gdb: add names to unwinders, add debug messages when looking for unwinder

I wrote this while debugging a problem where the expected unwinder for a
frame wasn't used.  It adds messages to show which unwinders are
considered for a frame, why they are not selected (if an exception is
thrown), and finally which unwinder is selected in the end.

To be able to show a meaningful, human-readable name for the unwinders,
add a "name" field to struct frame_unwind, and update all instances to
include a name.

Here's an example of the output:

    [frame] frame_unwind_find_by_frame: this_frame=0
    [frame] frame_unwind_try_unwinder: trying unwinder "dummy"
    [frame] frame_unwind_try_unwinder: no
    [frame] frame_unwind_try_unwinder: trying unwinder "dwarf2 tailcall"
    [frame] frame_unwind_try_unwinder: no
    [frame] frame_unwind_try_unwinder: trying unwinder "inline"
    [frame] frame_unwind_try_unwinder: no
    [frame] frame_unwind_try_unwinder: trying unwinder "jit"
    [frame] frame_unwind_try_unwinder: no
    [frame] frame_unwind_try_unwinder: trying unwinder "python"
    [frame] frame_unwind_try_unwinder: no
    [frame] frame_unwind_try_unwinder: trying unwinder "amd64 epilogue"
    [frame] frame_unwind_try_unwinder: no
    [frame] frame_unwind_try_unwinder: trying unwinder "i386 epilogue"
    [frame] frame_unwind_try_unwinder: no
    [frame] frame_unwind_try_unwinder: trying unwinder "dwarf2"
    [frame] frame_unwind_try_unwinder: yes

gdb/ChangeLog:

	* frame-unwind.h (struct frame_unwind) <name>: New.  Update
	instances everywhere to include this field.
	* frame-unwind.c (frame_unwind_try_unwinder,
	frame_unwind_find_by_frame): Add debug messages.

Change-Id: I813f17777422425f0d08b22499817b23922e8ddb
This commit is contained in:
Simon Marchi 2021-06-29 12:05:03 -04:00
parent a05a883fba
commit a154d838a7
78 changed files with 133 additions and 5 deletions

View file

@ -680,6 +680,7 @@ pyuw_on_new_gdbarch (struct gdbarch *newarch)
struct frame_unwind *unwinder
= GDBARCH_OBSTACK_ZALLOC (newarch, struct frame_unwind);
unwinder->name = "python";
unwinder->type = NORMAL_FRAME;
unwinder->stop_reason = default_frame_unwind_stop_reason;
unwinder->this_id = pyuw_this_id;