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[FlowSensitive] [StatusOr] [6/N] support pointer comparison #164856

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Merged
merged 1 commit into from
Oct 23, 2025
Merged

[FlowSensitive] [StatusOr] [6/N] support pointer comparison #164856

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75 changes: 75 additions & 0 deletions clang/lib/Analysis/FlowSensitive/Models/UncheckedStatusOrAccessModel.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -168,6 +168,15 @@ static auto isNotOkStatusCall() {
"::absl::UnimplementedError", "::absl::UnknownError"))));
}

static auto isPointerComparisonOperatorCall(std::string operator_name) {
using namespace ::clang::ast_matchers; // NOLINT: Too many names
return binaryOperator(hasOperatorName(operator_name),
hasLHS(hasType(hasCanonicalType(pointerType(
pointee(anyOf(statusOrType(), statusType())))))),
hasRHS(hasType(hasCanonicalType(pointerType(
pointee(anyOf(statusOrType(), statusType())))))));
}

static auto
buildDiagnoseMatchSwitch(const UncheckedStatusOrAccessModelOptions &Options) {
return CFGMatchSwitchBuilder<const Environment,
Expand Down Expand Up @@ -438,6 +447,58 @@ static void transferComparisonOperator(const CXXOperatorCallExpr *Expr,
State.Env.setValue(*Expr, *LhsAndRhsVal);
}

static RecordStorageLocation *getPointeeLocation(const Expr &Expr,
Environment &Env) {
if (auto *PointerVal = Env.get<PointerValue>(Expr))
return dyn_cast<RecordStorageLocation>(&PointerVal->getPointeeLoc());
return nullptr;
}

static BoolValue *evaluatePointerEquality(const Expr *LhsExpr,
const Expr *RhsExpr,
Environment &Env) {
assert(LhsExpr->getType()->isPointerType());
assert(RhsExpr->getType()->isPointerType());
RecordStorageLocation *LhsStatusLoc = nullptr;
RecordStorageLocation *RhsStatusLoc = nullptr;
if (isStatusOrType(LhsExpr->getType()->getPointeeType()) &&
isStatusOrType(RhsExpr->getType()->getPointeeType())) {
auto *LhsStatusOrLoc = getPointeeLocation(*LhsExpr, Env);
auto *RhsStatusOrLoc = getPointeeLocation(*RhsExpr, Env);
if (LhsStatusOrLoc == nullptr || RhsStatusOrLoc == nullptr)
return nullptr;
LhsStatusLoc = &locForStatus(*LhsStatusOrLoc);
RhsStatusLoc = &locForStatus(*RhsStatusOrLoc);
} else if (isStatusType(LhsExpr->getType()->getPointeeType()) &&
isStatusType(RhsExpr->getType()->getPointeeType())) {
LhsStatusLoc = getPointeeLocation(*LhsExpr, Env);
RhsStatusLoc = getPointeeLocation(*RhsExpr, Env);
}
if (LhsStatusLoc == nullptr || RhsStatusLoc == nullptr)
return nullptr;
auto &LhsOkVal = valForOk(*LhsStatusLoc, Env);
auto &RhsOkVal = valForOk(*RhsStatusLoc, Env);
auto &Res = Env.makeAtomicBoolValue();
auto &A = Env.arena();
Env.assume(A.makeImplies(
Res.formula(), A.makeEquals(LhsOkVal.formula(), RhsOkVal.formula())));
return &Res;
}

static void transferPointerComparisonOperator(const BinaryOperator *Expr,
LatticeTransferState &State,
bool IsNegative) {
auto *LhsAndRhsVal =
evaluatePointerEquality(Expr->getLHS(), Expr->getRHS(), State.Env);
if (LhsAndRhsVal == nullptr)
return;

if (IsNegative)
State.Env.setValue(*Expr, State.Env.makeNot(*LhsAndRhsVal));
else
State.Env.setValue(*Expr, *LhsAndRhsVal);
}

static void transferOkStatusCall(const CallExpr *Expr,
const MatchFinder::MatchResult &,
LatticeTransferState &State) {
Expand Down Expand Up @@ -482,6 +543,20 @@ buildTransferMatchSwitch(ASTContext &Ctx,
transferComparisonOperator(Expr, State,
/*IsNegative=*/true);
})
.CaseOfCFGStmt<BinaryOperator>(
isPointerComparisonOperatorCall("=="),
[](const BinaryOperator *Expr, const MatchFinder::MatchResult &,
LatticeTransferState &State) {
transferPointerComparisonOperator(Expr, State,
/*IsNegative=*/false);
})
.CaseOfCFGStmt<BinaryOperator>(
isPointerComparisonOperatorCall("!="),
[](const BinaryOperator *Expr, const MatchFinder::MatchResult &,
LatticeTransferState &State) {
transferPointerComparisonOperator(Expr, State,
/*IsNegative=*/true);
})
.CaseOfCFGStmt<CallExpr>(isOkStatusCall(), transferOkStatusCall)
.CaseOfCFGStmt<CallExpr>(isNotOkStatusCall(), transferNotOkStatusCall)
.Build();
Expand Down
57 changes: 57 additions & 0 deletions clang/unittests/Analysis/FlowSensitive/UncheckedStatusOrAccessModelTestFixture.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2871,6 +2871,63 @@ TEST_P(UncheckedStatusOrAccessModelTest, EqualityCheck) {
)cc");
}

TEST_P(UncheckedStatusOrAccessModelTest, PointerEqualityCheck) {
ExpectDiagnosticsFor(
R"cc(
#include "unchecked_statusor_access_test_defs.h"

void target(STATUSOR_INT* x, STATUSOR_INT* y) {
if (x->ok()) {
if (x == y)
y->value();
else
y->value(); // [[unsafe]]
}
}
)cc");
ExpectDiagnosticsFor(
R"cc(
#include "unchecked_statusor_access_test_defs.h"

void target(STATUSOR_INT* x, STATUSOR_INT* y) {
if (x->ok()) {
if (x != y)
y->value(); // [[unsafe]]
else
y->value();
}
}
)cc");
ExpectDiagnosticsFor(
R"cc(
#include "unchecked_statusor_access_test_defs.h"

void target(STATUS* x, STATUS* y) {
auto sor = Make<STATUSOR_INT>();
if (x->ok()) {
if (x == y && sor.status() == *y)
sor.value();
else
sor.value(); // [[unsafe]]
}
}
)cc");
ExpectDiagnosticsFor(
R"cc(
#include "unchecked_statusor_access_test_defs.h"

void target(STATUS* x, STATUS* y) {
auto sor = Make<STATUSOR_INT>();
if (x->ok()) {
if (x != y)
sor.value(); // [[unsafe]]
else if (sor.status() == *y)
sor.value();
}
}
)cc");
}

} // namespace

std::string
Expand Down
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