This feature is specifically for the C++ compiler to offload calling
thread_local object destructors on thread program exit, to glibc.
This is to overcome the possible complication of destructors of
thread_local objects getting called after the DSO in which they're
defined is unloaded by the dynamic linker. The DSO is marked as
'unloadable' if it has a constructed thread_local object and marked as
'unloadable' again when all the constructed thread_local objects
defined in it are destroyed.
Previously, we would see a bad frame in the gdb backtrace output, e.g.:
(gdb) bt
#0 foo () at foo.c:5
#1 0x000000aaaab68ee8 in start_thread () from /lib/libpthread.so.0
#2 0x000000aaaad01c88 in clone () from /lib/libc.so.6
#3 0x0000000000000000 in ?? ()
With this change the bogus frame #3 is gone and we have the
same output as x86 does for the same program.
We can discover our x,y coordinate in the core mesh with an
mfspr instruction, multiply y by the core mesh width, and have
the core number without needing to ask the kernel.
The previous dummy definition (as type int) was fine in general, since
tile doesn't have floating-point registers, but it confused gdb's
configure, leading to later compile errors. This change also makes
prfpregset_t parallel to prgregset_t, which seems like generally the
right thing regardless of the non-existence of the actual registers :-)
(__ptrace_eventcodes): Add new value PTRACE_EVENT_SECCOMP from Linux 3.5.
(__ptrace_setoptions): Add new value PTRACE_O_TRACESECCOMP, adjust PTRACE_O_MASK.
