On OS X, TSan already passes all unit and lit tests, but for real-world applications (even very simple ones), we currently produce a lot of false positive reports about data races. This makes TSan useless at this point, because the noise dominates real bugs. This introduces a runtime flag, "ignore_interceptors_accesses", off by default, which makes TSan ignore all memory accesses that happen from interceptors. This will significantly lower the coverage and miss a lot of bugs, but it eliminates most of the current false positives on OS X.
Differential Revision: http://reviews.llvm.org/D15189
llvm-svn: 257760
We're using the dispatch group itself to synchronize (to call Release() and Acquire() on it), but in dispatch group notifications, the group can already be disposed/deallocated. This causes a later assertion failure at `DCHECK_EQ(*meta, 0);` in `MetaMap::AllocBlock` when the same memory is reused (note that the failure only happens in debug builds).
Fixing this by retaining the group and releasing it in the notification. Adding a stress test case that reproduces this.
Differential Revision: http://reviews.llvm.org/D15380
llvm-svn: 255494
This patch adds release and acquire semantics for dispatch groups, plus a test case.
Differential Revision: http://reviews.llvm.org/D15048
llvm-svn: 255020
On OS X, there are other-than-pthread locking APIs that are used quite extensively - OSSpinLock and os_lock_lock. Let's add interceptors for those.
Differential Revision: http://reviews.llvm.org/D14987
llvm-svn: 254611
This patch adds release and acquire semantics for libdispatch semaphores and a test case.
Differential Revision: http://reviews.llvm.org/D14992
llvm-svn: 254412
This patch complete removed SANITIZER_AARCH64_VMA definition and usage.
AArch64 ports now supports runtime VMA detection and instrumentation
for 39 and 42-bit VMA.
It also Rewrite print_address to take a variadic argument list
(the addresses to print) and adjust the tests which uses it to the new
signature.
llvm-svn: 254319
Serial queues need extra happens-before between individual tasks executed in the same queue. This patch adds `Acquire(queue)` before the executed task and `Release(queue)` just after it (for serial queues only). Added a test case.
Differential Revision: http://reviews.llvm.org/D15011
llvm-svn: 254229
We need to intercept libdispatch APIs (dispatch_sync, dispatch_async, etc.) to add synchronization between the code that submits the task and the code that gets executed (possibly on a different thread). This patch adds release+acquire semantics for dispatch_sync, and dispatch_async (plus their "_f" and barrier variants). The synchronization is done on malloc'd contexts (separate for each submitted block/callback). Added tests to show usage of dispatch_sync and dispatch_async, for cases where we expect no warnings and for cases where TSan finds races.
Differential Revision: http://reviews.llvm.org/D14745
llvm-svn: 253982
Reimplement dispatch_once in an interceptor to solve these issues that may produce false positives with TSan on OS X:
1) there is a racy load inside an inlined part of dispatch_once,
2) the fast path in dispatch_once doesn't perform an acquire load, so we don't properly synchronize the initialization and subsequent uses of whatever is initialized,
3) dispatch_once is already used in a lot of already-compiled code, so TSan doesn't see the inlined fast-path.
This patch uses a trick to avoid ever taking the fast path (by never storing ~0 into the predicate), which means the interceptor will always be called even from already-compiled code. Within the interceptor, our own atomic reads and writes are not written into shadow cells, so the race in the inlined part is not reported (because the accesses are only loads).
Differential Revision: http://reviews.llvm.org/D14811
llvm-svn: 253552
I noticed that when a symbol is named just "x", it gets demangled to "long long". On POSIX, AFAIK, mangled names always start with "_Z", so lets just require that.
Differential Revision: http://reviews.llvm.org/D14637
llvm-svn: 253080
This patch adds support for symbolication of globals (implements `SymbolizeData`) for `AtosSymbolizer` on OS X.
Differential Revision: http://reviews.llvm.org/D14618
llvm-svn: 253015
`DlAddrSymbolizer` is used on OS X when we're running inside a sandbox that prevents us from spawning an external symbolizer. This patch adds support for symbolication of globals (implements `SymbolizeData`) for `DlAddrSymbolizer`.
Differential Revision: http://reviews.llvm.org/D14613
llvm-svn: 252899
Kuba Brecka