llvm-project/clang/lib/StaticAnalyzer/Core/SValBuilder.cpp

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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/AST/ExprCXX.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/SVals.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/SValBuilder.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/BasicValueFactory.h"
using namespace clang;
using namespace ento;
//===----------------------------------------------------------------------===//
// Basic SVal creation.
//===----------------------------------------------------------------------===//
void SValBuilder::anchor() { }
DefinedOrUnknownSVal SValBuilder::makeZeroVal(QualType type) {
if (Loc::isLocType(type))
return makeNull();
if (type->isIntegerType())
return makeIntVal(0, type);
// FIXME: Handle floats.
// FIXME: Handle structs.
return UnknownVal();
}
NonLoc SValBuilder::makeNonLoc(const SymExpr *lhs, BinaryOperator::Opcode op,
const llvm::APSInt& rhs, QualType type) {
// The Environment ensures we always get a persistent APSInt in
// BasicValueFactory, so we don't need to get the APSInt from
// BasicValueFactory again.
assert(lhs);
assert(!Loc::isLocType(type));
return nonloc::SymbolVal(SymMgr.getSymIntExpr(lhs, op, rhs, type));
}
NonLoc SValBuilder::makeNonLoc(const llvm::APSInt& lhs,
BinaryOperator::Opcode op, const SymExpr *rhs,
QualType type) {
assert(rhs);
assert(!Loc::isLocType(type));
return nonloc::SymbolVal(SymMgr.getIntSymExpr(lhs, op, rhs, type));
}
NonLoc SValBuilder::makeNonLoc(const SymExpr *lhs, BinaryOperator::Opcode op,
const SymExpr *rhs, QualType type) {
assert(lhs && rhs);
assert(haveSameType(lhs->getType(Context), rhs->getType(Context)) == true);
assert(!Loc::isLocType(type));
return nonloc::SymbolVal(SymMgr.getSymSymExpr(lhs, op, rhs, type));
}
NonLoc SValBuilder::makeNonLoc(const SymExpr *operand,
QualType fromTy, QualType toTy) {
assert(operand);
assert(!Loc::isLocType(toTy));
return nonloc::SymbolVal(SymMgr.getCastSymbol(operand, fromTy, toTy));
}
SVal SValBuilder::convertToArrayIndex(SVal val) {
if (val.isUnknownOrUndef())
return val;
// Common case: we have an appropriately sized integer.
if (nonloc::ConcreteInt* CI = dyn_cast<nonloc::ConcreteInt>(&val)) {
const llvm::APSInt& I = CI->getValue();
if (I.getBitWidth() == ArrayIndexWidth && I.isSigned())
return val;
}
return evalCastFromNonLoc(cast<NonLoc>(val), ArrayIndexTy);
}
nonloc::ConcreteInt SValBuilder::makeBoolVal(const CXXBoolLiteralExpr *boolean){
return makeTruthVal(boolean->getValue());
}
DefinedOrUnknownSVal
SValBuilder::getRegionValueSymbolVal(const TypedValueRegion* region) {
QualType T = region->getValueType();
if (!SymbolManager::canSymbolicate(T))
return UnknownVal();
SymbolRef sym = SymMgr.getRegionValueSymbol(region);
if (Loc::isLocType(T))
return loc::MemRegionVal(MemMgr.getSymbolicRegion(sym));
return nonloc::SymbolVal(sym);
}
DefinedOrUnknownSVal
SValBuilder::getConjuredSymbolVal(const void *symbolTag,
const Expr *expr,
const LocationContext *LCtx,
unsigned count) {
QualType T = expr->getType();
return getConjuredSymbolVal(symbolTag, expr, LCtx, T, count);
}
DefinedOrUnknownSVal
SValBuilder::getConjuredSymbolVal(const void *symbolTag,
const Expr *expr,
const LocationContext *LCtx,
QualType type,
unsigned count) {
if (!SymbolManager::canSymbolicate(type))
return UnknownVal();
SymbolRef sym = SymMgr.getConjuredSymbol(expr, LCtx, type, count, symbolTag);
if (Loc::isLocType(type))
return loc::MemRegionVal(MemMgr.getSymbolicRegion(sym));
return nonloc::SymbolVal(sym);
}
DefinedOrUnknownSVal
SValBuilder::getConjuredSymbolVal(const Stmt *stmt,
const LocationContext *LCtx,
QualType type,
unsigned visitCount) {
if (!SymbolManager::canSymbolicate(type))
return UnknownVal();
SymbolRef sym = SymMgr.getConjuredSymbol(stmt, LCtx, type, visitCount);
if (Loc::isLocType(type))
return loc::MemRegionVal(MemMgr.getSymbolicRegion(sym));
return nonloc::SymbolVal(sym);
}
DefinedSVal SValBuilder::getMetadataSymbolVal(const void *symbolTag,
const MemRegion *region,
const Expr *expr, QualType type,
unsigned count) {
assert(SymbolManager::canSymbolicate(type) && "Invalid metadata symbol type");
SymbolRef sym =
SymMgr.getMetadataSymbol(region, expr, type, count, symbolTag);
if (Loc::isLocType(type))
return loc::MemRegionVal(MemMgr.getSymbolicRegion(sym));
return nonloc::SymbolVal(sym);
}
DefinedOrUnknownSVal
SValBuilder::getDerivedRegionValueSymbolVal(SymbolRef parentSymbol,
const TypedValueRegion *region) {
QualType T = region->getValueType();
if (!SymbolManager::canSymbolicate(T))
return UnknownVal();
SymbolRef sym = SymMgr.getDerivedSymbol(parentSymbol, region);
if (Loc::isLocType(T))
return loc::MemRegionVal(MemMgr.getSymbolicRegion(sym));
return nonloc::SymbolVal(sym);
}
DefinedSVal SValBuilder::getFunctionPointer(const FunctionDecl *func) {
return loc::MemRegionVal(MemMgr.getFunctionTextRegion(func));
}
DefinedSVal SValBuilder::getBlockPointer(const BlockDecl *block,
CanQualType locTy,
const LocationContext *locContext) {
const BlockTextRegion *BC =
MemMgr.getBlockTextRegion(block, locTy, locContext->getAnalysisDeclContext());
const BlockDataRegion *BD = MemMgr.getBlockDataRegion(BC, locContext);
return loc::MemRegionVal(BD);
}
//===----------------------------------------------------------------------===//
SVal SValBuilder::makeGenericVal(ProgramStateRef State,
BinaryOperator::Opcode Op,
NonLoc LHS, NonLoc RHS,
QualType ResultTy) {
// If operands are tainted, create a symbol to ensure that we propagate taint.
if (State->isTainted(RHS) || State->isTainted(LHS)) {
const SymExpr *symLHS;
const SymExpr *symRHS;
if (const nonloc::ConcreteInt *rInt = dyn_cast<nonloc::ConcreteInt>(&RHS)) {
symLHS = LHS.getAsSymExpr();
return makeNonLoc(symLHS, Op, rInt->getValue(), ResultTy);
}
if (const nonloc::ConcreteInt *lInt = dyn_cast<nonloc::ConcreteInt>(&LHS)) {
symRHS = RHS.getAsSymExpr();
return makeNonLoc(lInt->getValue(), Op, symRHS, ResultTy);
}
symLHS = LHS.getAsSymExpr();
symRHS = RHS.getAsSymExpr();
return makeNonLoc(symLHS, Op, symRHS, ResultTy);
}
return UnknownVal();
}
SVal SValBuilder::evalBinOp(ProgramStateRef state, BinaryOperator::Opcode op,
SVal lhs, SVal rhs, QualType type) {
if (lhs.isUndef() || rhs.isUndef())
return UndefinedVal();
if (lhs.isUnknown() || rhs.isUnknown())
return UnknownVal();
if (isa<Loc>(lhs)) {
if (isa<Loc>(rhs))
return evalBinOpLL(state, op, cast<Loc>(lhs), cast<Loc>(rhs), type);
return evalBinOpLN(state, op, cast<Loc>(lhs), cast<NonLoc>(rhs), type);
}
if (isa<Loc>(rhs)) {
// 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(state, op, cast<Loc>(rhs), cast<NonLoc>(lhs), type);
}
return evalBinOpNN(state, op, cast<NonLoc>(lhs), cast<NonLoc>(rhs), type);
}
DefinedOrUnknownSVal SValBuilder::evalEQ(ProgramStateRef state,
DefinedOrUnknownSVal lhs,
DefinedOrUnknownSVal rhs) {
return cast<DefinedOrUnknownSVal>(evalBinOp(state, BO_EQ, lhs, rhs,
Context.IntTy));
}
/// Recursively check if the pointer types are equal modulo const, volatile,
/// and restrict qualifiers. Assumes the input types are canonical.
/// TODO: This is based off of code in SemaCast; can we reuse it.
static bool haveSimilarTypes(ASTContext &Context, QualType T1,
QualType T2) {
while (Context.UnwrapSimilarPointerTypes(T1, T2)) {
Qualifiers Quals1, Quals2;
T1 = Context.getUnqualifiedArrayType(T1, Quals1);
T2 = Context.getUnqualifiedArrayType(T2, Quals2);
// Make sure that non cvr-qualifiers the other qualifiers (e.g., address
// spaces) are identical.
Quals1.removeCVRQualifiers();
Quals2.removeCVRQualifiers();
if (Quals1 != Quals2)
return false;
}
if (T1 != T2)
return false;
return true;
}
2010-11-26 15:15:40 +08:00
// FIXME: should rewrite according to the cast kind.
SVal SValBuilder::evalCast(SVal val, QualType castTy, QualType originalTy) {
castTy = Context.getCanonicalType(castTy);
originalTy = Context.getCanonicalType(originalTy);
if (val.isUnknownOrUndef() || castTy == originalTy)
return val;
// For const casts, just propagate the value.
if (!castTy->isVariableArrayType() && !originalTy->isVariableArrayType())
if (haveSimilarTypes(Context, Context.getPointerType(castTy),
Context.getPointerType(originalTy)))
return val;
// Check for casts from pointers to integers.
if (castTy->isIntegerType() && Loc::isLocType(originalTy))
return evalCastFromLoc(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();
}
return dispatchCast(val, castTy);
}
// 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 evalCastFromLoc(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() || castTy->isReferenceType());
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();
}
return dispatchCast(val, castTy);
}