//===--- Expr.cpp - Expression AST Node Implementation --------------------===// // // The LLVM Compiler Infrastructure // // This file was developed by Chris Lattner and is distributed under // the University of Illinois Open Source License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// // // This file implements the Expr class and subclasses. // //===----------------------------------------------------------------------===// #include "clang/AST/Expr.h" #include "clang/AST/ASTContext.h" #include "clang/AST/StmtVisitor.h" #include "clang/Lex/IdentifierTable.h" using namespace clang; //===----------------------------------------------------------------------===// // Primary Expressions. //===----------------------------------------------------------------------===// StringLiteral::StringLiteral(const char *strData, unsigned byteLength, bool Wide, QualType t, SourceLocation firstLoc, SourceLocation lastLoc) : Expr(StringLiteralClass, t) { // OPTIMIZE: could allocate this appended to the StringLiteral. char *AStrData = new char[byteLength]; memcpy(AStrData, strData, byteLength); StrData = AStrData; ByteLength = byteLength; IsWide = Wide; firstTokLoc = firstLoc; lastTokLoc = lastLoc; } StringLiteral::~StringLiteral() { delete[] StrData; } bool UnaryOperator::isPostfix(Opcode Op) { switch (Op) { case PostInc: case PostDec: return true; default: return false; } } /// getOpcodeStr - Turn an Opcode enum value into the punctuation char it /// corresponds to, e.g. "sizeof" or "[pre]++". const char *UnaryOperator::getOpcodeStr(Opcode Op) { switch (Op) { default: assert(0 && "Unknown unary operator"); case PostInc: return "++"; case PostDec: return "--"; case PreInc: return "++"; case PreDec: return "--"; case AddrOf: return "&"; case Deref: return "*"; case Plus: return "+"; case Minus: return "-"; case Not: return "~"; case LNot: return "!"; case Real: return "__real"; case Imag: return "__imag"; case SizeOf: return "sizeof"; case AlignOf: return "alignof"; case Extension: return "__extension__"; } } //===----------------------------------------------------------------------===// // Postfix Operators. //===----------------------------------------------------------------------===// CallExpr::CallExpr(Expr *fn, Expr **args, unsigned numargs, QualType t, SourceLocation rparenloc) : Expr(CallExprClass, t), Fn(fn), NumArgs(numargs) { Args = new Expr*[numargs]; for (unsigned i = 0; i != numargs; ++i) Args[i] = args[i]; RParenLoc = rparenloc; } bool CallExpr::isBuiltinClassifyType(llvm::APSInt &Result) const { // The following enum mimics gcc's internal "typeclass.h" file. enum gcc_type_class { no_type_class = -1, void_type_class, integer_type_class, char_type_class, enumeral_type_class, boolean_type_class, pointer_type_class, reference_type_class, offset_type_class, real_type_class, complex_type_class, function_type_class, method_type_class, record_type_class, union_type_class, array_type_class, string_type_class, lang_type_class }; Result.setIsSigned(true); // All simple function calls (e.g. func()) are implicitly cast to pointer to // function. As a result, we try and obtain the DeclRefExpr from the // ImplicitCastExpr. const ImplicitCastExpr *ICE = dyn_cast(getCallee()); if (!ICE) // FIXME: deal with more complex calls (e.g. (func)(), (*func)()). return false; const DeclRefExpr *DRE = dyn_cast(ICE->getSubExpr()); if (!DRE) return false; // We have a DeclRefExpr. if (strcmp(DRE->getDecl()->getName(), "__builtin_classify_type") == 0) { // If no argument was supplied, default to "no_type_class". This isn't // ideal, however it's what gcc does. Result = static_cast(no_type_class); if (NumArgs >= 1) { QualType argType = getArg(0)->getType(); if (argType->isVoidType()) Result = void_type_class; else if (argType->isEnumeralType()) Result = enumeral_type_class; else if (argType->isBooleanType()) Result = boolean_type_class; else if (argType->isCharType()) Result = string_type_class; // gcc doesn't appear to use char_type_class else if (argType->isIntegerType()) Result = integer_type_class; else if (argType->isPointerType()) Result = pointer_type_class; else if (argType->isReferenceType()) Result = reference_type_class; else if (argType->isRealType()) Result = real_type_class; else if (argType->isComplexType()) Result = complex_type_class; else if (argType->isFunctionType()) Result = function_type_class; else if (argType->isStructureType()) Result = record_type_class; else if (argType->isUnionType()) Result = union_type_class; else if (argType->isArrayType()) Result = array_type_class; else if (argType->isUnionType()) Result = union_type_class; else // FIXME: offset_type_class, method_type_class, & lang_type_class? assert(1 && "CallExpr::isBuiltinClassifyType(): unimplemented type"); } return true; } return false; } /// getOpcodeStr - Turn an Opcode enum value into the punctuation char it /// corresponds to, e.g. "<<=". const char *BinaryOperator::getOpcodeStr(Opcode Op) { switch (Op) { default: assert(0 && "Unknown binary operator"); case Mul: return "*"; case Div: return "/"; case Rem: return "%"; case Add: return "+"; case Sub: return "-"; case Shl: return "<<"; case Shr: return ">>"; case LT: return "<"; case GT: return ">"; case LE: return "<="; case GE: return ">="; case EQ: return "=="; case NE: return "!="; case And: return "&"; case Xor: return "^"; case Or: return "|"; case LAnd: return "&&"; case LOr: return "||"; case Assign: return "="; case MulAssign: return "*="; case DivAssign: return "/="; case RemAssign: return "%="; case AddAssign: return "+="; case SubAssign: return "-="; case ShlAssign: return "<<="; case ShrAssign: return ">>="; case AndAssign: return "&="; case XorAssign: return "^="; case OrAssign: return "|="; case Comma: return ","; } } //===----------------------------------------------------------------------===// // Generic Expression Routines //===----------------------------------------------------------------------===// /// hasLocalSideEffect - Return true if this immediate expression has side /// effects, not counting any sub-expressions. bool Expr::hasLocalSideEffect() const { switch (getStmtClass()) { default: return false; case ParenExprClass: return cast(this)->getSubExpr()->hasLocalSideEffect(); case UnaryOperatorClass: { const UnaryOperator *UO = cast(this); switch (UO->getOpcode()) { default: return false; case UnaryOperator::PostInc: case UnaryOperator::PostDec: case UnaryOperator::PreInc: case UnaryOperator::PreDec: return true; // ++/-- case UnaryOperator::Deref: // Dereferencing a volatile pointer is a side-effect. return getType().isVolatileQualified(); case UnaryOperator::Real: case UnaryOperator::Imag: // accessing a piece of a volatile complex is a side-effect. return UO->getSubExpr()->getType().isVolatileQualified(); case UnaryOperator::Extension: return UO->getSubExpr()->hasLocalSideEffect(); } } case BinaryOperatorClass: return cast(this)->isAssignmentOp(); case MemberExprClass: case ArraySubscriptExprClass: // If the base pointer or element is to a volatile pointer/field, accessing // if is a side effect. return getType().isVolatileQualified(); case CallExprClass: // TODO: check attributes for pure/const. "void foo() { strlen("bar"); }" // should warn. return true; case CastExprClass: // If this is a cast to void, check the operand. Otherwise, the result of // the cast is unused. if (getType()->isVoidType()) return cast(this)->getSubExpr()->hasLocalSideEffect(); return false; } } /// isLvalue - C99 6.3.2.1: an lvalue is an expression with an object type or an /// incomplete type other than void. Nonarray expressions that can be lvalues: /// - name, where name must be a variable /// - e[i] /// - (e), where e must be an lvalue /// - e.name, where e must be an lvalue /// - e->name /// - *e, the type of e cannot be a function type /// - string-constant /// - reference type [C++ [expr]] /// Expr::isLvalueResult Expr::isLvalue() const { // first, check the type (C99 6.3.2.1) if (TR->isFunctionType()) // from isObjectType() return LV_NotObjectType; if (TR->isVoidType()) return LV_IncompleteVoidType; if (TR->isReferenceType()) // C++ [expr] return LV_Valid; // the type looks fine, now check the expression switch (getStmtClass()) { case StringLiteralClass: // C99 6.5.1p4 case ArraySubscriptExprClass: // C99 6.5.3p4 (e1[e2] == (*((e1)+(e2)))) // For vectors, make sure base is an lvalue (i.e. not a function call). if (cast(this)->getBase()->getType()->isVectorType()) return cast(this)->getBase()->isLvalue(); return LV_Valid; case DeclRefExprClass: // C99 6.5.1p2 if (isa(cast(this)->getDecl())) return LV_Valid; break; case MemberExprClass: { // C99 6.5.2.3p4 const MemberExpr *m = cast(this); return m->isArrow() ? LV_Valid : m->getBase()->isLvalue(); } case UnaryOperatorClass: // C99 6.5.3p4 if (cast(this)->getOpcode() == UnaryOperator::Deref) return LV_Valid; break; case ParenExprClass: // C99 6.5.1p5 return cast(this)->getSubExpr()->isLvalue(); case OCUVectorElementExprClass: if (cast(this)->containsDuplicateElements()) return LV_DuplicateVectorComponents; return LV_Valid; default: break; } return LV_InvalidExpression; } /// isModifiableLvalue - C99 6.3.2.1: an lvalue that does not have array type, /// does not have an incomplete type, does not have a const-qualified type, and /// if it is a structure or union, does not have any member (including, /// recursively, any member or element of all contained aggregates or unions) /// with a const-qualified type. Expr::isModifiableLvalueResult Expr::isModifiableLvalue() const { isLvalueResult lvalResult = isLvalue(); switch (lvalResult) { case LV_Valid: break; case LV_NotObjectType: return MLV_NotObjectType; case LV_IncompleteVoidType: return MLV_IncompleteVoidType; case LV_DuplicateVectorComponents: return MLV_DuplicateVectorComponents; case LV_InvalidExpression: return MLV_InvalidExpression; } if (TR.isConstQualified()) return MLV_ConstQualified; if (TR->isArrayType()) return MLV_ArrayType; if (TR->isIncompleteType()) return MLV_IncompleteType; if (const RecordType *r = dyn_cast(TR.getCanonicalType())) { if (r->hasConstFields()) return MLV_ConstQualified; } return MLV_Valid; } /// isIntegerConstantExpr - this recursive routine will test if an expression is /// an integer constant expression. Note: With the introduction of VLA's in /// C99 the result of the sizeof operator is no longer always a constant /// expression. The generalization of the wording to include any subexpression /// that is not evaluated (C99 6.6p3) means that nonconstant subexpressions /// can appear as operands to other operators (e.g. &&, ||, ?:). For instance, /// "0 || f()" can be treated as a constant expression. In C90 this expression, /// occurring in a context requiring a constant, would have been a constraint /// violation. FIXME: This routine currently implements C90 semantics. /// To properly implement C99 semantics this routine will need to evaluate /// expressions involving operators previously mentioned. /// FIXME: Pass up a reason why! Invalid operation in i-c-e, division by zero, /// comma, etc /// /// FIXME: This should ext-warn on overflow during evaluation! ISO C does not /// permit this. /// /// FIXME: Handle offsetof. Two things to do: Handle GCC's __builtin_offsetof /// to support gcc 4.0+ and handle the idiom GCC recognizes with a null pointer /// cast+dereference. bool Expr::isIntegerConstantExpr(llvm::APSInt &Result, ASTContext &Ctx, SourceLocation *Loc, bool isEvaluated) const { switch (getStmtClass()) { default: if (Loc) *Loc = getLocStart(); return false; case ParenExprClass: return cast(this)->getSubExpr()-> isIntegerConstantExpr(Result, Ctx, Loc, isEvaluated); case IntegerLiteralClass: Result = cast(this)->getValue(); break; case CharacterLiteralClass: { const CharacterLiteral *CL = cast(this); Result.zextOrTrunc(Ctx.getTypeSize(getType(), CL->getLoc())); Result = CL->getValue(); Result.setIsUnsigned(!getType()->isSignedIntegerType()); break; } case TypesCompatibleExprClass: { const TypesCompatibleExpr *TCE = cast(this); Result.zextOrTrunc(Ctx.getTypeSize(getType(), TCE->getLocStart())); Result = TCE->typesAreCompatible(); break; } case CallExprClass: { const CallExpr *CE = cast(this); Result.zextOrTrunc(Ctx.getTypeSize(getType(), CE->getLocStart())); if (CE->isBuiltinClassifyType(Result)) break; if (Loc) *Loc = getLocStart(); return false; } case DeclRefExprClass: if (const EnumConstantDecl *D = dyn_cast(cast(this)->getDecl())) { Result = D->getInitVal(); break; } if (Loc) *Loc = getLocStart(); return false; case UnaryOperatorClass: { const UnaryOperator *Exp = cast(this); // Get the operand value. If this is sizeof/alignof, do not evalute the // operand. This affects C99 6.6p3. if (Exp->isSizeOfAlignOfOp()) isEvaluated = false; if (!Exp->getSubExpr()->isIntegerConstantExpr(Result, Ctx,Loc, isEvaluated)) return false; switch (Exp->getOpcode()) { // Address, indirect, pre/post inc/dec, etc are not valid constant exprs. // See C99 6.6p3. default: if (Loc) *Loc = Exp->getOperatorLoc(); return false; case UnaryOperator::Extension: return true; // FIXME: this is wrong. case UnaryOperator::SizeOf: case UnaryOperator::AlignOf: // sizeof(vla) is not a constantexpr: C99 6.5.3.4p2. if (!Exp->getSubExpr()->getType()->isConstantSizeType(Ctx, Loc)) return false; // Return the result in the right width. Result.zextOrTrunc(Ctx.getTypeSize(getType(), Exp->getOperatorLoc())); // Get information about the size or align. if (Exp->getOpcode() == UnaryOperator::SizeOf) Result = Ctx.getTypeSize(Exp->getSubExpr()->getType(), Exp->getOperatorLoc()); else Result = Ctx.getTypeAlign(Exp->getSubExpr()->getType(), Exp->getOperatorLoc()); break; case UnaryOperator::LNot: { bool Val = Result != 0; Result.zextOrTrunc(Ctx.getTypeSize(getType(), Exp->getOperatorLoc())); Result = Val; break; } case UnaryOperator::Plus: break; case UnaryOperator::Minus: Result = -Result; break; case UnaryOperator::Not: Result = ~Result; break; } break; } case SizeOfAlignOfTypeExprClass: { const SizeOfAlignOfTypeExpr *Exp = cast(this); // alignof always evaluates to a constant. if (Exp->isSizeOf() && !Exp->getArgumentType()->isConstantSizeType(Ctx,Loc)) return false; // Return the result in the right width. Result.zextOrTrunc(Ctx.getTypeSize(getType(), Exp->getOperatorLoc())); // Get information about the size or align. if (Exp->isSizeOf()) Result = Ctx.getTypeSize(Exp->getArgumentType(), Exp->getOperatorLoc()); else Result = Ctx.getTypeAlign(Exp->getArgumentType(), Exp->getOperatorLoc()); break; } case BinaryOperatorClass: { const BinaryOperator *Exp = cast(this); // The LHS of a constant expr is always evaluated and needed. if (!Exp->getLHS()->isIntegerConstantExpr(Result, Ctx, Loc, isEvaluated)) return false; llvm::APSInt RHS(Result); // The short-circuiting &&/|| operators don't necessarily evaluate their // RHS. Make sure to pass isEvaluated down correctly. if (Exp->isLogicalOp()) { bool RHSEval; if (Exp->getOpcode() == BinaryOperator::LAnd) RHSEval = Result != 0; else { assert(Exp->getOpcode() == BinaryOperator::LOr &&"Unexpected logical"); RHSEval = Result == 0; } if (!Exp->getRHS()->isIntegerConstantExpr(RHS, Ctx, Loc, isEvaluated & RHSEval)) return false; } else { if (!Exp->getRHS()->isIntegerConstantExpr(RHS, Ctx, Loc, isEvaluated)) return false; } switch (Exp->getOpcode()) { default: if (Loc) *Loc = getLocStart(); return false; case BinaryOperator::Mul: Result *= RHS; break; case BinaryOperator::Div: if (RHS == 0) { if (!isEvaluated) break; if (Loc) *Loc = getLocStart(); return false; } Result /= RHS; break; case BinaryOperator::Rem: if (RHS == 0) { if (!isEvaluated) break; if (Loc) *Loc = getLocStart(); return false; } Result %= RHS; break; case BinaryOperator::Add: Result += RHS; break; case BinaryOperator::Sub: Result -= RHS; break; case BinaryOperator::Shl: Result <<= RHS.getLimitedValue(Result.getBitWidth()-1); break; case BinaryOperator::Shr: Result >>= RHS.getLimitedValue(Result.getBitWidth()-1); break; case BinaryOperator::LT: Result = Result < RHS; break; case BinaryOperator::GT: Result = Result > RHS; break; case BinaryOperator::LE: Result = Result <= RHS; break; case BinaryOperator::GE: Result = Result >= RHS; break; case BinaryOperator::EQ: Result = Result == RHS; break; case BinaryOperator::NE: Result = Result != RHS; break; case BinaryOperator::And: Result &= RHS; break; case BinaryOperator::Xor: Result ^= RHS; break; case BinaryOperator::Or: Result |= RHS; break; case BinaryOperator::LAnd: Result = Result != 0 && RHS != 0; break; case BinaryOperator::LOr: Result = Result != 0 || RHS != 0; break; case BinaryOperator::Comma: // C99 6.6p3: "shall not contain assignment, ..., or comma operators, // *except* when they are contained within a subexpression that is not // evaluated". Note that Assignment can never happen due to constraints // on the LHS subexpr, so we don't need to check it here. if (isEvaluated) { if (Loc) *Loc = getLocStart(); return false; } // The result of the constant expr is the RHS. Result = RHS; return true; } assert(!Exp->isAssignmentOp() && "LHS can't be a constant expr!"); break; } case ImplicitCastExprClass: case CastExprClass: { const Expr *SubExpr; SourceLocation CastLoc; if (const CastExpr *C = dyn_cast(this)) { SubExpr = C->getSubExpr(); CastLoc = C->getLParenLoc(); } else { SubExpr = cast(this)->getSubExpr(); CastLoc = getLocStart(); } // C99 6.6p6: shall only convert arithmetic types to integer types. if (!SubExpr->getType()->isArithmeticType() || !getType()->isIntegerType()) { if (Loc) *Loc = SubExpr->getLocStart(); return false; } // Handle simple integer->integer casts. if (SubExpr->getType()->isIntegerType()) { if (!SubExpr->isIntegerConstantExpr(Result, Ctx, Loc, isEvaluated)) return false; // Figure out if this is a truncate, extend or noop cast. unsigned DestWidth = Ctx.getTypeSize(getType(), CastLoc); // If the input is signed, do a sign extend, noop, or truncate. if (SubExpr->getType()->isSignedIntegerType()) Result.sextOrTrunc(DestWidth); else // If the input is unsigned, do a zero extend, noop, or truncate. Result.zextOrTrunc(DestWidth); break; } // Allow floating constants that are the immediate operands of casts or that // are parenthesized. const Expr *Operand = SubExpr; while (const ParenExpr *PE = dyn_cast(Operand)) Operand = PE->getSubExpr(); if (const FloatingLiteral *FL = dyn_cast(Operand)) { // FIXME: Evaluate this correctly! Result = (int)FL->getValue(); break; } if (Loc) *Loc = Operand->getLocStart(); return false; } case ConditionalOperatorClass: { const ConditionalOperator *Exp = cast(this); if (!Exp->getCond()->isIntegerConstantExpr(Result, Ctx, Loc, isEvaluated)) return false; const Expr *TrueExp = Exp->getLHS(); const Expr *FalseExp = Exp->getRHS(); if (Result == 0) std::swap(TrueExp, FalseExp); // Evaluate the false one first, discard the result. if (!FalseExp->isIntegerConstantExpr(Result, Ctx, Loc, false)) return false; // Evalute the true one, capture the result. if (!TrueExp->isIntegerConstantExpr(Result, Ctx, Loc, isEvaluated)) return false; break; } } // Cases that are valid constant exprs fall through to here. Result.setIsUnsigned(getType()->isUnsignedIntegerType()); return true; } /// isNullPointerConstant - C99 6.3.2.3p3 - Return true if this is either an /// integer constant expression with the value zero, or if this is one that is /// cast to void*. bool Expr::isNullPointerConstant(ASTContext &Ctx) const { // Strip off a cast to void*, if it exists. if (const CastExpr *CE = dyn_cast(this)) { // Check that it is a cast to void*. if (const PointerType *PT = dyn_cast(CE->getType())) { QualType Pointee = PT->getPointeeType(); if (Pointee.getQualifiers() == 0 && Pointee->isVoidType() && // to void* CE->getSubExpr()->getType()->isIntegerType()) // from int. return CE->getSubExpr()->isNullPointerConstant(Ctx); } } else if (const ParenExpr *PE = dyn_cast(this)) { // Accept ((void*)0) as a null pointer constant, as many other // implementations do. return PE->getSubExpr()->isNullPointerConstant(Ctx); } // This expression must be an integer type. if (!getType()->isIntegerType()) return false; // If we have an integer constant expression, we need to *evaluate* it and // test for the value 0. llvm::APSInt Val(32); return isIntegerConstantExpr(Val, Ctx, 0, true) && Val == 0; } unsigned OCUVectorElementExpr::getNumElements() const { return strlen(Accessor.getName()); } /// getComponentType - Determine whether the components of this access are /// "point" "color" or "texture" elements. OCUVectorElementExpr::ElementType OCUVectorElementExpr::getElementType() const { // derive the component type, no need to waste space. const char *compStr = Accessor.getName(); if (OCUVectorType::getPointAccessorIdx(*compStr) != -1) return Point; if (OCUVectorType::getColorAccessorIdx(*compStr) != -1) return Color; assert(OCUVectorType::getTextureAccessorIdx(*compStr) != -1 && "getComponentType(): Illegal accessor"); return Texture; } /// containsDuplicateElements - Return true if any element access is /// repeated. bool OCUVectorElementExpr::containsDuplicateElements() const { const char *compStr = Accessor.getName(); unsigned length = strlen(compStr); for (unsigned i = 0; i < length-1; i++) { const char *s = compStr+i; for (const char c = *s++; *s; s++) if (c == *s) return true; } return false; } /// getEncodedElementAccess - We encode fields with two bits per component. unsigned OCUVectorElementExpr::getEncodedElementAccess() const { const char *compStr = Accessor.getName(); unsigned length = getNumElements(); unsigned Result = 0; while (length--) { Result <<= 2; int Idx = OCUVectorType::getAccessorIdx(compStr[length]); assert(Idx != -1 && "Invalid accessor letter"); Result |= Idx; } return Result; }