BuiltinFunctionChecker.cpp revision 7c0a8b560ae78b28d72bff8614b94ac05cb2b469
1//=== BuiltinFunctionChecker.cpp --------------------------------*- C++ -*-===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This checker evaluates clang builtin functions. 11// 12//===----------------------------------------------------------------------===// 13 14#include "ClangSACheckers.h" 15#include "clang/Basic/Builtins.h" 16#include "clang/StaticAnalyzer/Core/Checker.h" 17#include "clang/StaticAnalyzer/Core/CheckerManager.h" 18#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h" 19 20using namespace clang; 21using namespace ento; 22 23namespace { 24 25class BuiltinFunctionChecker : public Checker<eval::Call> { 26public: 27 bool evalCall(const CallExpr *CE, CheckerContext &C) const; 28}; 29 30} 31 32bool BuiltinFunctionChecker::evalCall(const CallExpr *CE, 33 CheckerContext &C) const { 34 ProgramStateRef state = C.getState(); 35 const FunctionDecl *FD = C.getCalleeDecl(CE); 36 const LocationContext *LCtx = C.getLocationContext(); 37 if (!FD) 38 return false; 39 40 unsigned id = FD->getBuiltinID(); 41 42 if (!id) 43 return false; 44 45 switch (id) { 46 case Builtin::BI__builtin_expect: 47 case Builtin::BI__builtin_addressof: { 48 // For __builtin_expect, just return the value of the subexpression. 49 // __builtin_addressof is going from a reference to a pointer, but those 50 // are represented the same way in the analyzer. 51 assert (CE->arg_begin() != CE->arg_end()); 52 SVal X = state->getSVal(*(CE->arg_begin()), LCtx); 53 C.addTransition(state->BindExpr(CE, LCtx, X)); 54 return true; 55 } 56 57 case Builtin::BI__builtin_alloca: { 58 // FIXME: Refactor into StoreManager itself? 59 MemRegionManager& RM = C.getStoreManager().getRegionManager(); 60 const AllocaRegion* R = 61 RM.getAllocaRegion(CE, C.blockCount(), C.getLocationContext()); 62 63 // Set the extent of the region in bytes. This enables us to use the 64 // SVal of the argument directly. If we save the extent in bits, we 65 // cannot represent values like symbol*8. 66 DefinedOrUnknownSVal Size = 67 state->getSVal(*(CE->arg_begin()), LCtx).castAs<DefinedOrUnknownSVal>(); 68 69 SValBuilder& svalBuilder = C.getSValBuilder(); 70 DefinedOrUnknownSVal Extent = R->getExtent(svalBuilder); 71 DefinedOrUnknownSVal extentMatchesSizeArg = 72 svalBuilder.evalEQ(state, Extent, Size); 73 state = state->assume(extentMatchesSizeArg, true); 74 assert(state && "The region should not have any previous constraints"); 75 76 C.addTransition(state->BindExpr(CE, LCtx, loc::MemRegionVal(R))); 77 return true; 78 } 79 } 80 81 return false; 82} 83 84void ento::registerBuiltinFunctionChecker(CheckerManager &mgr) { 85 mgr.registerChecker<BuiltinFunctionChecker>(); 86} 87