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Diffstat (limited to 'contrib/llvm/tools/clang/lib/AST/ExprClassification.cpp')
| -rw-r--r-- | contrib/llvm/tools/clang/lib/AST/ExprClassification.cpp | 471 |
1 files changed, 471 insertions, 0 deletions
diff --git a/contrib/llvm/tools/clang/lib/AST/ExprClassification.cpp b/contrib/llvm/tools/clang/lib/AST/ExprClassification.cpp new file mode 100644 index 0000000..60ac347 --- /dev/null +++ b/contrib/llvm/tools/clang/lib/AST/ExprClassification.cpp @@ -0,0 +1,471 @@ +//===--- ExprClassification.cpp - Expression AST Node Implementation ------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This file implements Expr::classify. +// +//===----------------------------------------------------------------------===// + +#include "llvm/Support/ErrorHandling.h" +#include "clang/AST/Expr.h" +#include "clang/AST/ExprCXX.h" +#include "clang/AST/ExprObjC.h" +#include "clang/AST/ASTContext.h" +#include "clang/AST/DeclObjC.h" +#include "clang/AST/DeclCXX.h" +#include "clang/AST/DeclTemplate.h" +using namespace clang; + +typedef Expr::Classification Cl; + +static Cl::Kinds ClassifyInternal(ASTContext &Ctx, const Expr *E); +static Cl::Kinds ClassifyDecl(ASTContext &Ctx, const Decl *D); +static Cl::Kinds ClassifyUnnamed(ASTContext &Ctx, QualType T); +static Cl::Kinds ClassifyMemberExpr(ASTContext &Ctx, const MemberExpr *E); +static Cl::Kinds ClassifyBinaryOp(ASTContext &Ctx, const BinaryOperator *E); +static Cl::Kinds ClassifyConditional(ASTContext &Ctx, + const ConditionalOperator *E); +static Cl::ModifiableType IsModifiable(ASTContext &Ctx, const Expr *E, + Cl::Kinds Kind, SourceLocation &Loc); + +Cl Expr::ClassifyImpl(ASTContext &Ctx, SourceLocation *Loc) const { + assert(!TR->isReferenceType() && "Expressions can't have reference type."); + + Cl::Kinds kind = ClassifyInternal(Ctx, this); + // C99 6.3.2.1: An lvalue is an expression with an object type or an + // incomplete type other than void. + if (!Ctx.getLangOptions().CPlusPlus) { + // Thus, no functions. + if (TR->isFunctionType() || TR == Ctx.OverloadTy) + kind = Cl::CL_Function; + // No void either, but qualified void is OK because it is "other than void". + else if (TR->isVoidType() && !Ctx.getCanonicalType(TR).hasQualifiers()) + kind = Cl::CL_Void; + } + + Cl::ModifiableType modifiable = Cl::CM_Untested; + if (Loc) + modifiable = IsModifiable(Ctx, this, kind, *Loc); + return Classification(kind, modifiable); +} + +static Cl::Kinds ClassifyInternal(ASTContext &Ctx, const Expr *E) { + // This function takes the first stab at classifying expressions. + const LangOptions &Lang = Ctx.getLangOptions(); + + switch (E->getStmtClass()) { + // First come the expressions that are always lvalues, unconditionally. + + case Expr::ObjCIsaExprClass: + // C++ [expr.prim.general]p1: A string literal is an lvalue. + case Expr::StringLiteralClass: + // @encode is equivalent to its string + case Expr::ObjCEncodeExprClass: + // __func__ and friends are too. + case Expr::PredefinedExprClass: + // Property references are lvalues + case Expr::ObjCPropertyRefExprClass: + case Expr::ObjCImplicitSetterGetterRefExprClass: + // C++ [expr.typeid]p1: The result of a typeid expression is an lvalue of... + case Expr::CXXTypeidExprClass: + // Unresolved lookups get classified as lvalues. + // FIXME: Is this wise? Should they get their own kind? + case Expr::UnresolvedLookupExprClass: + case Expr::UnresolvedMemberExprClass: + // ObjC instance variables are lvalues + // FIXME: ObjC++0x might have different rules + case Expr::ObjCIvarRefExprClass: + // C99 6.5.2.5p5 says that compound literals are lvalues. + // FIXME: C++ might have a different opinion. + case Expr::CompoundLiteralExprClass: + return Cl::CL_LValue; + + // Next come the complicated cases. + + // C++ [expr.sub]p1: The result is an lvalue of type "T". + // However, subscripting vector types is more like member access. + case Expr::ArraySubscriptExprClass: + if (cast<ArraySubscriptExpr>(E)->getBase()->getType()->isVectorType()) + return ClassifyInternal(Ctx, cast<ArraySubscriptExpr>(E)->getBase()); + return Cl::CL_LValue; + + // C++ [expr.prim.general]p3: The result is an lvalue if the entity is a + // function or variable and a prvalue otherwise. + case Expr::DeclRefExprClass: + return ClassifyDecl(Ctx, cast<DeclRefExpr>(E)->getDecl()); + // We deal with names referenced from blocks the same way. + case Expr::BlockDeclRefExprClass: + return ClassifyDecl(Ctx, cast<BlockDeclRefExpr>(E)->getDecl()); + + // Member access is complex. + case Expr::MemberExprClass: + return ClassifyMemberExpr(Ctx, cast<MemberExpr>(E)); + + case Expr::UnaryOperatorClass: + switch (cast<UnaryOperator>(E)->getOpcode()) { + // C++ [expr.unary.op]p1: The unary * operator performs indirection: + // [...] the result is an lvalue referring to the object or function + // to which the expression points. + case UnaryOperator::Deref: + return Cl::CL_LValue; + + // GNU extensions, simply look through them. + case UnaryOperator::Real: + case UnaryOperator::Imag: + case UnaryOperator::Extension: + return ClassifyInternal(Ctx, cast<UnaryOperator>(E)->getSubExpr()); + + // C++ [expr.pre.incr]p1: The result is the updated operand; it is an + // lvalue, [...] + // Not so in C. + case UnaryOperator::PreInc: + case UnaryOperator::PreDec: + return Lang.CPlusPlus ? Cl::CL_LValue : Cl::CL_PRValue; + + default: + return Cl::CL_PRValue; + } + + // Implicit casts are lvalues if they're lvalue casts. Other than that, we + // only specifically record class temporaries. + case Expr::ImplicitCastExprClass: + if (cast<ImplicitCastExpr>(E)->isLvalueCast()) + return Cl::CL_LValue; + return Lang.CPlusPlus && E->getType()->isRecordType() ? + Cl::CL_ClassTemporary : Cl::CL_PRValue; + + // C++ [expr.prim.general]p4: The presence of parentheses does not affect + // whether the expression is an lvalue. + case Expr::ParenExprClass: + return ClassifyInternal(Ctx, cast<ParenExpr>(E)->getSubExpr()); + + case Expr::BinaryOperatorClass: + case Expr::CompoundAssignOperatorClass: + // C doesn't have any binary expressions that are lvalues. + if (Lang.CPlusPlus) + return ClassifyBinaryOp(Ctx, cast<BinaryOperator>(E)); + return Cl::CL_PRValue; + + case Expr::CallExprClass: + case Expr::CXXOperatorCallExprClass: + case Expr::CXXMemberCallExprClass: + return ClassifyUnnamed(Ctx, cast<CallExpr>(E)->getCallReturnType()); + + // __builtin_choose_expr is equivalent to the chosen expression. + case Expr::ChooseExprClass: + return ClassifyInternal(Ctx, cast<ChooseExpr>(E)->getChosenSubExpr(Ctx)); + + // Extended vector element access is an lvalue unless there are duplicates + // in the shuffle expression. + case Expr::ExtVectorElementExprClass: + return cast<ExtVectorElementExpr>(E)->containsDuplicateElements() ? + Cl::CL_DuplicateVectorComponents : Cl::CL_LValue; + + // Simply look at the actual default argument. + case Expr::CXXDefaultArgExprClass: + return ClassifyInternal(Ctx, cast<CXXDefaultArgExpr>(E)->getExpr()); + + // Same idea for temporary binding. + case Expr::CXXBindTemporaryExprClass: + return ClassifyInternal(Ctx, cast<CXXBindTemporaryExpr>(E)->getSubExpr()); + + // And the temporary lifetime guard. + case Expr::CXXExprWithTemporariesClass: + return ClassifyInternal(Ctx, cast<CXXExprWithTemporaries>(E)->getSubExpr()); + + // Casts depend completely on the target type. All casts work the same. + case Expr::CStyleCastExprClass: + case Expr::CXXFunctionalCastExprClass: + case Expr::CXXStaticCastExprClass: + case Expr::CXXDynamicCastExprClass: + case Expr::CXXReinterpretCastExprClass: + case Expr::CXXConstCastExprClass: + // Only in C++ can casts be interesting at all. + if (!Lang.CPlusPlus) return Cl::CL_PRValue; + return ClassifyUnnamed(Ctx, cast<ExplicitCastExpr>(E)->getTypeAsWritten()); + + case Expr::ConditionalOperatorClass: + // Once again, only C++ is interesting. + if (!Lang.CPlusPlus) return Cl::CL_PRValue; + return ClassifyConditional(Ctx, cast<ConditionalOperator>(E)); + + // ObjC message sends are effectively function calls, if the target function + // is known. + case Expr::ObjCMessageExprClass: + if (const ObjCMethodDecl *Method = + cast<ObjCMessageExpr>(E)->getMethodDecl()) { + return ClassifyUnnamed(Ctx, Method->getResultType()); + } + + // Some C++ expressions are always class temporaries. + case Expr::CXXConstructExprClass: + case Expr::CXXTemporaryObjectExprClass: + case Expr::CXXScalarValueInitExprClass: + return Cl::CL_ClassTemporary; + + // Everything we haven't handled is a prvalue. + default: + return Cl::CL_PRValue; + } +} + +/// ClassifyDecl - Return the classification of an expression referencing the +/// given declaration. +static Cl::Kinds ClassifyDecl(ASTContext &Ctx, const Decl *D) { + // C++ [expr.prim.general]p6: The result is an lvalue if the entity is a + // function, variable, or data member and a prvalue otherwise. + // In C, functions are not lvalues. + // In addition, NonTypeTemplateParmDecl derives from VarDecl but isn't an + // lvalue unless it's a reference type (C++ [temp.param]p6), so we need to + // special-case this. + bool islvalue; + if (const NonTypeTemplateParmDecl *NTTParm = + dyn_cast<NonTypeTemplateParmDecl>(D)) + islvalue = NTTParm->getType()->isReferenceType(); + else + islvalue = isa<VarDecl>(D) || isa<FieldDecl>(D) || + (Ctx.getLangOptions().CPlusPlus && + (isa<FunctionDecl>(D) || isa<FunctionTemplateDecl>(D))); + + return islvalue ? Cl::CL_LValue : Cl::CL_PRValue; +} + +/// ClassifyUnnamed - Return the classification of an expression yielding an +/// unnamed value of the given type. This applies in particular to function +/// calls and casts. +static Cl::Kinds ClassifyUnnamed(ASTContext &Ctx, QualType T) { + // In C, function calls are always rvalues. + if (!Ctx.getLangOptions().CPlusPlus) return Cl::CL_PRValue; + + // C++ [expr.call]p10: A function call is an lvalue if the result type is an + // lvalue reference type or an rvalue reference to function type, an xvalue + // if the result type is an rvalue refernence to object type, and a prvalue + // otherwise. + if (T->isLValueReferenceType()) + return Cl::CL_LValue; + const RValueReferenceType *RV = T->getAs<RValueReferenceType>(); + if (!RV) // Could still be a class temporary, though. + return T->isRecordType() ? Cl::CL_ClassTemporary : Cl::CL_PRValue; + + return RV->getPointeeType()->isFunctionType() ? Cl::CL_LValue : Cl::CL_XValue; +} + +static Cl::Kinds ClassifyMemberExpr(ASTContext &Ctx, const MemberExpr *E) { + // Handle C first, it's easier. + if (!Ctx.getLangOptions().CPlusPlus) { + // C99 6.5.2.3p3 + // For dot access, the expression is an lvalue if the first part is. For + // arrow access, it always is an lvalue. + if (E->isArrow()) + return Cl::CL_LValue; + // ObjC property accesses are not lvalues, but get special treatment. + Expr *Base = E->getBase(); + if (isa<ObjCPropertyRefExpr>(Base) || + isa<ObjCImplicitSetterGetterRefExpr>(Base)) + return Cl::CL_SubObjCPropertySetting; + return ClassifyInternal(Ctx, Base); + } + + NamedDecl *Member = E->getMemberDecl(); + // C++ [expr.ref]p3: E1->E2 is converted to the equivalent form (*(E1)).E2. + // C++ [expr.ref]p4: If E2 is declared to have type "reference to T", then + // E1.E2 is an lvalue. + if (ValueDecl *Value = dyn_cast<ValueDecl>(Member)) + if (Value->getType()->isReferenceType()) + return Cl::CL_LValue; + + // Otherwise, one of the following rules applies. + // -- If E2 is a static member [...] then E1.E2 is an lvalue. + if (isa<VarDecl>(Member) && Member->getDeclContext()->isRecord()) + return Cl::CL_LValue; + + // -- If E2 is a non-static data member [...]. If E1 is an lvalue, then + // E1.E2 is an lvalue; if E1 is an xvalue, then E1.E2 is an xvalue; + // otherwise, it is a prvalue. + if (isa<FieldDecl>(Member)) { + // *E1 is an lvalue + if (E->isArrow()) + return Cl::CL_LValue; + return ClassifyInternal(Ctx, E->getBase()); + } + + // -- If E2 is a [...] member function, [...] + // -- If it refers to a static member function [...], then E1.E2 is an + // lvalue; [...] + // -- Otherwise [...] E1.E2 is a prvalue. + if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(Member)) + return Method->isStatic() ? Cl::CL_LValue : Cl::CL_MemberFunction; + + // -- If E2 is a member enumerator [...], the expression E1.E2 is a prvalue. + // So is everything else we haven't handled yet. + return Cl::CL_PRValue; +} + +static Cl::Kinds ClassifyBinaryOp(ASTContext &Ctx, const BinaryOperator *E) { + assert(Ctx.getLangOptions().CPlusPlus && + "This is only relevant for C++."); + // C++ [expr.ass]p1: All [...] return an lvalue referring to the left operand. + if (E->isAssignmentOp()) + return Cl::CL_LValue; + + // C++ [expr.comma]p1: the result is of the same value category as its right + // operand, [...]. + if (E->getOpcode() == BinaryOperator::Comma) + return ClassifyInternal(Ctx, E->getRHS()); + + // C++ [expr.mptr.oper]p6: The result of a .* expression whose second operand + // is a pointer to a data member is of the same value category as its first + // operand. + if (E->getOpcode() == BinaryOperator::PtrMemD) + return E->getType()->isFunctionType() ? Cl::CL_MemberFunction : + ClassifyInternal(Ctx, E->getLHS()); + + // C++ [expr.mptr.oper]p6: The result of an ->* expression is an lvalue if its + // second operand is a pointer to data member and a prvalue otherwise. + if (E->getOpcode() == BinaryOperator::PtrMemI) + return E->getType()->isFunctionType() ? + Cl::CL_MemberFunction : Cl::CL_LValue; + + // All other binary operations are prvalues. + return Cl::CL_PRValue; +} + +static Cl::Kinds ClassifyConditional(ASTContext &Ctx, + const ConditionalOperator *E) { + assert(Ctx.getLangOptions().CPlusPlus && + "This is only relevant for C++."); + + Expr *True = E->getTrueExpr(); + Expr *False = E->getFalseExpr(); + // C++ [expr.cond]p2 + // If either the second or the third operand has type (cv) void, [...] + // the result [...] is a prvalue. + if (True->getType()->isVoidType() || False->getType()->isVoidType()) + return Cl::CL_PRValue; + + // Note that at this point, we have already performed all conversions + // according to [expr.cond]p3. + // C++ [expr.cond]p4: If the second and third operands are glvalues of the + // same value category [...], the result is of that [...] value category. + // C++ [expr.cond]p5: Otherwise, the result is a prvalue. + Cl::Kinds LCl = ClassifyInternal(Ctx, True), + RCl = ClassifyInternal(Ctx, False); + return LCl == RCl ? LCl : Cl::CL_PRValue; +} + +static Cl::ModifiableType IsModifiable(ASTContext &Ctx, const Expr *E, + Cl::Kinds Kind, SourceLocation &Loc) { + // As a general rule, we only care about lvalues. But there are some rvalues + // for which we want to generate special results. + if (Kind == Cl::CL_PRValue) { + // For the sake of better diagnostics, we want to specifically recognize + // use of the GCC cast-as-lvalue extension. + if (const CStyleCastExpr *CE = dyn_cast<CStyleCastExpr>(E->IgnoreParens())){ + if (CE->getSubExpr()->Classify(Ctx).isLValue()) { + Loc = CE->getLParenLoc(); + return Cl::CM_LValueCast; + } + } + } + if (Kind != Cl::CL_LValue) + return Cl::CM_RValue; + + // This is the lvalue case. + // Functions are lvalues in C++, but not modifiable. (C++ [basic.lval]p6) + if (Ctx.getLangOptions().CPlusPlus && E->getType()->isFunctionType()) + return Cl::CM_Function; + + // You cannot assign to a variable outside a block from within the block if + // it is not marked __block, e.g. + // void takeclosure(void (^C)(void)); + // void func() { int x = 1; takeclosure(^{ x = 7; }); } + if (const BlockDeclRefExpr *BDR = dyn_cast<BlockDeclRefExpr>(E)) { + if (!BDR->isByRef() && isa<VarDecl>(BDR->getDecl())) + return Cl::CM_NotBlockQualified; + } + + // Assignment to a property in ObjC is an implicit setter access. But a + // setter might not exist. + if (const ObjCImplicitSetterGetterRefExpr *Expr = + dyn_cast<ObjCImplicitSetterGetterRefExpr>(E)) { + if (Expr->getSetterMethod() == 0) + return Cl::CM_NoSetterProperty; + } + + CanQualType CT = Ctx.getCanonicalType(E->getType()); + // Const stuff is obviously not modifiable. + if (CT.isConstQualified()) + return Cl::CM_ConstQualified; + // Arrays are not modifiable, only their elements are. + if (CT->isArrayType()) + return Cl::CM_ArrayType; + // Incomplete types are not modifiable. + if (CT->isIncompleteType()) + return Cl::CM_IncompleteType; + + // Records with any const fields (recursively) are not modifiable. + if (const RecordType *R = CT->getAs<RecordType>()) { + assert(!Ctx.getLangOptions().CPlusPlus && + "C++ struct assignment should be resolved by the " + "copy assignment operator."); + if (R->hasConstFields()) + return Cl::CM_ConstQualified; + } + + return Cl::CM_Modifiable; +} + +Expr::isLvalueResult Expr::isLvalue(ASTContext &Ctx) const { + Classification VC = Classify(Ctx); + switch (VC.getKind()) { + case Cl::CL_LValue: return LV_Valid; + case Cl::CL_XValue: return LV_InvalidExpression; + case Cl::CL_Function: return LV_NotObjectType; + case Cl::CL_Void: return LV_IncompleteVoidType; + case Cl::CL_DuplicateVectorComponents: return LV_DuplicateVectorComponents; + case Cl::CL_MemberFunction: return LV_MemberFunction; + case Cl::CL_SubObjCPropertySetting: return LV_SubObjCPropertySetting; + case Cl::CL_ClassTemporary: return LV_ClassTemporary; + case Cl::CL_PRValue: return LV_InvalidExpression; + } + llvm_unreachable("Unhandled kind"); +} + +Expr::isModifiableLvalueResult +Expr::isModifiableLvalue(ASTContext &Ctx, SourceLocation *Loc) const { + SourceLocation dummy; + Classification VC = ClassifyModifiable(Ctx, Loc ? *Loc : dummy); + switch (VC.getKind()) { + case Cl::CL_LValue: break; + case Cl::CL_XValue: return MLV_InvalidExpression; + case Cl::CL_Function: return MLV_NotObjectType; + case Cl::CL_Void: return MLV_IncompleteVoidType; + case Cl::CL_DuplicateVectorComponents: return MLV_DuplicateVectorComponents; + case Cl::CL_MemberFunction: return MLV_MemberFunction; + case Cl::CL_SubObjCPropertySetting: return MLV_SubObjCPropertySetting; + case Cl::CL_ClassTemporary: return MLV_ClassTemporary; + case Cl::CL_PRValue: + return VC.getModifiable() == Cl::CM_LValueCast ? + MLV_LValueCast : MLV_InvalidExpression; + } + assert(VC.getKind() == Cl::CL_LValue && "Unhandled kind"); + switch (VC.getModifiable()) { + case Cl::CM_Untested: llvm_unreachable("Did not test modifiability"); + case Cl::CM_Modifiable: return MLV_Valid; + case Cl::CM_RValue: llvm_unreachable("CM_RValue and CL_LValue don't match"); + case Cl::CM_Function: return MLV_NotObjectType; + case Cl::CM_LValueCast: + llvm_unreachable("CM_LValueCast and CL_LValue don't match"); + case Cl::CM_NotBlockQualified: return MLV_NotBlockQualified; + case Cl::CM_NoSetterProperty: return MLV_NoSetterProperty; + case Cl::CM_ConstQualified: return MLV_ConstQualified; + case Cl::CM_ArrayType: return MLV_ArrayType; + case Cl::CM_IncompleteType: return MLV_IncompleteType; + } + llvm_unreachable("Unhandled modifiable type"); +} |
