xref: /freebsd-src/contrib/llvm-project/clang/lib/AST/Interp/Descriptor.h (revision 0fca6ea1d4eea4c934cfff25ac9ee8ad6fe95583)
1a7dea167SDimitry Andric //===--- Descriptor.h - Types for the constexpr VM --------------*- C++ -*-===//
2a7dea167SDimitry Andric //
3a7dea167SDimitry Andric // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4a7dea167SDimitry Andric // See https://llvm.org/LICENSE.txt for license information.
5a7dea167SDimitry Andric // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6a7dea167SDimitry Andric //
7a7dea167SDimitry Andric //===----------------------------------------------------------------------===//
8a7dea167SDimitry Andric //
9a7dea167SDimitry Andric // Defines descriptors which characterise allocations.
10a7dea167SDimitry Andric //
11a7dea167SDimitry Andric //===----------------------------------------------------------------------===//
12a7dea167SDimitry Andric 
13a7dea167SDimitry Andric #ifndef LLVM_CLANG_AST_INTERP_DESCRIPTOR_H
14a7dea167SDimitry Andric #define LLVM_CLANG_AST_INTERP_DESCRIPTOR_H
15a7dea167SDimitry Andric 
16*0fca6ea1SDimitry Andric #include "PrimType.h"
17a7dea167SDimitry Andric #include "clang/AST/Decl.h"
18a7dea167SDimitry Andric #include "clang/AST/Expr.h"
19a7dea167SDimitry Andric 
20a7dea167SDimitry Andric namespace clang {
21a7dea167SDimitry Andric namespace interp {
22a7dea167SDimitry Andric class Block;
23a7dea167SDimitry Andric class Record;
245f757f3fSDimitry Andric struct InitMap;
25a7dea167SDimitry Andric struct Descriptor;
26a7dea167SDimitry Andric enum PrimType : unsigned;
27a7dea167SDimitry Andric 
28a7dea167SDimitry Andric using DeclTy = llvm::PointerUnion<const Decl *, const Expr *>;
295f757f3fSDimitry Andric using InitMapPtr = std::optional<std::pair<bool, std::shared_ptr<InitMap>>>;
30a7dea167SDimitry Andric 
31a7dea167SDimitry Andric /// Invoked whenever a block is created. The constructor method fills in the
32a7dea167SDimitry Andric /// inline descriptors of all fields and array elements. It also initializes
33a7dea167SDimitry Andric /// all the fields which contain non-trivial types.
345f757f3fSDimitry Andric using BlockCtorFn = void (*)(Block *Storage, std::byte *FieldPtr, bool IsConst,
35a7dea167SDimitry Andric                              bool IsMutable, bool IsActive,
3606c3fb27SDimitry Andric                              const Descriptor *FieldDesc);
37a7dea167SDimitry Andric 
38a7dea167SDimitry Andric /// Invoked when a block is destroyed. Invokes the destructors of all
39a7dea167SDimitry Andric /// non-trivial nested fields of arrays and records.
405f757f3fSDimitry Andric using BlockDtorFn = void (*)(Block *Storage, std::byte *FieldPtr,
4106c3fb27SDimitry Andric                              const Descriptor *FieldDesc);
42a7dea167SDimitry Andric 
43a7dea167SDimitry Andric /// Invoked when a block with pointers referencing it goes out of scope. Such
44a7dea167SDimitry Andric /// blocks are persisted: the move function copies all inline descriptors and
45a7dea167SDimitry Andric /// non-trivial fields, as existing pointers might need to reference those
46a7dea167SDimitry Andric /// descriptors. Data is not copied since it cannot be legally read.
475f757f3fSDimitry Andric using BlockMoveFn = void (*)(Block *Storage, const std::byte *SrcFieldPtr,
485f757f3fSDimitry Andric                              std::byte *DstFieldPtr,
495f757f3fSDimitry Andric                              const Descriptor *FieldDesc);
50a7dea167SDimitry Andric 
51*0fca6ea1SDimitry Andric enum class GlobalInitState {
52*0fca6ea1SDimitry Andric   Initialized,
53*0fca6ea1SDimitry Andric   NoInitializer,
54*0fca6ea1SDimitry Andric   InitializerFailed,
55*0fca6ea1SDimitry Andric };
56*0fca6ea1SDimitry Andric 
57*0fca6ea1SDimitry Andric /// Descriptor used for global variables.
58*0fca6ea1SDimitry Andric struct alignas(void *) GlobalInlineDescriptor {
59*0fca6ea1SDimitry Andric   GlobalInitState InitState = GlobalInitState::InitializerFailed;
60*0fca6ea1SDimitry Andric };
61*0fca6ea1SDimitry Andric static_assert(sizeof(GlobalInlineDescriptor) == sizeof(void *), "");
62*0fca6ea1SDimitry Andric 
63a7dea167SDimitry Andric /// Inline descriptor embedded in structures and arrays.
64a7dea167SDimitry Andric ///
65a7dea167SDimitry Andric /// Such descriptors precede all composite array elements and structure fields.
66a7dea167SDimitry Andric /// If the base of a pointer is not zero, the base points to the end of this
67a7dea167SDimitry Andric /// structure. The offset field is used to traverse the pointer chain up
68a7dea167SDimitry Andric /// to the root structure which allocated the object.
69a7dea167SDimitry Andric struct InlineDescriptor {
70a7dea167SDimitry Andric   /// Offset inside the structure/array.
71a7dea167SDimitry Andric   unsigned Offset;
72a7dea167SDimitry Andric 
73a7dea167SDimitry Andric   /// Flag indicating if the storage is constant or not.
74a7dea167SDimitry Andric   /// Relevant for primitive fields.
75*0fca6ea1SDimitry Andric   LLVM_PREFERRED_TYPE(bool)
76a7dea167SDimitry Andric   unsigned IsConst : 1;
77a7dea167SDimitry Andric   /// For primitive fields, it indicates if the field was initialized.
78a7dea167SDimitry Andric   /// Primitive fields in static storage are always initialized.
79a7dea167SDimitry Andric   /// Arrays are always initialized, even though their elements might not be.
80a7dea167SDimitry Andric   /// Base classes are initialized after the constructor is invoked.
81*0fca6ea1SDimitry Andric   LLVM_PREFERRED_TYPE(bool)
82a7dea167SDimitry Andric   unsigned IsInitialized : 1;
83a7dea167SDimitry Andric   /// Flag indicating if the field is an embedded base class.
84*0fca6ea1SDimitry Andric   LLVM_PREFERRED_TYPE(bool)
85a7dea167SDimitry Andric   unsigned IsBase : 1;
86*0fca6ea1SDimitry Andric   LLVM_PREFERRED_TYPE(bool)
87*0fca6ea1SDimitry Andric   unsigned IsVirtualBase : 1;
88a7dea167SDimitry Andric   /// Flag indicating if the field is the active member of a union.
89*0fca6ea1SDimitry Andric   LLVM_PREFERRED_TYPE(bool)
90a7dea167SDimitry Andric   unsigned IsActive : 1;
91a7dea167SDimitry Andric   /// Flag indicating if the field is mutable (if in a record).
92*0fca6ea1SDimitry Andric   LLVM_PREFERRED_TYPE(bool)
93bdd1243dSDimitry Andric   unsigned IsFieldMutable : 1;
94a7dea167SDimitry Andric 
955f757f3fSDimitry Andric   const Descriptor *Desc;
96*0fca6ea1SDimitry Andric 
97*0fca6ea1SDimitry Andric   InlineDescriptor(const Descriptor *D)
98*0fca6ea1SDimitry Andric       : Offset(sizeof(InlineDescriptor)), IsConst(false), IsInitialized(false),
99*0fca6ea1SDimitry Andric         IsBase(false), IsActive(false), IsFieldMutable(false), Desc(D) {}
100*0fca6ea1SDimitry Andric 
101*0fca6ea1SDimitry Andric   void dump() const { dump(llvm::errs()); }
102*0fca6ea1SDimitry Andric   void dump(llvm::raw_ostream &OS) const;
103a7dea167SDimitry Andric };
104*0fca6ea1SDimitry Andric static_assert(sizeof(GlobalInlineDescriptor) != sizeof(InlineDescriptor), "");
105a7dea167SDimitry Andric 
106bdd1243dSDimitry Andric /// Describes a memory block created by an allocation site.
107bdd1243dSDimitry Andric struct Descriptor final {
108bdd1243dSDimitry Andric private:
109bdd1243dSDimitry Andric   /// Original declaration, used to emit the error message.
110bdd1243dSDimitry Andric   const DeclTy Source;
111bdd1243dSDimitry Andric   /// Size of an element, in host bytes.
11206c3fb27SDimitry Andric   const unsigned ElemSize;
113bdd1243dSDimitry Andric   /// Size of the storage, in host bytes.
11406c3fb27SDimitry Andric   const unsigned Size;
1155f757f3fSDimitry Andric   /// Size of the metadata.
11606c3fb27SDimitry Andric   const unsigned MDSize;
117bdd1243dSDimitry Andric   /// Size of the allocation (storage + metadata), in host bytes.
11806c3fb27SDimitry Andric   const unsigned AllocSize;
119bdd1243dSDimitry Andric 
120bdd1243dSDimitry Andric   /// Value to denote arrays of unknown size.
121bdd1243dSDimitry Andric   static constexpr unsigned UnknownSizeMark = (unsigned)-1;
122bdd1243dSDimitry Andric 
123bdd1243dSDimitry Andric public:
124bdd1243dSDimitry Andric   /// Token to denote structures of unknown size.
125bdd1243dSDimitry Andric   struct UnknownSize {};
126bdd1243dSDimitry Andric 
12706c3fb27SDimitry Andric   using MetadataSize = std::optional<unsigned>;
128bdd1243dSDimitry Andric   static constexpr MetadataSize InlineDescMD = sizeof(InlineDescriptor);
129*0fca6ea1SDimitry Andric   static constexpr MetadataSize GlobalMD = sizeof(GlobalInlineDescriptor);
130*0fca6ea1SDimitry Andric 
131*0fca6ea1SDimitry Andric   /// Maximum number of bytes to be used for array elements.
132*0fca6ea1SDimitry Andric   static constexpr unsigned MaxArrayElemBytes =
133*0fca6ea1SDimitry Andric       std::numeric_limits<decltype(AllocSize)>::max() - sizeof(InitMapPtr) -
134*0fca6ea1SDimitry Andric       align(std::max(*InlineDescMD, *GlobalMD));
135bdd1243dSDimitry Andric 
136bdd1243dSDimitry Andric   /// Pointer to the record, if block contains records.
137297eecfbSDimitry Andric   const Record *const ElemRecord = nullptr;
138bdd1243dSDimitry Andric   /// Descriptor of the array element.
1395f757f3fSDimitry Andric   const Descriptor *const ElemDesc = nullptr;
140*0fca6ea1SDimitry Andric   /// The primitive type this descriptor was created for,
141*0fca6ea1SDimitry Andric   /// or the primitive element type in case this is
142*0fca6ea1SDimitry Andric   /// a primitive array.
143*0fca6ea1SDimitry Andric   const std::optional<PrimType> PrimT = std::nullopt;
144bdd1243dSDimitry Andric   /// Flag indicating if the block is mutable.
145bdd1243dSDimitry Andric   const bool IsConst = false;
146bdd1243dSDimitry Andric   /// Flag indicating if a field is mutable.
147bdd1243dSDimitry Andric   const bool IsMutable = false;
148bdd1243dSDimitry Andric   /// Flag indicating if the block is a temporary.
149bdd1243dSDimitry Andric   const bool IsTemporary = false;
150bdd1243dSDimitry Andric   /// Flag indicating if the block is an array.
151bdd1243dSDimitry Andric   const bool IsArray = false;
1525f757f3fSDimitry Andric   /// Flag indicating if this is a dummy descriptor.
153*0fca6ea1SDimitry Andric   bool IsDummy = false;
154bdd1243dSDimitry Andric 
155bdd1243dSDimitry Andric   /// Storage management methods.
156bdd1243dSDimitry Andric   const BlockCtorFn CtorFn = nullptr;
157bdd1243dSDimitry Andric   const BlockDtorFn DtorFn = nullptr;
158bdd1243dSDimitry Andric   const BlockMoveFn MoveFn = nullptr;
159bdd1243dSDimitry Andric 
160bdd1243dSDimitry Andric   /// Allocates a descriptor for a primitive.
161bdd1243dSDimitry Andric   Descriptor(const DeclTy &D, PrimType Type, MetadataSize MD, bool IsConst,
162bdd1243dSDimitry Andric              bool IsTemporary, bool IsMutable);
163bdd1243dSDimitry Andric 
164bdd1243dSDimitry Andric   /// Allocates a descriptor for an array of primitives.
165bdd1243dSDimitry Andric   Descriptor(const DeclTy &D, PrimType Type, MetadataSize MD, size_t NumElems,
166bdd1243dSDimitry Andric              bool IsConst, bool IsTemporary, bool IsMutable);
167bdd1243dSDimitry Andric 
168bdd1243dSDimitry Andric   /// Allocates a descriptor for an array of primitives of unknown size.
169*0fca6ea1SDimitry Andric   Descriptor(const DeclTy &D, PrimType Type, MetadataSize MDSize,
170*0fca6ea1SDimitry Andric              bool IsTemporary, UnknownSize);
171bdd1243dSDimitry Andric 
172bdd1243dSDimitry Andric   /// Allocates a descriptor for an array of composites.
1735f757f3fSDimitry Andric   Descriptor(const DeclTy &D, const Descriptor *Elem, MetadataSize MD,
174bdd1243dSDimitry Andric              unsigned NumElems, bool IsConst, bool IsTemporary, bool IsMutable);
175bdd1243dSDimitry Andric 
176bdd1243dSDimitry Andric   /// Allocates a descriptor for an array of composites of unknown size.
177*0fca6ea1SDimitry Andric   Descriptor(const DeclTy &D, const Descriptor *Elem, MetadataSize MD,
178*0fca6ea1SDimitry Andric              bool IsTemporary, UnknownSize);
179bdd1243dSDimitry Andric 
180bdd1243dSDimitry Andric   /// Allocates a descriptor for a record.
181297eecfbSDimitry Andric   Descriptor(const DeclTy &D, const Record *R, MetadataSize MD, bool IsConst,
182bdd1243dSDimitry Andric              bool IsTemporary, bool IsMutable);
183bdd1243dSDimitry Andric 
184*0fca6ea1SDimitry Andric   /// Allocates a dummy descriptor.
185*0fca6ea1SDimitry Andric   Descriptor(const DeclTy &D);
186*0fca6ea1SDimitry Andric 
187*0fca6ea1SDimitry Andric   /// Make this descriptor a dummy descriptor.
188*0fca6ea1SDimitry Andric   void makeDummy() { IsDummy = true; }
1895f757f3fSDimitry Andric 
190bdd1243dSDimitry Andric   QualType getType() const;
1915f757f3fSDimitry Andric   QualType getElemQualType() const;
192bdd1243dSDimitry Andric   SourceLocation getLocation() const;
193bdd1243dSDimitry Andric 
194bdd1243dSDimitry Andric   const Decl *asDecl() const { return Source.dyn_cast<const Decl *>(); }
195bdd1243dSDimitry Andric   const Expr *asExpr() const { return Source.dyn_cast<const Expr *>(); }
196*0fca6ea1SDimitry Andric   const DeclTy &getSource() const { return Source; }
197bdd1243dSDimitry Andric 
198bdd1243dSDimitry Andric   const ValueDecl *asValueDecl() const {
199bdd1243dSDimitry Andric     return dyn_cast_if_present<ValueDecl>(asDecl());
200bdd1243dSDimitry Andric   }
201bdd1243dSDimitry Andric 
202*0fca6ea1SDimitry Andric   const VarDecl *asVarDecl() const {
203*0fca6ea1SDimitry Andric     return dyn_cast_if_present<VarDecl>(asDecl());
204*0fca6ea1SDimitry Andric   }
205*0fca6ea1SDimitry Andric 
206bdd1243dSDimitry Andric   const FieldDecl *asFieldDecl() const {
207bdd1243dSDimitry Andric     return dyn_cast_if_present<FieldDecl>(asDecl());
208bdd1243dSDimitry Andric   }
209bdd1243dSDimitry Andric 
210bdd1243dSDimitry Andric   const RecordDecl *asRecordDecl() const {
211bdd1243dSDimitry Andric     return dyn_cast_if_present<RecordDecl>(asDecl());
212bdd1243dSDimitry Andric   }
213bdd1243dSDimitry Andric 
214bdd1243dSDimitry Andric   /// Returns the size of the object without metadata.
215bdd1243dSDimitry Andric   unsigned getSize() const {
216bdd1243dSDimitry Andric     assert(!isUnknownSizeArray() && "Array of unknown size");
217bdd1243dSDimitry Andric     return Size;
218bdd1243dSDimitry Andric   }
219bdd1243dSDimitry Andric 
220*0fca6ea1SDimitry Andric   PrimType getPrimType() const {
221*0fca6ea1SDimitry Andric     assert(isPrimitiveArray() || isPrimitive());
222*0fca6ea1SDimitry Andric     return *PrimT;
223*0fca6ea1SDimitry Andric   }
224*0fca6ea1SDimitry Andric 
225bdd1243dSDimitry Andric   /// Returns the allocated size, including metadata.
226bdd1243dSDimitry Andric   unsigned getAllocSize() const { return AllocSize; }
227bdd1243dSDimitry Andric   /// returns the size of an element when the structure is viewed as an array.
228bdd1243dSDimitry Andric   unsigned getElemSize()  const { return ElemSize; }
229bdd1243dSDimitry Andric   /// Returns the size of the metadata.
230bdd1243dSDimitry Andric   unsigned getMetadataSize() const { return MDSize; }
231bdd1243dSDimitry Andric 
232bdd1243dSDimitry Andric   /// Returns the number of elements stored in the block.
233bdd1243dSDimitry Andric   unsigned getNumElems() const {
234bdd1243dSDimitry Andric     return Size == UnknownSizeMark ? 0 : (getSize() / getElemSize());
235bdd1243dSDimitry Andric   }
236bdd1243dSDimitry Andric 
237bdd1243dSDimitry Andric   /// Checks if the descriptor is of an array of primitives.
238bdd1243dSDimitry Andric   bool isPrimitiveArray() const { return IsArray && !ElemDesc; }
23906c3fb27SDimitry Andric   /// Checks if the descriptor is of an array of composites.
24006c3fb27SDimitry Andric   bool isCompositeArray() const { return IsArray && ElemDesc; }
241bdd1243dSDimitry Andric   /// Checks if the descriptor is of an array of zero size.
242bdd1243dSDimitry Andric   bool isZeroSizeArray() const { return Size == 0; }
243bdd1243dSDimitry Andric   /// Checks if the descriptor is of an array of unknown size.
244bdd1243dSDimitry Andric   bool isUnknownSizeArray() const { return Size == UnknownSizeMark; }
245bdd1243dSDimitry Andric 
246bdd1243dSDimitry Andric   /// Checks if the descriptor is of a primitive.
247bdd1243dSDimitry Andric   bool isPrimitive() const { return !IsArray && !ElemRecord; }
248bdd1243dSDimitry Andric 
249bdd1243dSDimitry Andric   /// Checks if the descriptor is of an array.
250bdd1243dSDimitry Andric   bool isArray() const { return IsArray; }
2515f757f3fSDimitry Andric   /// Checks if the descriptor is of a record.
2525f757f3fSDimitry Andric   bool isRecord() const { return !IsArray && ElemRecord; }
2535f757f3fSDimitry Andric   /// Checks if this is a dummy descriptor.
2545f757f3fSDimitry Andric   bool isDummy() const { return IsDummy; }
255*0fca6ea1SDimitry Andric 
256*0fca6ea1SDimitry Andric   void dump() const;
257*0fca6ea1SDimitry Andric   void dump(llvm::raw_ostream &OS) const;
258bdd1243dSDimitry Andric };
259bdd1243dSDimitry Andric 
260a7dea167SDimitry Andric /// Bitfield tracking the initialisation status of elements of primitive arrays.
261bdd1243dSDimitry Andric struct InitMap final {
262a7dea167SDimitry Andric private:
263a7dea167SDimitry Andric   /// Type packing bits.
264a7dea167SDimitry Andric   using T = uint64_t;
265a7dea167SDimitry Andric   /// Bits stored in a single field.
266a7dea167SDimitry Andric   static constexpr uint64_t PER_FIELD = sizeof(T) * CHAR_BIT;
267a7dea167SDimitry Andric 
268a7dea167SDimitry Andric public:
2695f757f3fSDimitry Andric   /// Initializes the map with no fields set.
2705f757f3fSDimitry Andric   explicit InitMap(unsigned N);
271a7dea167SDimitry Andric 
272a7dea167SDimitry Andric private:
2735f757f3fSDimitry Andric   friend class Pointer;
2745f757f3fSDimitry Andric 
2755f757f3fSDimitry Andric   /// Returns a pointer to storage.
2765f757f3fSDimitry Andric   T *data() { return Data.get(); }
2775f757f3fSDimitry Andric   const T *data() const { return Data.get(); }
2785f757f3fSDimitry Andric 
2795f757f3fSDimitry Andric   /// Initializes an element. Returns true when object if fully initialized.
2805f757f3fSDimitry Andric   bool initializeElement(unsigned I);
2815f757f3fSDimitry Andric 
2825f757f3fSDimitry Andric   /// Checks if an element was initialized.
2835f757f3fSDimitry Andric   bool isElementInitialized(unsigned I) const;
2845f757f3fSDimitry Andric 
2855f757f3fSDimitry Andric   static constexpr size_t numFields(unsigned N) {
2865f757f3fSDimitry Andric     return (N + PER_FIELD - 1) / PER_FIELD;
2875f757f3fSDimitry Andric   }
2885f757f3fSDimitry Andric   /// Number of fields not initialized.
289a7dea167SDimitry Andric   unsigned UninitFields;
2905f757f3fSDimitry Andric   std::unique_ptr<T[]> Data;
291a7dea167SDimitry Andric };
292a7dea167SDimitry Andric 
293a7dea167SDimitry Andric } // namespace interp
294a7dea167SDimitry Andric } // namespace clang
295a7dea167SDimitry Andric 
296a7dea167SDimitry Andric #endif
297