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#include <stddef.h>
#include <stdint.h>
#include <string.h>
#include <mlibc/debug.hpp>
#include <mlibc/internal-sysdeps.hpp>
namespace {
// Itanium ABI static initialization guard.
struct Guard {
// bit of the mutex member variable.
// indicates that the mutex is locked.
static constexpr int32_t locked = 1;
void lock() {
uint32_t v = 0;
if(__atomic_compare_exchange_n(&mutex, &v, Guard::locked, false,
__ATOMIC_ACQUIRE, __ATOMIC_RELAXED))
return;
mlibc::sys_libc_log("__cxa_guard_acquire contention");
__builtin_trap();
}
void unlock() {
__atomic_store_n(&mutex, 0, __ATOMIC_RELEASE);
}
// the first byte's meaning is fixed by the ABI.
// it indicates whether initialization has already been completed.
uint8_t complete;
// we use some of the remaining bytes to implement a mutex.
uint32_t mutex;
};
static_assert(sizeof(Guard) == sizeof(int64_t));
} // namespace { }
extern "C" [[ gnu::visibility("hidden") ]] void __cxa_pure_virtual() {
mlibc::panicLogger() << "mlibc: Pure virtual function called from IP "
<< (void *)__builtin_return_address(0) << frg::endlog;
}
extern "C" [[ gnu::visibility("hidden") ]] int __cxa_guard_acquire(int64_t *ptr) {
auto guard = reinterpret_cast<Guard *>(ptr);
guard->lock();
// relaxed ordering is sufficient because
// Guard::complete is only modified while the mutex is held.
if(__atomic_load_n(&guard->complete, __ATOMIC_RELAXED)) {
guard->unlock();
return 0;
}else{
return 1;
}
}
extern "C" [[ gnu::visibility("hidden") ]] void __cxa_guard_release(int64_t *ptr) {
auto guard = reinterpret_cast<Guard *>(ptr);
// do a store-release so that compiler generated code can skip calling
// __cxa_guard_acquire by doing a load-acquire on Guard::complete.
__atomic_store_n(&guard->complete, 1, __ATOMIC_RELEASE);
guard->unlock();
}
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