Summary:
I realized that control variable analysis was broken when we had multiple back-edges for the same loop. This is often the case when we have a switch statement combined with continue in a loop (see `test_switch` in `switch_continue.c`) or when we have disjunctive guards in do-while loops.
This diff fixes that by
- defining a loop by its loophead (the target of its backedges) rather than its back-edges. Then it converts back-edge list to a map from loop_head to sources of the loop's back-edges.
- collecting multiple guard nodes that come from potentially multiple exit nodes per loop head
In addition, it also removes the wrong assumption that an exit node belongs to a single loop head.
Reviewed By: mbouaziz
Differential Revision: D8398061
fbshipit-source-id: abaf288
Summary:
We need to report on non-private methods (the opposite even leads to FPs sometimes on deadlocks). To do this, the domain needs to change so that the interpretation of an order pair `a,b` is no longer "lock `a` is taken in the *current method* and held until lock `b` is taken". Instead the meaning is now "lock `a` is taken in some method *of the same class with the current method* and is held until `b` is taken".
These changes are quite drastic because the previous implementation optimised extensively around the previous use case.
Reviewed By: mbouaziz
Differential Revision: D8395351
fbshipit-source-id: a2bd22b
Summary:
The deadlock reports (the actual string) were too low level, in order to avoid bug hash clashes. Now that we deduplicate this is less of an issue, so it's an opportunity to improve readability.
```
Potential deadlock.
Trace 1 (starts at `void Interproc.interproc1Bad(InterprocA)`) first locks `this` in class `Interproc*` (line 9 in `void Interproc.interproc1Bad(InterprocA)`) and then locks `b` in class `InterprocA*` (line 14 in `void Interproc.interproc2Bad(InterprocA)`).
Trace 2 (starts at `void InterprocA.interproc1Bad(Interproc)`), first locks `this` in class `InterprocA*` (line 37 in `void InterprocA.interproc1Bad(Interproc)`) and then locks `d` in class `Interproc*` (line 42 in `void InterprocA.interproc2Bad(Interproc)`).
```
Reviewed By: mbouaziz
Differential Revision: D8394978
fbshipit-source-id: 671ccb0
Summary:
The deadlock reports (the actual string) were too low level, in order to avoid bug hash clashes. Now that we deduplicate this is less of an issue, so it's an opportunity to improve readability.
```
Potential deadlock.
Trace 1 (starts at `void Interproc.interproc1Bad(InterprocA)`) first locks `this` in class `Interproc*` (line 9 in `void Interproc.interproc1Bad(InterprocA)`) and then locks `b` in class `InterprocA*` (line 14 in `void Interproc.interproc2Bad(InterprocA)`).
Trace 2 (starts at `void InterprocA.interproc1Bad(Interproc)`), first locks `this` in class `InterprocA*` (line 37 in `void InterprocA.interproc1Bad(Interproc)`) and then locks `d` in class `Interproc*` (line 42 in `void InterprocA.interproc2Bad(Interproc)`).
```
Reviewed By: mbouaziz
Differential Revision: D8379328
fbshipit-source-id: bc33983
Summary: Deadlocks can be very noisy, so dedup reports on same line by showing only the one with the shortest trace and a count of the suppressed ones.
Reviewed By: mbouaziz
Differential Revision: D8351148
fbshipit-source-id: 8913db2
Summary: Introduce an annotation that forces the summary of a method to be free of blocking events, without suppressing other reports.
Reviewed By: jeremydubreil
Differential Revision: D8276787
fbshipit-source-id: be9eed8
Summary: Create mechanism for suppressing starvation reports. To do that, refactor and expose a Checkers function.
Reviewed By: mbouaziz
Differential Revision: D8259583
fbshipit-source-id: f5b5a63
Summary:
Use the component of the abstract state `events` to report. This set contains reachability facts about blocking calls and lock acquisitions.
The other component, `order`, contained pairs of a reachable event `e'` from an event option with the semantics that if the option is `None` then we have an element that now goes into `events`, and if the option is `Some e` then the element represents a lock acquired and a trace *from* `e` to `e'`
Now, `order` can be simplified to proper pairs of events, without the option.
Reviewed By: jvillard
Differential Revision: D8227665
fbshipit-source-id: e6f4dac
Summary:
It's useful to test that the bucket a given error is classified as doesn't
change over time without notice.
This records the bucket for *all* the tests, even though some never produce a
bucket. This is to be on the safe size instead of risking to forget adding the
bucket information when the test changes, or when copy/pasting from a test that
doesn't have buckets to one that does.
The implementation is pretty crude: it greps the beginning of the qualifier
string for a `[bucket]`.
Reviewed By: mbouaziz
Differential Revision: D8236393
fbshipit-source-id: b3b1eb9
Summary:
Change the license of the source code from BSD + PATENTS to MIT.
Change `checkCopyright` to reflect the new license and learn some new file
types.
Generated with:
```
git grep BSD | xargs -n 1 ./scripts/checkCopyright -i
```
Reviewed By: jeremydubreil, mbouaziz, jberdine
Differential Revision: D8071249
fbshipit-source-id: 97ca23a
Summary:
There can be multiple reports per line, especially when calling in a method which has itself multiple reports.
When reporting at the callsite, report only the issue with the highest severity (picked manually per type of event).
Deadlocks are not de-duplicated, as they are relatively rare and the info in mupltiple reports may be important.
Reviewed By: mbouaziz
Differential Revision: D8160940
fbshipit-source-id: ea6a5c0
Summary: Track and surface the reasons why a method is assessed to run on the UI thread.
Reviewed By: mbouaziz
Differential Revision: D8096099
fbshipit-source-id: 2403c6c
Summary:
The reported location was always the start of the enclosing procedure, which is wrong in many ways.
A nice side-effect is that some code can then be eliminated and Ondemand.analyze used, avoiding getting the procdescs in the process.
Reviewed By: jeremydubreil
Differential Revision: D8056306
fbshipit-source-id: 67c2c8d
Summary:
Before we were computing the size of an abstract state (`range`) using the `NonNegativeBound` domain but it wasn't able to express product of symbolic values.
This diff introduces a domain for that.
The range of an interval is still computed in `NonNegativeBound` but then the product is done in `TopLiftedPolynomial` so all costs end up being of that type.
The //symbols// of a polynomial are `NonNegativeBound` (so the polynomial only represent non-negative values, perfect for a cost), which handles substitution correctly, i.e. it gives zero instead of negative values.
Reviewed By: ddino
Differential Revision: D7397229
fbshipit-source-id: 6868bb7
Summary:
The annotation UiThread can, and is, used on classes as opposed to just methods, so extend the modelling to account for this.
Also, consider the annotation hereditary.
Reviewed By: jeremydubreil
Differential Revision: D7910762
fbshipit-source-id: 0df2c81
Summary: Without the class name, it is not always clear from the error message where the method expecing non-null parameters defined.
Reviewed By: mbouaziz
Differential Revision: D7919492
fbshipit-source-id: 044fb83
Summary:
Make the starvation checker enabled by default.
Add a deadlock issue type, distinct to starvation, which will be kept for UI thread starvation.
Add checks so that checker will do nothing on non-Java code.
Reviewed By: mbouaziz, ddino
Differential Revision: D7908381
fbshipit-source-id: 889f373
Summary: Calling Future.get from UI thread, or under a lock the UI thread may try to take has been associated with ANRs.
Reviewed By: ddino
Differential Revision: D7859296
fbshipit-source-id: b87bd94
Summary:
This simplifies the frontends and backends in most cases. Before this diff,
returning `void` could be modelled either with a `None` return, or a dummy
return variable with type `Tvoid`. Now it's always the latter.
Reviewed By: sblackshear, dulmarod
Differential Revision: D7832938
fbshipit-source-id: 0a403d1
Summary:
The abstract interpreter tried to handle exceptional control-flow by propagating the *pre* of a block that threw an exception rather than the *post*.
This was a half-measure that isn't correct when an exception-throwing instruction isn't in the middle of a block.
The handling of exceptions wasn't actually used anywhere and was leading to further hacks in `ProcCfg`, so let's get rid of it.
Reviewed By: mbouaziz, jvillard
Differential Revision: D7843872
fbshipit-source-id: 2a4a815
Ezgi Çiçek
Mehdi Bouaziz
Nikos Gorogiannis
Jules Villard
Jeremy Dubreil
Martino Luca
Dino Distefano
Sam Blackshear