1 //===--- Program.cpp - Bytecode for the constexpr VM ------------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8
9 #include "Program.h"
10 #include "ByteCodeStmtGen.h"
11 #include "Context.h"
12 #include "Function.h"
13 #include "Opcode.h"
14 #include "PrimType.h"
15 #include "clang/AST/Decl.h"
16 #include "clang/AST/DeclCXX.h"
17
18 using namespace clang;
19 using namespace clang::interp;
20
getOrCreateNativePointer(const void * Ptr)21 unsigned Program::getOrCreateNativePointer(const void *Ptr) {
22 auto It = NativePointerIndices.find(Ptr);
23 if (It != NativePointerIndices.end())
24 return It->second;
25
26 unsigned Idx = NativePointers.size();
27 NativePointers.push_back(Ptr);
28 NativePointerIndices[Ptr] = Idx;
29 return Idx;
30 }
31
getNativePointer(unsigned Idx)32 const void *Program::getNativePointer(unsigned Idx) {
33 return NativePointers[Idx];
34 }
35
createGlobalString(const StringLiteral * S)36 unsigned Program::createGlobalString(const StringLiteral *S) {
37 const size_t CharWidth = S->getCharByteWidth();
38 const size_t BitWidth = CharWidth * Ctx.getCharBit();
39
40 PrimType CharType;
41 switch (CharWidth) {
42 case 1:
43 CharType = PT_Sint8;
44 break;
45 case 2:
46 CharType = PT_Uint16;
47 break;
48 case 4:
49 CharType = PT_Uint32;
50 break;
51 default:
52 llvm_unreachable("unsupported character width");
53 }
54
55 // Create a descriptor for the string.
56 Descriptor *Desc =
57 allocateDescriptor(S, CharType, std::nullopt, S->getLength() + 1,
58 /*isConst=*/true,
59 /*isTemporary=*/false,
60 /*isMutable=*/false);
61
62 // Allocate storage for the string.
63 // The byte length does not include the null terminator.
64 unsigned I = Globals.size();
65 unsigned Sz = Desc->getAllocSize();
66 auto *G = new (Allocator, Sz) Global(Desc, /*isStatic=*/true,
67 /*isExtern=*/false);
68 G->block()->invokeCtor();
69 Globals.push_back(G);
70
71 // Construct the string in storage.
72 const Pointer Ptr(G->block());
73 for (unsigned I = 0, N = S->getLength(); I <= N; ++I) {
74 Pointer Field = Ptr.atIndex(I).narrow();
75 const uint32_t CodePoint = I == N ? 0 : S->getCodeUnit(I);
76 switch (CharType) {
77 case PT_Sint8: {
78 using T = PrimConv<PT_Sint8>::T;
79 Field.deref<T>() = T::from(CodePoint, BitWidth);
80 break;
81 }
82 case PT_Uint16: {
83 using T = PrimConv<PT_Uint16>::T;
84 Field.deref<T>() = T::from(CodePoint, BitWidth);
85 break;
86 }
87 case PT_Uint32: {
88 using T = PrimConv<PT_Uint32>::T;
89 Field.deref<T>() = T::from(CodePoint, BitWidth);
90 break;
91 }
92 default:
93 llvm_unreachable("unsupported character type");
94 }
95 }
96 return I;
97 }
98
getPtrGlobal(unsigned Idx)99 Pointer Program::getPtrGlobal(unsigned Idx) {
100 assert(Idx < Globals.size());
101 return Pointer(Globals[Idx]->block());
102 }
103
getGlobal(const ValueDecl * VD)104 std::optional<unsigned> Program::getGlobal(const ValueDecl *VD) {
105 auto It = GlobalIndices.find(VD);
106 if (It != GlobalIndices.end())
107 return It->second;
108
109 // Find any previous declarations which were already evaluated.
110 std::optional<unsigned> Index;
111 for (const Decl *P = VD; P; P = P->getPreviousDecl()) {
112 auto It = GlobalIndices.find(P);
113 if (It != GlobalIndices.end()) {
114 Index = It->second;
115 break;
116 }
117 }
118
119 // Map the decl to the existing index.
120 if (Index) {
121 GlobalIndices[VD] = *Index;
122 return {};
123 }
124
125 return Index;
126 }
127
getOrCreateGlobal(const ValueDecl * VD,const Expr * Init)128 std::optional<unsigned> Program::getOrCreateGlobal(const ValueDecl *VD,
129 const Expr *Init) {
130 if (auto Idx = getGlobal(VD))
131 return Idx;
132
133 if (auto Idx = createGlobal(VD, Init)) {
134 GlobalIndices[VD] = *Idx;
135 return Idx;
136 }
137 return {};
138 }
139
getOrCreateDummy(const ParmVarDecl * PD)140 std::optional<unsigned> Program::getOrCreateDummy(const ParmVarDecl *PD) {
141 auto &ASTCtx = Ctx.getASTContext();
142
143 // Create a pointer to an incomplete array of the specified elements.
144 QualType ElemTy = PD->getType()->castAs<PointerType>()->getPointeeType();
145 QualType Ty = ASTCtx.getIncompleteArrayType(ElemTy, ArrayType::Normal, 0);
146
147 // Dedup blocks since they are immutable and pointers cannot be compared.
148 auto It = DummyParams.find(PD);
149 if (It != DummyParams.end())
150 return It->second;
151
152 if (auto Idx = createGlobal(PD, Ty, /*isStatic=*/true, /*isExtern=*/true)) {
153 DummyParams[PD] = *Idx;
154 return Idx;
155 }
156 return {};
157 }
158
createGlobal(const ValueDecl * VD,const Expr * Init)159 std::optional<unsigned> Program::createGlobal(const ValueDecl *VD,
160 const Expr *Init) {
161 assert(!getGlobal(VD));
162 bool IsStatic, IsExtern;
163 if (auto *Var = dyn_cast<VarDecl>(VD)) {
164 IsStatic = !Var->hasLocalStorage();
165 IsExtern = !Var->getAnyInitializer();
166 } else {
167 IsStatic = false;
168 IsExtern = true;
169 }
170 if (auto Idx = createGlobal(VD, VD->getType(), IsStatic, IsExtern, Init)) {
171 for (const Decl *P = VD; P; P = P->getPreviousDecl())
172 GlobalIndices[P] = *Idx;
173 return *Idx;
174 }
175 return {};
176 }
177
createGlobal(const Expr * E)178 std::optional<unsigned> Program::createGlobal(const Expr *E) {
179 return createGlobal(E, E->getType(), /*isStatic=*/true, /*isExtern=*/false);
180 }
181
createGlobal(const DeclTy & D,QualType Ty,bool IsStatic,bool IsExtern,const Expr * Init)182 std::optional<unsigned> Program::createGlobal(const DeclTy &D, QualType Ty,
183 bool IsStatic, bool IsExtern,
184 const Expr *Init) {
185 // Create a descriptor for the global.
186 Descriptor *Desc;
187 const bool IsConst = Ty.isConstQualified();
188 const bool IsTemporary = D.dyn_cast<const Expr *>();
189 if (auto T = Ctx.classify(Ty)) {
190 Desc = createDescriptor(D, *T, std::nullopt, IsConst, IsTemporary);
191 } else {
192 Desc = createDescriptor(D, Ty.getTypePtr(), std::nullopt, IsConst,
193 IsTemporary);
194 }
195 if (!Desc)
196 return {};
197
198 // Allocate a block for storage.
199 unsigned I = Globals.size();
200
201 auto *G = new (Allocator, Desc->getAllocSize())
202 Global(getCurrentDecl(), Desc, IsStatic, IsExtern);
203 G->block()->invokeCtor();
204
205 Globals.push_back(G);
206
207 return I;
208 }
209
getFunction(const FunctionDecl * F)210 Function *Program::getFunction(const FunctionDecl *F) {
211 F = F->getCanonicalDecl();
212 assert(F);
213 auto It = Funcs.find(F);
214 return It == Funcs.end() ? nullptr : It->second.get();
215 }
216
getOrCreateRecord(const RecordDecl * RD)217 Record *Program::getOrCreateRecord(const RecordDecl *RD) {
218 // Use the actual definition as a key.
219 RD = RD->getDefinition();
220 if (!RD)
221 return nullptr;
222
223 // Deduplicate records.
224 auto It = Records.find(RD);
225 if (It != Records.end()) {
226 return It->second;
227 }
228
229 // We insert nullptr now and replace that later, so recursive calls
230 // to this function with the same RecordDecl don't run into
231 // infinite recursion.
232 Records.insert({RD, nullptr});
233
234 // Number of bytes required by fields and base classes.
235 unsigned BaseSize = 0;
236 // Number of bytes required by virtual base.
237 unsigned VirtSize = 0;
238
239 // Helper to get a base descriptor.
240 auto GetBaseDesc = [this](const RecordDecl *BD, Record *BR) -> Descriptor * {
241 if (!BR)
242 return nullptr;
243 return allocateDescriptor(BD, BR, std::nullopt, /*isConst=*/false,
244 /*isTemporary=*/false,
245 /*isMutable=*/false);
246 };
247
248 // Reserve space for base classes.
249 Record::BaseList Bases;
250 Record::VirtualBaseList VirtBases;
251 if (auto *CD = dyn_cast<CXXRecordDecl>(RD)) {
252 for (const CXXBaseSpecifier &Spec : CD->bases()) {
253 if (Spec.isVirtual())
254 continue;
255
256 const RecordDecl *BD = Spec.getType()->castAs<RecordType>()->getDecl();
257 Record *BR = getOrCreateRecord(BD);
258 if (Descriptor *Desc = GetBaseDesc(BD, BR)) {
259 BaseSize += align(sizeof(InlineDescriptor));
260 Bases.push_back({BD, BaseSize, Desc, BR});
261 BaseSize += align(BR->getSize());
262 continue;
263 }
264 return nullptr;
265 }
266
267 for (const CXXBaseSpecifier &Spec : CD->vbases()) {
268 const RecordDecl *BD = Spec.getType()->castAs<RecordType>()->getDecl();
269 Record *BR = getOrCreateRecord(BD);
270
271 if (Descriptor *Desc = GetBaseDesc(BD, BR)) {
272 VirtSize += align(sizeof(InlineDescriptor));
273 VirtBases.push_back({BD, VirtSize, Desc, BR});
274 VirtSize += align(BR->getSize());
275 continue;
276 }
277 return nullptr;
278 }
279 }
280
281 // Reserve space for fields.
282 Record::FieldList Fields;
283 for (const FieldDecl *FD : RD->fields()) {
284 // Reserve space for the field's descriptor and the offset.
285 BaseSize += align(sizeof(InlineDescriptor));
286
287 // Classify the field and add its metadata.
288 QualType FT = FD->getType();
289 const bool IsConst = FT.isConstQualified();
290 const bool IsMutable = FD->isMutable();
291 Descriptor *Desc;
292 if (std::optional<PrimType> T = Ctx.classify(FT)) {
293 Desc = createDescriptor(FD, *T, std::nullopt, IsConst,
294 /*isTemporary=*/false, IsMutable);
295 } else {
296 Desc = createDescriptor(FD, FT.getTypePtr(), std::nullopt, IsConst,
297 /*isTemporary=*/false, IsMutable);
298 }
299 if (!Desc)
300 return nullptr;
301 Fields.push_back({FD, BaseSize, Desc});
302 BaseSize += align(Desc->getAllocSize());
303 }
304
305 Record *R = new (Allocator) Record(RD, std::move(Bases), std::move(Fields),
306 std::move(VirtBases), VirtSize, BaseSize);
307 Records[RD] = R;
308 return R;
309 }
310
createDescriptor(const DeclTy & D,const Type * Ty,Descriptor::MetadataSize MDSize,bool IsConst,bool IsTemporary,bool IsMutable,const Expr * Init)311 Descriptor *Program::createDescriptor(const DeclTy &D, const Type *Ty,
312 Descriptor::MetadataSize MDSize,
313 bool IsConst, bool IsTemporary,
314 bool IsMutable, const Expr *Init) {
315 // Classes and structures.
316 if (auto *RT = Ty->getAs<RecordType>()) {
317 if (auto *Record = getOrCreateRecord(RT->getDecl()))
318 return allocateDescriptor(D, Record, MDSize, IsConst, IsTemporary,
319 IsMutable);
320 }
321
322 // Arrays.
323 if (auto ArrayType = Ty->getAsArrayTypeUnsafe()) {
324 QualType ElemTy = ArrayType->getElementType();
325 // Array of well-known bounds.
326 if (auto CAT = dyn_cast<ConstantArrayType>(ArrayType)) {
327 size_t NumElems = CAT->getSize().getZExtValue();
328 if (std::optional<PrimType> T = Ctx.classify(ElemTy)) {
329 // Arrays of primitives.
330 unsigned ElemSize = primSize(*T);
331 if (std::numeric_limits<unsigned>::max() / ElemSize <= NumElems) {
332 return {};
333 }
334 return allocateDescriptor(D, *T, MDSize, NumElems, IsConst, IsTemporary,
335 IsMutable);
336 } else {
337 // Arrays of composites. In this case, the array is a list of pointers,
338 // followed by the actual elements.
339 Descriptor *ElemDesc = createDescriptor(
340 D, ElemTy.getTypePtr(), std::nullopt, IsConst, IsTemporary);
341 if (!ElemDesc)
342 return nullptr;
343 InterpSize ElemSize =
344 ElemDesc->getAllocSize() + sizeof(InlineDescriptor);
345 if (std::numeric_limits<unsigned>::max() / ElemSize <= NumElems)
346 return {};
347 return allocateDescriptor(D, ElemDesc, MDSize, NumElems, IsConst,
348 IsTemporary, IsMutable);
349 }
350 }
351
352 // Array of unknown bounds - cannot be accessed and pointer arithmetic
353 // is forbidden on pointers to such objects.
354 if (isa<IncompleteArrayType>(ArrayType)) {
355 if (std::optional<PrimType> T = Ctx.classify(ElemTy)) {
356 return allocateDescriptor(D, *T, IsTemporary,
357 Descriptor::UnknownSize{});
358 } else {
359 Descriptor *Desc = createDescriptor(D, ElemTy.getTypePtr(), MDSize,
360 IsConst, IsTemporary);
361 if (!Desc)
362 return nullptr;
363 return allocateDescriptor(D, Desc, IsTemporary,
364 Descriptor::UnknownSize{});
365 }
366 }
367 }
368
369 // Atomic types.
370 if (auto *AT = Ty->getAs<AtomicType>()) {
371 const Type *InnerTy = AT->getValueType().getTypePtr();
372 return createDescriptor(D, InnerTy, MDSize, IsConst, IsTemporary,
373 IsMutable);
374 }
375
376 // Complex types - represented as arrays of elements.
377 if (auto *CT = Ty->getAs<ComplexType>()) {
378 PrimType ElemTy = *Ctx.classify(CT->getElementType());
379 return allocateDescriptor(D, ElemTy, MDSize, 2, IsConst, IsTemporary,
380 IsMutable);
381 }
382
383 return nullptr;
384 }
385