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// SValBuilder.cpp - Basic class for all SValBuilder implementations -*- C++ -*-
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines SValBuilder, the base class for all (complete) SValBuilder
// implementations.
//
//===----------------------------------------------------------------------===//
#include "clang/StaticAnalyzer/PathSensitive/MemRegion.h"
#include "clang/StaticAnalyzer/PathSensitive/SVals.h"
#include "clang/StaticAnalyzer/PathSensitive/SValBuilder.h"
#include "clang/StaticAnalyzer/PathSensitive/GRState.h"
#include "clang/StaticAnalyzer/PathSensitive/BasicValueFactory.h"
using namespace clang;
using namespace ento;
//===----------------------------------------------------------------------===//
// Basic SVal creation.
//===----------------------------------------------------------------------===//
DefinedOrUnknownSVal SValBuilder::makeZeroVal(QualType T) {
if (Loc::IsLocType(T))
return makeNull();
if (T->isIntegerType())
return makeIntVal(0, T);
// FIXME: Handle floats.
// FIXME: Handle structs.
return UnknownVal();
}
NonLoc SValBuilder::makeNonLoc(const SymExpr *lhs, BinaryOperator::Opcode op,
const llvm::APSInt& v, QualType T) {
// The Environment ensures we always get a persistent APSInt in
// BasicValueFactory, so we don't need to get the APSInt from
// BasicValueFactory again.
assert(!Loc::IsLocType(T));
return nonloc::SymExprVal(SymMgr.getSymIntExpr(lhs, op, v, T));
}
NonLoc SValBuilder::makeNonLoc(const SymExpr *lhs, BinaryOperator::Opcode op,
const SymExpr *rhs, QualType T) {
assert(SymMgr.getType(lhs) == SymMgr.getType(rhs));
assert(!Loc::IsLocType(T));
return nonloc::SymExprVal(SymMgr.getSymSymExpr(lhs, op, rhs, T));
}
SVal SValBuilder::convertToArrayIndex(SVal V) {
if (V.isUnknownOrUndef())
return V;
// Common case: we have an appropriately sized integer.
if (nonloc::ConcreteInt* CI = dyn_cast<nonloc::ConcreteInt>(&V)) {
const llvm::APSInt& I = CI->getValue();
if (I.getBitWidth() == ArrayIndexWidth && I.isSigned())
return V;
}
return evalCastNL(cast<NonLoc>(V), ArrayIndexTy);
}
DefinedOrUnknownSVal
SValBuilder::getRegionValueSymbolVal(const TypedRegion* R) {
QualType T = R->getValueType();
if (!SymbolManager::canSymbolicate(T))
return UnknownVal();
SymbolRef sym = SymMgr.getRegionValueSymbol(R);
if (Loc::IsLocType(T))
return loc::MemRegionVal(MemMgr.getSymbolicRegion(sym));
return nonloc::SymbolVal(sym);
}
DefinedOrUnknownSVal SValBuilder::getConjuredSymbolVal(const void *SymbolTag,
const Expr *E,
unsigned Count) {
QualType T = E->getType();
if (!SymbolManager::canSymbolicate(T))
return UnknownVal();
SymbolRef sym = SymMgr.getConjuredSymbol(E, Count, SymbolTag);
if (Loc::IsLocType(T))
return loc::MemRegionVal(MemMgr.getSymbolicRegion(sym));
return nonloc::SymbolVal(sym);
}
DefinedOrUnknownSVal SValBuilder::getConjuredSymbolVal(const void *SymbolTag,
const Expr *E,
QualType T,
unsigned Count) {
if (!SymbolManager::canSymbolicate(T))
return UnknownVal();
SymbolRef sym = SymMgr.getConjuredSymbol(E, T, Count, SymbolTag);
if (Loc::IsLocType(T))
return loc::MemRegionVal(MemMgr.getSymbolicRegion(sym));
return nonloc::SymbolVal(sym);
}
DefinedSVal SValBuilder::getMetadataSymbolVal(const void *SymbolTag,
const MemRegion *MR,
const Expr *E, QualType T,
unsigned Count) {
assert(SymbolManager::canSymbolicate(T) && "Invalid metadata symbol type");
SymbolRef sym = SymMgr.getMetadataSymbol(MR, E, T, Count, SymbolTag);
if (Loc::IsLocType(T))
return loc::MemRegionVal(MemMgr.getSymbolicRegion(sym));
return nonloc::SymbolVal(sym);
}
DefinedOrUnknownSVal
SValBuilder::getDerivedRegionValueSymbolVal(SymbolRef parentSymbol,
const TypedRegion *R) {
QualType T = R->getValueType();
if (!SymbolManager::canSymbolicate(T))
return UnknownVal();
SymbolRef sym = SymMgr.getDerivedSymbol(parentSymbol, R);
if (Loc::IsLocType(T))
return loc::MemRegionVal(MemMgr.getSymbolicRegion(sym));
return nonloc::SymbolVal(sym);
}
DefinedSVal SValBuilder::getFunctionPointer(const FunctionDecl* FD) {
return loc::MemRegionVal(MemMgr.getFunctionTextRegion(FD));
}
DefinedSVal SValBuilder::getBlockPointer(const BlockDecl *D,
CanQualType locTy,
const LocationContext *LC) {
const BlockTextRegion *BC =
MemMgr.getBlockTextRegion(D, locTy, LC->getAnalysisContext());
const BlockDataRegion *BD = MemMgr.getBlockDataRegion(BC, LC);
return loc::MemRegionVal(BD);
}
//===----------------------------------------------------------------------===//
SVal SValBuilder::evalBinOp(const GRState *ST, BinaryOperator::Opcode Op,
SVal L, SVal R, QualType T) {
if (L.isUndef() || R.isUndef())
return UndefinedVal();
if (L.isUnknown() || R.isUnknown())
return UnknownVal();
if (isa<Loc>(L)) {
if (isa<Loc>(R))
return evalBinOpLL(ST, Op, cast<Loc>(L), cast<Loc>(R), T);
return evalBinOpLN(ST, Op, cast<Loc>(L), cast<NonLoc>(R), T);
}
if (isa<Loc>(R)) {
// Support pointer arithmetic where the addend is on the left
// and the pointer on the right.
assert(Op == BO_Add);
// Commute the operands.
return evalBinOpLN(ST, Op, cast<Loc>(R), cast<NonLoc>(L), T);
}
return evalBinOpNN(ST, Op, cast<NonLoc>(L), cast<NonLoc>(R), T);
}
DefinedOrUnknownSVal SValBuilder::evalEQ(const GRState *ST,
DefinedOrUnknownSVal L,
DefinedOrUnknownSVal R) {
return cast<DefinedOrUnknownSVal>(evalBinOp(ST, BO_EQ, L, R,
Context.IntTy));
}
// FIXME: should rewrite according to the cast kind.
SVal SValBuilder::evalCast(SVal val, QualType castTy, QualType originalTy) {
if (val.isUnknownOrUndef() || castTy == originalTy)
return val;
// For const casts, just propagate the value.
if (!castTy->isVariableArrayType() && !originalTy->isVariableArrayType())
if (Context.hasSameUnqualifiedType(castTy, originalTy))
return val;
// Check for casts to real or complex numbers. We don't handle these at all
// right now.
if (castTy->isFloatingType() || castTy->isAnyComplexType())
return UnknownVal();
// Check for casts from integers to integers.
if (castTy->isIntegerType() && originalTy->isIntegerType())
return evalCastNL(cast<NonLoc>(val), castTy);
// Check for casts from pointers to integers.
if (castTy->isIntegerType() && Loc::IsLocType(originalTy))
return evalCastL(cast<Loc>(val), castTy);
// Check for casts from integers to pointers.
if (Loc::IsLocType(castTy) && originalTy->isIntegerType()) {
if (nonloc::LocAsInteger *LV = dyn_cast<nonloc::LocAsInteger>(&val)) {
if (const MemRegion *R = LV->getLoc().getAsRegion()) {
StoreManager &storeMgr = StateMgr.getStoreManager();
R = storeMgr.CastRegion(R, castTy);
return R ? SVal(loc::MemRegionVal(R)) : UnknownVal();
}
return LV->getLoc();
}
goto DispatchCast;
}
// Just pass through function and block pointers.
if (originalTy->isBlockPointerType() || originalTy->isFunctionPointerType()) {
assert(Loc::IsLocType(castTy));
return val;
}
// Check for casts from array type to another type.
if (originalTy->isArrayType()) {
// We will always decay to a pointer.
val = StateMgr.ArrayToPointer(cast<Loc>(val));
// Are we casting from an array to a pointer? If so just pass on
// the decayed value.
if (castTy->isPointerType())
return val;
// Are we casting from an array to an integer? If so, cast the decayed
// pointer value to an integer.
assert(castTy->isIntegerType());
// FIXME: Keep these here for now in case we decide soon that we
// need the original decayed type.
// QualType elemTy = cast<ArrayType>(originalTy)->getElementType();
// QualType pointerTy = C.getPointerType(elemTy);
return evalCastL(cast<Loc>(val), castTy);
}
// Check for casts from a region to a specific type.
if (const MemRegion *R = val.getAsRegion()) {
// FIXME: We should handle the case where we strip off view layers to get
// to a desugared type.
if (!Loc::IsLocType(castTy)) {
// FIXME: There can be gross cases where one casts the result of a function
// (that returns a pointer) to some other value that happens to fit
// within that pointer value. We currently have no good way to
// model such operations. When this happens, the underlying operation
// is that the caller is reasoning about bits. Conceptually we are
// layering a "view" of a location on top of those bits. Perhaps
// we need to be more lazy about mutual possible views, even on an
// SVal? This may be necessary for bit-level reasoning as well.
return UnknownVal();
}
// We get a symbolic function pointer for a dereference of a function
// pointer, but it is of function type. Example:
// struct FPRec {
// void (*my_func)(int * x);
// };
//
// int bar(int x);
//
// int f1_a(struct FPRec* foo) {
// int x;
// (*foo->my_func)(&x);
// return bar(x)+1; // no-warning
// }
assert(Loc::IsLocType(originalTy) || originalTy->isFunctionType() ||
originalTy->isBlockPointerType());
StoreManager &storeMgr = StateMgr.getStoreManager();
// Delegate to store manager to get the result of casting a region to a
// different type. If the MemRegion* returned is NULL, this expression
// Evaluates to UnknownVal.
R = storeMgr.CastRegion(R, castTy);
return R ? SVal(loc::MemRegionVal(R)) : UnknownVal();
}
DispatchCast:
// All other cases.
return isa<Loc>(val) ? evalCastL(cast<Loc>(val), castTy)
: evalCastNL(cast<NonLoc>(val), castTy);
}