Summary:
Before D7100561, the frontend translated capture-by-ref and capture-by-value in the same way.
Now we can tell the difference and report bugs in the capture-by-value case.
Reviewed By: jeremydubreil
Differential Revision: D7102214
fbshipit-source-id: e9d3ac7
Summary:
You can capture a variable by reference in a lambda, assign to it, and then invoke the lambda.
This looks like a dead store from the perspective of the current analysis.
This diff mitigates the problem by computing an additional analysis that tracks variables captured by ref at each program point.
It refuses to report a dead store on a variable that has already been captured by reference.
Later, we might want to incorporate the results of this analysis directly into the liveness analysis instead of just using it to gate reporting.
Reviewed By: jeremydubreil
Differential Revision: D7090291
fbshipit-source-id: 25eeffa
Summary:
As da319 points out, we did not handle this case correctly before. There were a few reasons why:
(1) An assignment like `struct S s = mk_s()` gets translated as `tmp = mk_s(); S(&s, tmp)`, so we didn't see the write to `s`.
(2) We counted uses of variables in destructors and dummy `_ = *s` assignments as reads, which meant that any struct values were considered as live.
This diff fixes these limitations so we can report on dead stores of struct values.
Reviewed By: da319
Differential Revision: D6327564
fbshipit-source-id: 2ead4be
Summary:
The "placement new" operator `new (e) T` constructs a `T` in the pre-allocated memory address `e`.
We weren't translating the `e` part, which was leading to false positives in the dead store analysis.
Reviewed By: dulmarod
Differential Revision: D5814191
fbshipit-source-id: 05c6fa9
Summary:
When a lambda has an `auto` parameter, the inferred type of the parameter because part of the name.
Our heuristic for identifying lambda was checking if the lambda's name was exactly `operator()`, which won't catch this case.
Reviewed By: jvillard
Differential Revision: D5753323
fbshipit-source-id: 85ff75a
Summary:
Not translating these properly was causing false positives for the dead store analysis in cases like
```
int i = 0;
return [j = i]() { return j; }();
```
Reviewed By: da319
Differential Revision: D5731562
fbshipit-source-id: ae79ac8
Summary:
Pretty basic: warn when we see an assignment instruction `x = ...` and `x` is not live in the post of the instruction.
Only enabled for Clang at the moment because linters already warn on this for Java. But we can enable it later if we want to (should be fully generic).
Reviewed By: jeremydubreil
Differential Revision: D5450439
fbshipit-source-id: 693514c
Jeremy Dubreil
Sam Blackshear