419 lines
15 KiB
C++
419 lines
15 KiB
C++
// SValBuilder.cpp - Basic class for all SValBuilder implementations -*- C++ -*-
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file defines SValBuilder, the base class for all (complete) SValBuilder
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// implementations.
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//
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//===----------------------------------------------------------------------===//
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#include "clang/AST/ExprCXX.h"
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#include "clang/AST/DeclCXX.h"
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#include "clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h"
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#include "clang/StaticAnalyzer/Core/PathSensitive/SVals.h"
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#include "clang/StaticAnalyzer/Core/PathSensitive/SValBuilder.h"
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#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
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#include "clang/StaticAnalyzer/Core/PathSensitive/BasicValueFactory.h"
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using namespace clang;
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using namespace ento;
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//===----------------------------------------------------------------------===//
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// Basic SVal creation.
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//===----------------------------------------------------------------------===//
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void SValBuilder::anchor() { }
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DefinedOrUnknownSVal SValBuilder::makeZeroVal(QualType type) {
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if (Loc::isLocType(type))
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return makeNull();
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if (type->isIntegerType())
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return makeIntVal(0, type);
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// FIXME: Handle floats.
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// FIXME: Handle structs.
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return UnknownVal();
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}
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NonLoc SValBuilder::makeNonLoc(const SymExpr *lhs, BinaryOperator::Opcode op,
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const llvm::APSInt& rhs, QualType type) {
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// The Environment ensures we always get a persistent APSInt in
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// BasicValueFactory, so we don't need to get the APSInt from
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// BasicValueFactory again.
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assert(lhs);
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assert(!Loc::isLocType(type));
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return nonloc::SymbolVal(SymMgr.getSymIntExpr(lhs, op, rhs, type));
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}
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NonLoc SValBuilder::makeNonLoc(const llvm::APSInt& lhs,
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BinaryOperator::Opcode op, const SymExpr *rhs,
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QualType type) {
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assert(rhs);
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assert(!Loc::isLocType(type));
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return nonloc::SymbolVal(SymMgr.getIntSymExpr(lhs, op, rhs, type));
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}
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NonLoc SValBuilder::makeNonLoc(const SymExpr *lhs, BinaryOperator::Opcode op,
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const SymExpr *rhs, QualType type) {
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assert(lhs && rhs);
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assert(!Loc::isLocType(type));
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return nonloc::SymbolVal(SymMgr.getSymSymExpr(lhs, op, rhs, type));
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}
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NonLoc SValBuilder::makeNonLoc(const SymExpr *operand,
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QualType fromTy, QualType toTy) {
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assert(operand);
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assert(!Loc::isLocType(toTy));
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return nonloc::SymbolVal(SymMgr.getCastSymbol(operand, fromTy, toTy));
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}
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SVal SValBuilder::convertToArrayIndex(SVal val) {
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if (val.isUnknownOrUndef())
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return val;
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// Common case: we have an appropriately sized integer.
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if (nonloc::ConcreteInt* CI = dyn_cast<nonloc::ConcreteInt>(&val)) {
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const llvm::APSInt& I = CI->getValue();
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if (I.getBitWidth() == ArrayIndexWidth && I.isSigned())
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return val;
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}
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return evalCastFromNonLoc(cast<NonLoc>(val), ArrayIndexTy);
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}
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nonloc::ConcreteInt SValBuilder::makeBoolVal(const CXXBoolLiteralExpr *boolean){
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return makeTruthVal(boolean->getValue());
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}
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DefinedOrUnknownSVal
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SValBuilder::getRegionValueSymbolVal(const TypedValueRegion* region) {
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QualType T = region->getValueType();
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if (!SymbolManager::canSymbolicate(T))
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return UnknownVal();
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SymbolRef sym = SymMgr.getRegionValueSymbol(region);
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if (Loc::isLocType(T))
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return loc::MemRegionVal(MemMgr.getSymbolicRegion(sym));
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return nonloc::SymbolVal(sym);
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}
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DefinedOrUnknownSVal
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SValBuilder::getConjuredSymbolVal(const void *symbolTag,
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const Expr *expr,
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const LocationContext *LCtx,
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unsigned count) {
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QualType T = expr->getType();
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return getConjuredSymbolVal(symbolTag, expr, LCtx, T, count);
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}
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DefinedOrUnknownSVal
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SValBuilder::getConjuredSymbolVal(const void *symbolTag,
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const Expr *expr,
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const LocationContext *LCtx,
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QualType type,
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unsigned count) {
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if (!SymbolManager::canSymbolicate(type))
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return UnknownVal();
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SymbolRef sym = SymMgr.getConjuredSymbol(expr, LCtx, type, count, symbolTag);
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if (Loc::isLocType(type))
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return loc::MemRegionVal(MemMgr.getSymbolicRegion(sym));
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return nonloc::SymbolVal(sym);
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}
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DefinedOrUnknownSVal
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SValBuilder::getConjuredSymbolVal(const Stmt *stmt,
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const LocationContext *LCtx,
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QualType type,
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unsigned visitCount) {
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if (!SymbolManager::canSymbolicate(type))
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return UnknownVal();
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SymbolRef sym = SymMgr.getConjuredSymbol(stmt, LCtx, type, visitCount);
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if (Loc::isLocType(type))
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return loc::MemRegionVal(MemMgr.getSymbolicRegion(sym));
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return nonloc::SymbolVal(sym);
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}
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DefinedOrUnknownSVal
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SValBuilder::getConjuredHeapSymbolVal(const Expr *E,
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const LocationContext *LCtx,
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unsigned VisitCount) {
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QualType T = E->getType();
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assert(Loc::isLocType(T));
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assert(SymbolManager::canSymbolicate(T));
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SymbolRef sym = SymMgr.getConjuredSymbol(E, LCtx, T, VisitCount);
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return loc::MemRegionVal(MemMgr.getSymbolicHeapRegion(sym));
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}
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DefinedSVal SValBuilder::getMetadataSymbolVal(const void *symbolTag,
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const MemRegion *region,
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const Expr *expr, QualType type,
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unsigned count) {
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assert(SymbolManager::canSymbolicate(type) && "Invalid metadata symbol type");
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SymbolRef sym =
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SymMgr.getMetadataSymbol(region, expr, type, count, symbolTag);
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if (Loc::isLocType(type))
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return loc::MemRegionVal(MemMgr.getSymbolicRegion(sym));
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return nonloc::SymbolVal(sym);
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}
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DefinedOrUnknownSVal
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SValBuilder::getDerivedRegionValueSymbolVal(SymbolRef parentSymbol,
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const TypedValueRegion *region) {
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QualType T = region->getValueType();
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if (!SymbolManager::canSymbolicate(T))
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return UnknownVal();
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SymbolRef sym = SymMgr.getDerivedSymbol(parentSymbol, region);
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if (Loc::isLocType(T))
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return loc::MemRegionVal(MemMgr.getSymbolicRegion(sym));
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return nonloc::SymbolVal(sym);
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}
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DefinedSVal SValBuilder::getFunctionPointer(const FunctionDecl *func) {
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return loc::MemRegionVal(MemMgr.getFunctionTextRegion(func));
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}
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DefinedSVal SValBuilder::getBlockPointer(const BlockDecl *block,
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CanQualType locTy,
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const LocationContext *locContext) {
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const BlockTextRegion *BC =
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MemMgr.getBlockTextRegion(block, locTy, locContext->getAnalysisDeclContext());
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const BlockDataRegion *BD = MemMgr.getBlockDataRegion(BC, locContext);
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return loc::MemRegionVal(BD);
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}
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/// Return a memory region for the 'this' object reference.
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loc::MemRegionVal SValBuilder::getCXXThis(const CXXMethodDecl *D,
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const StackFrameContext *SFC) {
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return loc::MemRegionVal(getRegionManager().
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getCXXThisRegion(D->getThisType(getContext()), SFC));
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}
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/// Return a memory region for the 'this' object reference.
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loc::MemRegionVal SValBuilder::getCXXThis(const CXXRecordDecl *D,
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const StackFrameContext *SFC) {
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const Type *T = D->getTypeForDecl();
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QualType PT = getContext().getPointerType(QualType(T, 0));
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return loc::MemRegionVal(getRegionManager().getCXXThisRegion(PT, SFC));
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}
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//===----------------------------------------------------------------------===//
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SVal SValBuilder::makeSymExprValNN(ProgramStateRef State,
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BinaryOperator::Opcode Op,
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NonLoc LHS, NonLoc RHS,
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QualType ResultTy) {
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if (!State->isTainted(RHS) && !State->isTainted(LHS))
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return UnknownVal();
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const SymExpr *symLHS = LHS.getAsSymExpr();
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const SymExpr *symRHS = RHS.getAsSymExpr();
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// TODO: When the Max Complexity is reached, we should conjure a symbol
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// instead of generating an Unknown value and propagate the taint info to it.
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const unsigned MaxComp = 10000; // 100000 28X
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if (symLHS && symRHS &&
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(symLHS->computeComplexity() + symRHS->computeComplexity()) < MaxComp)
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return makeNonLoc(symLHS, Op, symRHS, ResultTy);
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if (symLHS && symLHS->computeComplexity() < MaxComp)
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if (const nonloc::ConcreteInt *rInt = dyn_cast<nonloc::ConcreteInt>(&RHS))
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return makeNonLoc(symLHS, Op, rInt->getValue(), ResultTy);
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if (symRHS && symRHS->computeComplexity() < MaxComp)
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if (const nonloc::ConcreteInt *lInt = dyn_cast<nonloc::ConcreteInt>(&LHS))
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return makeNonLoc(lInt->getValue(), Op, symRHS, ResultTy);
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return UnknownVal();
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}
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SVal SValBuilder::evalBinOp(ProgramStateRef state, BinaryOperator::Opcode op,
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SVal lhs, SVal rhs, QualType type) {
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if (lhs.isUndef() || rhs.isUndef())
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return UndefinedVal();
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if (lhs.isUnknown() || rhs.isUnknown())
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return UnknownVal();
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if (isa<Loc>(lhs)) {
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if (isa<Loc>(rhs))
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return evalBinOpLL(state, op, cast<Loc>(lhs), cast<Loc>(rhs), type);
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return evalBinOpLN(state, op, cast<Loc>(lhs), cast<NonLoc>(rhs), type);
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}
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if (isa<Loc>(rhs)) {
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// Support pointer arithmetic where the addend is on the left
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// and the pointer on the right.
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assert(op == BO_Add);
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// Commute the operands.
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return evalBinOpLN(state, op, cast<Loc>(rhs), cast<NonLoc>(lhs), type);
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}
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return evalBinOpNN(state, op, cast<NonLoc>(lhs), cast<NonLoc>(rhs), type);
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}
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DefinedOrUnknownSVal SValBuilder::evalEQ(ProgramStateRef state,
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DefinedOrUnknownSVal lhs,
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DefinedOrUnknownSVal rhs) {
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return cast<DefinedOrUnknownSVal>(evalBinOp(state, BO_EQ, lhs, rhs,
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Context.IntTy));
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}
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/// Recursively check if the pointer types are equal modulo const, volatile,
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/// and restrict qualifiers. Assumes the input types are canonical.
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/// TODO: This is based off of code in SemaCast; can we reuse it.
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static bool haveSimilarTypes(ASTContext &Context, QualType T1,
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QualType T2) {
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while (Context.UnwrapSimilarPointerTypes(T1, T2)) {
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Qualifiers Quals1, Quals2;
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T1 = Context.getUnqualifiedArrayType(T1, Quals1);
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T2 = Context.getUnqualifiedArrayType(T2, Quals2);
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// Make sure that non cvr-qualifiers the other qualifiers (e.g., address
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// spaces) are identical.
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Quals1.removeCVRQualifiers();
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Quals2.removeCVRQualifiers();
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if (Quals1 != Quals2)
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return false;
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}
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if (T1 != T2)
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return false;
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return true;
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}
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// FIXME: should rewrite according to the cast kind.
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SVal SValBuilder::evalCast(SVal val, QualType castTy, QualType originalTy) {
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castTy = Context.getCanonicalType(castTy);
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originalTy = Context.getCanonicalType(originalTy);
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if (val.isUnknownOrUndef() || castTy == originalTy)
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return val;
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// For const casts, just propagate the value.
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if (!castTy->isVariableArrayType() && !originalTy->isVariableArrayType())
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if (haveSimilarTypes(Context, Context.getPointerType(castTy),
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Context.getPointerType(originalTy)))
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return val;
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// Check for casts from pointers to integers.
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if (castTy->isIntegerType() && Loc::isLocType(originalTy))
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return evalCastFromLoc(cast<Loc>(val), castTy);
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// Check for casts from integers to pointers.
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if (Loc::isLocType(castTy) && originalTy->isIntegerType()) {
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if (nonloc::LocAsInteger *LV = dyn_cast<nonloc::LocAsInteger>(&val)) {
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if (const MemRegion *R = LV->getLoc().getAsRegion()) {
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StoreManager &storeMgr = StateMgr.getStoreManager();
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R = storeMgr.castRegion(R, castTy);
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return R ? SVal(loc::MemRegionVal(R)) : UnknownVal();
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}
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return LV->getLoc();
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}
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return dispatchCast(val, castTy);
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}
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// Just pass through function and block pointers.
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if (originalTy->isBlockPointerType() || originalTy->isFunctionPointerType()) {
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assert(Loc::isLocType(castTy));
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return val;
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}
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// Check for casts from array type to another type.
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if (originalTy->isArrayType()) {
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// We will always decay to a pointer.
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val = StateMgr.ArrayToPointer(cast<Loc>(val));
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// Are we casting from an array to a pointer? If so just pass on
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// the decayed value.
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if (castTy->isPointerType() || castTy->isReferenceType())
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return val;
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// Are we casting from an array to an integer? If so, cast the decayed
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// pointer value to an integer.
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assert(castTy->isIntegerType());
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// FIXME: Keep these here for now in case we decide soon that we
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// need the original decayed type.
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// QualType elemTy = cast<ArrayType>(originalTy)->getElementType();
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// QualType pointerTy = C.getPointerType(elemTy);
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return evalCastFromLoc(cast<Loc>(val), castTy);
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}
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// Check for casts from a region to a specific type.
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if (const MemRegion *R = val.getAsRegion()) {
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// Handle other casts of locations to integers.
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if (castTy->isIntegerType())
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return evalCastFromLoc(loc::MemRegionVal(R), castTy);
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// FIXME: We should handle the case where we strip off view layers to get
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// to a desugared type.
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if (!Loc::isLocType(castTy)) {
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// FIXME: There can be gross cases where one casts the result of a function
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// (that returns a pointer) to some other value that happens to fit
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// within that pointer value. We currently have no good way to
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// model such operations. When this happens, the underlying operation
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// is that the caller is reasoning about bits. Conceptually we are
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// layering a "view" of a location on top of those bits. Perhaps
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// we need to be more lazy about mutual possible views, even on an
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// SVal? This may be necessary for bit-level reasoning as well.
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return UnknownVal();
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}
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// We get a symbolic function pointer for a dereference of a function
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// pointer, but it is of function type. Example:
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// struct FPRec {
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// void (*my_func)(int * x);
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// };
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//
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// int bar(int x);
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//
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// int f1_a(struct FPRec* foo) {
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// int x;
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// (*foo->my_func)(&x);
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// return bar(x)+1; // no-warning
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// }
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assert(Loc::isLocType(originalTy) || originalTy->isFunctionType() ||
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originalTy->isBlockPointerType() || castTy->isReferenceType());
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StoreManager &storeMgr = StateMgr.getStoreManager();
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// Delegate to store manager to get the result of casting a region to a
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// different type. If the MemRegion* returned is NULL, this expression
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// Evaluates to UnknownVal.
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R = storeMgr.castRegion(R, castTy);
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return R ? SVal(loc::MemRegionVal(R)) : UnknownVal();
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}
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return dispatchCast(val, castTy);
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}
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