Now with patch!
On 3 June 2011 00:36, Nick Lewycky <[email protected]> wrote:
> The attached patch implements the ARM EABI versions of
> __cxa_guard_{acquire,release,abort} while trying to share as much code as
> possible. It appears to me that it's unlikely that this will build correctly
> on __APPLE__ machines, but that's beyond my ability to deal with here. I
> have also not actually tested this on an ARM machine, but I did #define
> LIBCXXABI_ARMEABI and build the tests and those pass on x86-64.
>
> Once again, please review!
>
> Nick
>
>
Index: include/cxxabi.h
===================================================================
--- include/cxxabi.h (revision 132528)
+++ include/cxxabi.h (working copy)
@@ -61,9 +61,15 @@
extern LIBCXXABI_NORETURN void __cxa_deleted_virtual(void);
// 3.3.2 One-time Construction API
+#ifdef LIBCXXABI_ARMEABI
+extern int __cxa_guard_acquire(uint32_t*);
+extern void __cxa_guard_release(uint32_t*);
+extern void __cxa_guard_abort(uint32_t*);
+#else
extern int __cxa_guard_acquire(uint64_t*);
extern void __cxa_guard_release(uint64_t*);
extern void __cxa_guard_abort(uint64_t*);
+#endif
// 3.3.3 Array Construction and Destruction API
extern void* __cxa_vec_new(size_t element_count,
Index: src/cxa_guard.cpp
===================================================================
--- src/cxa_guard.cpp (revision 132528)
+++ src/cxa_guard.cpp (working copy)
@@ -20,6 +20,38 @@
namespace
{
+#if LIBCXX_ARMEABI
+
+// A 32-bit, 4-byte-aligned static data value. The least significant 2 bits must
+// be statically initialized to 0.
+typedef uint32_t guard_type;
+
+// Test the lowest bit.
+inline bool is_initialized(guard_type* guard_object) {
+ return (*guard_object) & 1;
+}
+
+inline void set_initialized(guard_type* guard_object) {
+ *guard_object |= 1;
+}
+
+#else
+
+typedef uint64_t guard_type;
+
+bool is_initialized(guard_type* guard_object) {
+ char* initialized = (char*)guard_object;
+ return *initialized;
+}
+
+void set_initialized(guard_type* guard_object) {
+ char* initialized = (char*)guard_object;
+ *initialized = 1;
+}
+
+#endif
+
+
void abort_message(const char* s)
{
fputs(s, stderr);
@@ -96,6 +128,31 @@
x = f.guard;
}
+inline
+lock_type
+get_lock(uint32_t x)
+{
+ union
+ {
+ uint32_t guard;
+ uint8_t lock[2];
+ } f = {x};
+ return f.lock[1] != 0;
+}
+
+inline
+void
+set_lock(uint32_t& x, lock_type y)
+{
+ union
+ {
+ uint32_t guard;
+ uint8_t lock[2];
+ } f = {0};
+ f.lock[1] = y;
+ x = f.guard;
+}
+
#endif // __APPLE__
} // unnamed namespace
@@ -103,7 +160,7 @@
extern "C"
{
-int __cxa_guard_acquire(uint64_t* guard_object)
+int __cxa_guard_acquire(guard_type* guard_object)
{
char* initialized = (char*)guard_object;
if (pthread_mutex_lock(&guard_mut))
@@ -125,7 +182,7 @@
abort_message("__cxa_guard_acquire condition variable wait failed");
lock = get_lock(*guard_object);
} while (lock);
- result = *initialized == 0;
+ result = !is_initialized();
if (result)
set_lock(*guard_object, id);
}
@@ -145,20 +202,19 @@
return result;
}
-void __cxa_guard_release(uint64_t* guard_object)
+void __cxa_guard_release(guard_type* guard_object)
{
- char* initialized = (char*)guard_object;
if (pthread_mutex_lock(&guard_mut))
abort_message("__cxa_guard_release failed to acquire mutex");
*guard_object = 0;
- *initialized = 1;
+ set_initialized(guard_object);
if (pthread_mutex_unlock(&guard_mut))
abort_message("__cxa_guard_release failed to release mutex");
if (pthread_cond_broadcast(&guard_cv))
abort_message("__cxa_guard_release failed to broadcast condition variable");
}
-void __cxa_guard_abort(uint64_t* guard_object)
+void __cxa_guard_abort(guard_type* guard_object)
{
if (pthread_mutex_lock(&guard_mut))
abort_message("__cxa_guard_abort failed to acquire mutex");
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