Summary:
The boolean lock domain is simple and surprisingly effective.
But it's starting to cause false positives in the case where locks are nested.
Releasing the inner lock also releases the outer lock.
This diff introduces a new locks domain: a map of locks (access paths) to a bounded count representing an underapproximation of the number of times the lock has been acquired.
For now, we just use a single dummy access path to represent all locks (and thus a count actually would have been sufficiently expressive; we don't need the map yet).
But I'm planning to remove this limitation in a follow-up by refactoring the lock models to give us an access path.
Knowing the names of locks could be useful for error messages and suggesting fixes.
Reviewed By: jberdine
Differential Revision: D6182006
fbshipit-source-id: 6624971
Summary:
Previously, we could understand than an access was safe either because it was possibly owned or protected by a thread/lock, but not both. If an access was both protected by a lock and rooted in a paramer (i.e., possibly owned), we would forget the ownership part of the precondition and remember only the lock bit. This leads to false positives in cases where an access protected by a lock is owned, but another unowned access to the same memory is not protected by a lock (see the new `unownedLockedWriteOk` E2E test for an example).
This diff makes access safety conditions disjunctive so we can simultaneously track whether an access is owned and whether an access is protected by a thread/lock. This will fix false positives like the one explained in T24015160.
Reviewed By: jberdine
Differential Revision: D6671489
fbshipit-source-id: d17715f
Summary: More general version of the fix in D6138749. This diff moves RacerD's lock modeling into a separate module and uses the module in the HIL translation to check when a function has lock/unlock semantics.
Reviewed By: jberdine, da319
Differential Revision: D6191886
fbshipit-source-id: 6e1fdc3
Summary:
If you write
```
boolean readUnderLockOk() {
synchronized (mLock) {
return mField;
}
}
```
it will be turned into
```
lock()
irvar0 = mField
unlock()
return irvar0
```
in the bytecode. Since HIL eliminates reads/writes to temporaries, it will make the above code appear to perform a read of `mField` outside of the lock.
This diff fixes the problem by forcing HIL to perform all pending reads/writes before you exit a critical section.
Reviewed By: jberdine
Differential Revision: D6138749
fbshipit-source-id: e8ad9a0
Sam Blackshear