503 lines
22 KiB
C++
503 lines
22 KiB
C++
//===----- CGCXXABI.h - Interface to C++ ABIs -------------------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This provides an abstract class for C++ code generation. Concrete subclasses
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// of this implement code generation for specific C++ ABIs.
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//
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//===----------------------------------------------------------------------===//
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#ifndef CLANG_CODEGEN_CXXABI_H
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#define CLANG_CODEGEN_CXXABI_H
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#include "CodeGenFunction.h"
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#include "clang/Basic/LLVM.h"
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namespace llvm {
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class Constant;
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class Type;
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class Value;
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}
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namespace clang {
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class CastExpr;
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class CXXConstructorDecl;
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class CXXDestructorDecl;
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class CXXMethodDecl;
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class CXXRecordDecl;
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class FieldDecl;
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class MangleContext;
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namespace CodeGen {
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class CodeGenFunction;
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class CodeGenModule;
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/// \brief Implements C++ ABI-specific code generation functions.
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class CGCXXABI {
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protected:
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CodeGenModule &CGM;
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OwningPtr<MangleContext> MangleCtx;
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CGCXXABI(CodeGenModule &CGM)
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: CGM(CGM), MangleCtx(CGM.getContext().createMangleContext()) {}
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protected:
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ImplicitParamDecl *&getThisDecl(CodeGenFunction &CGF) {
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return CGF.CXXABIThisDecl;
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}
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llvm::Value *&getThisValue(CodeGenFunction &CGF) {
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return CGF.CXXABIThisValue;
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}
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/// Issue a diagnostic about unsupported features in the ABI.
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void ErrorUnsupportedABI(CodeGenFunction &CGF, StringRef S);
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/// Get a null value for unsupported member pointers.
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llvm::Constant *GetBogusMemberPointer(QualType T);
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// FIXME: Every place that calls getVTT{Decl,Value} is something
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// that needs to be abstracted properly.
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ImplicitParamDecl *&getVTTDecl(CodeGenFunction &CGF) {
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return CGF.CXXStructorImplicitParamDecl;
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}
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llvm::Value *&getVTTValue(CodeGenFunction &CGF) {
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return CGF.CXXStructorImplicitParamValue;
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}
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ImplicitParamDecl *&getStructorImplicitParamDecl(CodeGenFunction &CGF) {
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return CGF.CXXStructorImplicitParamDecl;
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}
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llvm::Value *&getStructorImplicitParamValue(CodeGenFunction &CGF) {
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return CGF.CXXStructorImplicitParamValue;
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}
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/// Build a parameter variable suitable for 'this'.
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void BuildThisParam(CodeGenFunction &CGF, FunctionArgList &Params);
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/// Perform prolog initialization of the parameter variable suitable
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/// for 'this' emitted by BuildThisParam.
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void EmitThisParam(CodeGenFunction &CGF);
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ASTContext &getContext() const { return CGM.getContext(); }
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virtual bool requiresArrayCookie(const CXXDeleteExpr *E, QualType eltType);
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virtual bool requiresArrayCookie(const CXXNewExpr *E);
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public:
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virtual ~CGCXXABI();
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/// Gets the mangle context.
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MangleContext &getMangleContext() {
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return *MangleCtx;
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}
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/// Returns true if the given constructor or destructor is one of the
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/// kinds that the ABI says returns 'this' (only applies when called
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/// non-virtually for destructors).
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///
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/// There currently is no way to indicate if a destructor returns 'this'
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/// when called virtually, and code generation does not support the case.
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virtual bool HasThisReturn(GlobalDecl GD) const { return false; }
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/// Returns true if the given record type should be returned indirectly.
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virtual bool isReturnTypeIndirect(const CXXRecordDecl *RD) const = 0;
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/// Specify how one should pass an argument of a record type.
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enum RecordArgABI {
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/// Pass it using the normal C aggregate rules for the ABI, potentially
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/// introducing extra copies and passing some or all of it in registers.
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RAA_Default = 0,
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/// Pass it on the stack using its defined layout. The argument must be
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/// evaluated directly into the correct stack position in the arguments area,
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/// and the call machinery must not move it or introduce extra copies.
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RAA_DirectInMemory,
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/// Pass it as a pointer to temporary memory.
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RAA_Indirect
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};
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/// Returns how an argument of the given record type should be passed.
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virtual RecordArgABI getRecordArgABI(const CXXRecordDecl *RD) const = 0;
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/// Find the LLVM type used to represent the given member pointer
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/// type.
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virtual llvm::Type *
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ConvertMemberPointerType(const MemberPointerType *MPT);
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/// Load a member function from an object and a member function
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/// pointer. Apply the this-adjustment and set 'This' to the
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/// adjusted value.
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virtual llvm::Value *
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EmitLoadOfMemberFunctionPointer(CodeGenFunction &CGF,
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llvm::Value *&This,
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llvm::Value *MemPtr,
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const MemberPointerType *MPT);
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/// Calculate an l-value from an object and a data member pointer.
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virtual llvm::Value *EmitMemberDataPointerAddress(CodeGenFunction &CGF,
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llvm::Value *Base,
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llvm::Value *MemPtr,
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const MemberPointerType *MPT);
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/// Perform a derived-to-base, base-to-derived, or bitcast member
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/// pointer conversion.
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virtual llvm::Value *EmitMemberPointerConversion(CodeGenFunction &CGF,
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const CastExpr *E,
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llvm::Value *Src);
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/// Perform a derived-to-base, base-to-derived, or bitcast member
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/// pointer conversion on a constant value.
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virtual llvm::Constant *EmitMemberPointerConversion(const CastExpr *E,
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llvm::Constant *Src);
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/// Return true if the given member pointer can be zero-initialized
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/// (in the C++ sense) with an LLVM zeroinitializer.
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virtual bool isZeroInitializable(const MemberPointerType *MPT);
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/// Create a null member pointer of the given type.
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virtual llvm::Constant *EmitNullMemberPointer(const MemberPointerType *MPT);
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/// Create a member pointer for the given method.
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virtual llvm::Constant *EmitMemberPointer(const CXXMethodDecl *MD);
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/// Create a member pointer for the given field.
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virtual llvm::Constant *EmitMemberDataPointer(const MemberPointerType *MPT,
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CharUnits offset);
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/// Create a member pointer for the given member pointer constant.
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virtual llvm::Constant *EmitMemberPointer(const APValue &MP, QualType MPT);
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/// Emit a comparison between two member pointers. Returns an i1.
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virtual llvm::Value *
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EmitMemberPointerComparison(CodeGenFunction &CGF,
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llvm::Value *L,
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llvm::Value *R,
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const MemberPointerType *MPT,
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bool Inequality);
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/// Determine if a member pointer is non-null. Returns an i1.
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virtual llvm::Value *
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EmitMemberPointerIsNotNull(CodeGenFunction &CGF,
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llvm::Value *MemPtr,
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const MemberPointerType *MPT);
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protected:
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/// A utility method for computing the offset required for the given
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/// base-to-derived or derived-to-base member-pointer conversion.
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/// Does not handle virtual conversions (in case we ever fully
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/// support an ABI that allows this). Returns null if no adjustment
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/// is required.
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llvm::Constant *getMemberPointerAdjustment(const CastExpr *E);
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/// \brief Computes the non-virtual adjustment needed for a member pointer
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/// conversion along an inheritance path stored in an APValue. Unlike
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/// getMemberPointerAdjustment(), the adjustment can be negative if the path
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/// is from a derived type to a base type.
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CharUnits getMemberPointerPathAdjustment(const APValue &MP);
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public:
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/// Adjust the given non-null pointer to an object of polymorphic
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/// type to point to the complete object.
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///
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/// The IR type of the result should be a pointer but is otherwise
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/// irrelevant.
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virtual llvm::Value *adjustToCompleteObject(CodeGenFunction &CGF,
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llvm::Value *ptr,
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QualType type) = 0;
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virtual llvm::Value *GetVirtualBaseClassOffset(CodeGenFunction &CGF,
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llvm::Value *This,
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const CXXRecordDecl *ClassDecl,
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const CXXRecordDecl *BaseClassDecl) = 0;
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/// Build the signature of the given constructor variant by adding
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/// any required parameters. For convenience, ArgTys has been initialized
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/// with the type of 'this' and ResTy has been initialized with the type of
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/// 'this' if HasThisReturn(GlobalDecl(Ctor, T)) is true or 'void' otherwise
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/// (although both may be changed by the ABI).
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///
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/// If there are ever any ABIs where the implicit parameters are
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/// intermixed with the formal parameters, we can address those
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/// then.
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virtual void BuildConstructorSignature(const CXXConstructorDecl *Ctor,
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CXXCtorType T,
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CanQualType &ResTy,
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SmallVectorImpl<CanQualType> &ArgTys) = 0;
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virtual llvm::BasicBlock *EmitCtorCompleteObjectHandler(CodeGenFunction &CGF,
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const CXXRecordDecl *RD);
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/// Emit the code to initialize hidden members required
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/// to handle virtual inheritance, if needed by the ABI.
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virtual void
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initializeHiddenVirtualInheritanceMembers(CodeGenFunction &CGF,
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const CXXRecordDecl *RD) {}
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/// Emit constructor variants required by this ABI.
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virtual void EmitCXXConstructors(const CXXConstructorDecl *D) = 0;
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/// Build the signature of the given destructor variant by adding
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/// any required parameters. For convenience, ArgTys has been initialized
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/// with the type of 'this' and ResTy has been initialized with the type of
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/// 'this' if HasThisReturn(GlobalDecl(Dtor, T)) is true or 'void' otherwise
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/// (although both may be changed by the ABI).
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virtual void BuildDestructorSignature(const CXXDestructorDecl *Dtor,
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CXXDtorType T,
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CanQualType &ResTy,
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SmallVectorImpl<CanQualType> &ArgTys) = 0;
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/// Returns true if the given destructor type should be emitted as a linkonce
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/// delegating thunk, regardless of whether the dtor is defined in this TU or
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/// not.
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virtual bool useThunkForDtorVariant(const CXXDestructorDecl *Dtor,
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CXXDtorType DT) const = 0;
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/// Emit destructor variants required by this ABI.
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virtual void EmitCXXDestructors(const CXXDestructorDecl *D) = 0;
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/// Get the type of the implicit "this" parameter used by a method. May return
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/// zero if no specific type is applicable, e.g. if the ABI expects the "this"
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/// parameter to point to some artificial offset in a complete object due to
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/// vbases being reordered.
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virtual const CXXRecordDecl *
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getThisArgumentTypeForMethod(const CXXMethodDecl *MD) {
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return MD->getParent();
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}
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/// Perform ABI-specific "this" argument adjustment required prior to
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/// a virtual function call.
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virtual llvm::Value *adjustThisArgumentForVirtualCall(CodeGenFunction &CGF,
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GlobalDecl GD,
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llvm::Value *This) {
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return This;
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}
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/// Build the ABI-specific portion of the parameter list for a
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/// function. This generally involves a 'this' parameter and
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/// possibly some extra data for constructors and destructors.
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///
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/// ABIs may also choose to override the return type, which has been
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/// initialized with the type of 'this' if HasThisReturn(CGF.CurGD) is true or
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/// the formal return type of the function otherwise.
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virtual void BuildInstanceFunctionParams(CodeGenFunction &CGF,
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QualType &ResTy,
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FunctionArgList &Params) = 0;
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/// Perform ABI-specific "this" parameter adjustment in a virtual function
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/// prologue.
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virtual llvm::Value *adjustThisParameterInVirtualFunctionPrologue(
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CodeGenFunction &CGF, GlobalDecl GD, llvm::Value *This) {
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return This;
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}
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/// Emit the ABI-specific prolog for the function.
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virtual void EmitInstanceFunctionProlog(CodeGenFunction &CGF) = 0;
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/// Emit the constructor call. Return the function that is called.
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virtual void EmitConstructorCall(CodeGenFunction &CGF,
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const CXXConstructorDecl *D,
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CXXCtorType Type,
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bool ForVirtualBase, bool Delegating,
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llvm::Value *This,
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CallExpr::const_arg_iterator ArgBeg,
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CallExpr::const_arg_iterator ArgEnd) = 0;
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/// Emits the VTable definitions required for the given record type.
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virtual void emitVTableDefinitions(CodeGenVTables &CGVT,
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const CXXRecordDecl *RD) = 0;
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/// Get the address point of the vtable for the given base subobject while
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/// building a constructor or a destructor. On return, NeedsVirtualOffset
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/// tells if a virtual base adjustment is needed in order to get the offset
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/// of the base subobject.
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virtual llvm::Value *getVTableAddressPointInStructor(
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CodeGenFunction &CGF, const CXXRecordDecl *RD, BaseSubobject Base,
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const CXXRecordDecl *NearestVBase, bool &NeedsVirtualOffset) = 0;
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/// Get the address point of the vtable for the given base subobject while
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/// building a constexpr.
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virtual llvm::Constant *
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getVTableAddressPointForConstExpr(BaseSubobject Base,
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const CXXRecordDecl *VTableClass) = 0;
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/// Get the address of the vtable for the given record decl which should be
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/// used for the vptr at the given offset in RD.
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virtual llvm::GlobalVariable *getAddrOfVTable(const CXXRecordDecl *RD,
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CharUnits VPtrOffset) = 0;
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/// Build a virtual function pointer in the ABI-specific way.
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virtual llvm::Value *getVirtualFunctionPointer(CodeGenFunction &CGF,
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GlobalDecl GD,
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llvm::Value *This,
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llvm::Type *Ty) = 0;
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/// Emit the ABI-specific virtual destructor call.
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virtual void EmitVirtualDestructorCall(CodeGenFunction &CGF,
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const CXXDestructorDecl *Dtor,
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CXXDtorType DtorType,
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SourceLocation CallLoc,
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llvm::Value *This) = 0;
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virtual void adjustCallArgsForDestructorThunk(CodeGenFunction &CGF,
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GlobalDecl GD,
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CallArgList &CallArgs) {}
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/// Emit any tables needed to implement virtual inheritance. For Itanium,
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/// this emits virtual table tables. For the MSVC++ ABI, this emits virtual
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/// base tables.
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virtual void emitVirtualInheritanceTables(const CXXRecordDecl *RD) = 0;
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virtual void setThunkLinkage(llvm::Function *Thunk, bool ForVTable) = 0;
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virtual llvm::Value *performThisAdjustment(CodeGenFunction &CGF,
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llvm::Value *This,
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const ThisAdjustment &TA) = 0;
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virtual llvm::Value *performReturnAdjustment(CodeGenFunction &CGF,
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llvm::Value *Ret,
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const ReturnAdjustment &RA) = 0;
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virtual void EmitReturnFromThunk(CodeGenFunction &CGF,
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RValue RV, QualType ResultType);
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/// Gets the pure virtual member call function.
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virtual StringRef GetPureVirtualCallName() = 0;
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/// Gets the deleted virtual member call name.
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virtual StringRef GetDeletedVirtualCallName() = 0;
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/// \brief Returns true iff static data members that are initialized in the
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/// class definition should have linkonce linkage.
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virtual bool isInlineInitializedStaticDataMemberLinkOnce() { return false; }
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/**************************** Array cookies ******************************/
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/// Returns the extra size required in order to store the array
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/// cookie for the given new-expression. May return 0 to indicate that no
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/// array cookie is required.
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///
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/// Several cases are filtered out before this method is called:
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/// - non-array allocations never need a cookie
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/// - calls to \::operator new(size_t, void*) never need a cookie
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///
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/// \param expr - the new-expression being allocated.
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virtual CharUnits GetArrayCookieSize(const CXXNewExpr *expr);
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/// Initialize the array cookie for the given allocation.
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///
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/// \param NewPtr - a char* which is the presumed-non-null
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/// return value of the allocation function
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/// \param NumElements - the computed number of elements,
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/// potentially collapsed from the multidimensional array case;
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/// always a size_t
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/// \param ElementType - the base element allocated type,
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/// i.e. the allocated type after stripping all array types
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virtual llvm::Value *InitializeArrayCookie(CodeGenFunction &CGF,
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llvm::Value *NewPtr,
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llvm::Value *NumElements,
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const CXXNewExpr *expr,
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QualType ElementType);
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/// Reads the array cookie associated with the given pointer,
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/// if it has one.
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///
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/// \param Ptr - a pointer to the first element in the array
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/// \param ElementType - the base element type of elements of the array
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/// \param NumElements - an out parameter which will be initialized
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/// with the number of elements allocated, or zero if there is no
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/// cookie
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/// \param AllocPtr - an out parameter which will be initialized
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/// with a char* pointing to the address returned by the allocation
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/// function
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/// \param CookieSize - an out parameter which will be initialized
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/// with the size of the cookie, or zero if there is no cookie
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virtual void ReadArrayCookie(CodeGenFunction &CGF, llvm::Value *Ptr,
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const CXXDeleteExpr *expr,
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QualType ElementType, llvm::Value *&NumElements,
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llvm::Value *&AllocPtr, CharUnits &CookieSize);
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/// Return whether the given global decl needs a VTT parameter.
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virtual bool NeedsVTTParameter(GlobalDecl GD);
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protected:
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/// Returns the extra size required in order to store the array
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/// cookie for the given type. Assumes that an array cookie is
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/// required.
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virtual CharUnits getArrayCookieSizeImpl(QualType elementType);
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/// Reads the array cookie for an allocation which is known to have one.
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/// This is called by the standard implementation of ReadArrayCookie.
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///
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/// \param ptr - a pointer to the allocation made for an array, as a char*
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/// \param cookieSize - the computed cookie size of an array
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///
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/// Other parameters are as above.
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///
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/// \return a size_t
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virtual llvm::Value *readArrayCookieImpl(CodeGenFunction &IGF,
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llvm::Value *ptr,
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CharUnits cookieSize);
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public:
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/*************************** Static local guards ****************************/
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/// Emits the guarded initializer and destructor setup for the given
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/// variable, given that it couldn't be emitted as a constant.
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/// If \p PerformInit is false, the initialization has been folded to a
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/// constant and should not be performed.
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///
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/// The variable may be:
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/// - a static local variable
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/// - a static data member of a class template instantiation
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virtual void EmitGuardedInit(CodeGenFunction &CGF, const VarDecl &D,
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llvm::GlobalVariable *DeclPtr,
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bool PerformInit) = 0;
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/// Emit code to force the execution of a destructor during global
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/// teardown. The default implementation of this uses atexit.
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///
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/// \param dtor - a function taking a single pointer argument
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/// \param addr - a pointer to pass to the destructor function.
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virtual void registerGlobalDtor(CodeGenFunction &CGF, const VarDecl &D,
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llvm::Constant *dtor, llvm::Constant *addr);
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/*************************** thread_local initialization ********************/
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/// Emits ABI-required functions necessary to initialize thread_local
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/// variables in this translation unit.
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///
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/// \param Decls The thread_local declarations in this translation unit.
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/// \param InitFunc If this translation unit contains any non-constant
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/// initialization or non-trivial destruction for thread_local
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/// variables, a function to perform the initialization. Otherwise, 0.
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virtual void EmitThreadLocalInitFuncs(
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llvm::ArrayRef<std::pair<const VarDecl *, llvm::GlobalVariable *> > Decls,
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llvm::Function *InitFunc);
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/// Emit a reference to a non-local thread_local variable (including
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/// triggering the initialization of all thread_local variables in its
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/// translation unit).
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virtual LValue EmitThreadLocalDeclRefExpr(CodeGenFunction &CGF,
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const DeclRefExpr *DRE);
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};
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// Create an instance of a C++ ABI class:
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/// Creates an Itanium-family ABI.
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CGCXXABI *CreateItaniumCXXABI(CodeGenModule &CGM);
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/// Creates a Microsoft-family ABI.
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CGCXXABI *CreateMicrosoftCXXABI(CodeGenModule &CGM);
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}
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}
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#endif
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