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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>.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@177572 91177308-0d34-0410-b5e6-96231b3b80d8
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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>
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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>
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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.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@177569 91177308-0d34-0410-b5e6-96231b3b80d8
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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>.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@177469 91177308-0d34-0410-b5e6-96231b3b80d8
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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>.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@177468 91177308-0d34-0410-b5e6-96231b3b80d8
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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.
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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.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@177448 91177308-0d34-0410-b5e6-96231b3b80d8
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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>
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@177353 91177308-0d34-0410-b5e6-96231b3b80d8
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Also, replace a std::string with a SmallString.
No functionality change.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@177352 91177308-0d34-0410-b5e6-96231b3b80d8
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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>
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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>
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@177216 91177308-0d34-0410-b5e6-96231b3b80d8
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...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.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@177215 91177308-0d34-0410-b5e6-96231b3b80d8
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I removed this check in the recursion->iteration commit, but forgot that
generatePathDiagnostic may be called multiple times if there are multiple
PathDiagnosticConsumers.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@177214 91177308-0d34-0410-b5e6-96231b3b80d8
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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.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@177206 91177308-0d34-0410-b5e6-96231b3b80d8
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wrapped in a cast.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@177205 91177308-0d34-0410-b5e6-96231b3b80d8
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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>
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@177189 91177308-0d34-0410-b5e6-96231b3b80d8
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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.)
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@177188 91177308-0d34-0410-b5e6-96231b3b80d8
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For debugging use only; no functionality change.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@177187 91177308-0d34-0410-b5e6-96231b3b80d8
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Silences a few false positives in LLVM.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@177186 91177308-0d34-0410-b5e6-96231b3b80d8
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Allows the suppression visitors trigger more often.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@177137 91177308-0d34-0410-b5e6-96231b3b80d8
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sure it attaches in the given edge case
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’.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@177121 91177308-0d34-0410-b5e6-96231b3b80d8
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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.)
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@176969 91177308-0d34-0410-b5e6-96231b3b80d8
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Fixes <rdar://problem/12322528>
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@176965 91177308-0d34-0410-b5e6-96231b3b80d8
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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>
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same node it was registered at
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.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@176756 91177308-0d34-0410-b5e6-96231b3b80d8
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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>
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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.)
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@176736 91177308-0d34-0410-b5e6-96231b3b80d8
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No functionality change.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@176600 91177308-0d34-0410-b5e6-96231b3b80d8
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node” rather than last “non-null”.
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.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@176576 91177308-0d34-0410-b5e6-96231b3b80d8
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No functionality change.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@176469 91177308-0d34-0410-b5e6-96231b3b80d8
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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.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@176402 91177308-0d34-0410-b5e6-96231b3b80d8
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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>
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@176388 91177308-0d34-0410-b5e6-96231b3b80d8
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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>
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By returning the (key, value) binding pairs, we save lookups afterwards.
This also enables further work later on.
No functionality change.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@176230 91177308-0d34-0410-b5e6-96231b3b80d8
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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>
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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>
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LLVM codebase.
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.
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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>.
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a VarRegion.
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.
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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.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@176069 91177308-0d34-0410-b5e6-96231b3b80d8
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or predecessor.
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%.
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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.
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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.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@176034 91177308-0d34-0410-b5e6-96231b3b80d8
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looking for is always a VarRegion.
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.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@176011 91177308-0d34-0410-b5e6-96231b3b80d8
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ExplodedNode pruning.
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.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@176010 91177308-0d34-0410-b5e6-96231b3b80d8
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