Summary:
Similarly to function parameters (and the return value), we need to
apply the pre/post of a function call to the globals mentioned in its
summary.
- tigthen summaries further to remember only abducible variables in the
post (as well as in the pre)
- take globals into account when applying pre/post pairs
Reviewed By: jberdine
Differential Revision: D14780800
fbshipit-source-id: fc0d180bb
Summary:
The heuristic to detect variables going out of scope was to detect any
access expression passed as argument to an injected destructor call.
However destructor calls are also injected in destructor bodies to
destruct each field of an object, so the heuristic would detect fields
going out of scope, which, erm, doesn't make sense. Limit the heuristic
to local program variables.
Reviewed By: jberdine
Differential Revision: D14771454
fbshipit-source-id: ffa3c9fe3
Summary:
Only throw values to the pre if they can be followed from "abducible"
variables: formals of the current method and globals.
Because figuring out if a `Pvar.t` is a formal of the current procedure
is actually a giant pain, hack something not too bad instead:
pre-register all formals at the start of the analysis of the
procedure. Then the only other variables we care about in the
precondition are globals, which we can detect easily.
This is mostly an optimisation (summaries won't include irrelevant
"abduced" facts about the procedure's local variables anymore), but it
also fixes a bug where we would sometimes overwrite things in the pre. I
think that's why the tests improved.
Reviewed By: ngorogiannis
Differential Revision: D14753493
fbshipit-source-id: 08e73637f
Summary:
This mostly doesn't make sense. The only thing this would have been good
for was to give the most accurate result on access paths such as
`*(&(x.f))`, but these are normalised anyway (into `x.f`) so we actually
never see these. That said there might be some use to some similar logic
in the future, but in the meantime let's delete the current feature as
it wasn't thought through.
Reviewed By: ezgicicek
Differential Revision: D14753492
fbshipit-source-id: 597cec027
Summary:
The previous message formatting had regressed and produced non-sensical messages.
More importantly, remove template parameters from error messages to
trigger the heuristic in `InferPrint` that deduplicates errors that are
on the same line with the same error type and message. Without this we
get hundreds of reports that correspond to as many instantiations of the
same code.
Reviewed By: ngorogiannis
Differential Revision: D14747979
fbshipit-source-id: 3c4aad2b1
Summary:
We see the magic function `__variable_initialization` at the point where
the variable is declared, eg `int x = foo()`. It's safe to reset `&x` at
that point. This circumvents an issue that pops up in some rare cases
where the ternary conditional operator `?:` and variable initialization
conspire to produce weird frontend results.
Some test becomes a FN again, but I think it was being reported for the
wrong reasons; will investigate more later.
Reviewed By: ngorogiannis
Differential Revision: D14747980
fbshipit-source-id: e75d6e30f
Summary:
This ensures that each attribute type can only be present once per
address. Makes ~80x time improvement on pathological cases such as
Duff's device.
This introduces a new kind of Set in `PrettyPrintable`.
Reviewed By: mbouaziz
Differential Revision: D14645091
fbshipit-source-id: c7f9b760c
Summary:
Detect when a variable goes out of scope. When that's the case, mark its
address *and* its contents as invalid.
Give subsequent uses a USE_AFTER_LIFETIME error type instead of
USE_AFTER_DESTRUCTOR.
Reviewed By: jberdine
Differential Revision: D14387147
fbshipit-source-id: a2c530fda
Summary:
Instead of emitting an ad-hoc builtin on variable declaration emit a new
metadata instruction. This allows us to remove the code matching on that
ad-hoc builtin that had to be inserted in several checkers.
Inferbo & pulse used that information meaningfully and had to undergo
some minor changes to cope with the new metada instruction.
Reviewed By: ezgicicek
Differential Revision: D14833100
fbshipit-source-id: 9b3009d22
Summary:
Bundle all non-semantic-bearing instructions into a `Metadata _`
instruction in SIL.
- On a documentation level this makes clearer the distinction between
instructions that encode the semantics of the program and those that are
just hints for the various backend analysis.
- This makes it easier to add more of these auxiliary instructions in
the future. For example, the next diff introduces a new `Skip` auxiliary
instruction to replace the hacky `ExitScope([], Location.dummy)`.
- It also makes it easier to surface all current and future such
auxiliary instructions to HIL as the datatype for these syntactic hints
can be shared between SIL and HIL. This diff brings `Nullify` and
`Abstract` to HIL for free.
Reviewed By: ngorogiannis
Differential Revision: D14827674
fbshipit-source-id: f68fe2110
Summary:
This diff accumulates LatestPrune in sequential prunings. It should be sound since Inferbo invalidates some data of LatestPrune if they are updated.
Depends on D14321534
Reviewed By: mbouaziz
Differential Revision: D14321575
fbshipit-source-id: 233dbae32
Summary:
Some of these tests were wrong, eg `~lambda()` calls `lambda()` then...
takes the bitwise complement or something? The intent was to call the
destructor.
Add interprocedural tests for later.
Reviewed By: jberdine
Differential Revision: D14324762
fbshipit-source-id: 40d2c32f5
Summary:
Previously we would say that `lhs <= rhs` (or `lhs |- rhs`) when a
mapping existed between the abstract addresses of `lhs` and `rhs` such
that `mapping(lhs)` was a supergraph of `rhs`. In particular,
we had that `x |-> x' * x' |-> x'' |- x |-> x'`. This is not entirely
great, in particular once we get pairs of state representing footprint +
current state. I'm not sure I have an extremely compelling argument why
though, except that it's not the usual way we do implication in SL, but
there wasn't a compelling argument for the previous state of affairs
either.
This changes `|-` to be true only when `mapping(lhs) = rhs` (modulo only
considering the addresses reachable from the stack variables).
Reviewed By: jberdine
Differential Revision: D14568272
fbshipit-source-id: 1bb83950e
Summary: This helps convergence when `<=` is based on physical equality for example, and widening is implemented as `widen ~prev ~next = join prev next`.
Reviewed By: skcho
Differential Revision: D14568270
fbshipit-source-id: ded5ed296
Summary:
Re-declarations of global variables sometimes hide constant
initializations in the original declaration, which caused FN before.
In this diff, it translates global variables to point to original
declarations, rather than following re-declarations, if possible.
Reviewed By: mbouaziz, jvillard
Differential Revision: D14596301
fbshipit-source-id: 55c3b5f95
Summary: In SIL, sometimes a return value is assigned to `__return_param`.
Reviewed By: ezgicicek, mbouaziz
Differential Revision: D14538590
fbshipit-source-id: dfbb74dc2
Summary:
To meet the pure parts of formulas, the process was to (a) call Rename.extend
with variables occuring in similar places and (b) extract substitutions out of
those. Two matching primed vars would both be replaced by some fresh primed var.
However, equivalence classes of primed variables would *not* be replaced by
one fresh (primed) variable. Now, that should work.
Reviewed By: mbouaziz
Differential Revision: D14150192
fbshipit-source-id: 90ca9216c
Summary:
This will be used in the future to determine what to do with destructors
in pulse.
Reviewed By: mbouaziz
Differential Revision: D14324759
fbshipit-source-id: bc3c34471
Summary:
When joining two lists of disjuncts we try to ensure there isn't a state
that under-approximates another already in the list. This helps reduce
the number of disjuncts that are generated by conditionals and loops.
Before we would always just add more disjuncts unless they were
physically equal but now we do a subgraph computation to assess
under-approximation.
We only do this half-heartedly for now however, only taking into
consideration the "new" disjuncts vs the "old" ones. It probably makes
sense to do a full quadratic search to minimise the number of disjuncts
from time to time but this isn't done here.
Reviewed By: mbouaziz
Differential Revision: D14258482
fbshipit-source-id: c2dad4889
Summary:
The disjunctive domain shouldn't really be a set in the first place as
comparing abstract states for equality is expensive to do naively
(walking the whole maps representing the abstract heap). Moreover in
practice these sets have a small max size (currently 50 for pulse, the
only client), so switching them to plain lists makes sense.
Reviewed By: mbouaziz
Differential Revision: D14258489
fbshipit-source-id: c512169eb
Summary:
It's useful to keep the size of states down, especially when humans are
trying to read it. It will also help keep the size of summaries down in
the inter-procedural pulse.
Reviewed By: mbouaziz
Differential Revision: D14258486
fbshipit-source-id: 45ebcac67
Summary: After a redeclaration of a global constant, it is not parsed as ICE(integral constant expression), which results in FN.
Reviewed By: ezgicicek
Differential Revision: D14299288
fbshipit-source-id: 394afd595
Summary:
Add an option to specify some classes that we really want to warn about
with the liveness checker, even when they appear used because of the
implicit destructor call inserted by the compiler.
Reviewed By: mbouaziz
Differential Revision: D13991129
fbshipit-source-id: 7fafdba84
Summary:
The purpose these serve is unclear to me. From the comment I *think*
they were used to hint to the biabduction backend that smart pointers
are just pointers. That said, The tests still mostly pass even without
that (just a few `weak_ptr` tests changed from `NULL_DEREFERENCE` to
`Bad_footprint`).
Moreover, this extra dereference was added unreliably. For instance,
this piece of code:
```
auto x = std::make_unique<X>(some_X);
```
would either get the extra dereference or not depending on which headers
were picked for the C++ stdlib.
The extra dereference was tripping up the liveness checker (see later in
the stack), and probably most checkers too.
Reviewed By: mbouaziz
Differential Revision: D13991130
fbshipit-source-id: 462923595
Summary: When a `VarDecl` has the attribute `unused` then do not assign its initialisation result to the corresponding variable.
Reviewed By: ngorogiannis
Differential Revision: D13974497
fbshipit-source-id: 28029f995
Summary:
This diff updates the reachability conditions of proof obligations at every function calls.
Depends on D13781124
Reviewed By: mbouaziz
Differential Revision: D13781147
fbshipit-source-id: 3c8768bd9
Summary: We do not want to export unnecessary information from clang plugin, hence, the solution to this false positive would be to annotate with `__unused__` attribute.
Reviewed By: jvillard
Differential Revision: D13861333
fbshipit-source-id: 774009f37
Jules Villard
David Lively
Sungkeun Cho
Jeremy Dubreil
Ezgi Çiçek
Lee Howes
Radu Grigore
Mehdi Bouaziz
Nikos Gorogiannis
Daiva Naudziuniene