1 //===--- LoopWidening.cpp - Widen loops -------------------------*- 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 file contains functions which are used to widen loops. A loop may be 11 /// widened to approximate the exit state(s), without analyzing every 12 /// iteration. The widening is done by invalidating anything which might be 13 /// modified by the body of the loop. 14 /// 15 //===----------------------------------------------------------------------===// 16 17 #include "clang/StaticAnalyzer/Core/PathSensitive/LoopWidening.h" 18 19 using namespace clang; 20 using namespace ento; 21 22 /// Return the loops condition Stmt or NULL if LoopStmt is not a loop 23 static const Expr *getLoopCondition(const Stmt *LoopStmt) { 24 switch (LoopStmt->getStmtClass()) { 25 default: 26 return nullptr; 27 case Stmt::ForStmtClass: 28 return cast<ForStmt>(LoopStmt)->getCond(); 29 case Stmt::WhileStmtClass: 30 return cast<WhileStmt>(LoopStmt)->getCond(); 31 case Stmt::DoStmtClass: 32 return cast<DoStmt>(LoopStmt)->getCond(); 33 } 34 } 35 36 namespace clang { 37 namespace ento { 38 39 ProgramStateRef getWidenedLoopState(ProgramStateRef PrevState, 40 const LocationContext *LCtx, 41 unsigned BlockCount, const Stmt *LoopStmt) { 42 43 assert(isa<ForStmt>(LoopStmt) || isa<WhileStmt>(LoopStmt) || 44 isa<DoStmt>(LoopStmt)); 45 46 // Invalidate values in the current state. 47 // TODO Make this more conservative by only invalidating values that might 48 // be modified by the body of the loop. 49 // TODO Nested loops are currently widened as a result of the invalidation 50 // being so inprecise. When the invalidation is improved, the handling 51 // of nested loops will also need to be improved. 52 const StackFrameContext *STC = LCtx->getCurrentStackFrame(); 53 MemRegionManager &MRMgr = PrevState->getStateManager().getRegionManager(); 54 const MemRegion *Regions[] = {MRMgr.getStackLocalsRegion(STC), 55 MRMgr.getStackArgumentsRegion(STC), 56 MRMgr.getGlobalsRegion()}; 57 RegionAndSymbolInvalidationTraits ITraits; 58 for (auto *Region : Regions) { 59 ITraits.setTrait(Region, 60 RegionAndSymbolInvalidationTraits::TK_EntireMemSpace); 61 } 62 return PrevState->invalidateRegions(Regions, getLoopCondition(LoopStmt), 63 BlockCount, LCtx, true, nullptr, nullptr, 64 &ITraits); 65 } 66 67 } // end namespace ento 68 } // end namespace clang 69
