946 lines
34 KiB
C++
946 lines
34 KiB
C++
// SimpleSValBuilder.cpp - A basic SValBuilder -----------------------*- 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 SimpleSValBuilder, a basic implementation of SValBuilder.
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//
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//===----------------------------------------------------------------------===//
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#include "clang/StaticAnalyzer/Core/PathSensitive/SValBuilder.h"
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#include "clang/StaticAnalyzer/Core/PathSensitive/APSIntType.h"
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#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
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using namespace clang;
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using namespace ento;
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namespace {
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class SimpleSValBuilder : public SValBuilder {
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protected:
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SVal dispatchCast(SVal val, QualType castTy) override;
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SVal evalCastFromNonLoc(NonLoc val, QualType castTy) override;
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SVal evalCastFromLoc(Loc val, QualType castTy) override;
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public:
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SimpleSValBuilder(llvm::BumpPtrAllocator &alloc, ASTContext &context,
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ProgramStateManager &stateMgr)
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: SValBuilder(alloc, context, stateMgr) {}
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~SimpleSValBuilder() override {}
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SVal evalMinus(NonLoc val) override;
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SVal evalComplement(NonLoc val) override;
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SVal evalBinOpNN(ProgramStateRef state, BinaryOperator::Opcode op,
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NonLoc lhs, NonLoc rhs, QualType resultTy) override;
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SVal evalBinOpLL(ProgramStateRef state, BinaryOperator::Opcode op,
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Loc lhs, Loc rhs, QualType resultTy) override;
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SVal evalBinOpLN(ProgramStateRef state, BinaryOperator::Opcode op,
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Loc lhs, NonLoc rhs, QualType resultTy) override;
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/// getKnownValue - evaluates a given SVal. If the SVal has only one possible
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/// (integer) value, that value is returned. Otherwise, returns NULL.
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const llvm::APSInt *getKnownValue(ProgramStateRef state, SVal V) override;
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SVal MakeSymIntVal(const SymExpr *LHS, BinaryOperator::Opcode op,
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const llvm::APSInt &RHS, QualType resultTy);
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};
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} // end anonymous namespace
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SValBuilder *ento::createSimpleSValBuilder(llvm::BumpPtrAllocator &alloc,
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ASTContext &context,
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ProgramStateManager &stateMgr) {
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return new SimpleSValBuilder(alloc, context, stateMgr);
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}
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//===----------------------------------------------------------------------===//
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// Transfer function for Casts.
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//===----------------------------------------------------------------------===//
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SVal SimpleSValBuilder::dispatchCast(SVal Val, QualType CastTy) {
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assert(Val.getAs<Loc>() || Val.getAs<NonLoc>());
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return Val.getAs<Loc>() ? evalCastFromLoc(Val.castAs<Loc>(), CastTy)
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: evalCastFromNonLoc(Val.castAs<NonLoc>(), CastTy);
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}
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SVal SimpleSValBuilder::evalCastFromNonLoc(NonLoc val, QualType castTy) {
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bool isLocType = Loc::isLocType(castTy);
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if (Optional<nonloc::LocAsInteger> LI = val.getAs<nonloc::LocAsInteger>()) {
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if (isLocType)
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return LI->getLoc();
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// FIXME: Correctly support promotions/truncations.
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unsigned castSize = Context.getTypeSize(castTy);
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if (castSize == LI->getNumBits())
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return val;
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return makeLocAsInteger(LI->getLoc(), castSize);
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}
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if (const SymExpr *se = val.getAsSymbolicExpression()) {
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QualType T = Context.getCanonicalType(se->getType());
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// If types are the same or both are integers, ignore the cast.
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// FIXME: Remove this hack when we support symbolic truncation/extension.
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// HACK: If both castTy and T are integers, ignore the cast. This is
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// not a permanent solution. Eventually we want to precisely handle
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// extension/truncation of symbolic integers. This prevents us from losing
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// precision when we assign 'x = y' and 'y' is symbolic and x and y are
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// different integer types.
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if (haveSameType(T, castTy))
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return val;
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if (!isLocType)
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return makeNonLoc(se, T, castTy);
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return UnknownVal();
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}
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// If value is a non-integer constant, produce unknown.
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if (!val.getAs<nonloc::ConcreteInt>())
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return UnknownVal();
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// Handle casts to a boolean type.
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if (castTy->isBooleanType()) {
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bool b = val.castAs<nonloc::ConcreteInt>().getValue().getBoolValue();
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return makeTruthVal(b, castTy);
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}
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// Only handle casts from integers to integers - if val is an integer constant
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// being cast to a non-integer type, produce unknown.
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if (!isLocType && !castTy->isIntegralOrEnumerationType())
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return UnknownVal();
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llvm::APSInt i = val.castAs<nonloc::ConcreteInt>().getValue();
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BasicVals.getAPSIntType(castTy).apply(i);
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if (isLocType)
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return makeIntLocVal(i);
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else
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return makeIntVal(i);
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}
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SVal SimpleSValBuilder::evalCastFromLoc(Loc val, QualType castTy) {
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// Casts from pointers -> pointers, just return the lval.
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//
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// Casts from pointers -> references, just return the lval. These
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// can be introduced by the frontend for corner cases, e.g
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// casting from va_list* to __builtin_va_list&.
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//
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if (Loc::isLocType(castTy) || castTy->isReferenceType())
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return val;
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// FIXME: Handle transparent unions where a value can be "transparently"
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// lifted into a union type.
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if (castTy->isUnionType())
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return UnknownVal();
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// Casting a Loc to a bool will almost always be true,
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// unless this is a weak function or a symbolic region.
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if (castTy->isBooleanType()) {
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switch (val.getSubKind()) {
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case loc::MemRegionKind: {
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const MemRegion *R = val.castAs<loc::MemRegionVal>().getRegion();
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if (const FunctionTextRegion *FTR = dyn_cast<FunctionTextRegion>(R))
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if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(FTR->getDecl()))
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if (FD->isWeak())
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// FIXME: Currently we are using an extent symbol here,
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// because there are no generic region address metadata
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// symbols to use, only content metadata.
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return nonloc::SymbolVal(SymMgr.getExtentSymbol(FTR));
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if (const SymbolicRegion *SymR = R->getSymbolicBase())
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return nonloc::SymbolVal(SymR->getSymbol());
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// FALL-THROUGH
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}
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case loc::GotoLabelKind:
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// Labels and non-symbolic memory regions are always true.
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return makeTruthVal(true, castTy);
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}
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}
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if (castTy->isIntegralOrEnumerationType()) {
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unsigned BitWidth = Context.getTypeSize(castTy);
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if (!val.getAs<loc::ConcreteInt>())
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return makeLocAsInteger(val, BitWidth);
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llvm::APSInt i = val.castAs<loc::ConcreteInt>().getValue();
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BasicVals.getAPSIntType(castTy).apply(i);
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return makeIntVal(i);
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}
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// All other cases: return 'UnknownVal'. This includes casting pointers
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// to floats, which is probably badness it itself, but this is a good
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// intermediate solution until we do something better.
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return UnknownVal();
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}
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//===----------------------------------------------------------------------===//
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// Transfer function for unary operators.
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//===----------------------------------------------------------------------===//
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SVal SimpleSValBuilder::evalMinus(NonLoc val) {
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switch (val.getSubKind()) {
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case nonloc::ConcreteIntKind:
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return val.castAs<nonloc::ConcreteInt>().evalMinus(*this);
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default:
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return UnknownVal();
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}
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}
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SVal SimpleSValBuilder::evalComplement(NonLoc X) {
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switch (X.getSubKind()) {
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case nonloc::ConcreteIntKind:
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return X.castAs<nonloc::ConcreteInt>().evalComplement(*this);
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default:
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return UnknownVal();
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}
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}
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//===----------------------------------------------------------------------===//
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// Transfer function for binary operators.
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//===----------------------------------------------------------------------===//
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SVal SimpleSValBuilder::MakeSymIntVal(const SymExpr *LHS,
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BinaryOperator::Opcode op,
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const llvm::APSInt &RHS,
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QualType resultTy) {
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bool isIdempotent = false;
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// Check for a few special cases with known reductions first.
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switch (op) {
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default:
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// We can't reduce this case; just treat it normally.
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break;
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case BO_Mul:
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// a*0 and a*1
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if (RHS == 0)
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return makeIntVal(0, resultTy);
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else if (RHS == 1)
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isIdempotent = true;
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break;
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case BO_Div:
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// a/0 and a/1
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if (RHS == 0)
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// This is also handled elsewhere.
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return UndefinedVal();
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else if (RHS == 1)
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isIdempotent = true;
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break;
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case BO_Rem:
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// a%0 and a%1
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if (RHS == 0)
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// This is also handled elsewhere.
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return UndefinedVal();
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else if (RHS == 1)
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return makeIntVal(0, resultTy);
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break;
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case BO_Add:
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case BO_Sub:
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case BO_Shl:
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case BO_Shr:
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case BO_Xor:
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// a+0, a-0, a<<0, a>>0, a^0
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if (RHS == 0)
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isIdempotent = true;
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break;
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case BO_And:
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// a&0 and a&(~0)
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if (RHS == 0)
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return makeIntVal(0, resultTy);
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else if (RHS.isAllOnesValue())
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isIdempotent = true;
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break;
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case BO_Or:
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// a|0 and a|(~0)
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if (RHS == 0)
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isIdempotent = true;
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else if (RHS.isAllOnesValue()) {
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const llvm::APSInt &Result = BasicVals.Convert(resultTy, RHS);
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return nonloc::ConcreteInt(Result);
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}
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break;
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}
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// Idempotent ops (like a*1) can still change the type of an expression.
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// Wrap the LHS up in a NonLoc again and let evalCastFromNonLoc do the
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// dirty work.
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if (isIdempotent)
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return evalCastFromNonLoc(nonloc::SymbolVal(LHS), resultTy);
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// If we reach this point, the expression cannot be simplified.
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// Make a SymbolVal for the entire expression, after converting the RHS.
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const llvm::APSInt *ConvertedRHS = &RHS;
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if (BinaryOperator::isComparisonOp(op)) {
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// We're looking for a type big enough to compare the symbolic value
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// with the given constant.
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// FIXME: This is an approximation of Sema::UsualArithmeticConversions.
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ASTContext &Ctx = getContext();
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QualType SymbolType = LHS->getType();
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uint64_t ValWidth = RHS.getBitWidth();
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uint64_t TypeWidth = Ctx.getTypeSize(SymbolType);
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if (ValWidth < TypeWidth) {
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// If the value is too small, extend it.
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ConvertedRHS = &BasicVals.Convert(SymbolType, RHS);
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} else if (ValWidth == TypeWidth) {
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// If the value is signed but the symbol is unsigned, do the comparison
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// in unsigned space. [C99 6.3.1.8]
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// (For the opposite case, the value is already unsigned.)
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if (RHS.isSigned() && !SymbolType->isSignedIntegerOrEnumerationType())
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ConvertedRHS = &BasicVals.Convert(SymbolType, RHS);
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}
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} else
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ConvertedRHS = &BasicVals.Convert(resultTy, RHS);
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return makeNonLoc(LHS, op, *ConvertedRHS, resultTy);
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}
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SVal SimpleSValBuilder::evalBinOpNN(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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NonLoc InputLHS = lhs;
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NonLoc InputRHS = rhs;
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// Handle trivial case where left-side and right-side are the same.
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if (lhs == rhs)
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switch (op) {
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default:
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break;
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case BO_EQ:
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case BO_LE:
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case BO_GE:
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return makeTruthVal(true, resultTy);
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case BO_LT:
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case BO_GT:
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case BO_NE:
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return makeTruthVal(false, resultTy);
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case BO_Xor:
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case BO_Sub:
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if (resultTy->isIntegralOrEnumerationType())
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return makeIntVal(0, resultTy);
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return evalCastFromNonLoc(makeIntVal(0, /*Unsigned=*/false), resultTy);
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case BO_Or:
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case BO_And:
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return evalCastFromNonLoc(lhs, resultTy);
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}
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while (1) {
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switch (lhs.getSubKind()) {
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default:
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return makeSymExprValNN(state, op, lhs, rhs, resultTy);
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case nonloc::LocAsIntegerKind: {
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Loc lhsL = lhs.castAs<nonloc::LocAsInteger>().getLoc();
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switch (rhs.getSubKind()) {
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case nonloc::LocAsIntegerKind:
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return evalBinOpLL(state, op, lhsL,
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rhs.castAs<nonloc::LocAsInteger>().getLoc(),
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resultTy);
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case nonloc::ConcreteIntKind: {
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// Transform the integer into a location and compare.
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llvm::APSInt i = rhs.castAs<nonloc::ConcreteInt>().getValue();
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BasicVals.getAPSIntType(Context.VoidPtrTy).apply(i);
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return evalBinOpLL(state, op, lhsL, makeLoc(i), resultTy);
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}
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default:
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switch (op) {
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case BO_EQ:
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return makeTruthVal(false, resultTy);
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case BO_NE:
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return makeTruthVal(true, resultTy);
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default:
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// This case also handles pointer arithmetic.
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return makeSymExprValNN(state, op, InputLHS, InputRHS, resultTy);
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}
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}
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}
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case nonloc::ConcreteIntKind: {
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llvm::APSInt LHSValue = lhs.castAs<nonloc::ConcreteInt>().getValue();
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// If we're dealing with two known constants, just perform the operation.
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if (const llvm::APSInt *KnownRHSValue = getKnownValue(state, rhs)) {
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llvm::APSInt RHSValue = *KnownRHSValue;
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if (BinaryOperator::isComparisonOp(op)) {
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// We're looking for a type big enough to compare the two values.
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// FIXME: This is not correct. char + short will result in a promotion
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// to int. Unfortunately we have lost types by this point.
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APSIntType CompareType = std::max(APSIntType(LHSValue),
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APSIntType(RHSValue));
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CompareType.apply(LHSValue);
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CompareType.apply(RHSValue);
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} else if (!BinaryOperator::isShiftOp(op)) {
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APSIntType IntType = BasicVals.getAPSIntType(resultTy);
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IntType.apply(LHSValue);
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IntType.apply(RHSValue);
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}
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const llvm::APSInt *Result =
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BasicVals.evalAPSInt(op, LHSValue, RHSValue);
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if (!Result)
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return UndefinedVal();
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return nonloc::ConcreteInt(*Result);
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}
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// Swap the left and right sides and flip the operator if doing so
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// allows us to better reason about the expression (this is a form
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// of expression canonicalization).
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// While we're at it, catch some special cases for non-commutative ops.
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switch (op) {
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case BO_LT:
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case BO_GT:
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case BO_LE:
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case BO_GE:
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op = BinaryOperator::reverseComparisonOp(op);
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// FALL-THROUGH
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case BO_EQ:
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case BO_NE:
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case BO_Add:
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case BO_Mul:
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case BO_And:
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case BO_Xor:
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case BO_Or:
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std::swap(lhs, rhs);
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continue;
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case BO_Shr:
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// (~0)>>a
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if (LHSValue.isAllOnesValue() && LHSValue.isSigned())
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return evalCastFromNonLoc(lhs, resultTy);
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// FALL-THROUGH
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case BO_Shl:
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// 0<<a and 0>>a
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if (LHSValue == 0)
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return evalCastFromNonLoc(lhs, resultTy);
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return makeSymExprValNN(state, op, InputLHS, InputRHS, resultTy);
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default:
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return makeSymExprValNN(state, op, InputLHS, InputRHS, resultTy);
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}
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}
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case nonloc::SymbolValKind: {
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// We only handle LHS as simple symbols or SymIntExprs.
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SymbolRef Sym = lhs.castAs<nonloc::SymbolVal>().getSymbol();
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// LHS is a symbolic expression.
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if (const SymIntExpr *symIntExpr = dyn_cast<SymIntExpr>(Sym)) {
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// Is this a logical not? (!x is represented as x == 0.)
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if (op == BO_EQ && rhs.isZeroConstant()) {
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// We know how to negate certain expressions. Simplify them here.
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BinaryOperator::Opcode opc = symIntExpr->getOpcode();
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switch (opc) {
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default:
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// We don't know how to negate this operation.
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// Just handle it as if it were a normal comparison to 0.
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break;
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case BO_LAnd:
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case BO_LOr:
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llvm_unreachable("Logical operators handled by branching logic.");
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case BO_Assign:
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case BO_MulAssign:
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case BO_DivAssign:
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case BO_RemAssign:
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case BO_AddAssign:
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case BO_SubAssign:
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case BO_ShlAssign:
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case BO_ShrAssign:
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case BO_AndAssign:
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case BO_XorAssign:
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case BO_OrAssign:
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case BO_Comma:
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llvm_unreachable("'=' and ',' operators handled by ExprEngine.");
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case BO_PtrMemD:
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case BO_PtrMemI:
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llvm_unreachable("Pointer arithmetic not handled here.");
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case BO_LT:
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case BO_GT:
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case BO_LE:
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case BO_GE:
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case BO_EQ:
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case BO_NE:
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assert(resultTy->isBooleanType() ||
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resultTy == getConditionType());
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assert(symIntExpr->getType()->isBooleanType() ||
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getContext().hasSameUnqualifiedType(symIntExpr->getType(),
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getConditionType()));
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// Negate the comparison and make a value.
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opc = BinaryOperator::negateComparisonOp(opc);
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return makeNonLoc(symIntExpr->getLHS(), opc,
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symIntExpr->getRHS(), resultTy);
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}
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}
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// For now, only handle expressions whose RHS is a constant.
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if (const llvm::APSInt *RHSValue = getKnownValue(state, rhs)) {
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// If both the LHS and the current expression are additive,
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// fold their constants and try again.
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if (BinaryOperator::isAdditiveOp(op)) {
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BinaryOperator::Opcode lop = symIntExpr->getOpcode();
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if (BinaryOperator::isAdditiveOp(lop)) {
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// Convert the two constants to a common type, then combine them.
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// resultTy may not be the best type to convert to, but it's
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// probably the best choice in expressions with mixed type
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// (such as x+1U+2LL). The rules for implicit conversions should
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|
// choose a reasonable type to preserve the expression, and will
|
|
// at least match how the value is going to be used.
|
|
APSIntType IntType = BasicVals.getAPSIntType(resultTy);
|
|
const llvm::APSInt &first = IntType.convert(symIntExpr->getRHS());
|
|
const llvm::APSInt &second = IntType.convert(*RHSValue);
|
|
|
|
const llvm::APSInt *newRHS;
|
|
if (lop == op)
|
|
newRHS = BasicVals.evalAPSInt(BO_Add, first, second);
|
|
else
|
|
newRHS = BasicVals.evalAPSInt(BO_Sub, first, second);
|
|
|
|
assert(newRHS && "Invalid operation despite common type!");
|
|
rhs = nonloc::ConcreteInt(*newRHS);
|
|
lhs = nonloc::SymbolVal(symIntExpr->getLHS());
|
|
op = lop;
|
|
continue;
|
|
}
|
|
}
|
|
|
|
// Otherwise, make a SymIntExpr out of the expression.
|
|
return MakeSymIntVal(symIntExpr, op, *RHSValue, resultTy);
|
|
}
|
|
}
|
|
|
|
// Does the symbolic expression simplify to a constant?
|
|
// If so, "fold" the constant by setting 'lhs' to a ConcreteInt
|
|
// and try again.
|
|
ConstraintManager &CMgr = state->getConstraintManager();
|
|
if (const llvm::APSInt *Constant = CMgr.getSymVal(state, Sym)) {
|
|
lhs = nonloc::ConcreteInt(*Constant);
|
|
continue;
|
|
}
|
|
|
|
// Is the RHS a constant?
|
|
if (const llvm::APSInt *RHSValue = getKnownValue(state, rhs))
|
|
return MakeSymIntVal(Sym, op, *RHSValue, resultTy);
|
|
|
|
// Give up -- this is not a symbolic expression we can handle.
|
|
return makeSymExprValNN(state, op, InputLHS, InputRHS, resultTy);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
static SVal evalBinOpFieldRegionFieldRegion(const FieldRegion *LeftFR,
|
|
const FieldRegion *RightFR,
|
|
BinaryOperator::Opcode op,
|
|
QualType resultTy,
|
|
SimpleSValBuilder &SVB) {
|
|
// Only comparisons are meaningful here!
|
|
if (!BinaryOperator::isComparisonOp(op))
|
|
return UnknownVal();
|
|
|
|
// Next, see if the two FRs have the same super-region.
|
|
// FIXME: This doesn't handle casts yet, and simply stripping the casts
|
|
// doesn't help.
|
|
if (LeftFR->getSuperRegion() != RightFR->getSuperRegion())
|
|
return UnknownVal();
|
|
|
|
const FieldDecl *LeftFD = LeftFR->getDecl();
|
|
const FieldDecl *RightFD = RightFR->getDecl();
|
|
const RecordDecl *RD = LeftFD->getParent();
|
|
|
|
// Make sure the two FRs are from the same kind of record. Just in case!
|
|
// FIXME: This is probably where inheritance would be a problem.
|
|
if (RD != RightFD->getParent())
|
|
return UnknownVal();
|
|
|
|
// We know for sure that the two fields are not the same, since that
|
|
// would have given us the same SVal.
|
|
if (op == BO_EQ)
|
|
return SVB.makeTruthVal(false, resultTy);
|
|
if (op == BO_NE)
|
|
return SVB.makeTruthVal(true, resultTy);
|
|
|
|
// Iterate through the fields and see which one comes first.
|
|
// [C99 6.7.2.1.13] "Within a structure object, the non-bit-field
|
|
// members and the units in which bit-fields reside have addresses that
|
|
// increase in the order in which they are declared."
|
|
bool leftFirst = (op == BO_LT || op == BO_LE);
|
|
for (const auto *I : RD->fields()) {
|
|
if (I == LeftFD)
|
|
return SVB.makeTruthVal(leftFirst, resultTy);
|
|
if (I == RightFD)
|
|
return SVB.makeTruthVal(!leftFirst, resultTy);
|
|
}
|
|
|
|
llvm_unreachable("Fields not found in parent record's definition");
|
|
}
|
|
|
|
// FIXME: all this logic will change if/when we have MemRegion::getLocation().
|
|
SVal SimpleSValBuilder::evalBinOpLL(ProgramStateRef state,
|
|
BinaryOperator::Opcode op,
|
|
Loc lhs, Loc rhs,
|
|
QualType resultTy) {
|
|
// Only comparisons and subtractions are valid operations on two pointers.
|
|
// See [C99 6.5.5 through 6.5.14] or [C++0x 5.6 through 5.15].
|
|
// However, if a pointer is casted to an integer, evalBinOpNN may end up
|
|
// calling this function with another operation (PR7527). We don't attempt to
|
|
// model this for now, but it could be useful, particularly when the
|
|
// "location" is actually an integer value that's been passed through a void*.
|
|
if (!(BinaryOperator::isComparisonOp(op) || op == BO_Sub))
|
|
return UnknownVal();
|
|
|
|
// Special cases for when both sides are identical.
|
|
if (lhs == rhs) {
|
|
switch (op) {
|
|
default:
|
|
llvm_unreachable("Unimplemented operation for two identical values");
|
|
case BO_Sub:
|
|
return makeZeroVal(resultTy);
|
|
case BO_EQ:
|
|
case BO_LE:
|
|
case BO_GE:
|
|
return makeTruthVal(true, resultTy);
|
|
case BO_NE:
|
|
case BO_LT:
|
|
case BO_GT:
|
|
return makeTruthVal(false, resultTy);
|
|
}
|
|
}
|
|
|
|
switch (lhs.getSubKind()) {
|
|
default:
|
|
llvm_unreachable("Ordering not implemented for this Loc.");
|
|
|
|
case loc::GotoLabelKind:
|
|
// The only thing we know about labels is that they're non-null.
|
|
if (rhs.isZeroConstant()) {
|
|
switch (op) {
|
|
default:
|
|
break;
|
|
case BO_Sub:
|
|
return evalCastFromLoc(lhs, resultTy);
|
|
case BO_EQ:
|
|
case BO_LE:
|
|
case BO_LT:
|
|
return makeTruthVal(false, resultTy);
|
|
case BO_NE:
|
|
case BO_GT:
|
|
case BO_GE:
|
|
return makeTruthVal(true, resultTy);
|
|
}
|
|
}
|
|
// There may be two labels for the same location, and a function region may
|
|
// have the same address as a label at the start of the function (depending
|
|
// on the ABI).
|
|
// FIXME: we can probably do a comparison against other MemRegions, though.
|
|
// FIXME: is there a way to tell if two labels refer to the same location?
|
|
return UnknownVal();
|
|
|
|
case loc::ConcreteIntKind: {
|
|
// If one of the operands is a symbol and the other is a constant,
|
|
// build an expression for use by the constraint manager.
|
|
if (SymbolRef rSym = rhs.getAsLocSymbol()) {
|
|
// We can only build expressions with symbols on the left,
|
|
// so we need a reversible operator.
|
|
if (!BinaryOperator::isComparisonOp(op))
|
|
return UnknownVal();
|
|
|
|
const llvm::APSInt &lVal = lhs.castAs<loc::ConcreteInt>().getValue();
|
|
op = BinaryOperator::reverseComparisonOp(op);
|
|
return makeNonLoc(rSym, op, lVal, resultTy);
|
|
}
|
|
|
|
// If both operands are constants, just perform the operation.
|
|
if (Optional<loc::ConcreteInt> rInt = rhs.getAs<loc::ConcreteInt>()) {
|
|
SVal ResultVal =
|
|
lhs.castAs<loc::ConcreteInt>().evalBinOp(BasicVals, op, *rInt);
|
|
if (Optional<NonLoc> Result = ResultVal.getAs<NonLoc>())
|
|
return evalCastFromNonLoc(*Result, resultTy);
|
|
|
|
assert(!ResultVal.getAs<Loc>() && "Loc-Loc ops should not produce Locs");
|
|
return UnknownVal();
|
|
}
|
|
|
|
// Special case comparisons against NULL.
|
|
// This must come after the test if the RHS is a symbol, which is used to
|
|
// build constraints. The address of any non-symbolic region is guaranteed
|
|
// to be non-NULL, as is any label.
|
|
assert(rhs.getAs<loc::MemRegionVal>() || rhs.getAs<loc::GotoLabel>());
|
|
if (lhs.isZeroConstant()) {
|
|
switch (op) {
|
|
default:
|
|
break;
|
|
case BO_EQ:
|
|
case BO_GT:
|
|
case BO_GE:
|
|
return makeTruthVal(false, resultTy);
|
|
case BO_NE:
|
|
case BO_LT:
|
|
case BO_LE:
|
|
return makeTruthVal(true, resultTy);
|
|
}
|
|
}
|
|
|
|
// Comparing an arbitrary integer to a region or label address is
|
|
// completely unknowable.
|
|
return UnknownVal();
|
|
}
|
|
case loc::MemRegionKind: {
|
|
if (Optional<loc::ConcreteInt> rInt = rhs.getAs<loc::ConcreteInt>()) {
|
|
// If one of the operands is a symbol and the other is a constant,
|
|
// build an expression for use by the constraint manager.
|
|
if (SymbolRef lSym = lhs.getAsLocSymbol(true))
|
|
return MakeSymIntVal(lSym, op, rInt->getValue(), resultTy);
|
|
|
|
// Special case comparisons to NULL.
|
|
// This must come after the test if the LHS is a symbol, which is used to
|
|
// build constraints. The address of any non-symbolic region is guaranteed
|
|
// to be non-NULL.
|
|
if (rInt->isZeroConstant()) {
|
|
if (op == BO_Sub)
|
|
return evalCastFromLoc(lhs, resultTy);
|
|
|
|
if (BinaryOperator::isComparisonOp(op)) {
|
|
QualType boolType = getContext().BoolTy;
|
|
NonLoc l = evalCastFromLoc(lhs, boolType).castAs<NonLoc>();
|
|
NonLoc r = makeTruthVal(false, boolType).castAs<NonLoc>();
|
|
return evalBinOpNN(state, op, l, r, resultTy);
|
|
}
|
|
}
|
|
|
|
// Comparing a region to an arbitrary integer is completely unknowable.
|
|
return UnknownVal();
|
|
}
|
|
|
|
// Get both values as regions, if possible.
|
|
const MemRegion *LeftMR = lhs.getAsRegion();
|
|
assert(LeftMR && "MemRegionKind SVal doesn't have a region!");
|
|
|
|
const MemRegion *RightMR = rhs.getAsRegion();
|
|
if (!RightMR)
|
|
// The RHS is probably a label, which in theory could address a region.
|
|
// FIXME: we can probably make a more useful statement about non-code
|
|
// regions, though.
|
|
return UnknownVal();
|
|
|
|
const MemRegion *LeftBase = LeftMR->getBaseRegion();
|
|
const MemRegion *RightBase = RightMR->getBaseRegion();
|
|
const MemSpaceRegion *LeftMS = LeftBase->getMemorySpace();
|
|
const MemSpaceRegion *RightMS = RightBase->getMemorySpace();
|
|
const MemSpaceRegion *UnknownMS = MemMgr.getUnknownRegion();
|
|
|
|
// If the two regions are from different known memory spaces they cannot be
|
|
// equal. Also, assume that no symbolic region (whose memory space is
|
|
// unknown) is on the stack.
|
|
if (LeftMS != RightMS &&
|
|
((LeftMS != UnknownMS && RightMS != UnknownMS) ||
|
|
(isa<StackSpaceRegion>(LeftMS) || isa<StackSpaceRegion>(RightMS)))) {
|
|
switch (op) {
|
|
default:
|
|
return UnknownVal();
|
|
case BO_EQ:
|
|
return makeTruthVal(false, resultTy);
|
|
case BO_NE:
|
|
return makeTruthVal(true, resultTy);
|
|
}
|
|
}
|
|
|
|
// If both values wrap regions, see if they're from different base regions.
|
|
// Note, heap base symbolic regions are assumed to not alias with
|
|
// each other; for example, we assume that malloc returns different address
|
|
// on each invocation.
|
|
if (LeftBase != RightBase &&
|
|
((!isa<SymbolicRegion>(LeftBase) && !isa<SymbolicRegion>(RightBase)) ||
|
|
(isa<HeapSpaceRegion>(LeftMS) || isa<HeapSpaceRegion>(RightMS))) ){
|
|
switch (op) {
|
|
default:
|
|
return UnknownVal();
|
|
case BO_EQ:
|
|
return makeTruthVal(false, resultTy);
|
|
case BO_NE:
|
|
return makeTruthVal(true, resultTy);
|
|
}
|
|
}
|
|
|
|
// Handle special cases for when both regions are element regions.
|
|
const ElementRegion *RightER = dyn_cast<ElementRegion>(RightMR);
|
|
const ElementRegion *LeftER = dyn_cast<ElementRegion>(LeftMR);
|
|
if (RightER && LeftER) {
|
|
// Next, see if the two ERs have the same super-region and matching types.
|
|
// FIXME: This should do something useful even if the types don't match,
|
|
// though if both indexes are constant the RegionRawOffset path will
|
|
// give the correct answer.
|
|
if (LeftER->getSuperRegion() == RightER->getSuperRegion() &&
|
|
LeftER->getElementType() == RightER->getElementType()) {
|
|
// Get the left index and cast it to the correct type.
|
|
// If the index is unknown or undefined, bail out here.
|
|
SVal LeftIndexVal = LeftER->getIndex();
|
|
Optional<NonLoc> LeftIndex = LeftIndexVal.getAs<NonLoc>();
|
|
if (!LeftIndex)
|
|
return UnknownVal();
|
|
LeftIndexVal = evalCastFromNonLoc(*LeftIndex, ArrayIndexTy);
|
|
LeftIndex = LeftIndexVal.getAs<NonLoc>();
|
|
if (!LeftIndex)
|
|
return UnknownVal();
|
|
|
|
// Do the same for the right index.
|
|
SVal RightIndexVal = RightER->getIndex();
|
|
Optional<NonLoc> RightIndex = RightIndexVal.getAs<NonLoc>();
|
|
if (!RightIndex)
|
|
return UnknownVal();
|
|
RightIndexVal = evalCastFromNonLoc(*RightIndex, ArrayIndexTy);
|
|
RightIndex = RightIndexVal.getAs<NonLoc>();
|
|
if (!RightIndex)
|
|
return UnknownVal();
|
|
|
|
// Actually perform the operation.
|
|
// evalBinOpNN expects the two indexes to already be the right type.
|
|
return evalBinOpNN(state, op, *LeftIndex, *RightIndex, resultTy);
|
|
}
|
|
}
|
|
|
|
// Special handling of the FieldRegions, even with symbolic offsets.
|
|
const FieldRegion *RightFR = dyn_cast<FieldRegion>(RightMR);
|
|
const FieldRegion *LeftFR = dyn_cast<FieldRegion>(LeftMR);
|
|
if (RightFR && LeftFR) {
|
|
SVal R = evalBinOpFieldRegionFieldRegion(LeftFR, RightFR, op, resultTy,
|
|
*this);
|
|
if (!R.isUnknown())
|
|
return R;
|
|
}
|
|
|
|
// Compare the regions using the raw offsets.
|
|
RegionOffset LeftOffset = LeftMR->getAsOffset();
|
|
RegionOffset RightOffset = RightMR->getAsOffset();
|
|
|
|
if (LeftOffset.getRegion() != nullptr &&
|
|
LeftOffset.getRegion() == RightOffset.getRegion() &&
|
|
!LeftOffset.hasSymbolicOffset() && !RightOffset.hasSymbolicOffset()) {
|
|
int64_t left = LeftOffset.getOffset();
|
|
int64_t right = RightOffset.getOffset();
|
|
|
|
switch (op) {
|
|
default:
|
|
return UnknownVal();
|
|
case BO_LT:
|
|
return makeTruthVal(left < right, resultTy);
|
|
case BO_GT:
|
|
return makeTruthVal(left > right, resultTy);
|
|
case BO_LE:
|
|
return makeTruthVal(left <= right, resultTy);
|
|
case BO_GE:
|
|
return makeTruthVal(left >= right, resultTy);
|
|
case BO_EQ:
|
|
return makeTruthVal(left == right, resultTy);
|
|
case BO_NE:
|
|
return makeTruthVal(left != right, resultTy);
|
|
}
|
|
}
|
|
|
|
// At this point we're not going to get a good answer, but we can try
|
|
// conjuring an expression instead.
|
|
SymbolRef LHSSym = lhs.getAsLocSymbol();
|
|
SymbolRef RHSSym = rhs.getAsLocSymbol();
|
|
if (LHSSym && RHSSym)
|
|
return makeNonLoc(LHSSym, op, RHSSym, resultTy);
|
|
|
|
// If we get here, we have no way of comparing the regions.
|
|
return UnknownVal();
|
|
}
|
|
}
|
|
}
|
|
|
|
SVal SimpleSValBuilder::evalBinOpLN(ProgramStateRef state,
|
|
BinaryOperator::Opcode op,
|
|
Loc lhs, NonLoc rhs, QualType resultTy) {
|
|
assert(!BinaryOperator::isComparisonOp(op) &&
|
|
"arguments to comparison ops must be of the same type");
|
|
|
|
// Special case: rhs is a zero constant.
|
|
if (rhs.isZeroConstant())
|
|
return lhs;
|
|
|
|
// We are dealing with pointer arithmetic.
|
|
|
|
// Handle pointer arithmetic on constant values.
|
|
if (Optional<nonloc::ConcreteInt> rhsInt = rhs.getAs<nonloc::ConcreteInt>()) {
|
|
if (Optional<loc::ConcreteInt> lhsInt = lhs.getAs<loc::ConcreteInt>()) {
|
|
const llvm::APSInt &leftI = lhsInt->getValue();
|
|
assert(leftI.isUnsigned());
|
|
llvm::APSInt rightI(rhsInt->getValue(), /* isUnsigned */ true);
|
|
|
|
// Convert the bitwidth of rightI. This should deal with overflow
|
|
// since we are dealing with concrete values.
|
|
rightI = rightI.extOrTrunc(leftI.getBitWidth());
|
|
|
|
// Offset the increment by the pointer size.
|
|
llvm::APSInt Multiplicand(rightI.getBitWidth(), /* isUnsigned */ true);
|
|
rightI *= Multiplicand;
|
|
|
|
// Compute the adjusted pointer.
|
|
switch (op) {
|
|
case BO_Add:
|
|
rightI = leftI + rightI;
|
|
break;
|
|
case BO_Sub:
|
|
rightI = leftI - rightI;
|
|
break;
|
|
default:
|
|
llvm_unreachable("Invalid pointer arithmetic operation");
|
|
}
|
|
return loc::ConcreteInt(getBasicValueFactory().getValue(rightI));
|
|
}
|
|
}
|
|
|
|
// Handle cases where 'lhs' is a region.
|
|
if (const MemRegion *region = lhs.getAsRegion()) {
|
|
rhs = convertToArrayIndex(rhs).castAs<NonLoc>();
|
|
SVal index = UnknownVal();
|
|
const MemRegion *superR = nullptr;
|
|
QualType elementType;
|
|
|
|
if (const ElementRegion *elemReg = dyn_cast<ElementRegion>(region)) {
|
|
assert(op == BO_Add || op == BO_Sub);
|
|
index = evalBinOpNN(state, op, elemReg->getIndex(), rhs,
|
|
getArrayIndexType());
|
|
superR = elemReg->getSuperRegion();
|
|
elementType = elemReg->getElementType();
|
|
}
|
|
else if (isa<SubRegion>(region)) {
|
|
assert(op == BO_Add || op == BO_Sub);
|
|
index = (op == BO_Add) ? rhs : evalMinus(rhs);
|
|
superR = region;
|
|
if (resultTy->isAnyPointerType())
|
|
elementType = resultTy->getPointeeType();
|
|
}
|
|
|
|
if (Optional<NonLoc> indexV = index.getAs<NonLoc>()) {
|
|
return loc::MemRegionVal(MemMgr.getElementRegion(elementType, *indexV,
|
|
superR, getContext()));
|
|
}
|
|
}
|
|
return UnknownVal();
|
|
}
|
|
|
|
const llvm::APSInt *SimpleSValBuilder::getKnownValue(ProgramStateRef state,
|
|
SVal V) {
|
|
if (V.isUnknownOrUndef())
|
|
return nullptr;
|
|
|
|
if (Optional<loc::ConcreteInt> X = V.getAs<loc::ConcreteInt>())
|
|
return &X->getValue();
|
|
|
|
if (Optional<nonloc::ConcreteInt> X = V.getAs<nonloc::ConcreteInt>())
|
|
return &X->getValue();
|
|
|
|
if (SymbolRef Sym = V.getAsSymbol())
|
|
return state->getConstraintManager().getSymVal(state, Sym);
|
|
|
|
// FIXME: Add support for SymExprs.
|
|
return nullptr;
|
|
}
|