1353942Sdim//===--- Descriptor.h - Types for the constexpr VM --------------*- C++ -*-===// 2353942Sdim// 3353942Sdim// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4353942Sdim// See https://llvm.org/LICENSE.txt for license information. 5353942Sdim// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6353942Sdim// 7353942Sdim//===----------------------------------------------------------------------===// 8353942Sdim// 9353942Sdim// Defines descriptors which characterise allocations. 10353942Sdim// 11353942Sdim//===----------------------------------------------------------------------===// 12353942Sdim 13353942Sdim#ifndef LLVM_CLANG_AST_INTERP_DESCRIPTOR_H 14353942Sdim#define LLVM_CLANG_AST_INTERP_DESCRIPTOR_H 15353942Sdim 16353942Sdim#include "clang/AST/Decl.h" 17353942Sdim#include "clang/AST/Expr.h" 18353942Sdim 19353942Sdimnamespace clang { 20353942Sdimnamespace interp { 21353942Sdimclass Block; 22353942Sdimclass Record; 23353942Sdimstruct Descriptor; 24353942Sdimenum PrimType : unsigned; 25353942Sdim 26353942Sdimusing DeclTy = llvm::PointerUnion<const Decl *, const Expr *>; 27353942Sdim 28353942Sdim/// Invoked whenever a block is created. The constructor method fills in the 29353942Sdim/// inline descriptors of all fields and array elements. It also initializes 30353942Sdim/// all the fields which contain non-trivial types. 31353942Sdimusing BlockCtorFn = void (*)(Block *Storage, char *FieldPtr, bool IsConst, 32353942Sdim bool IsMutable, bool IsActive, 33353942Sdim Descriptor *FieldDesc); 34353942Sdim 35353942Sdim/// Invoked when a block is destroyed. Invokes the destructors of all 36353942Sdim/// non-trivial nested fields of arrays and records. 37353942Sdimusing BlockDtorFn = void (*)(Block *Storage, char *FieldPtr, 38353942Sdim Descriptor *FieldDesc); 39353942Sdim 40353942Sdim/// Invoked when a block with pointers referencing it goes out of scope. Such 41353942Sdim/// blocks are persisted: the move function copies all inline descriptors and 42353942Sdim/// non-trivial fields, as existing pointers might need to reference those 43353942Sdim/// descriptors. Data is not copied since it cannot be legally read. 44353942Sdimusing BlockMoveFn = void (*)(Block *Storage, char *SrcFieldPtr, 45353942Sdim char *DstFieldPtr, Descriptor *FieldDesc); 46353942Sdim 47353942Sdim/// Object size as used by the interpreter. 48353942Sdimusing InterpSize = unsigned; 49353942Sdim 50353942Sdim/// Describes a memory block created by an allocation site. 51353942Sdimstruct Descriptor { 52353942Sdimprivate: 53353942Sdim /// Original declaration, used to emit the error message. 54353942Sdim const DeclTy Source; 55353942Sdim /// Size of an element, in host bytes. 56353942Sdim const InterpSize ElemSize; 57353942Sdim /// Size of the storage, in host bytes. 58353942Sdim const InterpSize Size; 59353942Sdim /// Size of the allocation (storage + metadata), in host bytes. 60353942Sdim const InterpSize AllocSize; 61353942Sdim 62353942Sdim /// Value to denote arrays of unknown size. 63353942Sdim static constexpr unsigned UnknownSizeMark = (unsigned)-1; 64353942Sdim 65353942Sdimpublic: 66353942Sdim /// Token to denote structures of unknown size. 67353942Sdim struct UnknownSize {}; 68353942Sdim 69353942Sdim /// Pointer to the record, if block contains records. 70353942Sdim Record *const ElemRecord = nullptr; 71353942Sdim /// Descriptor of the array element. 72353942Sdim Descriptor *const ElemDesc = nullptr; 73353942Sdim /// Flag indicating if the block is mutable. 74353942Sdim const bool IsConst = false; 75353942Sdim /// Flag indicating if a field is mutable. 76353942Sdim const bool IsMutable = false; 77353942Sdim /// Flag indicating if the block is a temporary. 78353942Sdim const bool IsTemporary = false; 79353942Sdim /// Flag indicating if the block is an array. 80353942Sdim const bool IsArray = false; 81353942Sdim 82353942Sdim /// Storage management methods. 83353942Sdim const BlockCtorFn CtorFn = nullptr; 84353942Sdim const BlockDtorFn DtorFn = nullptr; 85353942Sdim const BlockMoveFn MoveFn = nullptr; 86353942Sdim 87353942Sdim /// Allocates a descriptor for a primitive. 88353942Sdim Descriptor(const DeclTy &D, PrimType Type, bool IsConst, bool IsTemporary, 89353942Sdim bool IsMutable); 90353942Sdim 91353942Sdim /// Allocates a descriptor for an array of primitives. 92353942Sdim Descriptor(const DeclTy &D, PrimType Type, size_t NumElems, bool IsConst, 93353942Sdim bool IsTemporary, bool IsMutable); 94353942Sdim 95353942Sdim /// Allocates a descriptor for an array of primitives of unknown size. 96353942Sdim Descriptor(const DeclTy &D, PrimType Type, bool IsTemporary, UnknownSize); 97353942Sdim 98353942Sdim /// Allocates a descriptor for an array of composites. 99353942Sdim Descriptor(const DeclTy &D, Descriptor *Elem, unsigned NumElems, bool IsConst, 100353942Sdim bool IsTemporary, bool IsMutable); 101353942Sdim 102353942Sdim /// Allocates a descriptor for an array of composites of unknown size. 103353942Sdim Descriptor(const DeclTy &D, Descriptor *Elem, bool IsTemporary, UnknownSize); 104353942Sdim 105353942Sdim /// Allocates a descriptor for a record. 106353942Sdim Descriptor(const DeclTy &D, Record *R, bool IsConst, bool IsTemporary, 107353942Sdim bool IsMutable); 108353942Sdim 109353942Sdim QualType getType() const; 110353942Sdim SourceLocation getLocation() const; 111353942Sdim 112353942Sdim const Decl *asDecl() const { return Source.dyn_cast<const Decl *>(); } 113353942Sdim const Expr *asExpr() const { return Source.dyn_cast<const Expr *>(); } 114353942Sdim 115353942Sdim const ValueDecl *asValueDecl() const { 116353942Sdim return dyn_cast_or_null<ValueDecl>(asDecl()); 117353942Sdim } 118353942Sdim 119353942Sdim const FieldDecl *asFieldDecl() const { 120353942Sdim return dyn_cast_or_null<FieldDecl>(asDecl()); 121353942Sdim } 122353942Sdim 123353942Sdim const RecordDecl *asRecordDecl() const { 124353942Sdim return dyn_cast_or_null<RecordDecl>(asDecl()); 125353942Sdim } 126353942Sdim 127353942Sdim /// Returns the size of the object without metadata. 128353942Sdim unsigned getSize() const { 129353942Sdim assert(!isUnknownSizeArray() && "Array of unknown size"); 130353942Sdim return Size; 131353942Sdim } 132353942Sdim 133353942Sdim /// Returns the allocated size, including metadata. 134353942Sdim unsigned getAllocSize() const { return AllocSize; } 135353942Sdim /// returns the size of an element when the structure is viewed as an array. 136353942Sdim unsigned getElemSize() const { return ElemSize; } 137353942Sdim 138353942Sdim /// Returns the number of elements stored in the block. 139353942Sdim unsigned getNumElems() const { 140353942Sdim return Size == UnknownSizeMark ? 0 : (getSize() / getElemSize()); 141353942Sdim } 142353942Sdim 143353942Sdim /// Checks if the descriptor is of an array of primitives. 144353942Sdim bool isPrimitiveArray() const { return IsArray && !ElemDesc; } 145353942Sdim /// Checks if the descriptor is of an array of zero size. 146353942Sdim bool isZeroSizeArray() const { return Size == 0; } 147353942Sdim /// Checks if the descriptor is of an array of unknown size. 148353942Sdim bool isUnknownSizeArray() const { return Size == UnknownSizeMark; } 149353942Sdim 150353942Sdim /// Checks if the descriptor is of a primitive. 151353942Sdim bool isPrimitive() const { return !IsArray && !ElemRecord; } 152353942Sdim 153353942Sdim /// Checks if the descriptor is of an array. 154353942Sdim bool isArray() const { return IsArray; } 155353942Sdim}; 156353942Sdim 157353942Sdim/// Inline descriptor embedded in structures and arrays. 158353942Sdim/// 159353942Sdim/// Such descriptors precede all composite array elements and structure fields. 160353942Sdim/// If the base of a pointer is not zero, the base points to the end of this 161353942Sdim/// structure. The offset field is used to traverse the pointer chain up 162353942Sdim/// to the root structure which allocated the object. 163353942Sdimstruct InlineDescriptor { 164353942Sdim /// Offset inside the structure/array. 165353942Sdim unsigned Offset; 166353942Sdim 167353942Sdim /// Flag indicating if the storage is constant or not. 168353942Sdim /// Relevant for primitive fields. 169353942Sdim unsigned IsConst : 1; 170353942Sdim /// For primitive fields, it indicates if the field was initialized. 171353942Sdim /// Primitive fields in static storage are always initialized. 172353942Sdim /// Arrays are always initialized, even though their elements might not be. 173353942Sdim /// Base classes are initialized after the constructor is invoked. 174353942Sdim unsigned IsInitialized : 1; 175353942Sdim /// Flag indicating if the field is an embedded base class. 176353942Sdim unsigned IsBase : 1; 177353942Sdim /// Flag indicating if the field is the active member of a union. 178353942Sdim unsigned IsActive : 1; 179353942Sdim /// Flag indicating if the field is mutable (if in a record). 180353942Sdim unsigned IsMutable : 1; 181353942Sdim 182353942Sdim Descriptor *Desc; 183353942Sdim}; 184353942Sdim 185353942Sdim/// Bitfield tracking the initialisation status of elements of primitive arrays. 186353942Sdim/// A pointer to this is embedded at the end of all primitive arrays. 187353942Sdim/// If the map was not yet created and nothing was initialied, the pointer to 188353942Sdim/// this structure is 0. If the object was fully initialized, the pointer is -1. 189353942Sdimstruct InitMap { 190353942Sdimprivate: 191353942Sdim /// Type packing bits. 192353942Sdim using T = uint64_t; 193353942Sdim /// Bits stored in a single field. 194353942Sdim static constexpr uint64_t PER_FIELD = sizeof(T) * CHAR_BIT; 195353942Sdim 196353942Sdim /// Initializes the map with no fields set. 197353942Sdim InitMap(unsigned N); 198353942Sdim 199353942Sdim /// Returns a pointer to storage. 200353942Sdim T *data(); 201353942Sdim 202353942Sdimpublic: 203353942Sdim /// Initializes an element. Returns true when object if fully initialized. 204353942Sdim bool initialize(unsigned I); 205353942Sdim 206353942Sdim /// Checks if an element was initialized. 207353942Sdim bool isInitialized(unsigned I); 208353942Sdim 209353942Sdim /// Allocates a map holding N elements. 210353942Sdim static InitMap *allocate(unsigned N); 211353942Sdim 212353942Sdimprivate: 213353942Sdim /// Number of fields initialized. 214353942Sdim unsigned UninitFields; 215353942Sdim}; 216353942Sdim 217353942Sdim} // namespace interp 218353942Sdim} // namespace clang 219353942Sdim 220353942Sdim#endif 221