From 751c7c72c0105c7d55e58bba3c069c36a74c8937 Mon Sep 17 00:00:00 2001 From: Tom de Vries Date: Wed, 3 May 2023 21:43:03 +0200 Subject: [PATCH] [gdb/build] Fix frame_list position in frame.c In commit 995a34b1772 ("Guard against frame.c destructors running before frame-info.c's") the following problem was addressed. The frame_info_ptr destructor: ... ~frame_info_ptr () { frame_list.erase (frame_list.iterator_to (*this)); } ... uses frame_list, which is a static member of class frame_info_ptr, instantiated in frame-info.c: ... intrusive_list frame_info_ptr::frame_list; ... Then there's a static frame_info_pointer variable named selected_frame in frame.c: ... static frame_info_ptr selected_frame; ... Because the destructor of selected_frame uses frame_list, its destructor needs to be called before the destructor of frame_list. But because they're in different compilation units, the initialization order and consequently destruction order is not guarantueed. The commit fixed this by handling the case that the destructor of frame_list is called first, adding a check on is_linked (): ... ~frame_info_ptr () { - frame_list.erase (frame_list.iterator_to (*this)); + /* If this node has static storage, it may be deleted after + frame_list. Attempting to erase ourselves would then trigger + internal errors, so make sure we are still linked first. */ + if (is_linked ()) + frame_list.erase (frame_list.iterator_to (*this)); } ... However, since then frame_list has been moved into frame.c, and initialization/destruction order is guarantueed inside a compilation unit. Revert aforementioned commit, and fix the destruction order problem by moving frame_list before selected_frame. Reverting the commit is another way of fixing the already fixed Wdangling-pointer warning reported in PR build/30413, in a different way than commit 9b0ccb1ebae ("Pass const frame_info_ptr reference for skip_[language_]trampoline"). Approved-By: Simon Marchi Tested on x86_64-linux. PR build/30413 Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30413 --- gdb/frame.c | 11 +++++++---- gdb/frame.h | 8 +++----- 2 files changed, 10 insertions(+), 9 deletions(-) diff --git a/gdb/frame.c b/gdb/frame.c index 36fb02f3c8e..c8b8d2e257e 100644 --- a/gdb/frame.c +++ b/gdb/frame.c @@ -1733,6 +1733,13 @@ get_current_frame (void) static frame_id selected_frame_id = null_frame_id; static int selected_frame_level = -1; +/* See frame.h. This definition should come before any definition of a static + frame_info_ptr, to ensure that frame_list is destroyed after any static + frame_info_ptr. This is necessary because the destructor of frame_info_ptr + uses frame_list. */ + +intrusive_list frame_info_ptr::frame_list; + /* The cached frame_info object pointing to the selected frame. Looked up on demand by get_selected_frame. */ static frame_info_ptr selected_frame; @@ -3275,10 +3282,6 @@ maintenance_print_frame_id (const char *args, int from_tty) /* See frame-info-ptr.h. */ -intrusive_list frame_info_ptr::frame_list; - -/* See frame-info-ptr.h. */ - frame_info_ptr::frame_info_ptr (struct frame_info *ptr) : m_ptr (ptr) { diff --git a/gdb/frame.h b/gdb/frame.h index 6ed8db0af56..355150ab585 100644 --- a/gdb/frame.h +++ b/gdb/frame.h @@ -254,11 +254,9 @@ public: ~frame_info_ptr () { - /* If this node has static storage, it may be deleted after - frame_list. Attempting to erase ourselves would then trigger - internal errors, so make sure we are still linked first. */ - if (is_linked ()) - frame_list.erase (frame_list.iterator_to (*this)); + /* If this node has static storage, it should be be deleted before + frame_list. */ + frame_list.erase (frame_list.iterator_to (*this)); } frame_info_ptr &operator= (const frame_info_ptr &other) -- 2.30.2