According to docs, the order is unspecified, but running them in
reverse order would be more logical.
When libstdc++ is built, it can either provide its own implementation
of __cxa_thread_atexit or use one from the host environment.
When libstdc++ is cross compiled, the configure script doesn't do any
linking tests and doesn't detect the mingw-w64-crt implementation of
__cxa_thread_atexit, and always provides its own implementation
instead.
When the libstdc++/libsupc++ implementation of __cxa_thread_atexit is
used in conjunction with emulated TLS, both emutls and libsupc++
register destructors to be executed via pthread_key_create; one for
freeing the per-thread memory allocated for the TLS objects, and
one for executing the destructors. They are registered in a sequential
order; first emutls registers the destructor for freeing the memory,
followed by libsupc++ registers a destructor for running the TLS
object destructors.
Therefore, running the pthread key destructors in reverse order makes
sure that the TLS object destructors are called (via libsupc++) before
their memory is deallocated (via emutls).
This pattern also matches how destructors normally are executed - in
opposite order compared with how they were constructors.
---
This part of the fix should at least work the same regardless of
whether winpthreads is in a separate DLL or statically linked into
the end user executable.
---
mingw-w64-libraries/winpthreads/src/thread.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/mingw-w64-libraries/winpthreads/src/thread.c
b/mingw-w64-libraries/winpthreads/src/thread.c
index 3535797e3..247cc2297 100644
--- a/mingw-w64-libraries/winpthreads/src/thread.c
+++ b/mingw-w64-libraries/winpthreads/src/thread.c
@@ -971,7 +971,8 @@ void
_pthread_cleanup_dest (pthread_t t)
{
_pthread_v *tv;
- unsigned int i, j;
+ unsigned int j;
+ int i;
if (!t)
return;
@@ -984,7 +985,7 @@ _pthread_cleanup_dest (pthread_t t)
int flag = 0;
pthread_spin_lock (&tv->spin_keys);
- for (i = 0; i < tv->keymax; i++)
+ for (i = tv->keymax - 1; i >= 0; i--)
{
void *val = tv->keyval[i];
--
2.43.0
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