PING!
(for the GCC-7 branch, I'll commit it after the 7.4 release)
On Thu, Nov 22, 2018 at 11:17 AM Janne Blomqvist <blomqvist.ja...@gmail.com>
wrote:
> From backtrace.h for backtrace_create_state:
>
> Calling this function allocates resources that can not be freed.
> There is no backtrace_free_state function. The state is used to
> cache information that is expensive to recompute. Programs are
> expected to call this function at most once and to save the return
> value for all later calls to backtrace functions.
>
> So instead of calling backtrace_create_state every time we wish to
> show a backtrace, do it once and store the result in a static
> variable. libbacktrace allows multiple threads to access the state,
> so no need to use TLS.
>
> Regtested on x86_64-pc-linux-gnu, Ok for trunk/8/7?
>
> libgfortran/ChangeLog:
>
> 2018-11-22 Janne Blomqvist <j...@gcc.gnu.org>
>
> PR libfortran/88137
> * runtime/backtrace.c (show_backtrace): Make lbstate a static
> variable, initialize once.
> ---
> libgfortran/runtime/backtrace.c | 12 ++++++++----
> 1 file changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/libgfortran/runtime/backtrace.c
> b/libgfortran/runtime/backtrace.c
> index e0c277044b6..3fc973a5e6d 100644
> --- a/libgfortran/runtime/backtrace.c
> +++ b/libgfortran/runtime/backtrace.c
> @@ -146,11 +146,15 @@ full_callback (void *data, uintptr_t pc, const char
> *filename,
> void
> show_backtrace (bool in_signal_handler)
> {
> - struct backtrace_state *lbstate;
> + /* Note that libbacktrace allows the state to be accessed from
> + multiple threads, so we don't need to use a TLS variable for the
> + state here. */
> + static struct backtrace_state *lbstate;
> struct mystate state = { 0, false, in_signal_handler };
> -
> - lbstate = backtrace_create_state (NULL, __gthread_active_p (),
> - error_callback, NULL);
> +
> + if (!lbstate)
> + lbstate = backtrace_create_state (NULL, __gthread_active_p (),
> + error_callback, NULL);
>
> if (lbstate == NULL)
> return;
> --
> 2.17.1
>
>
--
Janne Blomqvist
