[cfe-commits] r107007 - in /cfe/trunk: include/clang/AST/Expr.h lib/AST/CMakeLists.txt lib/AST/Expr.cpp lib/AST/ExprClassification.cpp
Sebastian Redl
sebastian.redl at getdesigned.at
Mon Jun 28 08:09:07 PDT 2010
Author: cornedbee
Date: Mon Jun 28 10:09:07 2010
New Revision: 107007
URL: http://llvm.org/viewvc/llvm-project?rev=107007&view=rev
Log:
Introduce Expr::Classify and Expr::ClassifyModifiable, which determine the classification of an expression under the C++0x taxology (value category). Reimplement isLvalue and isModifiableLvalue using these functions. No regressions in the test suite from this, and my rough performance check doesn't show any regressions either.
Added:
cfe/trunk/lib/AST/ExprClassification.cpp
Modified:
cfe/trunk/include/clang/AST/Expr.h
cfe/trunk/lib/AST/CMakeLists.txt
cfe/trunk/lib/AST/Expr.cpp
Modified: cfe/trunk/include/clang/AST/Expr.h
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/AST/Expr.h?rev=107007&r1=107006&r2=107007&view=diff
==============================================================================
--- cfe/trunk/include/clang/AST/Expr.h (original)
+++ cfe/trunk/include/clang/AST/Expr.h Mon Jun 28 10:09:07 2010
@@ -162,9 +162,6 @@
};
isLvalueResult isLvalue(ASTContext &Ctx) const;
- // Same as above, but excluding checks for non-object and void types in C
- isLvalueResult isLvalueInternal(ASTContext &Ctx) const;
-
/// 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,
@@ -194,6 +191,95 @@
isModifiableLvalueResult isModifiableLvalue(ASTContext &Ctx,
SourceLocation *Loc = 0) const;
+ /// \brief The return type of classify(). Represents the C++0x expression
+ /// taxonomy.
+ class Classification {
+ public:
+ /// \brief The various classification results. Most of these mean prvalue.
+ enum Kinds {
+ CL_LValue,
+ CL_XValue,
+ CL_Function, // Functions cannot be lvalues in C.
+ CL_Void, // Void cannot be an lvalue in C.
+ CL_DuplicateVectorComponents, // A vector shuffle with dupes.
+ CL_MemberFunction, // An expression referring to a member function
+ CL_SubObjCPropertySetting,
+ CL_ClassTemporary, // A prvalue of class type
+ CL_PRValue // A prvalue for any other reason, of any other type
+ };
+ /// \brief The results of modification testing.
+ enum ModifiableType {
+ CM_Untested, // testModifiable was false.
+ CM_Modifiable,
+ CM_RValue, // Not modifiable because it's an rvalue
+ CM_Function, // Not modifiable because it's a function; C++ only
+ CM_LValueCast, // Same as CM_RValue, but indicates GCC cast-as-lvalue ext
+ CM_NotBlockQualified, // Not captured in the closure
+ CM_NoSetterProperty,// Implicit assignment to ObjC property without setter
+ CM_ConstQualified,
+ CM_ArrayType,
+ CM_IncompleteType
+ };
+
+ private:
+ friend class Expr;
+
+ unsigned short Kind;
+ unsigned short Modifiable;
+
+ explicit Classification(Kinds k, ModifiableType m)
+ : Kind(k), Modifiable(m)
+ {}
+
+ public:
+ Classification() {}
+
+ Kinds getKind() const { return static_cast<Kinds>(Kind); }
+ ModifiableType getModifiable() const {
+ assert(Modifiable != CM_Untested && "Did not test for modifiability.");
+ return static_cast<ModifiableType>(Modifiable);
+ }
+ bool isLValue() const { return Kind == CL_LValue; }
+ bool isXValue() const { return Kind == CL_XValue; }
+ bool isGLValue() const { return Kind <= CL_XValue; }
+ bool isPRValue() const { return Kind >= CL_Function; }
+ bool isRValue() const { return Kind >= CL_XValue; }
+ bool isModifiable() const { return getModifiable() == CM_Modifiable; }
+ };
+ /// \brief classify - Classify this expression according to the C++0x
+ /// expression taxonomy.
+ ///
+ /// C++0x defines ([basic.lval]) a new taxonomy of expressions to replace the
+ /// old lvalue vs rvalue. This function determines the type of expression this
+ /// is. There are three expression types:
+ /// - lvalues are classical lvalues as in C++03.
+ /// - prvalues are equivalent to rvalues in C++03.
+ /// - xvalues are expressions yielding unnamed rvalue references, e.g. a
+ /// function returning an rvalue reference.
+ /// lvalues and xvalues are collectively referred to as glvalues, while
+ /// prvalues and xvalues together form rvalues.
+ /// If a
+ Classification Classify(ASTContext &Ctx) const {
+ return ClassifyImpl(Ctx, 0);
+ }
+
+ /// \brief classifyModifiable - Classify this expression according to the
+ /// C++0x expression taxonomy, and see if it is valid on the left side
+ /// of an assignment.
+ ///
+ /// This function extends classify in that it also tests whether the
+ /// expression is modifiable (C99 6.3.2.1p1).
+ /// \param Loc A source location that might be filled with a relevant location
+ /// if the expression is not modifiable.
+ Classification ClassifyModifiable(ASTContext &Ctx, SourceLocation &Loc) const{
+ return ClassifyImpl(Ctx, &Loc);
+ }
+
+private:
+ Classification ClassifyImpl(ASTContext &Ctx, SourceLocation *Loc) const;
+
+public:
+
/// \brief If this expression refers to a bit-field, retrieve the
/// declaration of that bit-field.
FieldDecl *getBitField();
Modified: cfe/trunk/lib/AST/CMakeLists.txt
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/CMakeLists.txt?rev=107007&r1=107006&r2=107007&view=diff
==============================================================================
--- cfe/trunk/lib/AST/CMakeLists.txt (original)
+++ cfe/trunk/lib/AST/CMakeLists.txt Mon Jun 28 10:09:07 2010
@@ -18,6 +18,7 @@
DeclPrinter.cpp
DeclTemplate.cpp
Expr.cpp
+ ExprClassification.cpp
ExprConstant.cpp
ExprCXX.cpp
FullExpr.cpp
Modified: cfe/trunk/lib/AST/Expr.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/Expr.cpp?rev=107007&r1=107006&r2=107007&view=diff
==============================================================================
--- cfe/trunk/lib/AST/Expr.cpp (original)
+++ cfe/trunk/lib/AST/Expr.cpp Mon Jun 28 10:09:07 2010
@@ -1146,378 +1146,6 @@
}
}
-/// DeclCanBeLvalue - Determine whether the given declaration can be
-/// an lvalue. This is a helper routine for isLvalue.
-static bool DeclCanBeLvalue(const NamedDecl *Decl, ASTContext &Ctx) {
- // C++ [temp.param]p6:
- // A non-type non-reference template-parameter is not an lvalue.
- if (const NonTypeTemplateParmDecl *NTTParm
- = dyn_cast<NonTypeTemplateParmDecl>(Decl))
- return NTTParm->getType()->isReferenceType();
-
- return isa<VarDecl>(Decl) || isa<FieldDecl>(Decl) ||
- // C++ 3.10p2: An lvalue refers to an object or function.
- (Ctx.getLangOptions().CPlusPlus &&
- (isa<FunctionDecl>(Decl) || isa<FunctionTemplateDecl>(Decl)));
-}
-
-/// 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
-/// - (__real__ e) and (__imag__ e) where e is an lvalue [GNU extension]
-/// - reference type [C++ [expr]]
-///
-Expr::isLvalueResult Expr::isLvalue(ASTContext &Ctx) const {
- assert(!TR->isReferenceType() && "Expressions can't have reference type.");
-
- isLvalueResult Res = isLvalueInternal(Ctx);
- if (Res != LV_Valid || Ctx.getLangOptions().CPlusPlus)
- return Res;
-
- // first, check the type (C99 6.3.2.1). Expressions with function
- // type in C are not lvalues, but they can be lvalues in C++.
- if (TR->isFunctionType() || TR == Ctx.OverloadTy)
- return LV_NotObjectType;
-
- // Allow qualified void which is an incomplete type other than void (yuck).
- if (TR->isVoidType() && !Ctx.getCanonicalType(TR).hasQualifiers())
- return LV_IncompleteVoidType;
-
- return LV_Valid;
-}
-
-// Check whether the expression can be sanely treated like an l-value
-Expr::isLvalueResult Expr::isLvalueInternal(ASTContext &Ctx) const {
- switch (getStmtClass()) {
- case ObjCIsaExprClass:
- case StringLiteralClass: // C99 6.5.1p4
- case ObjCEncodeExprClass: // @encode behaves like its string in every way.
- return LV_Valid;
- 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<ArraySubscriptExpr>(this)->getBase()->getType()->isVectorType())
- return cast<ArraySubscriptExpr>(this)->getBase()->isLvalue(Ctx);
- return LV_Valid;
- case DeclRefExprClass: { // C99 6.5.1p2
- const NamedDecl *RefdDecl = cast<DeclRefExpr>(this)->getDecl();
- if (DeclCanBeLvalue(RefdDecl, Ctx))
- return LV_Valid;
- break;
- }
- case BlockDeclRefExprClass: {
- const BlockDeclRefExpr *BDR = cast<BlockDeclRefExpr>(this);
- if (isa<VarDecl>(BDR->getDecl()))
- return LV_Valid;
- break;
- }
- case MemberExprClass: {
- const MemberExpr *m = cast<MemberExpr>(this);
- if (Ctx.getLangOptions().CPlusPlus) { // C++ [expr.ref]p4:
- NamedDecl *Member = m->getMemberDecl();
- // 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 LV_Valid;
-
- // -- If E2 is a static data member [...] then E1.E2 is an lvalue.
- if (isa<VarDecl>(Member) && Member->getDeclContext()->isRecord())
- return LV_Valid;
-
- // -- If E2 is a non-static data member [...]. If E1 is an
- // lvalue, then E1.E2 is an lvalue.
- if (isa<FieldDecl>(Member)) {
- if (m->isArrow())
- return LV_Valid;
- return m->getBase()->isLvalue(Ctx);
- }
-
- // -- If it refers to a static member function [...], then
- // E1.E2 is an lvalue.
- // -- Otherwise, if E1.E2 refers to a non-static member
- // function [...], then E1.E2 is not an lvalue.
- if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(Member))
- return Method->isStatic()? LV_Valid : LV_MemberFunction;
-
- // -- If E2 is a member enumerator [...], the expression E1.E2
- // is not an lvalue.
- if (isa<EnumConstantDecl>(Member))
- return LV_InvalidExpression;
-
- // Not an lvalue.
- return LV_InvalidExpression;
- }
-
- // C99 6.5.2.3p4
- if (m->isArrow())
- return LV_Valid;
- Expr *BaseExp = m->getBase();
- if (BaseExp->getStmtClass() == ObjCPropertyRefExprClass ||
- BaseExp->getStmtClass() == ObjCImplicitSetterGetterRefExprClass)
- return LV_SubObjCPropertySetting;
- return
- BaseExp->isLvalue(Ctx);
- }
- case UnaryOperatorClass:
- if (cast<UnaryOperator>(this)->getOpcode() == UnaryOperator::Deref)
- return LV_Valid; // C99 6.5.3p4
-
- if (cast<UnaryOperator>(this)->getOpcode() == UnaryOperator::Real ||
- cast<UnaryOperator>(this)->getOpcode() == UnaryOperator::Imag ||
- cast<UnaryOperator>(this)->getOpcode() == UnaryOperator::Extension)
- return cast<UnaryOperator>(this)->getSubExpr()->isLvalue(Ctx); // GNU.
-
- if (Ctx.getLangOptions().CPlusPlus && // C++ [expr.pre.incr]p1
- (cast<UnaryOperator>(this)->getOpcode() == UnaryOperator::PreInc ||
- cast<UnaryOperator>(this)->getOpcode() == UnaryOperator::PreDec))
- return LV_Valid;
- break;
- case ImplicitCastExprClass:
- if (cast<ImplicitCastExpr>(this)->isLvalueCast())
- return LV_Valid;
-
- // If this is a conversion to a class temporary, make a note of
- // that.
- if (Ctx.getLangOptions().CPlusPlus && getType()->isRecordType())
- return LV_ClassTemporary;
-
- break;
- case ParenExprClass: // C99 6.5.1p5
- return cast<ParenExpr>(this)->getSubExpr()->isLvalue(Ctx);
- case BinaryOperatorClass:
- case CompoundAssignOperatorClass: {
- const BinaryOperator *BinOp = cast<BinaryOperator>(this);
-
- if (Ctx.getLangOptions().CPlusPlus && // C++ [expr.comma]p1
- BinOp->getOpcode() == BinaryOperator::Comma)
- return BinOp->getRHS()->isLvalue(Ctx);
-
- // C++ [expr.mptr.oper]p6
- // The result of a .* expression is an lvalue only if its first operand is
- // an lvalue and its second operand is a pointer to data member.
- if (BinOp->getOpcode() == BinaryOperator::PtrMemD &&
- !BinOp->getType()->isFunctionType())
- return BinOp->getLHS()->isLvalue(Ctx);
-
- // The result of an ->* expression is an lvalue only if its second operand
- // is a pointer to data member.
- if (BinOp->getOpcode() == BinaryOperator::PtrMemI &&
- !BinOp->getType()->isFunctionType()) {
- QualType Ty = BinOp->getRHS()->getType();
- if (Ty->isMemberPointerType() && !Ty->isMemberFunctionPointerType())
- return LV_Valid;
- }
-
- if (!BinOp->isAssignmentOp())
- return LV_InvalidExpression;
-
- if (Ctx.getLangOptions().CPlusPlus)
- // C++ [expr.ass]p1:
- // The result of an assignment operation [...] is an lvalue.
- return LV_Valid;
-
-
- // C99 6.5.16:
- // An assignment expression [...] is not an lvalue.
- return LV_InvalidExpression;
- }
- case CallExprClass:
- case CXXOperatorCallExprClass:
- case CXXMemberCallExprClass: {
- // C++0x [expr.call]p10
- // A function call is an lvalue if and only if the result type
- // is an lvalue reference.
- QualType ReturnType = cast<CallExpr>(this)->getCallReturnType();
- if (ReturnType->isLValueReferenceType())
- return LV_Valid;
-
- // If the function is returning a class temporary, make a note of
- // that.
- if (Ctx.getLangOptions().CPlusPlus && ReturnType->isRecordType())
- return LV_ClassTemporary;
-
- break;
- }
- case CompoundLiteralExprClass: // C99 6.5.2.5p5
- // FIXME: Is this what we want in C++?
- return LV_Valid;
- case ChooseExprClass:
- // __builtin_choose_expr is an lvalue if the selected operand is.
- return cast<ChooseExpr>(this)->getChosenSubExpr(Ctx)->isLvalue(Ctx);
- case ExtVectorElementExprClass:
- if (cast<ExtVectorElementExpr>(this)->containsDuplicateElements())
- return LV_DuplicateVectorComponents;
- return LV_Valid;
- case ObjCIvarRefExprClass: // ObjC instance variables are lvalues.
- return LV_Valid;
- case ObjCPropertyRefExprClass: // FIXME: check if read-only property.
- return LV_Valid;
- case ObjCImplicitSetterGetterRefExprClass:
- // FIXME: check if read-only property.
- return LV_Valid;
- case PredefinedExprClass:
- return LV_Valid;
- case UnresolvedLookupExprClass:
- case UnresolvedMemberExprClass:
- return LV_Valid;
- case CXXDefaultArgExprClass:
- return cast<CXXDefaultArgExpr>(this)->getExpr()->isLvalue(Ctx);
- case CStyleCastExprClass:
- case CXXFunctionalCastExprClass:
- case CXXStaticCastExprClass:
- case CXXDynamicCastExprClass:
- case CXXReinterpretCastExprClass:
- case CXXConstCastExprClass:
- // The result of an explicit cast is an lvalue if the type we are
- // casting to is an lvalue reference type. See C++ [expr.cast]p1,
- // C++ [expr.static.cast]p2, C++ [expr.dynamic.cast]p2,
- // C++ [expr.reinterpret.cast]p1, C++ [expr.const.cast]p1.
- if (cast<ExplicitCastExpr>(this)->getTypeAsWritten()->
- isLValueReferenceType())
- return LV_Valid;
-
- // If this is a conversion to a class temporary, make a note of
- // that.
- if (Ctx.getLangOptions().CPlusPlus &&
- cast<ExplicitCastExpr>(this)->getTypeAsWritten()->isRecordType())
- return LV_ClassTemporary;
-
- break;
- case CXXTypeidExprClass:
- // C++ 5.2.8p1: The result of a typeid expression is an lvalue of ...
- return LV_Valid;
- case CXXBindTemporaryExprClass:
- return cast<CXXBindTemporaryExpr>(this)->getSubExpr()->
- isLvalueInternal(Ctx);
- case CXXBindReferenceExprClass:
- // Something that's bound to a reference is always an lvalue.
- return LV_Valid;
- case ConditionalOperatorClass: {
- // Complicated handling is only for C++.
- if (!Ctx.getLangOptions().CPlusPlus)
- return LV_InvalidExpression;
-
- // Sema should have taken care to ensure that a CXXTemporaryObjectExpr is
- // everywhere there's an object converted to an rvalue. Also, any other
- // casts should be wrapped by ImplicitCastExprs. There's just the special
- // case involving throws to work out.
- const ConditionalOperator *Cond = cast<ConditionalOperator>(this);
- Expr *True = Cond->getTrueExpr();
- Expr *False = Cond->getFalseExpr();
- // C++0x 5.16p2
- // If either the second or the third operand has type (cv) void, [...]
- // the result [...] is an rvalue.
- if (True->getType()->isVoidType() || False->getType()->isVoidType())
- return LV_InvalidExpression;
-
- // Both sides must be lvalues for the result to be an lvalue.
- if (True->isLvalue(Ctx) != LV_Valid || False->isLvalue(Ctx) != LV_Valid)
- return LV_InvalidExpression;
-
- // That's it.
- return LV_Valid;
- }
-
- case Expr::CXXExprWithTemporariesClass:
- return cast<CXXExprWithTemporaries>(this)->getSubExpr()->isLvalue(Ctx);
-
- case Expr::ObjCMessageExprClass:
- if (const ObjCMethodDecl *Method
- = cast<ObjCMessageExpr>(this)->getMethodDecl())
- if (Method->getResultType()->isLValueReferenceType())
- return LV_Valid;
- break;
-
- case Expr::CXXConstructExprClass:
- case Expr::CXXTemporaryObjectExprClass:
- case Expr::CXXZeroInitValueExprClass:
- return LV_ClassTemporary;
-
- 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(ASTContext &Ctx, SourceLocation *Loc) const {
- isLvalueResult lvalResult = isLvalue(Ctx);
-
- switch (lvalResult) {
- case LV_Valid:
- // C++ 3.10p11: Functions cannot be modified, but pointers to
- // functions can be modifiable.
- if (Ctx.getLangOptions().CPlusPlus && TR->isFunctionType())
- return MLV_NotObjectType;
- break;
-
- case LV_NotObjectType: return MLV_NotObjectType;
- case LV_IncompleteVoidType: return MLV_IncompleteVoidType;
- case LV_DuplicateVectorComponents: return MLV_DuplicateVectorComponents;
- case LV_InvalidExpression:
- // If the top level is a C-style cast, and the subexpression is a valid
- // lvalue, then this is probably a use of the old-school "cast as lvalue"
- // GCC extension. We don't support it, but we want to produce good
- // diagnostics when it happens so that the user knows why.
- if (const CStyleCastExpr *CE = dyn_cast<CStyleCastExpr>(IgnoreParens())) {
- if (CE->getSubExpr()->isLvalue(Ctx) == LV_Valid) {
- if (Loc)
- *Loc = CE->getLParenLoc();
- return MLV_LValueCast;
- }
- }
- return MLV_InvalidExpression;
- case LV_MemberFunction: return MLV_MemberFunction;
- case LV_SubObjCPropertySetting: return MLV_SubObjCPropertySetting;
- case LV_ClassTemporary:
- return MLV_ClassTemporary;
- }
-
- // The following is illegal:
- // void takeclosure(void (^C)(void));
- // void func() { int x = 1; takeclosure(^{ x = 7; }); }
- //
- if (const BlockDeclRefExpr *BDR = dyn_cast<BlockDeclRefExpr>(this)) {
- if (!BDR->isByRef() && isa<VarDecl>(BDR->getDecl()))
- return MLV_NotBlockQualified;
- }
-
- // Assigning to an 'implicit' property?
- if (const ObjCImplicitSetterGetterRefExpr* Expr =
- dyn_cast<ObjCImplicitSetterGetterRefExpr>(this)) {
- if (Expr->getSetterMethod() == 0)
- return MLV_NoSetterProperty;
- }
-
- QualType CT = Ctx.getCanonicalType(getType());
-
- if (CT.isConstQualified())
- return MLV_ConstQualified;
- if (CT->isArrayType())
- return MLV_ArrayType;
- if (CT->isIncompleteType())
- return MLV_IncompleteType;
-
- if (const RecordType *r = CT->getAs<RecordType>()) {
- if (r->hasConstFields())
- return MLV_ConstQualified;
- }
-
- return MLV_Valid;
-}
-
/// isOBJCGCCandidate - Check if an expression is objc gc'able.
/// returns true, if it is; false otherwise.
bool Expr::isOBJCGCCandidate(ASTContext &Ctx) const {
Added: cfe/trunk/lib/AST/ExprClassification.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/ExprClassification.cpp?rev=107007&view=auto
==============================================================================
--- cfe/trunk/lib/AST/ExprClassification.cpp (added)
+++ cfe/trunk/lib/AST/ExprClassification.cpp Mon Jun 28 10:09:07 2010
@@ -0,0 +1,470 @@
+//===--- 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 "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::CXXZeroInitValueExprClass:
+ 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;
+ }
+ assert(false && "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: assert(false && "Did not test modifiability");
+ case Cl::CM_Modifiable: return MLV_Valid;
+ case Cl::CM_RValue: assert(false && "CM_RValue and CL_LValue don't match");
+ case Cl::CM_Function: return MLV_NotObjectType;
+ case Cl::CM_LValueCast:
+ assert(false && "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;
+ }
+ assert(false && "Unhandled modifiable type");
+}
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