Previously, `LazyCompoundVal` bindings to subregions referred by
`LazyCopoundVals`, were not marked as //lazily copied//.
This change returns `LazyCompoundVals` from `getInterestingValues()`,
so their regions can be marked as //lazily copied// in `RemoveDeadBindingsWorker::VisitBinding()`.
Depends on D134947
Authored by: Tomasz Kamiński <tomasz.kamiński@sonarsource.com>
Reviewed By: martong
Differential Revision: https://reviews.llvm.org/D135136
To illustrate our current understanding, let's start with the following program:
https://godbolt.org/z/33f6vheh1
```lang=c++
void clang_analyzer_printState();
struct C {
int x;
int y;
int more_padding;
};
struct D {
C c;
int z;
};
C foo(D d, int new_x, int new_y) {
d.c.x = new_x; // B1
assert(d.c.x < 13); // C1
C c = d.c; // L
assert(d.c.y < 10); // C2
assert(d.z < 5); // C3
d.c.y = new_y; // B2
assert(d.c.y < 10); // C4
return c; // R
}
```
In the code, we create a few bindings to subregions of root region `d` (`B1`, `B2`), a constrain on the values (`C1`, `C2`, ….), and create a `lazyCompoundVal` for the part of the region `d` at point `L`, which is returned at point `R`.
Now, the question is which of these should remain live as long the return value of the `foo` call is live. In perfect a word we should preserve:
# only the bindings of the subregions of `d.c`, which were created before the copy at `L`. In our example, this includes `B1`, and not `B2`. In other words, `new_x` should be live but `new_y` shouldn’t.
# constraints on the values of `d.c`, that are reachable through `c`. This can be created both before the point of making the copy (`L`) or after. In our case, that would be `C1` and `C2`. But not `C3` (`d.z` value is not reachable through `c`) and `C4` (the original value of`d.c.y` was overridden at `B2` after the creation of `c`).
The current code in the `RegionStore` covers the use case (1), by using the `getInterestingValues()` to extract bindings to parts of the referred region present in the store at the point of copy. This also partially covers point (2), in case when constraints are applied to a location that has binding at the point of the copy (in our case `d.c.x` in `C1` that has value `new_x`), but it fails to preserve the constraints that require creating a new symbol for location (`d.c.y` in `C2`).
We introduce the concept of //lazily copied// locations (regions) to the `SymbolReaper`, i.e. for which a program can access the value stored at that location, but not its address. These locations are constructed as a set of regions referred to by `lazyCompoundVal`. A //readable// location (region) is a location that //live// or //lazily copied// . And symbols that refer to values in regions are alive if the region is //readable//.
For simplicity, we follow the current approach to live regions and mark the base region as //lazily copied//, and consider any subregions as //readable//. This makes some symbols falsy live (`d.z` in our example) and keeps the corresponding constraints alive.
The rename `Regions` to `LiveRegions` inside `RegionStore` is NFC change, that was done to make it clear, what is difference between regions stored in this two sets.
Regression Test: https://reviews.llvm.org/D134941
Co-authored-by: Balazs Benics <benicsbalazs@gmail.com>
Reviewed By: martong, xazax.hun
Differential Revision: https://reviews.llvm.org/D134947
This is a change to how we represent type subsitution in the AST.
Instead of only storing the replaced type, we track the templated
entity we are substituting, plus an index.
We modify MLTAL to track the templated entity at each level.
Otherwise, it's much more expensive to go from the template parameter back
to the templated entity, and not possible to do in some cases, as when
we instantiate outer templates, parameters might still reference the
original entity.
This also allows us to very cheaply lookup the templated entity we saw in
the naming context and find the corresponding argument it was replaced
from, such as for implementing template specialization resugaring.
Signed-off-by: Matheus Izvekov <mizvekov@gmail.com>
Differential Revision: https://reviews.llvm.org/D131858
The Clang Static Analyzer will crash on this code:
```lang=C++
struct Box {
int value;
};
template <Box V> int get() {
return V.value;
}
template int get<Box{-1}>();
```
https://godbolt.org/z/5Yb1sMMMb
The problem is that we don't account for encountering `TemplateParamObjectDecl`s
within the `DeclRefExpr` handler in the `ExprEngine`.
IMO we should create a new memregion for representing such template
param objects, to model their language semantics.
Such as:
- it should have global static storage
- for two identical values, their addresses should be identical as well
http://eel.is/c%2B%2Bdraft/temp.param#8
I was thinking of introducing a `TemplateParamObjectRegion` under `DeclRegion`
for this purpose. It could have `TemplateParamObjectDecl` as a field.
The `TemplateParamObjectDecl::getValue()` returns `APValue`, which might
represent multiple levels of structures, unions and other goodies -
making the transformation from `APValue` to `SVal` a bit complicated.
That being said, for now, I think having `Unknowns` for such cases is
definitely an improvement to crashing, hence I'm proposing this patch.
Reviewed By: xazax.hun
Differential Revision: https://reviews.llvm.org/D135763
Before this change, the `NoReturnFunctionChecker` was missing function pointers
with a `[[noreturn]]` attribute, while `CFG` was constructed taking that into
account, which leads CSA to take impossible paths. The reason was that the
`NoReturnFunctionChecker` was looking for the attribute in the type of the
entire call expression rather than the type of the function being called.
This change makes the `[[noreturn]]` attribute of a function pointer visible
to `NoReturnFunctionChecker`. This leads to a more coherent behavior of the
CSA on the AST involving.
Reviewed By: xazax.hun
Differential Revision: https://reviews.llvm.org/D135682
ProcessMemberDtor(), ProcessDeleteDtor(), and ProcessAutomaticObjDtor():
Fix static analyzer warnings with suspicious dereference of pointer
'Pred' in function call before NULL checks - NFCI
Differential Revision: https://reviews.llvm.org/D135290
In the context of caching clang invocations it is important to emit diagnostics in deterministic order;
the same clang invocation should result in the same diagnostic output.
rdar://100336989
Differential Revision: https://reviews.llvm.org/D135118
In case when the prvalue is returned from the function (kind is one
of `SimpleReturnedValueKind`, `CXX17ElidedCopyReturnedValueKind`),
then it construction happens in context of the caller.
We pass `BldrCtx` explicitly, as `currBldrCtx` will always refer to callee
context.
In the following example:
```
struct Result {int value; };
Result create() { return Result{10}; }
int accessValue(Result r) { return r.value; }
void test() {
for (int i = 0; i < 2; ++i)
accessValue(create());
}
```
In case when the returned object was constructed directly into the
argument to a function call `accessValue(create())`, this led to
inappropriate value of `blockCount` being used to locate parameter region,
and as a consequence resulting object (from `create()`) was constructed
into a different region, that was later read by inlined invocation of
outer function (`accessValue`).
This manifests itself only in case when calling block is visited more
than once (loop in above example), as otherwise there is no difference
in `blockCount` value between callee and caller context.
This happens only in case when copy elision is disabled (before C++17).
Reviewed By: NoQ
Differential Revision: https://reviews.llvm.org/D132030
showBRParamDiagnostics assumed stores happen only via function parameters while that
can also happen via implicit parameters like 'self' or 'this'.
The regression test caused a failed assert in the original cast to ParmVarDecl.
Differential Revision: https://reviews.llvm.org/D133815
Most of the state traits used for non-POD array evaluation were
only cleaned up if the ctors/dtors were inlined, since the cleanup
happened in ExprEngine::processCallExit(). This patch makes sure
they are removed even if said functions are not inlined.
Differential Revision: https://reviews.llvm.org/D133643
By this change the `exploded-graph-rewriter` will display the class kind
of the expression of the environment entry. It makes easier to decide if
the given entry corresponds to the lvalue or to the rvalue of some
expression.
It turns out the rewriter already had support for visualizing it, but
probably was never actually used?
Reviewed By: martong
Differential Revision: https://reviews.llvm.org/D132109
`LazyCompoundVals` should only appear as `default` bindings in the
store. This fixes the second case in this patch-stack.
Depends on: D132142
Reviewed By: xazax.hun
Differential Revision: https://reviews.llvm.org/D132143
It turns out that in certain cases `SymbolRegions` are wrapped by
`ElementRegions`; in others, it's not. This discrepancy can cause the
analyzer not to recognize if the two regions are actually referring to
the same entity, which then can lead to unreachable paths discovered.
Consider this example:
```lang=C++
struct Node { int* ptr; };
void with_structs(Node* n1) {
Node c = *n1; // copy
Node* n2 = &c;
clang_analyzer_dump(*n1); // lazy...
clang_analyzer_dump(*n2); // lazy...
clang_analyzer_dump(n1->ptr); // rval(n1->ptr): reg_$2<int * SymRegion{reg_$0<struct Node * n1>}.ptr>
clang_analyzer_dump(n2->ptr); // rval(n2->ptr): reg_$1<int * Element{SymRegion{reg_$0<struct Node * n1>},0 S64b,struct Node}.ptr>
clang_analyzer_eval(n1->ptr != n2->ptr); // UNKNOWN, bad!
(void)(*n1);
(void)(*n2);
}
```
The copy of `n1` will insert a new binding to the store; but for doing
that it actually must create a `TypedValueRegion` which it could pass to
the `LazyCompoundVal`. Since the memregion in question is a
`SymbolicRegion` - which is untyped, it needs to first wrap it into an
`ElementRegion` basically implementing this untyped -> typed conversion
for the sake of passing it to the `LazyCompoundVal`.
So, this is why we have `Element{SymRegion{.}, 0,struct Node}` for `n1`.
The problem appears if the analyzer evaluates a read from the expression
`n1->ptr`. The same logic won't apply for `SymbolRegionValues`, since
they accept raw `SubRegions`, hence the `SymbolicRegion` won't be
wrapped into an `ElementRegion` in that case.
Later when we arrive at the equality comparison, we cannot prove that
they are equal.
For more details check the corresponding thread on discourse:
https://discourse.llvm.org/t/are-symbolicregions-really-untyped/64406
---
In this patch, I'm eagerly wrapping each `SymbolicRegion` by an
`ElementRegion`; basically canonicalizing to this form.
It seems reasonable to do so since any object can be thought of as a single
array of that object; so this should not make much of a difference.
The tests also underpin this assumption, as only a few were broken by
this change; and actually fixed a FIXME along the way.
About the second example, which does the same copy operation - but on
the heap - it will be fixed by the next patch.
Reviewed By: martong
Differential Revision: https://reviews.llvm.org/D132142
If an object has a trivial copy/move constructor, it's not inlined
on invocation but a trivial copy is performed instead. This patch
handles trivial copies in the bug reporter by matching the field
regions of the 2 objects involved in the copy/move construction,
and tracking the appropriate region further. This patch also
introduces some support for tracking values in initializer lists.
Differential Revision: https://reviews.llvm.org/D131262
This patch introduces a new checker, called NewArraySize checker,
which detects if the expression that yields the element count of
the array in new[], results in an Undefined value.
Differential Revision: https://reviews.llvm.org/D131299
This patch dumps every state trait in the egraph. Also
the empty state traits are no longer dumped, instead
they are treated as null by the egraph rewriter script,
which solves reverse compatibility issues.
Differential Revision: https://reviews.llvm.org/D131187
Some of the code used in StdLibraryFunctionsChecker is applicable to
other checkers, this is put into common functions. Errno related
parts of the checker are simplified and renamed. Documentations in
errno_modeling functions are updated.
This change makes it available to have more checkers that perform
modeling of some standard functions. These can set the errno state
with common functions and the bug report messages (note tags) can
look similar.
Reviewed By: steakhal, martong
Differential Revision: https://reviews.llvm.org/D131879
leaking in ARC mode
When ARC (automatic reference count) is enabled, (objective-c) block
objects are automatically retained and released thus they do not leak.
Without ARC, they still can leak from an expiring stack frame like
other stack variables.
With this commit, the static analyzer now puts a block object in an
"unknown" region if ARC is enabled because it is up to the
implementation to choose whether to put the object on stack initially
(then move to heap when needed) or in heap directly under ARC.
Therefore, the `StackAddrEscapeChecker` has no need to know
specifically about ARC at all and it will not report errors on objects
in "unknown" regions.
Reviewed By: NoQ (Artem Dergachev)
Differential Revision: https://reviews.llvm.org/D131009
Prior to this patch when the analyzer encountered a non-POD 0 length array,
it still invoked the constructor for 1 element, which lead to false positives.
This patch makes sure that we no longer construct any elements when we see a
0 length array.
Differential Revision: https://reviews.llvm.org/D131501
The constructors of non-POD array elements are evaluated under
certain conditions. This patch makes sure that in such cases
we also evaluate the destructors.
Differential Revision: https://reviews.llvm.org/D130737
Dead store detection automatically checks that an expression is a
CXXConstructor and skips it because of potential side effects. In C++17,
with guaranteed copy elision, this check can fail because we actually
receive the implicit cast of a CXXConstructor.
Most checks in the dead store analysis were already stripping all casts
and parenthesis and those that weren't were either forgotten (like the
constructor) or would not suffer from it, so this patch proposes to
factorize the stripping.
It has an impact on where the dead store warning is reported in the case
of an explicit cast, from
auto a = static_cast<B>(A());
^~~~~~~~~~~~~~~~~~~
to
auto a = static_cast<B>(A());
^~~
which we think is an improvement.
Patch By: frederic-tingaud-sonarsource
Reviewed By: steakhal
Differential Revision: https://reviews.llvm.org/D126534
This patch makes it possible for lambdas, implicit copy/move ctors
and structured bindings to handle non-POD multidimensional arrays.
Differential Revision: https://reviews.llvm.org/D131840
Prior to this patch we handled lambda captures based on their
initializer expression, which resulted in pattern matching. With
C++17 copy elision the initializer expression can be anything,
and this approach proved to be fragile and a source of crashes.
This patch removes pattern matching and only checks whether the
object is under construction or not.
Differential Revision: https://reviews.llvm.org/D131944
This patch adds a ProgramPointTag to the EpsilonPoint created
before we replay a call without inlining.
Differential Revision: https://reviews.llvm.org/D132246
Inside `ExprEngine::VisitLambdaExpr()` we wasn't prepared for a
copy elided initialized capture's `InitExpr`. This patch teaches
the analyzer how to handle such situation.
Differential Revision: https://reviews.llvm.org/D131784
Support for functions wmempcpy, wmemmove, wmemcmp is added to the checker.
The same tests are copied that exist for the non-wide versions, with
non-wide functions and character types changed to the wide version.
Reviewed By: martong
Differential Revision: https://reviews.llvm.org/D130470
This completes the implementation of P1091R3 and P1381R1.
This patch allow the capture of structured bindings
both for C++20+ and C++17, with extension/compat warning.
In addition, capturing an anonymous union member,
a bitfield, or a structured binding thereof now has a
better diagnostic.
We only support structured bindings - as opposed to other kinds
of structured statements/blocks. We still emit an error for those.
In addition, support for structured bindings capture is entirely disabled in
OpenMP mode as this needs more investigation - a specific diagnostic indicate the feature is not yet supported there.
Note that the rest of P1091R3 (static/thread_local structured bindings) was already implemented.
at the request of @shafik, i can confirm the correct behavior of lldb wit this change.
Fixes https://github.com/llvm/llvm-project/issues/54300
Fixes https://github.com/llvm/llvm-project/issues/54300
Fixes https://github.com/llvm/llvm-project/issues/52720
Reviewed By: aaron.ballman
Differential Revision: https://reviews.llvm.org/D122768
This completes the implementation of P1091R3 and P1381R1.
This patch allow the capture of structured bindings
both for C++20+ and C++17, with extension/compat warning.
In addition, capturing an anonymous union member,
a bitfield, or a structured binding thereof now has a
better diagnostic.
We only support structured bindings - as opposed to other kinds
of structured statements/blocks. We still emit an error for those.
In addition, support for structured bindings capture is entirely disabled in
OpenMP mode as this needs more investigation - a specific diagnostic indicate the feature is not yet supported there.
Note that the rest of P1091R3 (static/thread_local structured bindings) was already implemented.
at the request of @shafik, i can confirm the correct behavior of lldb wit this change.
Fixes https://github.com/llvm/llvm-project/issues/54300
Fixes https://github.com/llvm/llvm-project/issues/54300
Fixes https://github.com/llvm/llvm-project/issues/52720
Reviewed By: aaron.ballman
Differential Revision: https://reviews.llvm.org/D122768
In ExprEngine::bindReturnValue() we cast an SVal to DefinedOrUnknownSVal,
however this SVal can also be Undefined, which leads to an assertion failure.
Fixes: #56873
Differential Revision: https://reviews.llvm.org/D130974
I went over the output of the following mess of a command:
(ulimit -m 2000000; ulimit -v 2000000; git ls-files -z |
parallel --xargs -0 cat | aspell list --mode=none --ignore-case |
grep -E '^[A-Za-z][a-z]*$' | sort | uniq -c | sort -n |
grep -vE '.{25}' | aspell pipe -W3 | grep : | cut -d' ' -f2 | less)
and proceeded to spend a few days looking at it to find probable typos
and fixed a few hundred of them in all of the llvm project (note, the
ones I found are not anywhere near all of them, but it seems like a
good start).
Differential Revision: https://reviews.llvm.org/D130827
Without this patch, clang will not wrap in an ElaboratedType node types written
without a keyword and nested name qualifier, which goes against the intent that
we should produce an AST which retains enough details to recover how things are
written.
The lack of this sugar is incompatible with the intent of the type printer
default policy, which is to print types as written, but to fall back and print
them fully qualified when they are desugared.
An ElaboratedTypeLoc without keyword / NNS uses no storage by itself, but still
requires pointer alignment due to pre-existing bug in the TypeLoc buffer
handling.
---
Troubleshooting list to deal with any breakage seen with this patch:
1) The most likely effect one would see by this patch is a change in how
a type is printed. The type printer will, by design and default,
print types as written. There are customization options there, but
not that many, and they mainly apply to how to print a type that we
somehow failed to track how it was written. This patch fixes a
problem where we failed to distinguish between a type
that was written without any elaborated-type qualifiers,
such as a 'struct'/'class' tags and name spacifiers such as 'std::',
and one that has been stripped of any 'metadata' that identifies such,
the so called canonical types.
Example:
```
namespace foo {
struct A {};
A a;
};
```
If one were to print the type of `foo::a`, prior to this patch, this
would result in `foo::A`. This is how the type printer would have,
by default, printed the canonical type of A as well.
As soon as you add any name qualifiers to A, the type printer would
suddenly start accurately printing the type as written. This patch
will make it print it accurately even when written without
qualifiers, so we will just print `A` for the initial example, as
the user did not really write that `foo::` namespace qualifier.
2) This patch could expose a bug in some AST matcher. Matching types
is harder to get right when there is sugar involved. For example,
if you want to match a type against being a pointer to some type A,
then you have to account for getting a type that is sugar for a
pointer to A, or being a pointer to sugar to A, or both! Usually
you would get the second part wrong, and this would work for a
very simple test where you don't use any name qualifiers, but
you would discover is broken when you do. The usual fix is to
either use the matcher which strips sugar, which is annoying
to use as for example if you match an N level pointer, you have
to put N+1 such matchers in there, beginning to end and between
all those levels. But in a lot of cases, if the property you want
to match is present in the canonical type, it's easier and faster
to just match on that... This goes with what is said in 1), if
you want to match against the name of a type, and you want
the name string to be something stable, perhaps matching on
the name of the canonical type is the better choice.
3) This patch could expose a bug in how you get the source range of some
TypeLoc. For some reason, a lot of code is using getLocalSourceRange(),
which only looks at the given TypeLoc node. This patch introduces a new,
and more common TypeLoc node which contains no source locations on itself.
This is not an inovation here, and some other, more rare TypeLoc nodes could
also have this property, but if you use getLocalSourceRange on them, it's not
going to return any valid locations, because it doesn't have any. The right fix
here is to always use getSourceRange() or getBeginLoc/getEndLoc which will dive
into the inner TypeLoc to get the source range if it doesn't find it on the
top level one. You can use getLocalSourceRange if you are really into
micro-optimizations and you have some outside knowledge that the TypeLocs you are
dealing with will always include some source location.
4) Exposed a bug somewhere in the use of the normal clang type class API, where you
have some type, you want to see if that type is some particular kind, you try a
`dyn_cast` such as `dyn_cast<TypedefType>` and that fails because now you have an
ElaboratedType which has a TypeDefType inside of it, which is what you wanted to match.
Again, like 2), this would usually have been tested poorly with some simple tests with
no qualifications, and would have been broken had there been any other kind of type sugar,
be it an ElaboratedType or a TemplateSpecializationType or a SubstTemplateParmType.
The usual fix here is to use `getAs` instead of `dyn_cast`, which will look deeper
into the type. Or use `getAsAdjusted` when dealing with TypeLocs.
For some reason the API is inconsistent there and on TypeLocs getAs behaves like a dyn_cast.
5) It could be a bug in this patch perhaps.
Let me know if you need any help!
Signed-off-by: Matheus Izvekov <mizvekov@gmail.com>
Differential Revision: https://reviews.llvm.org/D112374
This patch introduces a new `ConstructionContext` for
lambda capture. This `ConstructionContext` allows the
analyzer to construct the captured object directly into
it's final region, and makes it possible to capture
non-POD arrays.
Differential Revision: https://reviews.llvm.org/D129967
This patch introduces the evaluation of ArrayInitLoopExpr
in case of structured bindings and implicit copy/move
constructor. The idea is to call the copy constructor for
every element in the array. The parameter of the copy
constructor is also manually selected, as it is not a part
of the CFG.
Differential Revision: https://reviews.llvm.org/D129496
Tomasz Kamiński