Re: [PATCH] libstdc++: Fix exceptions being generated when compiling with -fno-exceptions
Jonathan, I don't have commit access though, so if you could commit this for me it'd be great. Regards. 2015-04-15 11:55 GMT-03:00 Jonathan Wakely : > On 15/04/15 11:15 -0300, Federico Lenarduzzi wrote: >> >> The idea of this patch is that using this function not depends from a >> configuration >> flag but depends of a flag which participates in the selection of the >> correct multilib. > > > OK, then I agree it's better to make it conditional on > __cpp_exceptions which can have different values for your different > multilibs, whereas _GLIBCXX_VERBOSE would be the same in all of them. > > I have no objections to the change. -- Federico Lenarduzzi Software Engineer Taller Technologies Argentina San Lorenzo 47, 3rd Floor, Office 5 Cordoba, Argentina Phone: +54 351 4220701 Mobile: +54 358 4289083 Skype: federico.lenarduzzi1
[PATCH] libstdc++: Fix exceptions being generated when compiling with -fno-exceptions
When the libstdc++ is compiled, the compiler sets the std::terminate_handler
function with __verbose_terminate_handler() or std::abort() depending on
_GLIBCXX_HOSTED && _GLIBCXX_VERBOSE being true or false.
However, even if we compile with -fno-exceptions, the compiler will use
__verbose_terminate_handler(), which uses exceptions. Therefore, the library is
not fully exception-free.
This patch adds a check for __EXCEPTIONS to the #if _GLIBCXX_HOSTED &&
_GLIBCXX_VERBOSE condition. If __EXCEPTIONS is defined, the compiler will use
__verbose_terminate_handler() as a termination function; otherwise it'll use
std::abort() which doesn't have exceptions. It also makes
std::uncaught_exception() throw() return false if __EXCEPTIONS is not defined.
libstdc++-v3/
2015-04-14 Federico Lenarduzzi
* libsupc++/eh_catch.cc (std::uncaught_exception() throw()): Add an
#else
which returns false if __EXCEPTIONS is not defined.
* libsupc++/eh_term_handler.cc: Add a check for __EXCEPTIONS to the #if.
---
libstdc++-v3/libsupc++/eh_catch.cc| 4
libstdc++-v3/libsupc++/eh_term_handler.cc | 2 +-
2 files changed, 5 insertions(+), 1 deletion(-)
diff --git a/libstdc++-v3/libsupc++/eh_catch.cc
b/libstdc++-v3/libsupc++/eh_catch.cc
index 43e875a..6b500f6 100644
--- a/libstdc++-v3/libsupc++/eh_catch.cc
+++ b/libstdc++-v3/libsupc++/eh_catch.cc
@@ -136,6 +136,10 @@ __cxxabiv1::__cxa_end_catch ()
bool
std::uncaught_exception() throw()
{
+#ifdef __EXCEPTIONS
__cxa_eh_globals *globals = __cxa_get_globals ();
return globals->uncaughtExceptions != 0;
+#else
+ return false;
+#endif
}
diff --git a/libstdc++-v3/libsupc++/eh_term_handler.cc
b/libstdc++-v3/libsupc++/eh_term_handler.cc
index c855360..0935193 100644
--- a/libstdc++-v3/libsupc++/eh_term_handler.cc
+++ b/libstdc++-v3/libsupc++/eh_term_handler.cc
@@ -32,7 +32,7 @@
--disable-libstdcxx-verbose and rebuilding the library.
In a freestanding environment, we default to this latter approach. */
-#if _GLIBCXX_HOSTED && _GLIBCXX_VERBOSE
+#if _GLIBCXX_HOSTED && _GLIBCXX_VERBOSE && defined(__EXCEPTIONS)
/* The current installed user handler. */
std::terminate_handler __cxxabiv1::__terminate_handler =
__gnu_cxx::__verbose_terminate_handler;
--
1.9.3
Re: [PATCH] libstdc++: Fix exceptions being generated when compiling with -fno-exceptions
Thanks for comments. I forgot to mention that this change came of working with the target fragment file for the generation of libraries with and without exceptions. After that, the choice of the multilibs with or without exceptions will depend on the use the -fno-excepcions flag at the moment of compilation of an application. As you mentioned in the thread linked to this new flag, have the option --disable-libstdcxx-verbose is very useful, especially in embedded software development. Now, If I have the below case: I'm developing two applications, the first not want to have exception handling, therefore I would like to have the library without verbose_terminate_handler () function and the second application handles exceptions, with which I would like to have the library with the function mentioned above. To achieve this, I should have two copies compiled in different ways or recompile all gcc to enable or disable this function. The idea of this patch is that using this function not depends from a configuration flag but depends of a flag which participates in the selection of the correct multilib. I think it could be discuss, I would like read some opinions and comments about this. 2015-04-14 16:27 GMT-03:00 Jonathan Wakely : > On 14 April 2015 at 16:17, Federico Lenarduzzi wrote: > > When the libstdc++ is compiled, the compiler sets the > > std::terminate_handler function with __verbose_terminate_handler() or > > std::abort() depending on _GLIBCXX_HOSTED && _GLIBCXX_VERBOSE being true or > > false. > > > > However, even if we compile with -fno-exceptions, the compiler will use > > __verbose_terminate_handler(), which uses exceptions. Therefore, the > > library is not fully exception-free. > > I guess this makes sense, but you can just build with > --disable-libstdcxx-verbose to have the same effect. > > > It also makes std::uncaught_exception() throw() return false if > > __EXCEPTIONS is not defined. > > This part seems like a good idea, but we'll also need to do it to the > new uncaught_exceptions() function about to be added, so let's wait > until that in committed first (which will be shortly after the 5.1 > release). > > The checks should use __cpp_exceptions not __EXCEPTIONS, see the current > trunk. -- Federico Lenarduzzi Software Engineer Taller Technologies Argentina San Lorenzo 47, 3rd Floor, Office 5 Cordoba, Argentina Phone: +54 351 4220701 Mobile: +54 358 4289083 Skype: federico.lenarduzzi1 -- Federico Lenarduzzi Software Engineer Taller Technologies Argentina San Lorenzo 47, 3rd Floor, Office 5 Cordoba, Argentina Phone: +54 351 4220701 Mobile: +54 358 4289083 Skype: federico.lenarduzzi1
