This change is an extension to D103967 where I added dump methods for
(dis)equality classes of the State. There, the (dis)equality classes and their
contents are dumped in an ordered fashion, they are ordered based on their
string representation. This is very useful once we start to use FileCheck to
test the State dump in certain tests.
Differential Revision: https://reviews.llvm.org/D106642
https://bugs.llvm.org/show_bug.cgi?id=51109
When we merged two classes, `*this` became an obsolete representation of
the new `State`. This is b/c the member relations had changed during the
previous merge of another member of the same class in a way that `*this`
had no longer any members. (`mergeImpl` might keep the member relations
to `Other` and could dissolve `*this`.)
Differential Revision: https://reviews.llvm.org/D106285
../../git/llvm-project/clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp:2395:17: warning: 'clang::ento::ProgramStateRef {anonymous}::RangeConstraintManager::setRange(clang::ento::ProgramStateRef, {anonymous}::EquivalenceClass, clang::ento::RangeSet)' defined but not used [-Wunused-function]
../../git/llvm-project/clang/lib/StaticAnalyzer/Core/RangeConstraintManager.cpp:2384:10: warning: 'clang::ento::RangeSet {anonymous}::RangeConstraintManager::getRange(clang::ento::ProgramStateRef, {anonymous}::EquivalenceClass)' defined but not used [-Wunused-function]
Differential Revision: https://reviews.llvm.org/D106063
This patch simplifies the way we deal with (dis)equalities.
Due to the symmetry between constraint handler and range inferrer,
we can have very similar implementations of logic handling
questions about (dis)equality and assumptions involving (dis)equality.
It also helps us to remove one more visitor, and removes uncertainty
that we got all the right places to put `trackNE` and `trackEQ`.
Differential Revision: https://reviews.llvm.org/D105693
The new component is a symmetric response to SymbolicRangeInferrer.
While the latter is the unified component, which answers all the
questions what does the solver knows about a particular symbolic
expression, assignor associates new constraints (aka "assumes")
with symbolic expressions and can imply additional knowledge that
the solver can extract and use later on.
- Why do we need it and why is SymbolicRangeInferrer not enough?
As it is noted before, the inferrer only helps us to get the most
precise range information based on the existing knowledge and on the
mathematical foundations of different operations that symbolic
expressions actually represent. It doesn't introduce new constraints.
The assignor, on the other hand, can impose constraints on other
symbols using the same domain knowledge.
- But for some expressions, SymbolicRangeInferrer looks into constraints
for similar expressions, why can't we do that for all the cases?
That's correct! But in order to do something like this, we should
have a finite number of possible "similar expressions".
Let's say we are asked about `$a - $b` and we know something about
`$b - $a`. The inferrer can invert this expression and check
constraints for `$b - $a`. This is simple!
But let's say we are asked about `$a` and we know that `$a * $b != 0`.
In this situation, we can imply that `$a != 0`, but the inferrer shouldn't
try every possible symbolic expression `X` to check if `$a * X` or
`X * $a` is constrained to non-zero.
With the assignor mechanism, we can catch this implication right at
the moment we associate `$a * $b` with non-zero range, and set similar
constraints for `$a` and `$b` as well.
Differential Revision: https://reviews.llvm.org/D105692
Prior to this patch, we always gave priority to constraints that we
actually know about symbols in question. However, these can get
outdated and we can get better results if we look at all possible
sources of knowledge, including sub-expressions.
Differential Revision: https://reviews.llvm.org/D105436
This reverts commit 6f3b775c3e.
Test fails flakily, see comments on https://reviews.llvm.org/D103967
Also revert follow-up "[Analyzer] Attempt to fix windows bots test
failure b/c of new-line"
This reverts commit fe0e861a4d.
Since RangeSet::Factory actually contains BasicValueFactory, we can
remove value factory from many function signatures inside the solver.
Differential Revision: https://reviews.llvm.org/D105005
Consider the code
```
void f(int a0, int b0, int c)
{
int a1 = a0 - b0;
int b1 = (unsigned)a1 + c;
if (c == 0) {
int d = 7L / b1;
}
}
```
At the point of divisiion by `b1` that is considered to be non-zero,
which results in a new constraint for `$a0 - $b0 + $c`. The type
of this sym is unsigned, however, the simplified sym is `$a0 -
$b0` and its type is signed. This is probably the result of the
inherent improper handling of casts. Anyway, Range assignment
for constraints use this type information. Therefore, we must
make sure that first we simplify the symbol and only then we
assign the range.
Differential Revision: https://reviews.llvm.org/D104844
Update `setConstraint` to simplify existing equivalence classes when a
new constraint is added. In this patch we iterate over all existing
equivalence classes and constraints and try to simplfy them with
simplifySVal. This solves problematic cases where we have two symbols in
the tree, e.g.:
```
int test_rhs_further_constrained(int x, int y) {
if (x + y != 0)
return 0;
if (y != 0)
return 0;
clang_analyzer_eval(x + y == 0); // expected-warning{{TRUE}}
clang_analyzer_eval(y == 0); // expected-warning{{TRUE}}
return 0;
}
```
Differential Revision: https://reviews.llvm.org/D103314
<string> is currently the highest impact header in a clang+llvm build:
https://commondatastorage.googleapis.com/chromium-browser-clang/llvm-include-analysis.html
One of the most common places this is being included is the APInt.h header, which needs it for an old toString() implementation that returns std::string - an inefficient method compared to the SmallString versions that it actually wraps.
This patch replaces these APInt/APSInt methods with a pair of llvm::toString() helpers inside StringExtras.h, adjusts users accordingly and removes the <string> from APInt.h - I was hoping that more of these users could be converted to use the SmallString methods, but it appears that most end up creating a std::string anyhow. I avoided trying to use the raw_ostream << operators as well as I didn't want to lose having the integer radix explicit in the code.
Differential Revision: https://reviews.llvm.org/D103888
ImmutableSet doesn't seem like the perfect fit for the RangeSet
data structure. It is good for saving memory in a persistent
setting, but not for the case when the population of the container
is tiny. This commit replaces RangeSet implementation and
redesigns the most common operations to be more efficient.
Differential Revision: https://reviews.llvm.org/D86465
Additionally, this patch puts an assertion checking for feasible
constraints in every place where constraints are assigned to states.
Differential Revision: https://reviews.llvm.org/D98948
This patch fixes the situation when our knowledge of disequalities
can help us figuring out that some assumption is infeasible, but
the solver still produces a state with inconsistent constraints.
Additionally, this patch adds a couple of assertions to catch this
type of problems easier.
Differential Revision: https://reviews.llvm.org/D98341
Summary:
This commmit adds another relation that we can track separately from
range constraints. Symbol disequality can help us understand that
two equivalence classes are not equal to each other. We can generalize
this knowledge to classes because for every a,b,c, and d that
a == b, c == d, and b != c it is true that a != d.
As a result, we can reason about other equalities/disequalities of symbols
that we know nothing else about, i.e. no constraint ranges associated
with them. However, we also benefit from the knowledge of disequal
symbols by following the rule:
if a != b and b == C where C is a constant, a != C
This information can refine associated ranges for different classes
and reduce the number of false positives and paths to explore.
Differential Revision: https://reviews.llvm.org/D83286
Summary:
For the most cases, we try to reason about symbol either based on the
information we know about that symbol in particular or about its
composite parts. This is faster and eliminates costly brute force
searches through existing constraints.
However, we do want to support some cases that are widespread enough
and involve reasoning about different existing constraints at once.
These include:
* resoning about 'a - b' based on what we know about 'b - a'
* reasoning about 'a <= b' based on what we know about 'a > b' or 'a < b'
This commit expands on that part by tracking symbols known to be equal
while still avoiding brute force searches. It changes the way we track
constraints for individual symbols. If we know for a fact that 'a == b'
then there is no need in tracking constraints for both 'a' and 'b' especially
if these constraints are different. This additional relationship makes
dead/live logic for constraints harder as we want to maintain as much
information on the equivalence class as possible, but we still won't
carry the information that we don't need anymore.
Differential Revision: https://reviews.llvm.org/D82445
Summary:
* Add a new function to delete points from range sets.
* Introduce an internal generic interface for range set intersections.
* Remove unnecessary bits from a couple of solver functions.
* Add in-code sections.
Differential Revision: https://reviews.llvm.org/D82381
An old clang warns that the const object has no default constructor so it may
remain uninitialized forever. That's a false alarm because all fields
have a default initializer. Apply the suggested fixit anyway.
Summary:
Implemented RangeConstraintManager::getRangeForComparisonSymbol which handles comparison operators.
RangeConstraintManager::getRangeForComparisonSymbol cares about the sanity of comparison expressions sequences helps reasonably to branch an exploded graph.
It can significantly reduce the graph and speed up the analysis. For more details, please, see the differential revision.
This fixes https://bugs.llvm.org/show_bug.cgi?id=13426
Differential Revision: https://reviews.llvm.org/D78933
Summary:
New logic tries to narrow possible result values of the remainder operation
based on its operands and their ranges. It also tries to be conservative
with negative operands because according to the standard the sign of
the result is implementation-defined.
rdar://problem/44978988
Differential Revision: https://reviews.llvm.org/D80117
Summary:
Previously the current solver started reasoning about bitwise AND
expressions only when one of the operands is a constant. However,
very similar logic could be applied to ranges. This commit addresses
this shortcoming. Additionally, it refines how we deal with negative
operands.
rdar://problem/54359410
Differential Revision: https://reviews.llvm.org/D79434
Summary:
Previously the current solver started reasoning about bitwise OR
expressions only when one of the operands is a constant. However,
very similar logic could be applied to ranges. This commit addresses
this shortcoming. Additionally, it refines how we deal with negative
operands.
Differential Revision: https://reviews.llvm.org/D79336
Summary:
This change introduces a new component to unite all of the reasoning
we have about operations on ranges in the analyzer's solver.
In many cases, we might conclude that the range for a symbolic operation
is much more narrow than the type implies. While reasoning about
runtime conditions (especially in loops), we need to support more and
more of those little pieces of logic. The new component mostly plays
a role of an organizer for those, and allows us to focus on the actual
reasoning about ranges and not dispatching manually on the types of the
nested symbolic expressions.
Differential Revision: https://reviews.llvm.org/D79232
The `SubEngine` interface is an interface with only one implementation
`EpxrEngine`. Adding other implementations are difficult and very
unlikely in the near future. Currently, if anything from `ExprEngine` is
to be exposed to other classes it is moved to `SubEngine` which
restricts the alternative implementations. The virtual methods are have
a slight perofrmance impact. Furthermore, instead of the `LLVM`-style
inheritance a native inheritance is used here, which renders `LLVM`
functions like e.g. `cast<T>()` unusable here. This patch removes this
interface and allows usage of `ExprEngine` directly.
Differential Revision: https://reviews.llvm.org/D80548
Summary:
This fixes https://bugs.llvm.org/show_bug.cgi?id=41588
RangeSet Negate function shall handle unsigned ranges as well as signed ones.
RangeSet getRangeForMinusSymbol function shall use wider variety of ranges, not only concrete value ranges.
RangeSet Intersect functions shall not produce assertions.
Changes:
Improved safety of RangeSet::Intersect function. Added isEmpty() check to prevent an assertion.
Added support of handling unsigned ranges to RangeSet::Negate and RangeSet::getRangeForMinusSymbol.
Extended RangeSet::getRangeForMinusSymbol to return not only range sets with single value [n,n], but with wide ranges [n,m].
Added unit test for Negate function.
Added regression tests for unsigned values.
Differential Revision: https://reviews.llvm.org/D77802
Now that we've moved to C++14, we no longer need the llvm::make_unique
implementation from STLExtras.h. This patch is a mechanical replacement
of (hopefully) all the llvm::make_unique instances across the monorepo.
Differential revision: https://reviews.llvm.org/D66259
llvm-svn: 368942
Since rL335814, if the constraint manager cannot find a range set for `A - B`
(where `A` and `B` are symbols) it looks for a range for `B - A` and returns
it negated if it exists. However, if a range set for both `A - B` and `B - A`
is stored then it only returns the first one. If we both use `A - B` and
`B - A`, these expressions behave as two totally unrelated symbols. This way
we miss some useful deductions which may lead to false negatives or false
positives.
This tiny patch changes this behavior: if the symbolic expression the
constraint manager is looking for is a difference `A - B`, it tries to
retrieve the range for both `A - B` and `B - A` and if both exists it returns
the intersection of range `A - B` and the negated range of `B - A`. This way
every time a checker applies new constraints to the symbolic difference or to
its negated it always affects both the original difference and its negated.
Differential Revision: https://reviews.llvm.org/D55007
llvm-svn: 357167
Summary:
Removed the `GDM` checking what could prevent reports made by this visitor.
Now we rely on constraint changes instead.
(It reapplies 356318 with a feature from 356319 because build-bot failure.)
Reviewers: NoQ, george.karpenkov
Reviewed By: NoQ
Subscribers: cfe-commits, jdoerfert, gerazo, xazax.hun, baloghadamsoftware,
szepet, a.sidorin, mikhail.ramalho, Szelethus, donat.nagy, dkrupp
Tags: #clang
Differential Revision: https://reviews.llvm.org/D54811
llvm-svn: 356322
Summary: Removed the `GDM` checking what could prevent reports made by this visitor. Now we rely on constraint changes instead.
Reviewers: NoQ, george.karpenkov
Reviewed By: NoQ
Subscribers: jdoerfert, gerazo, xazax.hun, baloghadamsoftware, szepet, a.sidorin, mikhail.ramalho, Szelethus, donat.nagy, dkrupp
Tags: #clang
Differential Revision: https://reviews.llvm.org/D54811
llvm-svn: 356318
to reflect the new license.
We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.
Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.
llvm-svn: 351636
It's an old bug that consists in stale references to symbols remaining in the
GDM if they disappear from other program state sections as a result of any
operation that isn't the actual dead symbol collection. The most common example
here is:
FILE *fp = fopen("myfile.txt", "w");
fp = 0; // leak of file descriptor
In this example the leak were not detected previously because the symbol
disappears from the public part of the program state due to evaluating
the assignment. For that reason the checker never receives a notification
that the symbol is dead, and never reports a leak.
This patch not only causes leak false negatives, but also a number of other
problems, including false positives on some checkers.
What's worse, even though the program state contains a finite number of symbols,
the set of symbols that dies is potentially infinite. This means that is
impossible to compute the set of all dead symbols to pass off to the checkers
for cleaning up their part of the GDM.
No longer compute the dead set at all. Disallow iterating over dead symbols.
Disallow querying if any symbols are dead. Remove the API for marking symbols
as dead, as it is no longer necessary. Update checkers accordingly.
Differential Revision: https://reviews.llvm.org/D18860
llvm-svn: 347953
Remove an assertion in RangeConstraintManager that expects such symbols to never
appear, while admitting that the constraint manager doesn't yet handle them.
Differential Revision: https://reviews.llvm.org/D49703
llvm-svn: 337769
If range [m .. n] is stored for symbolic expression A - B, then we can deduce the range for B - A which is [-n .. -m]. This is only true for signed types, unless the range is [0 .. 0].
Differential Revision: https://reviews.llvm.org/D35110
llvm-svn: 335814
Summary:
Moved `RangedConstraintManager` header from `lib/StaticAnalyzer/Core/` to `clang/StaticAnalyzer/Core/PathSensitive/`. No changes to the code.
Reviewers: NoQ, george.karpenkov, dcoughlin
Reviewed By: george.karpenkov
Subscribers: NoQ, george.karpenkov, dcoughlin, ddcc
Differential Revision: https://reviews.llvm.org/D47640
llvm-svn: 333862
Summary: I could also move `RangedConstraintManager.h` under `include/` if you agree as it seems slightly out of place under `lib/`.
Patch by Réka Kovács
Reviewers: NoQ, george.karpenkov, dcoughlin, rnkovacs
Reviewed By: NoQ
Subscribers: mikhail.ramalho, whisperity, xazax.hun, baloghadamsoftware, szepet, a.sidorin, dkrupp, cfe-commits
Differential Revision: https://reviews.llvm.org/D45920
llvm-svn: 333179
This is similar to the LLVM change https://reviews.llvm.org/D46290.
We've been running doxygen with the autobrief option for a couple of
years now. This makes the \brief markers into our comments
redundant. Since they are a visual distraction and we don't want to
encourage more \brief markers in new code either, this patch removes
them all.
Patch produced by
for i in $(git grep -l '\@brief'); do perl -pi -e 's/\@brief //g' $i & done
for i in $(git grep -l '\\brief'); do perl -pi -e 's/\\brief //g' $i & done
Differential Revision: https://reviews.llvm.org/D46320
llvm-svn: 331834
Adding the new enumerator forced a bunch more changes into this patch than I
would have liked. The -Wtautological-compare warning was extended to properly
check the new comparison operator, clang-format needed updating because it uses
precedence levels as weights for determining where to break lines (and several
operators increased their precedence levels with this change), thread-safety
analysis needed changes to build its own IL properly for the new operator.
All "real" semantic checking for this operator has been deferred to a future
patch. For now, we use the relational comparison rules and arbitrarily give
the builtin form of the operator a return type of 'void'.
llvm-svn: 320707
Two copies of getSymLERange in RangeConstraintManager are virtually
identical, which is clearly bad.
This patch uses lambdas to call one from another (assuming that we would
like to avoid getting ranges from the state when necessary).
Differential Revision: https://reviews.llvm.org/D39709
llvm-svn: 319697
Patches the solver to assume that bitwise OR of an unsigned value with a
constant always produces a value larger-or-equal than the constant, and
bitwise AND with a constant always produces a value less-or-equal than
the constant.
This patch is especially useful in the context of using bitwise
arithmetic for error code encoding: the analyzer would be able to state
that the error code produced using a bitwise OR is non-zero.
Differential Revision: https://reviews.llvm.org/D39707
llvm-svn: 317820
Gabor Marton