Coverage Report

Created: 2020-02-15 09:57

/Users/buildslave/jenkins/workspace/coverage/llvm-project/clang/lib/StaticAnalyzer/Core/LoopWidening.cpp
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//===--- 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()6
) {
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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