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//=== AssumeModeling.cpp --------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This checker evaluates the builting assume functions.
// This checker also sinks execution paths leaving [[assume]] attributes with
// false assumptions.
//
//===----------------------------------------------------------------------===//
#include "clang/AST/AttrIterator.h"
#include "clang/Basic/Builtins.h"
#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
#include "clang/StaticAnalyzer/Core/Checker.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
#include "llvm/ADT/STLExtras.h"
using namespace clang;
using namespace ento;
namespace {
class AssumeModelingChecker
: public Checker<eval::Call, check::PostStmt<AttributedStmt>> {
public:
void checkPostStmt(const AttributedStmt *A, CheckerContext &C) const;
bool evalCall(const CallEvent &Call, CheckerContext &C) const;
};
} // namespace
void AssumeModelingChecker::checkPostStmt(const AttributedStmt *A,
CheckerContext &C) const {
if (!hasSpecificAttr<CXXAssumeAttr>(A->getAttrs()))
return;
for (const auto *Attr : getSpecificAttrs<CXXAssumeAttr>(A->getAttrs())) {
SVal AssumptionVal = C.getSVal(Attr->getAssumption());
// The assumption is not evaluated at all if it had sideffects; skip them.
if (AssumptionVal.isUnknown())
continue;
const auto *Assumption = AssumptionVal.getAsInteger();
if (Assumption && Assumption->isZero()) {
C.addSink();
}
}
}
bool AssumeModelingChecker::evalCall(const CallEvent &Call,
CheckerContext &C) const {
ProgramStateRef State = C.getState();
const auto *FD = dyn_cast_or_null<FunctionDecl>(Call.getDecl());
if (!FD)
return false;
if (!llvm::is_contained({Builtin::BI__builtin_assume, Builtin::BI__assume},
FD->getBuiltinID())) {
return false;
}
assert(Call.getNumArgs() > 0);
SVal Arg = Call.getArgSVal(0);
if (Arg.isUndef())
return true; // Return true to model purity.
State = State->assume(Arg.castAs<DefinedOrUnknownSVal>(), true);
if (!State) {
C.addSink();
return true;
}
C.addTransition(State);
return true;
}
void ento::registerAssumeModeling(CheckerManager &Mgr) {
Mgr.registerChecker<AssumeModelingChecker>();
}
bool ento::shouldRegisterAssumeModeling(const CheckerManager &) { return true; }
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