2946cd7010
to reflect the new license. We understand that people may be surprised that we're moving the header entirely to discuss the new license. We checked this carefully with the Foundation's lawyer and we believe this is the correct approach. Essentially, all code in the project is now made available by the LLVM project under our new license, so you will see that the license headers include that license only. Some of our contributors have contributed code under our old license, and accordingly, we have retained a copy of our old license notice in the top-level files in each project and repository. llvm-svn: 351636
100 lines
4.0 KiB
C++
100 lines
4.0 KiB
C++
//===--- LoopWidening.cpp - Widen loops -------------------------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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///
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/// This file contains functions which are used to widen loops. A loop may be
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/// widened to approximate the exit state(s), without analyzing every
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/// iteration. The widening is done by invalidating anything which might be
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/// modified by the body of the loop.
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///
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//===----------------------------------------------------------------------===//
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#include "clang/AST/AST.h"
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#include "clang/ASTMatchers/ASTMatchFinder.h"
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#include "clang/StaticAnalyzer/Core/PathSensitive/ExplodedGraph.h"
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#include "clang/StaticAnalyzer/Core/PathSensitive/LoopWidening.h"
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using namespace clang;
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using namespace ento;
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using namespace clang::ast_matchers;
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const auto MatchRef = "matchref";
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/// Return the loops condition Stmt or NULL if LoopStmt is not a loop
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static const Expr *getLoopCondition(const Stmt *LoopStmt) {
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switch (LoopStmt->getStmtClass()) {
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default:
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return nullptr;
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case Stmt::ForStmtClass:
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return cast<ForStmt>(LoopStmt)->getCond();
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case Stmt::WhileStmtClass:
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return cast<WhileStmt>(LoopStmt)->getCond();
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case Stmt::DoStmtClass:
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return cast<DoStmt>(LoopStmt)->getCond();
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}
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}
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namespace clang {
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namespace ento {
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ProgramStateRef getWidenedLoopState(ProgramStateRef PrevState,
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const LocationContext *LCtx,
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unsigned BlockCount, const Stmt *LoopStmt) {
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assert(isa<ForStmt>(LoopStmt) || isa<WhileStmt>(LoopStmt) ||
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isa<DoStmt>(LoopStmt));
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// Invalidate values in the current state.
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// TODO Make this more conservative by only invalidating values that might
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// be modified by the body of the loop.
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// TODO Nested loops are currently widened as a result of the invalidation
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// being so inprecise. When the invalidation is improved, the handling
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// of nested loops will also need to be improved.
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ASTContext &ASTCtx = LCtx->getAnalysisDeclContext()->getASTContext();
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const StackFrameContext *STC = LCtx->getStackFrame();
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MemRegionManager &MRMgr = PrevState->getStateManager().getRegionManager();
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const MemRegion *Regions[] = {MRMgr.getStackLocalsRegion(STC),
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MRMgr.getStackArgumentsRegion(STC),
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MRMgr.getGlobalsRegion()};
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RegionAndSymbolInvalidationTraits ITraits;
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for (auto *Region : Regions) {
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ITraits.setTrait(Region,
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RegionAndSymbolInvalidationTraits::TK_EntireMemSpace);
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}
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// References should not be invalidated.
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auto Matches = match(findAll(stmt(hasDescendant(varDecl(hasType(referenceType())).bind(MatchRef)))),
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*LCtx->getDecl()->getBody(), ASTCtx);
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for (BoundNodes Match : Matches) {
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const VarDecl *VD = Match.getNodeAs<VarDecl>(MatchRef);
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assert(VD);
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const VarRegion *VarMem = MRMgr.getVarRegion(VD, LCtx);
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ITraits.setTrait(VarMem,
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RegionAndSymbolInvalidationTraits::TK_PreserveContents);
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}
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// 'this' pointer is not an lvalue, we should not invalidate it. If the loop
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// is located in a method, constructor or destructor, the value of 'this'
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// pointer should remain unchanged. Ignore static methods, since they do not
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// have 'this' pointers.
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const CXXMethodDecl *CXXMD = dyn_cast<CXXMethodDecl>(STC->getDecl());
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if (CXXMD && !CXXMD->isStatic()) {
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const CXXThisRegion *ThisR =
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MRMgr.getCXXThisRegion(CXXMD->getThisType(), STC);
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ITraits.setTrait(ThisR,
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RegionAndSymbolInvalidationTraits::TK_PreserveContents);
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}
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return PrevState->invalidateRegions(Regions, getLoopCondition(LoopStmt),
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BlockCount, LCtx, true, nullptr, nullptr,
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&ITraits);
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}
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} // end namespace ento
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} // end namespace clang
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