From 854cedfd40f14e974060dd3ce4463712ed18274b Mon Sep 17 00:00:00 2001 From: Janne Blomqvist Date: Fri, 30 Nov 2018 18:44:27 +0200 Subject: [PATCH] Initialize backtrace state once 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. libgfortran/ChangeLog: 2018-11-30 Janne Blomqvist PR libfortran/88137 * runtime/backtrace.c (show_backtrace): Make lbstate a static variable, initialize once. From-SVN: r266677 --- libgfortran/ChangeLog | 6 ++++++ libgfortran/runtime/backtrace.c | 12 ++++++++---- 2 files changed, 14 insertions(+), 4 deletions(-) diff --git a/libgfortran/ChangeLog b/libgfortran/ChangeLog index d939762..f1f7cbe 100644 --- a/libgfortran/ChangeLog +++ b/libgfortran/ChangeLog @@ -1,3 +1,9 @@ +2018-11-30 Janne Blomqvist + + PR libfortran/88137 + * runtime/backtrace.c (show_backtrace): Make lbstate a static + variable, initialize once. + 2018-11-23 Janne Blomqvist * runtime/error.c (MAGIC): Remove. diff --git a/libgfortran/runtime/backtrace.c b/libgfortran/runtime/backtrace.c index e0c2770..3fc973a 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; -- 2.7.4