Re: [PATCH 08/11] [C++/mingw] Simplify first chance exception handling

Simon Marchi
2015-11-02T21:01:52Z

On 15-11-02 02:36 PM, Pedro Alves wrote:
> I can't figure out why we treat first chance exceptions any different
> here.
>
> We set last_sig to 1, and then call windows_resume passing signal==1,
> so the DBG_EXCEPTION_NOT_HANDLED code path in win32_resume is taken:
>
> ~~~
> if (sig != GDB_SIGNAL_0)
> {
> if (current_event.dwDebugEventCode != EXCEPTION_DEBUG_EVENT)
> {
> OUTMSG (("Cannot continue with signal %d here.\n", sig));
> }
> else if (sig == last_sig)
> continue_status = DBG_EXCEPTION_NOT_HANDLED;
> else
> OUTMSG (("Can only continue with recieved signal %d.\n", last_sig));
> }
> ~~~
>
> Fix this by removing this special casing. gdbserver also goes
> straight to continuing with DBG_EXCEPTION_NOT_HANDLED, AFAICS.
>
> gdb/ChangeLog:
> 2015-11-01 Pedro Alves <palves@redhat.com>
>
> * windows-nat.c (handle_exception): Return 0 for first chance
> exceptions.
> (get_windows_debug_event): Adjust.
> ---
> gdb/windows-nat.c | 24 ++++++------------------
> 1 file changed, 6 insertions(+), 18 deletions(-)
>
> diff --git a/gdb/windows-nat.c b/gdb/windows-nat.c
> index 2e12493..cfbd74a 100644
> --- a/gdb/windows-nat.c
> +++ b/gdb/windows-nat.c
> @@ -1124,7 +1124,7 @@ handle_exception (struct target_waitstatus *ourstatus)
> default:
> /* Treat unhandled first chance exceptions specially. */
> if (current_event.u.Exception.dwFirstChance)
> - return -1;
> + return 0;
> printf_unfiltered ("gdb: unknown target exception 0x%08x at %s\n",
> (unsigned) current_event.u.Exception.ExceptionRecord.ExceptionCode,
> host_address_to_string (
> @@ -1491,19 +1491,10 @@ get_windows_debug_event (struct target_ops *ops,
> "EXCEPTION_DEBUG_EVENT"));
> if (saw_create != 1)
> break;
> - switch (handle_exception (ourstatus))
> - {
> - case 0:
> - continue_status = DBG_EXCEPTION_NOT_HANDLED;
> - break;
> - case 1:
> - thread_id = current_event.dwThreadId;
> - break;
> - case -1:
> - last_sig = 1;
> - continue_status = -1;
> - break;
> - }
> + if (handle_exception (ourstatus))
> + thread_id = current_event.dwThreadId;
> + else
> + continue_status = DBG_EXCEPTION_NOT_HANDLED;
> break;
>
> case OUTPUT_DEBUG_STRING_EVENT: /* Message from the kernel. */
> @@ -1529,10 +1520,7 @@ get_windows_debug_event (struct target_ops *ops,
>
> if (!thread_id || saw_create != 1)
> {
> - if (continue_status == -1)
> - windows_resume (ops, minus_one_ptid, 0, 1);
> - else
> - CHECK (windows_continue (continue_status, -1, 0));
> + CHECK (windows_continue (continue_status, -1, 0));
> }
> else
> {
>

Does this change fix something initially related to C++?