Don't enable c++-temp-dtor-inlining by default yet, due to this reference
counting pointe problem.
Otherwise the new mode seems stable and allows us to incrementally fix C++
problems in much less hacky ways.
Differential Revision: https://reviews.llvm.org/D43804
llvm-svn: 326461
Originally submitted as r326323 and r326324.
Reverted in r326432.
Reverting the commit was a mistake.
The breakage was due to invalid build files in our internal buildsystem,
CMakeLists did not have any cyclic dependencies.
llvm-svn: 326439
Also revert "[analyzer] Fix a compiler warning"
This reverts commits r326323 and r326324.
Reason: the commits introduced a cyclic dependency in the build graph.
This happens to work with cmake, but breaks out internal integrate.
llvm-svn: 326432
This is a security check that warns when both PROT_WRITE and PROT_EXEC are
set during mmap(). If mmap()ed memory is both writable and executable, it makes
it easier for the attacker to execute arbitrary code when contents of this
memory are compromised. Some applications require such mmap()s though, such as
different sorts of JIT.
Re-applied after a revert in r324167.
Temporarily stays in the alpha package because it needs a better way of
determining macro values that are not immediately available in the AST.
Patch by David Carlier!
Differential Revision: https://reviews.llvm.org/D42645
llvm-svn: 326405
For now. We should also add support for ConstructorConversion casts as presented
in the attached test case, but this requires more changes because AST around
them seems different.
The check was originally present but was accidentally lost during r326021.
Differential Revision: https://reviews.llvm.org/D43840
llvm-svn: 326402
The aim of this patch is to be minimal to enable incremental development of
the feature on the top of the tree. This patch should be an NFC when the
feature is turned off. It is turned off by default and still considered as
experimental.
Technical details are available in the EuroLLVM Talk:
http://llvm.org/devmtg/2017-03//2017/02/20/accepted-sessions.html#7
Note that the initial prototype was done by A. Sidorin et al.: http://lists.llvm.org/pipermail/cfe-dev/2015-October/045730.html
Contributions to the measurements and the new version of the code: Peter Szecsi, Zoltan Gera, Daniel Krupp, Kareem Khazem.
Differential Revision: https://reviews.llvm.org/D30691
llvm-svn: 326323
When a class forgets to initialize a field in the constructor, and then gets
copied around, a warning is emitted that the value assigned to a specific field
is undefined.
When the copy/move constructor is implicit (not written out in the code) but not
trivial (is not a trivial memory copy, eg. because members have an explicit copy
constructor), the body of such constructor is auto-generated in the AST.
In this case the checker's warning message is squeezed at the top of
the class declaration, and it gets hard to guess which field is at fault.
Fix the warning message to include the name of the field.
Differential Revision: https://reviews.llvm.org/D43798
llvm-svn: 326258
Throw away MallocChecker warnings that occur after releasing a pointer within a
destructor (or its callees) after performing C11 atomic fetch_add or fetch_sub
within that destructor (or its callees).
This is an indication that the destructor's class is likely a
reference-counting pointer. The analyzer is not able to understand that the
original reference count is usually large enough to avoid most use-after-frees.
Even when the smart pointer is a local variable, we still have these false
positives that this patch suppresses, because the analyzer doesn't currently
support atomics well enough.
Differential Revision: https://reviews.llvm.org/D43791
llvm-svn: 326249
The SVal for any empty C++ object is an UnknownVal. Because RegionStore does
not have binding extents, binding an empty object to an UnknownVal may
potentially overwrite existing bindings at the same offset.
Therefore, when performing a trivial copy of an empty object, don't try to
take the value of the object and bind it to the copy. Doing nothing is accurate
enough, and it doesn't screw any existing bindings.
Differential Revision: https://reviews.llvm.org/D43714
llvm-svn: 326247
Sometimes it is not known at compile time which temporary objects will be
constructed, eg. 'x ? A() : B()' or 'C() || D()'. In this case we track which
temporary was constructed to know how to properly call the destructor.
Once the construction context for temporaries was introduced, we moved the
tracking code to the code that investigates the construction context.
Bring back the old mechanism because construction contexts are not always
available yet - eg. in the case where a temporary is constructed without a
constructor expression, eg. returned from a function by value. The mechanism
should still go away eventually.
Additionally, fix a bug in the temporary cleanup code for the case when
construction contexts are not available, which could lead to temporaries
staying in the program state and increasing memory consumption.
Differential Revision: https://reviews.llvm.org/D43666
llvm-svn: 326246
If a variable or an otherwise a concrete typed-value region is being
placement-new'ed into, its dynamic type may change in arbitrary manners. And
when the region is used, there may be a third type that's different from both
the static and the dynamic type. It cannot be *completely* different from the
dynamic type, but it may be a base class of the dynamic type - and in this case
there isn't (and shouldn't be) any indication anywhere in the AST that there is
a derived-to-base cast from the dynamic type to the third type.
Perform a generic cast (evalCast()) from the third type to the dynamic type
in this case. From the point of view of the SVal hierarchy, this would have
produced non-canonical SVals if we used such generic cast in the normal case,
but in this case there doesn't seem to be a better option.
Differential Revision: https://reviews.llvm.org/D43659
llvm-svn: 326245
Automatic destructors are missing in the CFG in situations like
const int &x = C().x;
For now it's better to disable construction inlining, because inlining
constructors while doing nothing on destructors is very bad.
Differential Revision: https://reviews.llvm.org/D43689
llvm-svn: 326240
This patch uses the reference to MaterializeTemporaryExpr stored in the
construction context since r326014 in order to model that expression correctly.
When modeling MaterializeTemporaryExpr, instead of copying the raw memory
contents from the sub-expression's rvalue to a completely new temporary region,
that we conjure up for the lack of better options, we now have the better
option to recall the region into which the object was originally constructed
and declare that region to be the value of the expression, which is semantically
correct.
This only works when the construction context is available, which is worked on
independently.
The temporary region's liveness (in the sense of removeDeadBindings) is extended
until the MaterializeTemporaryExpr is resolved, in order to keep the store
bindings around, because it wouldn't be referenced from anywhere else in the
program state.
Differential Revision: https://reviews.llvm.org/D43497
llvm-svn: 326236
Fixes https://bugs.llvm.org/show_bug.cgi?id=36474
In general, getSVal API should be changed so that it does not crash on
some non-obvious conditions.
It should either be updated to require a type, or to return Optional<SVal>.
Differential Revision: https://reviews.llvm.org/D43801
llvm-svn: 326233
See D42775 for discussion. Turns out, just exploring nodes which
weren't explored first is not quite enough, as e.g. the first quick
traversal resulting in a report can mark everything as "visited", and
then subsequent traversals of the same region will get all the pitfalls
of DFS.
Priority queue-based approach in comparison shows much greater
increase in coverage and even performance, without sacrificing memory.
Differential Revision: https://reviews.llvm.org/D43354
llvm-svn: 326136
Bison/YACC generated files result in a very large number of (presumably)
false positives from the analyzer.
These false positives are "true" in a sense of the information analyzer
sees: assuming that the lexer can return any token at any point a number
of uninitialized reads does occur.
(naturally, the analyzer can not capture a complex invariant that
certain tokens can only occur under certain conditions).
Current fix simply stops analysis on those files.
I have examined a very large number of such auto-generated files, and
they do all start with such a comment.
Conversely, user code is very unlikely to contain such a comment.
rdar://33608161
Differential Revision: https://reviews.llvm.org/D43421
llvm-svn: 326135
Addresses https://bugs.llvm.org/show_bug.cgi?id=36206
rdar://37159026
A proper fix would be much harder, and would involve changing the
appropriate code in ExprEngine to be aware of the size limitations of
the type used for addressing.
Differential Revision: https://reviews.llvm.org/D43218
llvm-svn: 326122
When a lifetime-extended temporary is on a branch of a conditional operator,
materialization of such temporary occurs after the condition is resolved.
This change allows us to understand, by including the MaterializeTemporaryExpr
in the construction context, the target for temporary materialization in such
cases.
Differential Revision: https://reviews.llvm.org/D43483
llvm-svn: 326019
In order to bind a temporary to a const lvalue reference, a no-op cast is added
to make the temporary itself const, and only then the reference is taken
(materialized). Skip the no-op cast when looking for the construction context.
Differential Revision: https://reviews.llvm.org/D43481
llvm-svn: 326016
When a constructor of a temporary with a single argument is treated
as a functional cast expression, skip the functional cast expression
and provide the correct construction context for the temporary.
Differential Revision: https://reviews.llvm.org/D43480
llvm-svn: 326015
When constructing a temporary that is going to be lifetime-extended through a
MaterializeTemporaryExpr later, CFG elements for the respective constructor
can now be queried to obtain the reference to that MaterializeTemporaryExpr
and therefore gain information about lifetime extension.
This may produce multi-layered construction contexts when information about
both temporary destruction and lifetime extension is available.
Differential Revision: https://reviews.llvm.org/D43477
llvm-svn: 326014
The assertion gets exposed when changing the exploration order.
This is a quick hacky fix, but the intention is that if the nodes do
merge, it should not matter which predecessor should be traverse.
A proper fix would be not to traverse predecessors at all, as all
information relevant for any decision should be avilable locally.
rdar://37540480
Differential Revision: https://reviews.llvm.org/D42773
llvm-svn: 325977
In the wild, many cases of null pointer dereference, or uninitialized
value read occur because the value was meant to be initialized by the
inlined function, but did not, most often due to error condition in the
inlined function.
This change highlights the return branch taken by the inlined function,
in order to help user understand the error report and see why the value
was uninitialized.
rdar://36287652
Differential Revision: https://reviews.llvm.org/D41848
llvm-svn: 325976
When viewing the report in the collapsed mode the label signifying where
did the execution go is often necessary for properly understanding the
context.
Differential Revision: https://reviews.llvm.org/D43145
llvm-svn: 325975
The checker marks the locations where the analyzer creates sinks. However, it
can happen that the sink was created because of a loop which does not contain
condition statement, only breaks in the body. The exhausted block is the block
which should contain the condition but empty, in this case.
This change only emits this marking in order to avoid the undefined behavior.
Differential Revision: https://reviews.llvm.org/D42266
llvm-svn: 325693
Array destructors, like constructors, need to be called for each element of the
array separately. We do not have any mechanisms to do this in the analyzer,
so for now all we do is evaluate a single constructor or destructor
conservatively and give up. It automatically causes the necessary invalidation
and pointer escape for the whole array, because this is how RegionStore works.
Implement this conservative behavior for temporary destructors. This fixes the
crash on the provided test.
Differential Revision: https://reviews.llvm.org/D43149
llvm-svn: 325286
Temporary destructors fire at the end of the full-expression. It is reasonable
to attach the path note for entering/leaving the temporary destructor to its
CXXBindTemporaryExpr. This would not affect lifetime-extended temporaries with
their automatic destructors which aren't temporary destructors.
The path note may be confusing in the case of destructors after elidable copy
constructors.
Differential Revision: https://reviews.llvm.org/D43144
llvm-svn: 325284
Inline them if possible - a separate flag is added to control this.
The whole thing is under the cfg-temporary-dtors flag, off by default so far.
Temporary destructors are called at the end of full-expression. If the
temporary is lifetime-extended, automatic destructors kick in instead,
which are not addressed in this patch, and normally already work well
modulo the overally broken support for lifetime extension.
The patch operates by attaching the this-region to the CXXBindTemporaryExpr in
the program state, and then recalling it during destruction that was triggered
by that CXXBindTemporaryExpr. It has become possible because
CXXBindTemporaryExpr is part of the construction context since r325210.
Differential revision: https://reviews.llvm.org/D43104
llvm-svn: 325282
Since r325210, in cfg-temporary-dtors mode, we can rely on the CFG to tell us
that we're indeed constructing a temporary, so we can trivially construct a
temporary region and inline the constructor.
Much like r325202, this is only done under the off-by-default
cfg-temporary-dtors flag because the temporary destructor, even if available,
will not be inlined and won't have the correct object value (target region).
Unless this is fixed, it is quite unsafe to inline the constructor.
If the temporary is lifetime-extended, the destructor would be an automatic
destructor, which would be evaluated with a "correct" target region - modulo
the series of incorrect relocations performed during the lifetime extension.
It means that at least, values within the object are guaranteed to be properly
escaped or invalidated.
Differential Revision: https://reviews.llvm.org/D43062
llvm-svn: 325211
Constructors of C++ temporary objects that have destructors now can be queried
to discover that they're indeed constructing temporary objects.
The respective CXXBindTemporaryExpr, which is also repsonsible for destroying
the temporary at the end of full-expression, is now available at the
construction site in the CFG. This is all the context we need to provide for
temporary objects that are not lifetime extended. For lifetime-extended
temporaries, more context is necessary.
Differential Revision: https://reviews.llvm.org/D43056
llvm-svn: 325210
EvalCallOptions were introduced in r324018 for allowing various parts of
ExprEngine to notify the inlining mechanism, while preparing for evaluating a
function call, of possible difficulties with evaluating the call that they
foresee. Then mayInlineCall() would still be a single place for making the
decision.
Use that mechanism for destructors as well - pass the necessary flags from the
CFG-element-specific destructor handlers.
Part of this patch accidentally leaked into r324018, which led into a change in
tests; this change is reverted now, because even though the change looked
correct, the underlying behavior wasn't. Both of these commits were not intended
to introduce any function changes otherwise.
Differential Revision: https://reviews.llvm.org/D42991
llvm-svn: 325209
This only affects the cfg-temporary-dtors mode - in this mode we begin inlining
constructors that are constructing function return values. These constructors
have a correct construction context since r324952.
Because temporary destructors are not only never inlined, but also don't have
the correct target region yet, this change is not entirely safe. But this
will be fixed in the subsequent commits, while this stays off behind the
cfg-temporary-dtors flag.
Lifetime extension for return values is still not modeled correctly.
Differential Revision: https://reviews.llvm.org/D42875
llvm-svn: 325202
See reviews.llvm.org/M1 for evaluation, and
lists.llvm.org/pipermail/cfe-dev/2018-January/056718.html for
discussion.
Differential Revision: https://reviews.llvm.org/D42775
llvm-svn: 324956
When the current function returns a C++ object by value, CFG elements for
constructors that construct the return values can now be queried to discover
that they're indeed participating in construction of the respective return value
at the respective return statement.
Differential Revision: https://reviews.llvm.org/D42875
llvm-svn: 324952
It was introduced when two -analyzer-config options were added almost
simultaneously in r324793 and r324668 and the option count was not
rebased correctly in the tests.
Fixes the buildbots.
llvm-svn: 324801
Now that we make it possible to query the CFG constructor element to find
information about the construction site, possible cleanup work represented by
ExprWithCleanups should not prevent us from providing this information.
This allows us to have a correct construction context for variables initialized
"by value" via elidable copy-constructors, such as 'i' in
iterator i = vector.begin();
Differential Revision: https://reviews.llvm.org/D42719
llvm-svn: 324798
CFG elements for constructors of fields and base classes that are being
initialized before the body of the whole-class constructor starts can now be
queried to discover that they're indeed participating in initialization of their
respective fields or bases before the whole-class constructor kicks in.
CFG construction contexts are now capable of representing CXXCtorInitializer
triggers, which aren't considered to be statements in the Clang AST.
Differential Revision: https://reviews.llvm.org/D42700
llvm-svn: 324796
Constructors of simple variables now can be queried to discover that they're
constructing into simple variables.
Differential Revision: https://reviews.llvm.org/D42699
llvm-svn: 324794
This expression may or may not be evaluated in compile time, so tracking the
result symbol is of potential interest. However, run-time offsetof is not yet
supported by the analyzer, so for now this callback is only there to assist
future implementation.
Patch by Henry Wong!
Differential Revision: https://reviews.llvm.org/D42300
llvm-svn: 324790
