When generating path notes, implicit function bodies are shown at the call
site, so that, say, copying a POD type in C++ doesn't jump you to a header
file. This is especially important when the synthesized function itself
calls another function (or block), in which case we should try to jump the
user around as little as possible.
By checking whether a called function has a body in the AST, we can tell
if the analyzer synthesized the body, and if we should therefore collapse
the call down to the call site like a true implicitly-defined function.
<rdar://problem/13978414>
llvm-svn: 182677
The new edge algorithm would keep track of the previous location in each
location context, so that it could draw arrows coming in and out of each
inlined call. However, it tried to access the location of the call before
it was actually set (at the CallEnter node). This only affected
unterminated calls at the end of a path; calls with visible exit nodes
already had a valid location.
This patch ditches the location context map, since we're processing the
nodes in order anyway, and just unconditionally updates the PrevLoc
variable after popping out of an inlined call.
<rdar://problem/13983470>
llvm-svn: 182676
Currently, blocks instantiated in templates lose their "signature as
written"; it's not clear if this is intentional. Change the analyzer's
use of BlockDecl::getSignatureAsWritten to check whether or not the
signature is actually there.
<rdar://problem/13954714>
llvm-svn: 182497
The crash is triggered by the newly added option (-analyzer-config report-in-main-source-file=true) introduced in r182058.
Note, ideally, we’d like to report the issue within the main source file here as well.
For now, just do not crash.
llvm-svn: 182445
The analyzer can't see the reference count for shared_ptr, so it doesn't
know whether a given destruction is going to delete the referenced object.
This leads to spurious leak and use-after-free warnings.
For now, just ban destructors named '~shared_ptr', which catches
std::shared_ptr, std::tr1::shared_ptr, and boost::shared_ptr.
PR15987
llvm-svn: 182071
Previously, we’ve used the last location of the analyzer issue path as the location of the
report. This might not provide the best user experience, when one analyzer a source
file and the issue appears in the header. Introduce an option to use the last location
of the path that is in the main source file as the report location.
New option can be enabled with -analyzer-config report-in-main-source-file=true.
llvm-svn: 182058
found for a receiver, note where receiver class
is declaraed (this is most common when receiver is a forward
class). // rdar://3258331
llvm-svn: 181847
In most cases it is, by just looking at the name. Also, this check prevents the heuristic from working in strange user settings.
radar://13839692
llvm-svn: 181615
Consider this example:
char *p = malloc(sizeof(char));
systemFunction(&p);
free(p);
In this case, when we call systemFunction, we know (because it's a system
function) that it won't free 'p'. However, we /don't/ know whether or not
it will /change/ 'p', so the analyzer is forced to invalidate 'p', wiping
out any bindings it contains. But now the malloc'd region looks like a
leak, since there are no more bindings pointing to it, and we'll get a
spurious leak warning.
The fix for this is to notice when something is becoming inaccessible due
to invalidation (i.e. an imperfect model, as opposed to being explicitly
overwritten) and stop tracking it at that point. Currently, the best way
to determine this for a call is the "indirect escape" pointer-escape kind.
In practice, all the patch does is take the "system functions don't free
memory" special case and limit it to direct parameters, i.e. just the
arguments to a call and not other regions accessible to them. This is a
conservative change that should only cause us to escape regions more
eagerly, which means fewer leak warnings.
This isn't perfect for several reasons, the main one being that this
example is treated the same as the one above:
char **p = malloc(sizeof(char *));
systemFunction(p + 1);
// leak
Currently, "addresses accessible by offsets of the starting region" and
"addresses accessible through bindings of the starting region" are both
considered "indirect" regions, hence this uniform treatment.
Another issue is our longstanding problem of not distinguishing const and
non-const bindings; if in the first example systemFunction's parameter were
a char * const *, we should know that the function will not overwrite 'p',
and thus we can safely report the leak.
<rdar://problem/13758386>
llvm-svn: 181607
This occurs because in C++11 the compound literal syntax can trigger a
constructor call via list-initialization. That is, "Point{x, y}" and
"(Point){x, y}" end up being equivalent. If this occurs, the inner
CXXConstructExpr will have already handled the object construction; the
CompoundLiteralExpr just needs to propagate that value forwards.
<rdar://problem/13804098>
llvm-svn: 181213
FindLastStoreBRVisitor is responsible for finding where a particular region
gets its value; if the region is a VarRegion, it's possible that value was
assigned at initialization, i.e. at its DeclStmt. However, if a function is
called recursively, the same DeclStmt may be evaluated multiple times in
multiple stack frames. FindLastStoreBRVisitor was not taking this into
account and just picking the first one it saw.
<rdar://problem/13787723>
llvm-svn: 180997
There were actually two bugs here:
- if we decided to look for an interesting lvalue or call expression, we
wouldn't go find its node if we also knew we were at a (different) call.
- if we looked through one message send with a nil receiver, we thought we
were still looking at an argument to the original call.
Put together, this kept us from being able to track the right values, which
means sub-par diagnostics and worse false-positive suppression.
Noticed by inspection.
llvm-svn: 180996
...and don't consider '0' to be a null pointer constant if it's the
initializer for a float!
Apparently null pointer constant evaluation looks through both
MaterializeTemporaryExpr and ImplicitCastExpr, so we have to be more
careful about types in the callers. For RegionStore this just means giving
up a little more; for ExprEngine this means handling the
MaterializeTemporaryExpr case explicitly.
Follow-up to r180894.
llvm-svn: 180944
It is unfortunate that we have to mark these exceptions in multiple places.
This was already in CallEvent. I suppose it does let us be more precise
about saying /which/ arguments have their retain counts invalidated -- the
connection's is still valid even though the context object's isn't -- but
we're not tracking the retain count of XPC objects anyway.
<rdar://problem/13783514>
llvm-svn: 180904
Previously, this was scattered across Environment (literal expressions),
ExprEngine (default arguments), and RegionStore (global constants). The
former special-cased several kinds of simple constant expressions, while
the latter two deferred to the AST's constant evaluator.
Now, these are all unified as SValBuilder::getConstantVal(). To keep
Environment fast, the special cases for simple constant expressions have
been left in, but the main benefits are that (a) unusual constants like
ObjCStringLiterals now work as default arguments and global constant
initializers, and (b) we're not duplicating code between ExprEngine and
RegionStore.
This actually caught a bug in our test suite, which is awesome: we stop
tracking allocated memory if it's passed as an argument along with some
kind of callback, but not if the callback is 0. We were testing this in
a case where the callback parameter had a default value, but that value
was 0. After this change, the analyzer now (correctly) flags that as a
leak!
<rdar://problem/13773117>
llvm-svn: 180894
This goes with r178516, which instructed the analyzer not to inline the
constructors and destructors of C++ container classes. This goes a step
further and does the same thing for iterators, so that the analyzer won't
falsely decide we're trying to construct an iterator pointing to a
nonexistent element.
The heuristic for determining whether something is an iterator is the
presence of an 'iterator_category' member. This is controlled under the
same -analyzer-config option as container constructor/destructor inlining:
'c++-container-inlining'.
<rdar://problem/13770187>
llvm-svn: 180890
This doesn't appear to be the cause of the slowdown. I'll have to try a
manual bisect to see if there's really anything there, or if it's just
the bot itself taking on additional load. Meanwhile, this change helps
with correctness.
This changes an assertion and adds a test case, then re-applies r180638,
which was reverted in r180714.
<rdar://problem/13296133> and PR15863
llvm-svn: 180864
This seems to be causing quite a slowdown on our internal analyzer bot,
and I'm not sure why. Needs further investigation.
This reverts r180638 / 9e161ea981f22ae017b6af09d660bfc3ddf16a09.
llvm-svn: 180714
In an Objective-C for-in loop "for (id element in collection) {}", the loop
will run 0 times if the collection is nil. This is because the for-in loop
is implemented using a protocol method that returns 0 when there are no
elements to iterate, and messages to nil will result in a 0 return value.
At some point we may want to actually model this message send, but for now
we may as well get the nil case correct, and avoid the false positives that
would come with this case.
<rdar://problem/13744632>
llvm-svn: 180639
Casts to bool (and _Bool) are equivalent to checks against zero,
not truncations to 1 bit or 8 bits.
This improved reasoning does cause a change in the behavior of the alpha
BoolAssignment checker. Previously, this checker complained about statements
like "bool x = y" if 'y' was known not to be 0 or 1. Now it does not, since
that conversion is well-defined. It's hard to say what the "best" behavior
here is: this conversion is safe, but might be better written as an explicit
comparison against zero.
More usefully, besides improving our model of booleans, this fixes spurious
warnings when returning the address of a local variable cast to bool.
<rdar://problem/13296133>
llvm-svn: 180638
We get a CallEnter with a null expression, when processing a destructor. All other users of
CallEnter::getCallExpr work fine with null as return value.
(Addresses PR15832, Thanks to Jordan for reducing the test case!)
llvm-svn: 180234
- If only partial invalidators exist and there are no full invalidators in @implementation, report every ivar that has
not been invalidated. (Previously, we reported the first Ivar in the list, which could actually have been invalidated
by a partial invalidator. The code assumed you cannot have only partial invalidators.)
- Do not report missing invalidation method declaration if a partial invalidation method declaration exists.
llvm-svn: 180170
The uniqueing location is the location which is part of the hash used to determine if two reports are
the same. This is used by the CmpRuns.py script to compare two analyzer runs and determine which
warnings are new.
llvm-svn: 180166
The 2 functions were computing the same location using different logic (each one had edge case bugs that the other
one did not). Refactor them to rely on the same logic.
The location of the warning reported in text/command line output format will now match that of the plist file.
There is one change in the plist output as well. When reporting an error on a BinaryOperator, we use the location of the
operator instead of the beginning of the BinaryOperator expression. This matches our output on command line and
looks better in most cases.
llvm-svn: 180165
The analyzer represents all pointer-to-pointer bitcasts the same way, but
this can be problematic if an implicit base cast gets layered on top of a
manual base cast (performed with reinterpret_cast instead of static_cast).
Fix this (and avoid a valid assertion) by looking through cast regions.
Using reinterpret_cast this way is only valid if the base class is at the
same offset as the derived class; this is checked by -Wreinterpret-base-class.
In the interest of performance, the analyzer doesn't repeat this check
anywhere; it will just silently do the wrong thing (use the wrong offsets
for fields of the base class) if the user code is wrong.
PR15394
llvm-svn: 180052
Introduce a new helper function, which computes the first symbolic region in
the base region chain. The corresponding symbol has been used for assuming that
a pointer is null. Now, it will also be used for checking if it is null.
This ensures that we are tracking a null pointer correctly in the BugReporter.
llvm-svn: 179916
The analyzer uses LazyCompoundVals to represent rvalues of aggregate types,
most importantly structs and arrays. This allows us to efficiently copy
around an entire struct, rather than doing a memberwise load every time a
struct rvalue is encountered. This can also keep memory usage down by
allowing several structs to "share" the same snapshotted bindings.
However, /lookup/ through LazyCompoundVals can be expensive, especially
since they can end up chaining back to the original value. While we try
to reuse LazyCompoundVals whenever it's safe, and cache information about
this transitivity, the fact is it's sometimes just not a good idea to
perpetuate LazyCompoundVals -- the tradeoffs just aren't worth it.
This commit changes RegionStore so that binding a LazyCompoundVal to struct
will do a memberwise copy if the struct is simple enough. Today's definition
of "simple enough" is "up to N scalar members" (see below), but that could
easily be changed in the future. This is enough to bring the test case in
PR15697 back down to a manageable analysis time (within 20% of its original
time, in an unfair test where the new analyzer is not compiled with LTO).
The actual value of "N" is controlled by a new -analyzer-config option,
'region-store-small-struct-limit'. It defaults to "2", meaning structs with
zero, one, or two scalar members will be considered "simple enough" for
this code path.
It's worth noting that a more straightforward implementation would do this
on load, not on bind, and make use of the structure we already have for this:
CompoundVal. A long time ago, this was actually how RegionStore modeled
aggregate-to-aggregate copies, but today it's only used for compound literals.
Unfortunately, it seems that we've special-cased LazyCompoundVal in certain
places (such as liveness checks) but failed to similarly special-case
CompoundVal in all of them. Until we're confident that CompoundVal is
handled properly everywhere, this solution is safer, since the entire
optimization is just an implementation detail of RegionStore.
<rdar://problem/13599304>
llvm-svn: 179767
A C++ overloaded operator may be implemented as an instance method, and
that instance method may be called on an rvalue object, which has no
associated region. The analyzer handles this by creating a temporary region
just for the evaluation of this call; however, it is possible that /by
creating the region/, the analyzer ends up in a previously-explored state.
In this case we don't need to continue along this path.
This doesn't actually show any behavioral change now, but it starts being
used with the next commit and prevents an assertion failure there.
llvm-svn: 179766
In the committed example, we now see a note that tells us when the pointer
was assumed to be null.
This is the only case in which getDerefExpr returned null (failed to get
the dereferenced expr) throughout our regression tests. (There were multiple
occurrences of this one.)
llvm-svn: 179736
We always register the visitor on a node in which the value we are tracking is live and constrained. However,
the visitation can restart at a node, later on the path, in which the value is under constrained because
it is no longer live. Previously, we just silently stopped tracking in that case.
llvm-svn: 179731
This was slightly tricky because BlockDecls don't currently store an
inferred return type. However, we can rely on the fact that blocks with
inferred return types will have return statements that match the inferred
type.
<rdar://problem/13665798>
llvm-svn: 179699
VerifyDiagnosticConsumer previously would not check that the diagnostic and
its matching directive referenced the same source file. Common practice was
to create directives that referenced other files but only by line number,
and this led to problems such as when the file containing the directive
didn't have enough lines to match the location of the diagnostic in the
other file, leading to bizarre file formatting and other oddities.
This patch causes VerifyDiagnosticConsumer to match source files as well as
line numbers. Therefore, a new syntax is made available for directives, for
example:
// expected-error@file:line {{diagnostic message}}
This extends the @line feature where "file" is the file where the diagnostic
is generated. The @line syntax is still available and uses the current file
for the diagnostic. "file" can be specified either as a relative or absolute
path - although the latter has less usefulness, I think! The #include search
paths will be used to locate the file and if it is not found an error will be
generated.
The new check is not optional: if the directive is in a different file to the
diagnostic, the file must be specified. Therefore, a number of test-cases
have been updated with regard to this.
This closes out PR15613.
llvm-svn: 179677
This is an opt-in tweak for leak diagnostics to reference the allocation
site if the diagnostic consumer only wants a pithy amount of information,
and not the entire path.
This is a strawman enhancement that I expect to see some experimentation
with over the next week, and can go away if we don't want it.
Currently it is only used by RetainCountChecker, but could be used
by MallocChecker if and when we decide this should stay in.
llvm-svn: 179634
When computing the value of ?: expression, we rely on the last expression in
the previous basic block to be the resulting value of the expression. This is
not the case for binary "?:" operator (GNU extension) in C++. As the last
basic block has the expression for the condition subexpression, which is an
R-value, whereas the true subexpression is the L-value.
Note the operator evaluation just happens to work in C since the true
subexpression is an R-value (like the condition subexpression). CFG is the
same in C and C++ case, but the AST nodes are different, which the LValue to
Rvalue conversion happening after the BinaryConditionalOperator evaluation.
Changed the logic to only use the last expression from the predecessor only
if it matches either true or false subexpression. Note, the logic needed
fortification anyway: L and R were passed but not even used by the function.
Also, change the conjureSymbolVal to correctly compute the type, when the
expression is an LG-value.
llvm-svn: 179574
While we don't do anything intelligent with pointers-to-members today,
it's perfectly legal to need a temporary of pointer-to-member type to, say,
pass by const reference. Tweak an assertion to allow this.
PR15742 and PR15747
llvm-svn: 179563
Now that we're invalidating global regions properly, we want to continue
taking advantage of a particular optimization: if all global regions are
invalidated together, we can represent the bindings of each region with
a "derived region value" symbol. Essentially, this lazily links each
global region with a single symbol created at invalidation time, rather
than binding each region with a new symbolic value.
We used to do this, but haven't been for a while; the previous commit
re-enabled this code path, and this handles the fallout.
<rdar://problem/13464044>
llvm-svn: 179554
This fixes a regression where a call to a function we can't reason about
would not actually invalidate global regions that had explicit bindings.
void test_that_now_works() {
globalInt = 42;
clang_analyzer_eval(globalInt == 42); // expected-warning{{TRUE}}
invalidateGlobals();
clang_analyzer_eval(globalInt == 42); // expected-warning{{UNKNOWN}}
}
This has probably been around since the initial "cluster" refactoring of
RegionStore, if not longer.
<rdar://problem/13464044>
llvm-svn: 179553
Some checkers ascribe different behavior to functions declared in system
headers, so when working with standard library functions it's probably best
to always have them in a standard location.
Test change only (no functionality change), but necessary for the next commit.
llvm-svn: 179552
There are few cases where we can track the region, but cannot print the note,
which makes the testing limited. (Though, I’ve tested this manually by making
all regions non-printable.) Even though the applicability is limited now, the enhancement
will be more relevant as we start tracking more regions.
llvm-svn: 179396
Before:
1. Calling 'foo'
2. Doing something interesting
3. Returning from 'foo'
4. Some kind of error here
After:
1. Calling 'foo'
2. Doing something interesting
3. Returning from 'foo'
4. Some kind of error here
The location of the note is already in the caller, not the callee, so this
just brings the "depth" attribute in line with that.
This only affects plist diagnostic consumers (i.e. Xcode). It's necessary
for Xcode to associate the control flow arrows with the right stack frame.
<rdar://problem/13634363>
llvm-svn: 179351
In this code
int getZero() {
return 0;
}
void test() {
int problem = 1 / getZero(); // expected-warning {{Division by zero}}
}
we generate these arrows:
+-----------------+
| v
int problem = 1 / getZero();
^ |
+---+
where the top one represents the control flow up to the first call, and the
bottom one represents the flow to the division.* It turns out, however, that
we were generating the top arrow twice, as if attempting to "set up context"
after we had already returned from the call. This resulted in poor
highlighting in Xcode.
* Arguably the best location for the division is the '/', but that's a
different problem.
<rdar://problem/13326040>
llvm-svn: 179350
For this source:
const int &ref = someStruct.bitfield;
We used to generate this AST:
DeclStmt [...]
`-VarDecl [...] ref 'const int &'
`-MaterializeTemporaryExpr [...] 'const int' lvalue
`-ImplicitCastExpr [...] 'const int' lvalue <NoOp>
`-MemberExpr [...] 'int' lvalue bitfield .bitfield [...]
`-DeclRefExpr [...] 'struct X' lvalue ParmVar [...] 'someStruct' 'struct X'
Notice the lvalue inside the MaterializeTemporaryExpr, which is very
confusing (and caused an assertion to fire in the analyzer - PR15694).
We now generate this:
DeclStmt [...]
`-VarDecl [...] ref 'const int &'
`-MaterializeTemporaryExpr [...] 'const int' lvalue
`-ImplicitCastExpr [...] 'int' <LValueToRValue>
`-MemberExpr [...] 'int' lvalue bitfield .bitfield [...]
`-DeclRefExpr [...] 'struct X' lvalue ParmVar [...] 'someStruct' 'struct X'
Which makes a lot more sense. This allows us to remove code in both
CodeGen and AST that hacked around this special case.
The commit also makes Clang accept this (legal) C++11 code:
int &&ref = std::move(someStruct).bitfield
PR15694 / <rdar://problem/13600396>
llvm-svn: 179250
The heuristic here (proposed by Jordan) is that, usually, if a leak is due to an early exit from init, the allocation site will be
a call to alloc. Note that in other cases init resets self to [super init], which becomes the allocation site of the object.
llvm-svn: 179221
Previously, the analyzer used isIntegerType() everywhere, which uses the C
definition of "integer". The C++ predicate with the same behavior is
isIntegerOrUnscopedEnumerationType().
However, the analyzer is /really/ using this to ask if it's some sort of
"integrally representable" type, i.e. it should include C++11 scoped
enumerations as well. hasIntegerRepresentation() sounds like the right
predicate, but that includes vectors, which the analyzer represents by its
elements.
This commit audits all uses of isIntegerType() and replaces them with the
general isIntegerOrEnumerationType(), except in some specific cases where
it makes sense to exclude scoped enumerations, or any enumerations. These
cases now use isIntegerOrUnscopedEnumerationType() and getAs<BuiltinType>()
plus BuiltinType::isInteger().
isIntegerType() is hereby banned in the analyzer - lib/StaticAnalysis and
include/clang/StaticAnalysis. :-)
Fixes real assertion failures. PR15703 / <rdar://problem/12350701>
llvm-svn: 179081
Test that the path notes do not change. I don’t think we should print a note on escape.
Also, I’ve removed a check that assumed that the family stored in the RefStete could be
AF_None and added an assert in the constructor.
llvm-svn: 179075
This is important because sometimes two nodes are identical, except the
second one is a sink.
This bug has probably been around for a while, but it wouldn't have been an
issue in the old report graph algorithm. I'm ashamed to say I actually looked
at this the first time around and thought it would never be a problem...and
then didn't include an assertion to back that up.
PR15684
llvm-svn: 178944
As mentioned in the previous commit message, the use-after-free and
double-free warnings for 'delete' are worth enabling even while the
leak warnings still have false positives.
llvm-svn: 178891
This splits the leak-checking part of alpha.cplusplus.NewDelete into a
separate user-level checker, alpha.cplusplus.NewDeleteLeaks. All the
difficult false positives we've seen with the new/delete checker have been
spurious leak warnings; the use-after-free warnings and mismatched
deallocator warnings, while rare, have always been valid.
<rdar://problem/6194569>
llvm-svn: 178890
This fixes an issue pointed to by Jordan: if unix.Malloc and unix.MismatchedDeallocator are both on, then we end up still tracking leaks of memory allocated by new.
Moved the guards right before emitting the bug reports to unify and simplify the logic of handling of multiple checkers. Now all the checkers perform their checks regardless of if they were enabled, or not, and it is decided just before the emitting of the report, if it should be emitted. (idea from Anna).
Additional changes:
improved test coverage for checker correlations;
refactoring: BadDealloc -> MismatchedDealloc
llvm-svn: 178814
This turns on not only destructor inlining, but inlining of constructors
for types with non-trivial destructors. Per r178516, we will still not
inline the constructor or destructor of anything that looks like a
container unless the analyzer-config option 'c++-container-inlining' is
set to 'true'.
In addition to the more precise path-sensitive model, this allows us to
catch simple smart pointer issues:
#include <memory>
void test() {
std::auto_ptr<int> releaser(new int[4]);
} // memory allocated with 'new[]' should not be deleted with 'delete'
<rdar://problem/12295363>
llvm-svn: 178805
...and add a new test case.
I thought this was broken, but it isn't; refactoring and reformatting anyway
so that I don't make the same mistake again. No functionality change.
llvm-svn: 178799
Improvement of r178684 and r178685.
Jordan has pointed out that I should not rely on the value of the condition to know which expression branch
has been taken. It will not work in cases the branch condition is an unknown value (ex: we do not track the constraints for floats).
The better way of doing this would be to find out if the current node is the right or left successor of the node
that has the ternary operator as a terminator (which is how this is done in other places, like ConditionBRVisitor).
llvm-svn: 178701
The lifetime of a temporary can be extended when it is immediately bound
to a local reference:
const Value &MyVal = Value("temporary");
In this case, the temporary object's lifetime is extended for the entire
scope of the reference; at the end of the scope it is destroyed.
The analyzer was modeling this improperly in two ways:
- Since we don't model temporary constructors just yet, we create a fake
temporary region when it comes time to "materialize" a temporary into
a real object (lvalue). This wasn't taking base casts into account when
the bindings being materialized was Unknown; now it always respects base
casts except when the temporary region is itself a pointer.
- When actually destroying the region, the analyzer did not actually load
from the reference variable -- it was basically destroying the reference
instead of its referent. Now it does do the load.
This will be more useful whenever we finally start modeling temporaries,
or at least those that get bound to local reference variables.
<rdar://problem/13552274>
llvm-svn: 178697
1) Look for the node where the condition expression is live when checking if
it is constrained to true or false.
2) Fix a bug in ProgramState::isNull, which was masking the problem. When
the expression is not a symbol (,which is the case when it is Unknown) return
unconstrained value, instead of value constrained to “false”!
(Thankfully other callers of isNull have not been effected by the bug.)
llvm-svn: 178684
- Find the correct region to represent the first array element when
constructing a CXXConstructorCall.
- If the array is trivial, model the copy with a primitive load/store.
- Don't warn about the "uninitialized" subscript in the AST -- we don't use
the helper variable that Sema provides.
<rdar://problem/13091608>
llvm-svn: 178602
Refactor invalidateRegions to take SVals instead of Regions as input and teach RegionStore
about processing LazyCompoundVal as a top-level “escaping” value.
This addresses several false positives that get triggered by the NewDelete checker, but the
underlying issue is reproducible with other checkers as well (for example, MallocChecker).
llvm-svn: 178518
This is a heuristic to make up for the fact that the analyzer doesn't
model C++ containers very well. One example is modeling that
'std::distance(I, E) == 0' implies 'I == E'. In the future, it would be
nice to model this explicitly, but for now it just results in a lot of
false positives.
The actual heuristic checks if the base type has a member named 'begin' or
'iterator'. If so, we treat the constructors and destructors of that type
as opaque, rather than inlining them.
This is intended to drastically reduce the number of false positives
reported with experimental destructor support turned on. We can tweak the
heuristic in the future, but we'd rather err on the side of false negatives
for now.
<rdar://problem/13497258>
llvm-svn: 178516
This is controlled by the 'suppress-c++-stdlib' analyzer-config flag.
It is currently off by default.
This is more suppression than we'd like to do, since obviously there can
be user-caused issues within 'std', but it gives us the option to wield
a large hammer to suppress false positives the user likely can't work
around.
llvm-svn: 178513
Evaluating a C++ new expression now includes generating an intermediate
ExplodedNode, and this node could very well represent a previously-
reachable state in the ExplodedGraph. If so, we can short-circuit the
rest of the evaluation.
Caught by the assertion a few lines later.
<rdar://problem/13510065>
llvm-svn: 178401
We can check if the receiver is nil in the node that corresponds to the StmtPoint of the message send.
At that point, the receiver is guaranteed to be live. We will find at least one unreclaimed node due to
my previous commit (look for StmtPoint instead of PostStmt) and the fact that the nil receiver nodes are tagged.
+ a couple of extra tests.
llvm-svn: 178381
Add a new callback that notifies checkers when a const pointer escapes. Currently, this only works
for const pointers passed as a top level parameter into a function. We need to differentiate the const
pointers escape from regular escape since the content pointed by const pointer will not change;
if it’s a file handle, a file cannot be closed; but delete is allowed on const pointers.
This should suppress several false positives reported by the NewDelete checker on llvm codebase.
llvm-svn: 178310
We should only suppress a bug report if the IDCed or null returned nil value is directly related to the value we are warning about. This was
not the case for nil receivers - we would suppress a bug report that had an IDCed nil receiver on the path regardless of how it’s
related to the warning.
1) Thread EnableNullFPSuppression parameter through the visitors to differentiate between tracking the value which
is directly responsible for the bug and other values that visitors are tracking (ex: general tracking of nil receivers).
2) in trackNullOrUndef specifically address the case when a value of the message send is nil due to the receiver being nil.
llvm-svn: 178309
+ Improved display names for allocators and deallocators
The checker checks if a deallocation function matches allocation one. ('free' for 'malloc', 'delete' for 'new' etc.)
llvm-svn: 178250
These types will not have a CXXConstructExpr to do the initialization for
them. Previously we just used a simple call to ProgramState::bindLoc, but
that doesn't trigger proper checker callbacks (like pointer escape).
Found by Anton Yartsev.
llvm-svn: 178160
Previously all unimplemented methods for a class were grouped under
a single warning, with all the unimplemented methods mentioned
as notes. Based on feedback from users, most users would like
a separate warning for each method, with a note pointing back to
the original method declaration.
Implements <rdar://problem/13350414>
llvm-svn: 178097
Register the nil tracking visitors with the region and refactor trackNullOrUndefValue a bit.
Also adds the cast and paren stripping before checking if the value is an OpaqueValueExpr
or ExprWithCleanups.
llvm-svn: 178093
This addresses an undefined value false positive from concreteOffsetBindingIsInvalidatedBySymbolicOffsetAssignment.
Fixes PR14877; radar://12991168.
llvm-svn: 177905
These aren't generated by default, but they are needed when either side of
the comparison is tainted.
Should fix our internal buildbot.
llvm-svn: 177846
In C, comparisons between signed and unsigned numbers are always done in
unsigned-space. Thus, we should know that "i >= 0U" is always true, even
if 'i' is signed. Similarly, "u >= 0" is also always true, even though '0'
is signed.
Part of <rdar://problem/13239003> (false positives related to std::vector)
llvm-svn: 177806
We can support the full range of comparison operations between two locations
by canonicalizing them as subtraction, as in the previous commit.
This won't work (well) if either location includes an offset, or (again)
if the comparisons are not consistent about which region comes first.
<rdar://problem/13239003>
llvm-svn: 177803
Canonicalizing these two forms allows us to better model containers like
std::vector, which use "m_start != m_finish" to implement empty() but
"m_finish - m_start" to implement size(). The analyzer should have a
consistent interpretation of these two symbolic expressions, even though
it's not properly reasoning about either one yet.
The other unfortunate thing is that while the size() expression will only
ever be written "m_finish - m_start", the comparison may be written
"m_finish == m_start" or "m_start == m_finish". Right now the analyzer does
not attempt to canonicalize those two expressions, since it doesn't know
which length expression to pick. Doing this correctly will probably require
implementing unary minus as a new SymExpr kind (<rdar://problem/12351075>).
For now, the analyzer inverts the order of arguments in the comparison to
build the subtraction, on the assumption that "begin() != end()" is
written more often than "end() != begin()". This is purely speculation.
<rdar://problem/13239003>
llvm-svn: 177801
We just treat this as opaque symbols, but even that allows us to handle
simple cases where the same condition is tested twice. This is very common
in the STL, which means that any project using the STL gets spurious errors.
Part of <rdar://problem/13239003>.
llvm-svn: 177800
This fixes some mistaken condition logic in RegionStore that caused
global variables to be invalidated when /any/ region was invalidated,
rather than only as part of opaque function calls. This was only
being used by CStringChecker, and so users will now see that strcpy()
and friends do not invalidate global variables.
Also, add a test case we don't handle properly: explicitly-assigned
global variables aren't being invalidated by opaque calls. This is
being tracked by <rdar://problem/13464044>.
llvm-svn: 177572
Due to improper modelling of copy constructors (specifically, their
const reference arguments), we were producing spurious leak warnings
for allocated memory stored in structs. In order to silence this, we
decided to consider storing into a struct to be the same as escaping.
However, the previous commit has fixed this issue and we can now properly
distinguish leaked memory that happens to be in a struct from a buffer
that escapes within a struct wrapper.
Originally applied in r161511, reverted in r174468.
<rdar://problem/12945937>
llvm-svn: 177571
In this case, the value of 'x' may be changed after the call to indirectAccess:
struct Wrapper {
int *ptr;
};
void indirectAccess(const Wrapper &w);
void test() {
int x = 42;
Wrapper w = { x };
clang_analyzer_eval(x == 42); // TRUE
indirectAccess(w);
clang_analyzer_eval(x == 42); // UNKNOWN
}
This is important for modelling return-by-value objects in C++, to show
that the contents of the struct are escaping in the return copy-constructor.
<rdar://problem/13239826>
llvm-svn: 177570
A floating-point version is nice for testing unknown values, but it's
good to be able to check all parts of the structure as well.
Test change only, no functionality change.
llvm-svn: 177455
This fixes a crash when analyzing LLVM that was exposed by r177220 (modeling of
trivial copy/move assignment operators).
When we look up a lazy binding for “Builder”, we see the direct binding of Loc at offset 0.
Previously, we believed the binding, which led to a crash. Now, we do not believe it as
the types do not match.
llvm-svn: 177453
r175234 allowed the analyzer to model trivial copy/move constructors as
an aggregate bind. This commit extends that to trivial assignment
operators as well. Like the last commit, one of the motivating factors here
is not warning when the right-hand object is partially-initialized, which
can have legitimate uses.
<rdar://problem/13405162>
llvm-svn: 177220
Fixes a FIXME, improves dead symbol collection, suppresses a false positive,
which resulted from reusing the same symbol twice for simulation of 2 calls to the same function.
Fixing this lead to 2 possible false negatives in CString checker. Since the checker is still alpha and
the solution will not require revert of this commit, move the tests to a FIXME section.
llvm-svn: 177206
In the test case below, the value V is not constrained to 0 in ErrorNode but it is in node N.
So we used to fail to register the Suppression visitor.
We also need to change the way we determine that the Visitor should kick in because the node N belongs to
the ExplodedGraph and might not be on the BugReporter path that the visitor sees. Instead of trying to match the node,
turn on the visitor when we see the last node in which the symbol is ‘0’.
llvm-svn: 177121
We were failing to match the output line, which led to us collecting no
stats at all, which led to a divide-by-zero error.
Fixes PR15510.
llvm-svn: 177084
When BugReporter tracks C++ references involved in a null pointer violation, we
want to differentiate between a null reference and a reference to a null pointer. In the
first case, we want to track the region for the reference location; in the second, we want
to track the null pointer.
In addition, the core creates CXXTempObjectRegion to represent the location of the
C++ reference, so teach FindLastStoreBRVisitor about it.
This helps null pointer suppression to kick in.
(Patch by Anna and Jordan.)
llvm-svn: 176969
The visitor used to assume that the value it’s tracking is null in the first node it examines. This is not true.
If we are registering the Suppress Inlined Defensive checks visitor while traversing in another visitor
(such as FindlastStoreVisitor). When we restart with the IDC visitor, the invariance of the visitor does
not hold since the symbol we are tracking no longer exists at that point.
I had to pass the ErrorNode when creating the IDC visitor, because, in some cases, node N is
neither the error node nor will be visible along the path (we had not finalized the path at that point
and are dealing with ExplodedGraph.)
We should revisit the other visitors which might not be aware that they might get nodes, which are
later in path than the trigger point.
This suppresses a number of inline defensive checks in JavaScriptCore.
llvm-svn: 176756
Jordan Rose