + + If SELECTED_FRAME_ID / SELECTED_FRAME_LEVEL are null_frame_id / -1, + and the target has stack and is stopped, the selected frame is the + current (innermost) frame. This means that SELECTED_FRAME_LEVEL is + never 0 and SELECTED_FRAME_ID is never the ID of the innermost + frame. + + If SELECTED_FRAME_ID / SELECTED_FRAME_LEVEL are null_frame_id / -1, + and the target has no stack or is executing, then there's no + selected frame. */ +static frame_id selected_frame_id = null_frame_id; +static int selected_frame_level = -1; + +/* The cached frame_info object pointing to the selected frame. + Looked up on demand by get_selected_frame. */ static struct frame_info *selected_frame; +/* See frame.h. */ + +void +save_selected_frame (frame_id *frame_id, int *frame_level) + noexcept +{ + *frame_id = selected_frame_id; + *frame_level = selected_frame_level; +} + +/* See frame.h. */ + +void +restore_selected_frame (frame_id frame_id, int frame_level) + noexcept +{ + /* save_selected_frame never returns level == 0, so we shouldn't see + it here either. */ + gdb_assert (frame_level != 0); + + /* FRAME_ID can be null_frame_id only IFF frame_level is -1. */ + gdb_assert ((frame_level == -1 && !frame_id_p (frame_id)) + || (frame_level != -1 && frame_id_p (frame_id))); + + selected_frame_id = frame_id; + selected_frame_level = frame_level; + + /* Will be looked up later by get_selected_frame. */ + selected_frame = nullptr; +} + bool has_stack_frames () { @@ -1716,9 +1767,7 @@ has_stack_frames () return true; } -/* Return the selected frame. Always non-NULL (unless there isn't an - inferior sufficient for creating a frame) in which case an error is - thrown. */ +/* See frame.h. */ struct frame_info * get_selected_frame (const char *message) @@ -1727,24 +1776,14 @@ get_selected_frame (const char *message) { if (message != NULL && !has_stack_frames ()) error (("%s"), message); - /* Hey! Don't trust this. It should really be re-finding the - last selected frame of the currently selected thread. This, - though, is better than nothing. */ - select_frame (get_current_frame ()); + + lookup_selected_frame (selected_frame_id, selected_frame_level); } /* There is always a frame. */ gdb_assert (selected_frame != NULL); return selected_frame; } -/* If there is a selected frame, return it. Otherwise, return NULL. */ - -struct frame_info * -get_selected_frame_if_set (void) -{ - return selected_frame; -} - /* This is a variant of get_selected_frame() which can be called when the inferior does not have a frame; in that case it will return NULL instead of calling error(). */ @@ -1757,12 +1796,42 @@ deprecated_safe_get_selected_frame (void) return get_selected_frame (NULL); } -/* Select frame FI (or NULL - to invalidate the current frame). */ +/* Select frame FI (or NULL - to invalidate the selected frame). */ void select_frame (struct frame_info *fi) { selected_frame = fi; + selected_frame_level = frame_relative_level (fi); + if (selected_frame_level == 0) + { + /* Treat the current frame especially -- we want to always + save/restore it without warning, even if the frame ID changes + (see lookup_selected_frame). E.g.: + + // The current frame is selected, the target had just stopped. + { + scoped_restore_selected_frame restore_frame; + some_operation_that_changes_the_stack (); + } + // scoped_restore_selected_frame's dtor runs, but the + // original frame_id can't be found. No matter whether it + // is found or not, we still end up with the now-current + // frame selected. Warning in lookup_selected_frame in this + // case seems pointless. + + Also get_frame_id may access the target's registers/memory, + and thus skipping get_frame_id optimizes the common case. + + Saving the selected frame this way makes get_selected_frame + and restore_current_frame return/re-select whatever frame is + the innermost (current) then. */ + selected_frame_level = -1; + selected_frame_id = null_frame_id; + } + else + selected_frame_id = get_frame_id (fi); + /* NOTE: cagney/2002-05-04: FI can be NULL. This occurs when the frame is being invalidated. */ |