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Unpack pointer null state prior to comparison in modeling Abseil's CHECK_NE, in case it is Top #677

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Unpack pointer null state prior to comparison in modeling Abseil's CHECK_NE, in case it is Top #677

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2 changes: 1 addition & 1 deletion bazel/llvm.bzl
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Original file line number Diff line number Diff line change
Expand Up @@ -53,7 +53,7 @@ def _llvm_loader_repository(repository_ctx):
executable = False,
)

LLVM_COMMIT_SHA = "fdd62de9a5f3c92436f91fadedc7578e295c38da"
LLVM_COMMIT_SHA = "bf2e4585d248af8f9998bff8d252a2cc0bc77a37"

def llvm_loader_repository_dependencies():
# This *declares* the dependency, but it won't actually be *downloaded* unless it's used.
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21 changes: 21 additions & 0 deletions nullability/test/check_macros.cc
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Expand Up @@ -65,6 +65,27 @@ TEST void checkNERightSmartPointer(std::unique_ptr<int> P) {
nonnull(P);
}

// Test where a loop can result in Top pointer null states.
// Make sure we can still do a null check after the loop, despite the Top
// null state.
TEST void checkNEAfterLoop(int* _Nullable P, int Bound, bool B) {
int X = 17;
for (int I = 0; I < Bound; ++I) {
if (B) P = &X;
}
CHECK_NE(P, nullptr);
nonnull(P);
}

TEST void checkNEAfterLoopSmartPointer(_Nullable std::unique_ptr<int> P,
int Bound, bool B) {
for (int I = 0; I < Bound; ++I) {
if (B) P = std::make_unique<int>(17);
}
CHECK_NE(P, nullptr);
nonnull(P);
}

TEST void utilCheckNEImplModelEqualAndNull() {
int *P = nullptr;
// `P` is definitely equal to `nullptr`, so result is nonnull.
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12 changes: 11 additions & 1 deletion nullability/value_transferer.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -917,8 +917,18 @@ static void modelGetReferenceableValue(const CallExpr& CE, Environment& Env) {
if (!CE.isGLValue()) return;
assert(CE.getNumArgs() == 1);
assert(CE.getArg(0) != nullptr);
if (StorageLocation* Loc = Env.getStorageLocation(*CE.getArg(0)))
if (StorageLocation* Loc = Env.getStorageLocation(*CE.getArg(0))) {
Env.setStorageLocation(CE, *Loc);
// Normally, we do unpackPointerValue during an LValueToRValue conversion
// for raw pointers (smart pointers are already unpacked during
// ensureSmartPointerInitialized). Since the result of GetReferenceableValue
// is passed to a helper function (`CheckNE_Impl`), the LValueToRValue
// cast is in the separate function and not in the current function.
// Unpack as if the LValueToRValue happens in the current function.
if (isSupportedRawPointerType(CE.getArg(0)->getType())) {
unpackPointerValue(*Loc, Env);
}
}
}

// Models the Abseil-logging `CheckNE_Impl` function. Essentially, associates
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