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/StaticAnalyzer/Core/Checker.h" 16 #include "clang/StaticAnalyzer/Core/CheckerManager.h" 17 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h" 18 #include "clang/Basic/Builtins.h" 19 20 using namespace clang; 21 using namespace ento; 22 23 namespace { 24 25 class BuiltinFunctionChecker : public Checker<eval::Call> { 26 public: 27 bool evalCall(const CallExpr *CE, CheckerContext &C) const; 28 }; 29 30 } 31 32 bool 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 // For __builtin_expect, just return the value of the subexpression. 48 assert (CE->arg_begin() != CE->arg_end()); 49 SVal X = state->getSVal(*(CE->arg_begin()), LCtx); 50 C.addTransition(state->BindExpr(CE, LCtx, X)); 51 return true; 52 } 53 54 case Builtin::BI__builtin_alloca: { 55 // FIXME: Refactor into StoreManager itself? 56 MemRegionManager& RM = C.getStoreManager().getRegionManager(); 57 const AllocaRegion* R = 58 RM.getAllocaRegion(CE, C.getCurrentBlockCount(), C.getLocationContext()); 59 60 // Set the extent of the region in bytes. This enables us to use the 61 // SVal of the argument directly. If we save the extent in bits, we 62 // cannot represent values like symbol*8. 63 DefinedOrUnknownSVal Size = 64 cast<DefinedOrUnknownSVal>(state->getSVal(*(CE->arg_begin()), LCtx)); 65 66 SValBuilder& svalBuilder = C.getSValBuilder(); 67 DefinedOrUnknownSVal Extent = R->getExtent(svalBuilder); 68 DefinedOrUnknownSVal extentMatchesSizeArg = 69 svalBuilder.evalEQ(state, Extent, Size); 70 state = state->assume(extentMatchesSizeArg, true); 71 72 C.addTransition(state->BindExpr(CE, LCtx, loc::MemRegionVal(R))); 73 return true; 74 } 75 } 76 77 return false; 78 } 79 80 void ento::registerBuiltinFunctionChecker(CheckerManager &mgr) { 81 mgr.registerChecker<BuiltinFunctionChecker>(); 82 } 83
