This change was a lot bigger than I originally anticipated; among
other things it requires us storing more information in the CFG to
record what block-level expressions need to be evaluated as lvalues.
The big change is that CFGBlocks no longer contain Stmt*'s by
CFGElements. Currently CFGElements just wrap Stmt*, but they also
store a bit indicating whether the block-level expression should be
evalauted as an lvalue. DeclStmts involving the initialization of a
reference require us treating the initialization expression as an
lvalue, even though that information isn't recorded in the AST.
Conceptually this change isn't that complicated, but it required
bubbling up the data through the CFGBuilder, to GRCoreEngine, and
eventually to GRExprEngine.
The addition of CFGElement is also useful for when we want to handle
more control-flow constructs or other data we want to keep in the CFG
that isn't represented well with just a block of statements.
In GRExprEngine, this patch introduces logic for evaluating the
lvalues of references, which currently retrieves the internal "pointer
value" that the reference represents. EvalLoad does a two stage load
to catch null dereferences involving an invalid reference (although
this could possibly be caught earlier during the initialization of a
reference).
Symbols are currently symbolicated using the reference type, instead
of a pointer type, and special handling is required creating
ElementRegions that layer on SymbolicRegions (see the changes to
RegionStoreManager).
Along the way, the DeadStoresChecker also silences warnings involving
dead stores to references. This was the original change I introduced
(which I wrote test cases for) that I realized caused GRExprEngine to
crash.
llvm-svn: 91501
- Refactor the MemRegion hierarchy to distinguish between different StackSpaceRegions for locals and parameters.
- VarRegions for "captured" variables now have the BlockDataRegion as their super region (except those passed by reference)
- Add transfer function support to GRExprEngine for BlockDeclRefExprs.
This change also supports analyzing blocks as an analysis entry point
(top-of-the-stack), which required pushing more context-sensitivity
around in the MemRegion hierarchy via the use of LocationContext
objects. Functionally almost everything is the same, except we track
LocationContexts in a few more areas and StackSpaceRegions now refer
to a StackFrameContext object. In the future we will need to modify
MemRegionManager to allow multiple StackSpaceRegions in flight at once
(for the analysis of multiple stack frames).
llvm-svn: 90809
'BlockDataRegion' to distinguish between the code associated with a
block (which is represented by 'BlockTextRegion') and an instance of a
block, which includes both code and data. 'BlockDataRegion' has an
associated LocationContext, which can be used to eventually model the
lifetime of a block object once LocationContexts can represent scopes
(and iterations around a loop, etc.).
llvm-svn: 89900
* Add a load type to GRExprEngine::EvalLoad().
* When retrieve from 'theValue' of OSAtomic funcitions, use the type of the
region instead of the argument expression as the load type.
* Then we can convert CastRetrievedSVal to a pure assertion. In the future
we can let all Retrieve() methods simply return SVal.
llvm-svn: 88888
ArrayType>()) does not instantiate. Update all callers that used this
unsafe feature to use the appropriate ASTContext::getAs*ArrayType method.
llvm-svn: 86596
by Zhongxing Xu. RemoveDeadBindings() would falsely prune
SymbolicRegions from the store that wrapped derived symbols whose
liveness could only be determined after scanning the store.
llvm-svn: 85484
RegionStoreManager::Retrieve() that was intended to handle conflated uses of pointers as integers.
It turns out this isn't needed, and resulted in inconsistent behavior when creating symbolic values on the following test case in 'tests/Analysis/misc-ps.m':
typedef struct _BStruct { void *grue; } BStruct;
void testB_aux(void *ptr);
void testB(BStruct *b) {
{
int *__gruep__ = ((int *)&((b)->grue));
int __gruev__ = *__gruep__;
testB_aux(__gruep__);
}
{
int *__gruep__ = ((int *)&((b)->grue));
int __gruev__ = *__gruep__;
if (~0 != __gruev__) {}
}
}
When the code was analyzed with '-arch x86_64', the value assigned to '__gruev__' be would be a
symbolic integer, but for '-arch i386' the value assigned to '__gruev__' would be a symbolic region
(a blob of memory). With this change the value created is always a symbolic integer.
Since the code being removed was added to support analysis of code calling
OSAtomicCompareAndSwapXXX(), I also modified 'test/Analysis/NSString.m' to analyze the code in both
'-arch i386' and '-arch x86_64', and also added some complementary test cases to test the presence
of leaks when using OSAtomicCompareAndSwap32Barrier()/OSAtomicCompareAndSwap64Barrier() instead of
just their absence. This code change reveals that previously both RegionStore and BasicStore were
handling these cases wrong, and would never cause the analyzer to emit a leak in these cases (false
negatives). Now RegionStore gets it right, but BasicStore still gets it wrong (and hence it has been
disabled temporarily for this test case).
llvm-svn: 84163
default binding for regions. This allows us to simply a lot of code. A
further simplification could be done is that many methods of
regionstore can only work on Store instead of GRState.
llvm-svn: 83762
adding assert
This fix required a few changes:
SimpleSValuator:
- Eagerly replace a symbolic value with its constant value in EvalBinOpNN
when it is constrained to a constant. This allows us to better constant fold
values along a path.
- Handle trivial case of '<', '>' comparison of pointers when the two pointers
are exactly the same.
RegionStoreManager:
llvm-svn: 83358
concrete types. Use unqualified desugaring for getAs<> and sundry.
Fix a few users to either not desugar or use qualified desugar, as seemed
appropriate. Removed Type's qualified desugar method, as it was easy
to accidentally use instead of QualType's.
llvm-svn: 83116
identified with a false positive reported by Thomas Clement. This
involved doing another rewrite of
RegionStoreManager::RemoveDeadBindings(), which phrases the entire
problem of scanning for dead regions as a graph exploration problem.
It is more methodic than the previous implementation.
llvm-svn: 83053
are only specially treated by RegionStore::InvalidateRegion() when
their super region is also invalidated. When this isn't the case,
conjure a new symbol for a FieldRegion. Thanks to Zhongxing Xu and
Daniel Dunbar for pointing out this issue.
llvm-svn: 83043
<rdar://problem/6914474> checker doesn't realize that variable might
have been assigned if a pointer to that variable was passed to another
function via a structure
The problem here was the RegionStoreManager::InvalidateRegion didn't
invalidate the bindings of invalidated regions. This required a
rewrite of this method using a worklist.
As part of this fix, changed ValueManager::getConjuredSymbolVal() to
require a 'void*' SymbolTag argument. This tag is used to
differentiate two different symbols created at the same location.
llvm-svn: 82920
The issue was a discrepancy between how RegionStoreManager::Bind() and
RegionStoreManager::Retrieve() derived the "key" for the first element
of a symbolic region.
llvm-svn: 82680
Zhongxing Xu