Previously, SValBuilder knew how to evaluate StringLiterals, but couldn't
handle an array-to-pointer decay for constant values. Additionally,
RegionStore was being too strict about loading from an array, refusing to
return a 'char' value from a 'const char' array. Both of these have been
fixed.
llvm-svn: 186520
Previously, the use of a std::initializer_list (actually, a
CXXStdInitializerListExpr) would cause the analyzer to give up on the rest
of the path. Now, it just uses an opaque symbolic value for the
initializer_list and continues on.
At some point in the future we can add proper support for initializer_list,
with access to the elements in the InitListExpr.
<rdar://problem/14340207>
llvm-svn: 186519
Summary:
This patch enables ExprEndgine to reason about temporary object destructors.
However, these destructor calls are never inlined, since this feature is still
broken. Still, this is sufficient to properly handle noreturn temporary
destructors and close bug #15599. I have also enabled the cfg-temporary-dtors
analyzer option by default.
Reviewers: jordan_rose
CC: cfe-commits
Differential Revision: http://llvm-reviews.chandlerc.com/D1131
llvm-svn: 186498
Previously, we asserted that whenever 'new' did not include a constructor
call, the type must be a non-record type. In C++11, however, uniform
initialization syntax (braces) allow 'new' to construct records with
list-initialization: "new Point{1, 2}".
Removing this assertion should be perfectly safe; the code here matches
what VisitDeclStmt does for regions allocated on the stack.
<rdar://problem/14403437>
llvm-svn: 186028
list is the name of a class, not a namespace. Change the test as well - the previous
version did not test properly.
Fixes radar://14317928.
llvm-svn: 185898
We should not be asking unique_file to prepend the system temporary directory
when creating the html report. Unfortunately I don't think we can test this
with the current infrastructure since unique_file ignores MakeAbsolute if the
directory is already absolute and the paths provided by lit are.
I will take a quick look at making this api a bit less error prone.
llvm-svn: 185707
The motivation is to suppresses false use-after-free reports that occur when calling
std::list::pop_front() or std::list::pop_back() twice. The analyzer does not
reason about the internal invariants of the list implementation, so just do not report
any of warnings in std::list.
Fixes radar://14317928.
llvm-svn: 185609
While we don't model pointers-to-members besides "null" and "non-null",
we were using Loc symbols for valid pointers and NonLoc integers for the
null case. This hit the assert committed in r185401.
Fixed by using a true (Loc) null for null member pointers.
llvm-svn: 185444
Summary:
Static analyzer used to abort when encountering AttributedStmts, because it
asserted that the statements should not appear in the CFG. This is however not
the case, since at least the clang::fallthrough annotation makes it through.
This commit simply makes the analyzer ignore the statement attributes.
CC: cfe-commits
Differential Revision: http://llvm-reviews.chandlerc.com/D1030
llvm-svn: 185417
The one bit of code that was using this is gone, and neither C nor C++
actually allows this. Add an assertion and remove dead code.
Found by Matthew Dempsky!
llvm-svn: 185401
Re-apply r184511, reverted in r184561, with the trivial default constructor
fast path removed -- it turned out not to be necessary here.
Certain expressions can cause a constructor invocation to zero-initialize
its object even if the constructor itself does no initialization. The
analyzer now handles that before evaluating the call to the constructor,
using the same "default binding" mechanism that calloc() uses, rather
than simply ignoring the zero-initialization flag.
<rdar://problem/14212563>
llvm-svn: 184815
In order to make sure virtual base classes are always initialized once,
the AST contains initializers for the base class in /all/ of its
descendents, not just the immediate descendents. However, at runtime,
the most-derived object is responsible for initializing all the virtual
base classes; all the other initializers will be ignored.
The analyzer now checks to see if it's being called from another base
constructor, and if so does not perform virtual base initialization.
<rdar://problem/14236851>
llvm-svn: 184814
Per review from Anna, this really should have been two commits, and besides
it's causing problems on our internal buildbot. Reverting until these have
been worked out.
This reverts r184511 / 98123284826bb4ce422775563ff1a01580ec5766.
llvm-svn: 184561
Certain expressions can cause a constructor invocation to zero-initialize
its object even if the constructor itself does no initialization. The
analyzer now handles that before evaluating the call to the constructor,
using the same "default binding" mechanism that calloc() uses, rather
than simply ignoring the zero-initialization flag.
As a bonus, trivial default constructors are now no longer inlined; they
are instead processed explicitly by ExprEngine. This has a (positive)
effect on the generated path edges: they no longer stop at a default
constructor call unless there's a user-provided implementation.
<rdar://problem/14212563>
llvm-svn: 184511
Summary:
When doing a reinterpret+dynamic cast from an incomplete type, the analyzer
would crash (bug #16308). This fix makes the dynamic cast evaluator ignore
incomplete types, as they can never be used in a dynamic_cast. Also adding a
regression test.
CC: cfe-commits
Differential Revision: http://llvm-reviews.chandlerc.com/D1006
llvm-svn: 184403
Summary:
When processing a call to a function, which got passed less arguments than it
expects, the analyzer would crash.
I've also added a test for that and a analyzer warning which detects these
cases.
CC: cfe-commits
Differential Revision: http://llvm-reviews.chandlerc.com/D994
llvm-svn: 184288
The untemplated implementation of getParents() doesn't need to be in a
header file.
RecursiveASTVisitor.h is full of repeated macro expansion. Moving this
include to ASTContext.cpp speeds up compilation of
LambdaMangleContext.cpp, a small C++ file with few includes, from 3.7s
to 2.8s for me locally. I haven't measured a full build, but it can't
hurt.
I had to fix a few static analyzer files that were depending on
transitive includes of C++ AST headers.
Reviewers: rsmith, klimek
Differential Revision: http://llvm-reviews.chandlerc.com/D982
llvm-svn: 184075
Introduce CXXStdInitializerListExpr node, representing the implicit
construction of a std::initializer_list<T> object from its underlying array.
The AST representation of such an expression goes from an InitListExpr with a
flag set, to a CXXStdInitializerListExpr containing a MaterializeTemporaryExpr
containing an InitListExpr (possibly wrapped in a CXXBindTemporaryExpr).
This more detailed representation has several advantages, the most important of
which is that the new MaterializeTemporaryExpr allows us to directly model
lifetime extension of the underlying temporary array. Using that, this patch
*drastically* simplifies the IR generation of this construct, provides IR
generation support for nested global initializer_list objects, fixes several
bugs where the destructors for the underlying array would accidentally not get
invoked, and provides constant expression evaluation support for
std::initializer_list objects.
llvm-svn: 183872
We drew the diagnostic edges to wrong statements in cases the note was on a macro.
The fix is simple, but seems to work just fine for a whole bunch of test cases (plist-macros.cpp).
Also, removes an unnecessary edge in edges-new.mm, when function signature starts with a macro.
llvm-svn: 183599
The function in which we were doing it used to be conditionalized. Add a new unconditional
cleanup step.
This fixes PR16227 (radar://14073870) - a crash when generating html output for one of the test files.
llvm-svn: 183451
Previously our edges were completely broken here; now, the final result
is a very simple set of edges in most cases: one up to the "for" keyword
for context, and one into the body of the loop. This matches the behavior
for ObjC for-in loops.
In the AST, however, CXXForRangeStmts are handled very differently from
ObjCForCollectionStmts. Since they are specified in terms of equivalent
statements in the C++ standard, we actually have implicit AST nodes for
all of the semantic statements. This makes evaluation very easy, but
diagnostic locations a bit trickier. Fortunately, the problem can be
generally defined away by marking all of the implicit statements as
part of the top-level for-range statement.
One of the implicit statements in a for-range statement is the declaration
of implicit iterators __begin and __end. The CFG synthesizes two
separate DeclStmts to match each of these decls, but until now these
synthetic DeclStmts weren't in the function's ParentMap. Now, the CFG
keeps track of its synthetic statements, and the AnalysisDeclContext will
make sure to add them to the ParentMap.
<rdar://problem/14038483>
llvm-svn: 183449
When processing ArrayToPointerDecay, we expect the array to be a location, not a LazyCompoundVal.
Special case the rvalue arrays by using a location to represent them. This case is handled similarly
elsewhere in the code.
Fixes PR16206.
llvm-svn: 183359
We previously asserted that there was a top-level function entry edge, but
if the function decl's location is invalid (or within a macro) this edge
might not exist. Change the assertion to an actual check, and don't drop
the first path piece if it doesn't match.
<rdar://problem/14070304>
llvm-svn: 183358
The edge optimizer needs to see edges for, say, implicit casts (which have
the same source location as their operand) to uniformly simplify the
entire path. However, we still don't want to produce edges from a statement
to /itself/, which could occur when two nodes in a row have the same
statement location.
This necessitated moving the check for redundant notes to after edge
optimization, since the check relies on notes being adjacent in the path.
<rdar://problem/14061675>
llvm-svn: 183357
...but don't yet migrate over the existing plist tests. Some of these
would be trivial to migrate; others could use a bit of inspection first.
In any case, though, the new edge algorithm seems to have proven itself,
and we'd like more coverage (and more usage) of it going forwards.
llvm-svn: 183165
A.1 -> A -> B
becomes
A.1 -> B
This only applies if there's an edge from a subexpression to its parent
expression, and that is immediately followed by another edge from the
parent expression to a subsequent expression. Normally this is useful for
bringing the edges back to the left side of the code, but when the
subexpression is on a different line the backedge ends up looking strange,
and may even obscure code. In these cases, it's better to just continue
to the next top-level statement.
llvm-svn: 183164
Specifically, if the line is over 80 characters, or if the top-level
statement spans mulitple lines, we should preserve sub-expression edges
even if they form a simple cycle as described in the last commit, because
it's harder to infer what's going on than it is for shorter lines.
llvm-svn: 183163
Generating context arrows can result in quite a few arrows surrounding a
relatively simple expression, often containing only a single path note.
|
1 +--2---+
v/ v
auto m = new m // 3 (the path note)
|\ |
5 +--4---+
v
Note also that 5 and 1 are two ends of the "same" arrow, i.e. they go from
event to event. 3 is not an arrow but the path note itself.
Now, if we see a pair of edges like 2 and 4---where 4 is the reverse of 2
and there is optionally a single path note between them---we will
eliminate /both/ edges. Anything more complicated will be left as is
(more edges involved, an inlined call, etc).
The next commit will refine this to preserve the arrows in a larger
expression, so that we don't lose all context.
llvm-svn: 183162
The old edge builder didn't have a notion of nested statement contexts,
so there was no special treatment of a logical operator inside an if
(or inside another logical operator). The new edge builder always tries
to establish the full context up to the top-level statement, so it's
important to know how much context has been established already rather
than just checking the innermost context.
This restores some of the old behavior for the old edge generation:
the context of a logical operator's non-controlling expression is the
subexpression in the old edge algorithm, but the entire operator
expression in the new algorithm.
llvm-svn: 183160
The current edge-generation algorithm sometimes creates edges from a
top-level statement A to a sub-expression B.1 that's not at the start of B.
This creates a "swoosh" effect where the arrow is drawn on top of the
text at the start of B. In these cases, the results are clearer if we see
an edge from A to B, then another one from B to B.1.
Admittedly, this does create a /lot/ of arrows, some of which merely hop
into a subexpression and then out again for a single note. The next commit
will eliminate these if the subexpression is simple enough.
This updates and reuses some of the infrastructure from the old edge-
generation algorithm to find the "enclosing statement" context for a
given expression. One change in particular marks the context of the
LHS or RHS of a logical binary operator (&&, ||) as the entire operator
expression, rather than the subexpression itself. This matches our behavior
for ?:, and allows us to handle nested context information.
<rdar://problem/13902816>
llvm-svn: 183159
Although we don't want to show a function entry edge for a top-level path,
having it makes optimizing edges a little more uniform.
This does not affect any edges now, but will affect context edge generation
(next commit).
llvm-svn: 183158
In many cases, the edge from the "if" to the condition, followed by an edge from the branch condition to the target code, is uninteresting.
In such cases, we should fold the two edges into one from the "if" to the target.
This also applies to loops.
Implements <rdar://problem/14034763>.
llvm-svn: 183018
...and make this work correctly in the current codebase.
After living on this for a while, it turns out to look very strange for
inlined functions that have only a single statement, and somewhat strange
for inlined functions in general (since they are still conceptually in the
middle of the path, and there is a function-entry path note).
It's worth noting that this only affects inlined functions; in the new
arrow generation algorithm, the top-level function still starts at the
first real statement in the function body, not the enclosing CompoundStmt.
This reverts r182078 / dbfa950abe0e55b173286a306ee620eff5f72ea.
llvm-svn: 182963
It is okay to declare a block without an argument list: ^ {} or ^void {}.
In these cases, the BlockDecl's signature-as-written will just contain
the return type, rather than the entire function type. It is unclear if
this is intentional, but the analyzer shouldn't crash because of it.
<rdar://problem/14018351>
llvm-svn: 182948
Most loop notes (like "entering loop body") are attached to the condition
expression guarding a loop or its equivalent. For loops may not have a
condition expression, though. Rather than crashing, just use the entire
ForStmt as the location. This is probably the best we can do.
<rdar://problem/14016063>
llvm-svn: 182904
In C, 'void' is treated like any other incomplete type, and though it is
never completed, you can cast the address of a void-typed variable to do
something useful. (In C++ it's illegal to declare a variable with void type.)
Previously we asserted on this code; now we just treat it like any other
incomplete type.
And speaking of incomplete types, we don't know their extent. Actually
check that in TypedValueRegion::getExtent, though that's not being used
by any checkers that are on by default.
llvm-svn: 182880
This gives slightly better precision, specifically, in cases where a non-typed region represents the array
or when the type is a non-array type, which can happen when an array is a result of a reinterpret_cast.
llvm-svn: 182810
It’s important for us to reason about the cast as it is used in std::addressof. The reason we did not
handle the cast previously was a crash on a test case (see commit r157478). The crash was in
processing array to pointer decay when the region type was not an array. Address the issue, by
just returning an unknown in that case.
llvm-svn: 182808
In addition to enabling more code reuse, this suppresses some false positives by allowing us to
compare an element region to its base. See the ptr-arith.cpp test cases for an example.
llvm-svn: 182780
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
Ted and I spent a long time discussing this today and found out that neither
the existing code nor the new code was doing what either of us thought it
was, which is never good. The good news is we found a much simpler way to
fix the motivating test case (an ObjCSubscriptExpr).
This reverts r182083, but pieces of it will come back in subsequent commits.
llvm-svn: 182185
This optimizes some spurious edges resulting from PseudoObjectExprs.
This required far more changes than I anticipated. The current
ParentMap does not record any hierarchy information between
a PseudoObjectExpr and its *semantic* expressions that may be
wrapped in OpaqueValueExprs, which are the expressions actually
laid out in the CFG. This means the arrow pruning logic could
not map from an expression to its containing PseudoObjectExprs.
To solve this, this patch adds a variant of ParentMap that
returns the "semantic" parentage of expressions (essentially
as they are viewed by the CFG). This alternate ParentMap is then
used by the arrow reducing logic to identify edges into pseudo
object expressions, and then eliminate them.
llvm-svn: 182083
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
ASTDumper was already trying to do this & instead got an implicit bool
conversion by surprise (thus printing out 0 or 1 instead of the name of
the declaration). To avoid that issue & simplify call sites, simply make
it the normal/expected operator<<(raw_ostream&, ...) overload & simplify
all the existing call sites. (bonus: this function doesn't need to be a
member or friend, it's just using public API in DeclarationName)
llvm-svn: 181832
This patch renames getLinkage to getLinkageInternal. Only code that
needs to handle UniqueExternalLinkage specially should call this.
Linkage, as defined in the c++ standard, is provided by
getFormalLinkage. It maps UniqueExternalLinkage to ExternalLinkage.
Most places in the compiler actually want isExternallyVisible, which
handles UniqueExternalLinkage as internal.
llvm-svn: 181677
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
The one user has been changed to use getLValue on the compound literal
expression and then use the normal bindLoc to assign a value. No need
to special case this in the StoreManager.
llvm-svn: 181214
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
This change required some minor changes to LocationContextMap to have it map
from PathPieces to LocationContexts instead of PathDiagnosticCallPieces to
LocationContexts. These changes are in the other diagnostic
generation logic as well, but are functionally equivalent.
Interestingly, this optimize requires delaying "cleanUpLocation()" until
later; possibly after all edges have been optimized. This is because
we need PathDiagnosticLocations to refer to the semantic entity (e.g. a statement)
as long as possible. Raw source locations tell us nothing about
the semantic relationship between two locations in a path.
llvm-svn: 181084
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
BugReporter is used to process ALL bug reports. By using a shared map,
we are having mappings from different PathDiagnosticPieces to LocationContexts
well beyond the point where we are processing a given report. This
state is inherently error prone, and is analogous to using a global
variable. Instead, just create a temporary map, one per report,
and when we are done with it we throw it away. No extra state.
llvm-svn: 180974
...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
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
Much of this patch outside of PathDiagnostics.h are just minor
syntactic changes due to the return type for operator* and the like
changing for the iterator, so the real focus should be on
PathPieces itself.
This change is motivated so that we can do efficient insertion
and removal of individual pieces from within a PathPiece, just like
this was a kind of "IR" for static analyzer diagnostics. We
currently implement path transformations by iterating over an
entire PathPiece and making a copy. This isn't very natural for
some algorithms.
We use an ilist here instead of std::list because we want operations
to rip out/insert nodes in place, just like IR manipulation. This
isn't being used yet, but opens the door for more powerful
transformation algorithms on diagnostic paths.
llvm-svn: 180741
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
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
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
Add a CXXDefaultInitExpr, analogous to CXXDefaultArgExpr, and use it both in
CXXCtorInitializers and in InitListExprs to represent a default initializer.
There's an additional complication here: because the default initializer can
refer to the initialized object via its 'this' pointer, we need to make sure
that 'this' points to the right thing within the evaluation.
llvm-svn: 179958
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
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
Structs and arrays can take advantage of the single top-level global
symbol optimization (described in the previous commit) just as well
as scalars.
No intended behavioral change.
llvm-svn: 179555
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
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
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
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
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
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
Certain properties of a function can determine ahead of time whether or not
the function is inlineable, such as its kind, its signature, or its
location. We can cache this value in the FunctionSummaries map to avoid
rechecking these static properties for every call.
Note that the analyzer may still decide not to inline a specific call to
a function because of the particular dynamic properties of the call along
the current path.
No intended functionality change.
llvm-svn: 178515
The summaries lasted for the lifetime of the map anyway; no reason to
include an extra allocation.
Also, use SmallBitVector instead of BitVector to track the visited basic
blocks -- most functions will have less than 64 basic blocks -- and
use bitfields for the other fields to reduce the size of the structure.
No functionality change.
llvm-svn: 178514
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
trackNullOrUndefValue tries to find the first node that matches the statement it is tracking.
Since we collect PostStmt nodes (in node reclamation), none of those might be on the
current path, so relax the search to look for any StmtPoint.
llvm-svn: 178380
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
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
The visitor should look for the PreStmt node as the receiver is nil in the PreStmt and this is the node. Also, tag the nil
receiver nodes with a special tag for consistency.
llvm-svn: 178152
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
For two concrete locations, we were producing another concrete location and
then casting it to an integer. We should just create a nonloc::ConcreteInt
to begin with.
No functionality change.
llvm-svn: 177805
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
The algorithm used here was ridiculously slow when a potential back-edge
pointed to a node that already had a lot of successors. The previous commit
makes this feature unnecessary anyway.
This reverts r177468 / f4cf6b10f863b9bc716a09b2b2a8c497dcc6aa9b.
Conflicts:
lib/StaticAnalyzer/Core/BugReporter.cpp
llvm-svn: 177765
For a given bug equivalence class, we'd like to emit the report with the
shortest path. So far to do this we've been trimming the ExplodedGraph to
only contain relevant nodes, then doing a reverse BFS (starting at all the
error nodes) to find the shortest paths from the root. However, this is
fairly expensive when we are suppressing many bug reports in the same
equivalence class.
r177468-9 tried to solve this problem by breaking cycles during graph
trimming, then updating the BFS priorities after each suppressed report
instead of recomputing the whole thing. However, breaking cycles is not
a cheap operation because an analysis graph minus cycles is still a DAG,
not a tree.
This fix changes the algorithm to do a single forward BFS (starting from the
root) and to use that to choose the report with the shortest path by looking
at the error nodes with the lowest BFS priorities. This was Anna's idea, and
has the added advantage of requiring no update step: we can just pick the
error node with the next lowest priority to produce the next bug report.
<rdar://problem/13474689>
llvm-svn: 177764
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
This is a bit of old code trying to deal with the fact that functions that
take pointers often use them to access an entire array via pointer
arithmetic. However, RegionStore already conservatively assumes you can use
pointer arithmetic to access any part of a region.
Some day we may want to go back to handling this specifically for calls,
but we can do that in the future.
No functionality change.
llvm-svn: 177569
With the assurance that the trimmed graph does not contain cycles,
this patch is safe (with a few tweaks), and provides the performance
boost it was intended to.
Part of performance work for <rdar://problem/13433687>.
llvm-svn: 177469
Having a trimmed graph with no cycles (a DAG) is much more convenient for
trying to find shortest paths, which is exactly what BugReporter needs to do.
Part of the performance work for <rdar://problem/13433687>.
llvm-svn: 177468
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
The whole reason we were doing a BFS in the first place is because an
ExplodedGraph can have cycles. Unfortunately, my removeErrorNode "update"
doesn't work at all if there are cycles.
I'd still like to be able to avoid doing the BFS every time, but I'll come
back to it later.
This reverts r177353 / 481fa5071c203bc8ba4f88d929780f8d0f8837ba.
llvm-svn: 177448
Splitting the graph trimming and the path-finding (r177216) already
recovered quite a bit of performance lost to increased suppression.
We can still do better by also performing the reverse BFS up front
(needed for shortest-path-finding) and only walking the shortest path
for each report. This does mean we have to walk back up the path and
invalidate all the BFS numbers if the report turns out to be invalid,
but it's probably still faster than redoing the full BFS every time.
More performance work for <rdar://problem/13433687>
llvm-svn: 177353
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
When we generate a path diagnostic for a bug report, we have to take the
full ExplodedGraph and limit it down to a single path. We do this in two
steps: "trimming", which limits the graph to all the paths that lead to
this particular bug, and "creating the report graph", which finds the
shortest path in the trimmed path to any error node.
With BugReporterVisitor false positive suppression, this becomes more
expensive: it's possible for some paths through the trimmed graph to be
invalid (i.e. likely false positives) but others to be valid. Therefore
we have to run the visitors over each path in the graph until we find one
that is valid, or until we've ruled them all out. This can become quite
expensive.
This commit separates out graph trimming from creating the report graph,
performing the first only once per bug equivalence class and the second
once per bug report. It also cleans up that portion of the code by
introducing some wrapper classes.
This seems to recover most of the performance regression described in my
last commit.
<rdar://problem/13433687>
llvm-svn: 177216
...in favor of this typedef:
typedef llvm::DenseMap<const ExplodedNode *, const ExplodedNode *>
InterExplodedGraphMap;
Use this everywhere the previous class and typedef were used.
Took the opportunity to ArrayRef-ize ExplodedGraph::trim while I'm at it.
No functionality change.
llvm-svn: 177215
I removed this check in the recursion->iteration commit, but forgot that
generatePathDiagnostic may be called multiple times if there are multiple
PathDiagnosticConsumers.
llvm-svn: 177214
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
The previous generatePathDiagnostic() was intended to be tail-recursive,
restarting and trying again if a report was marked invalid. However:
(1) this leaked all the cloned visitors, which weren't being deleted, and
(2) this wasn't actually tail-recursive because some local variables had
non-trivial destructors.
This was causing us to overflow the stack on inputs with large numbers of
reports in the same equivalence class, such as sqlite3.c. Being iterative
at least prevents us from blowing out the stack, but doesn't solve the
performance issue: suppressing thousands (yes, thousands) of paths in the
same equivalence class is expensive. I'm looking into that now.
<rdar://problem/13423498>
llvm-svn: 177189
We discovered that sqlite3.c currently has 2600 reports in a single
equivalence class; it would be good to know if this is a recent
development or what.
(For the curious, the different reports in an equivalence class represent
the same bug found along different paths. When we're suppressing false
positives, we need to go through /every/ path to make sure there isn't a
valid path to a bug. This is a flaw in our after-the-fact suppression,
made worse by the fact that that function isn't particularly optimized.)
llvm-svn: 177188
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
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
r176737 fixed bugreporter::trackNullOrUndefValue to find nodes for an lvalue
even if the rvalue node had already been collected. This commit extends that
to call statement nodes as well, so that if a call is contained within
implicit casts we can still track the return value.
No test case because node reclamation is extremely finicky (dependent on
how the AST and CFG are built, and then on our current reclamation rules,
and /then/ on how many nodes were generated by the analyzer core and the
current set of checkers). I consider this a low-risk change, though, and
it will only happen in cases of reclamation when the rvalue node isn't
available.
<rdar://problem/13340764>
llvm-svn: 176829
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
r176010 introduced the notion of "interesting" lvalue expressions, whose
nodes are guaranteed never to be reclaimed by the ExplodedGraph. This was
used in bugreporter::trackNullOrUndefValue to find the region that contains
the null or undef value being tracked.
However, the /rvalue/ nodes (i.e. the loads from these lvalues that produce
a null or undef value) /are/ still being reclaimed, and if we couldn't
find the node for the rvalue, we just give up. This patch changes that so
that we look for the node for either the rvalue or the lvalue -- preferring
the former, since it lets us fall back to value-only tracking in cases
where we can't get a region, but allowing the latter as well.
<rdar://problem/13342842>
llvm-svn: 176737
Previously, ReturnVisitor waited to suppress a null return path until it
had found the inlined "return" statement. Now, it checks up front whether
the return value was NULL, and suppresses the warning right away if so.
We still have to wait until generating the path notes to invalidate the bug
report, or counter-suppression will never be triggered. (Counter-suppression
happens while generating path notes, but the generation won't happen for
reports already marked invalid.)
This isn't actually an issue today because we never reclaim nodes for
top-level statements (like return statements), but it could be an issue
some day in the future. (But, no expected behavioral change and no new
test case.)
llvm-svn: 176736
The second modification does not lead to any visible result, but, theoretically, is what we should
have been looking at to begin with since we are checking if the node was assumed to be null in
an inlined function.
llvm-svn: 176576
Inlining brought a few "null pointer use" false positives, which occur because
the callee defensively checks if a pointer is NULL, whereas the caller knows
that the pointer cannot be NULL in the context of the given call.
This is a first attempt to silence these warnings by tracking the symbolic value
along the execution path in the BugReporter. The new visitor finds the node
in which the symbol was first constrained to NULL. If the node belongs to
a function on the active stack, the warning is reported, otherwise, it is
suppressed.
There are several areas for follow up work, for example:
- How do we differentiate the cases where the first check is followed by
another one, which does happen on the active stack?
Also, this only silences a fraction of null pointer use warnings. For example, it
does not do anything for the cases where NULL was assigned inside a callee.
llvm-svn: 176402
Previously we were assuming that we'd never ask for the sub-region bindings
of a bitfield, since a bitfield cannot have subregions. However,
unification of code paths has made that assumption invalid. While we could
take advantage of this by just checking for the single possible binding,
it's probably better to do the right thing, so that if/when we someday
support unions we'll do the right thing there, too.
This fixes a handful of false positives in analyzing LLVM.
<rdar://problem/13325522>
llvm-svn: 176388
Most map types have an operator[] that inserts a new element if the key
isn't found, then returns a reference to the value slot so that you can
assign into it. However, if the value type is a pointer, it will be
initialized to null. This is usually no problem.
However, if the user /knows/ the map contains a value for a particular key,
they may just use it immediately:
// From ClangSACheckersEmitter.cpp
recordGroupMap[group]->Checkers
In this case the analyzer reports a null dereference on the path where the
key is not in the map, even though the user knows that path is impossible
here. They could silence the warning by adding an assertion, but that means
splitting up the expression and introducing a local variable. (Note that
the analyzer has no way of knowing that recordGroupMap[group] will return
the same reference if called twice in a row!)
We already have logic that says a null dereference has a high chance of
being a false positive if the null came from an inlined function. This
patch simply extends that to references whose rvalues are null as well,
silencing several false positives in LLVM.
<rdar://problem/13239854>
llvm-svn: 176371
By returning the (key, value) binding pairs, we save lookups afterwards.
This also enables further work later on.
No functionality change.
llvm-svn: 176230
Consider this case:
int *p = 0;
p = getPointerThatMayBeNull();
*p = 1;
If we inline 'getPointerThatMayBeNull', we might know that the value of 'p'
is NULL, and thus emit a null pointer dereference report. However, we
usually want to suppress such warnings as error paths, and we do so by using
FindLastStoreBRVisitor to see where the NULL came from. In this case, though,
because 'p' was NULL both before and after the assignment, the visitor
would decide that the "last store" was the initialization, not the
re-assignment.
This commit changes FindLastStoreBRVisitor to consider all PostStore nodes
that assign to this region. This still won't catches changes made directly
by checkers if they re-assign the same value, but it does handle the common
case in user-written code and will trigger ReturnVisitor's suppression
machinery as expected.
<rdar://problem/13299738>
llvm-svn: 176201
This enables constructor inlining for types with non-trivial destructors.
The plan is to enable destructor inlining within the next month, but that
needs further verification.
<rdar://problem/12295329>
llvm-svn: 176200
This potentially reduces a performance optimization of throwing away
PreStmtPurgeDeadSymbols nodes. I'll investigate the performance impact
soon and see if we need something better.
llvm-svn: 176149
This is essentially the same problem as r174031: a lazy binding for the first
field of a struct may stomp on an existing default binding for the
entire struct. Because of the way RegionStore is set up, we can't help
but lose the top-level binding, but then we need to make sure that accessing
one of the other fields doesn't come back as Undefined.
In this case, RegionStore is now correctly detecting that the lazy binding
we have isn't the right type, but then failing to follow through on the
implications of that: we don't know anything about the other fields in the
aggregate. This fix adds a test when searching for other kinds of default
values to see if there's a lazy binding we rejected, and if so returns
a symbolic value instead of Undefined.
The long-term fix for this is probably a new Store model; see
<rdar://problem/12701038>.
Fixes <rdar://problem/13292559>.
llvm-svn: 176144
Fixes PR15358 and <rdar://problem/13295437>.
Along the way, shorten path diagnostics that say "Variable 'x'" to just
be "'x'". By the context, it is obvious that we have a variable,
and so this just consumes text space.
llvm-svn: 176115
Normally, we need to look through derived-to-base casts when creating
temporary object regions (added in r175854). However, if the temporary
is a pointer (rather than a struct/class instance), we need to /preserve/
the base casts that have been applied.
This also ensures that we really do create a new temporary region when
we need to: MaterializeTemporaryExpr and lvalue CXXDefaultArgExprs.
Fixes PR15342, although the test case doesn't include the crash because
I couldn't isolate it.
llvm-svn: 176069
These nodes are never consulted by any analyzer client code, so they are
used only for machinery for removing dead bindings. Once successor nodes
are generated they can be safely removed.
This greatly reduces the amount of nodes that are generated in some case,
lowering the memory regression when analyzing Sema.cpp introduced by
r176010 from 14% to 2%.
llvm-svn: 176050
r175026 added support for default values, but didn't take reference
parameters into account, which expect the default argument to be an
lvalue. Use createTemporaryRegionIfNeeded if we can evaluate the default
expr as an rvalue but the expected result is an lvalue.
Fixes the most recent report of PR12915. The original report predates
default argument support, so that can't be it.
llvm-svn: 176042
While RegionStore checks to make sure casts on TypedValueRegions are valid,
it does not do the same for SymbolicRegions, which do not have perfect type
info anyway. Additionally, MemRegion::getAsOffset does not take a
ProgramState, so it can't use dynamic type info to determine a better type
for the regions. (This could also be dangerous if the type of a super-region
changes!)
Account for this by checking that a base object region is valid on top of a
symbolic region, and falling back to "symbolic offset" mode if not.
Fixes PR15345.
llvm-svn: 176034
This was triggering assertion failures when analyzing the LLVM codebase. This
is fallout from r175988.
I've got delta chewing away on a test case, but I wanted the fix to go
in now.
llvm-svn: 176011
r175988 modified the ExplodedGraph trimming algorithm to retain all
nodes for "lvalue" expressions. This patch refines that notion to
only "interesting" expressions that would be used for diagnostics.
llvm-svn: 176010
This required more changes than I originally expected:
- ObjCIvarRegion implements "canPrintPretty" et al
- DereferenceChecker indicates the null pointer source is an ivar
- bugreporter::trackNullOrUndefValue() uses an alternate algorithm
to compute the location region to track by scouring the ExplodedGraph.
This allows us to get the actual MemRegion for variables, ivars,
fields, etc. We only hand construct a VarRegion for C++ references.
- ExplodedGraph no longer drops nodes for expressions that are marked
'lvalue'. This is to facilitate the logic in the previous bullet.
This may lead to a slight increase in size in the ExplodedGraph,
which I have not measured, but it is likely not to be a big deal.
I have validated each of the changed plist output.
Fixes <rdar://problem/12114812>
llvm-svn: 175988
Use Optional<CFG*> where invalid states were needed previously. In the one case
where that's not possible (beginAutomaticObjDtorsInsert) just use a dummy
CFGAutomaticObjDtor.
Thanks for the help from Jordan Rose & discussion/feedback from Ted Kremenek
and Doug Gregor.
Post commit code review feedback on r175796 by Ted Kremenek.
llvm-svn: 175938
This Decl shouldn't be the canonical Decl; it should be the Decl used by
the CXXBaseSpecifier in the subclass. Unfortunately, that means continuing
to throw getCanonicalDecl() on all comparisons.
This fixes MemRegion::getAsOffset's use of ASTRecordLayout when redeclarations
are involved.
llvm-svn: 175913
Jordan Rose