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//=== BuiltinFunctionChecker.cpp --------------------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This checker evaluates clang builtin functions.
//
//===----------------------------------------------------------------------===//
#include "ClangSACheckers.h"
#include "clang/StaticAnalyzer/Core/Checker.h"
#include "clang/StaticAnalyzer/Core/CheckerManager.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
#include "clang/Basic/Builtins.h"
using namespace clang;
using namespace ento;
namespace {
class BuiltinFunctionChecker : public Checker<eval::Call> {
public:
bool evalCall(const CallExpr *CE, CheckerContext &C) const;
};
}
bool BuiltinFunctionChecker::evalCall(const CallExpr *CE,
CheckerContext &C) const {
ProgramStateRef state = C.getState();
const FunctionDecl *FD = C.getCalleeDecl(CE);
const LocationContext *LCtx = C.getLocationContext();
if (!FD)
return false;
unsigned id = FD->getBuiltinID();
if (!id)
return false;
switch (id) {
case Builtin::BI__builtin_expect: {
// For __builtin_expect, just return the value of the subexpression.
assert (CE->arg_begin() != CE->arg_end());
SVal X = state->getSVal(*(CE->arg_begin()), LCtx);
C.addTransition(state->BindExpr(CE, LCtx, X));
return true;
}
case Builtin::BI__builtin_alloca: {
// FIXME: Refactor into StoreManager itself?
MemRegionManager& RM = C.getStoreManager().getRegionManager();
const AllocaRegion* R =
RM.getAllocaRegion(CE, C.getCurrentBlockCount(), C.getLocationContext());
// Set the extent of the region in bytes. This enables us to use the
// SVal of the argument directly. If we save the extent in bits, we
// cannot represent values like symbol*8.
DefinedOrUnknownSVal Size =
cast<DefinedOrUnknownSVal>(state->getSVal(*(CE->arg_begin()), LCtx));
SValBuilder& svalBuilder = C.getSValBuilder();
DefinedOrUnknownSVal Extent = R->getExtent(svalBuilder);
DefinedOrUnknownSVal extentMatchesSizeArg =
svalBuilder.evalEQ(state, Extent, Size);
state = state->assume(extentMatchesSizeArg, true);
C.addTransition(state->BindExpr(CE, LCtx, loc::MemRegionVal(R)));
return true;
}
}
return false;
}
void ento::registerBuiltinFunctionChecker(CheckerManager &mgr) {
mgr.registerChecker<BuiltinFunctionChecker>();
}
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