1 //===--- CGNonTrivialStruct.cpp - Emit Special Functions for C Structs ----===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file defines functions to generate various special functions for C
11 // structs.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "CodeGenFunction.h"
16 #include "CodeGenModule.h"
17 #include "clang/AST/NonTrivialTypeVisitor.h"
18 #include "llvm/Support/ScopedPrinter.h"
19 #include <array>
20 
21 using namespace clang;
22 using namespace CodeGen;
23 
24 // Return the size of a field in number of bits.
25 static uint64_t getFieldSize(const FieldDecl *FD, QualType FT,
26                              ASTContext &Ctx) {
27   if (FD && FD->isBitField())
28     return FD->getBitWidthValue(Ctx);
29   return Ctx.getTypeSize(FT);
30 }
31 
32 namespace {
33 enum { DstIdx = 0, SrcIdx = 1 };
34 const char *ValNameStr[2] = {"dst", "src"};
35 
36 template <class Derived> struct StructVisitor {
37   StructVisitor(ASTContext &Ctx) : Ctx(Ctx) {}
38 
39   template <class... Ts>
40   void visitStructFields(QualType QT, CharUnits CurStructOffset, Ts... Args) {
41     const RecordDecl *RD = QT->castAs<RecordType>()->getDecl();
42 
43     // Iterate over the fields of the struct.
44     for (const FieldDecl *FD : RD->fields()) {
45       QualType FT = FD->getType();
46       FT = QT.isVolatileQualified() ? FT.withVolatile() : FT;
47       asDerived().visit(FT, FD, CurStructOffset, Args...);
48     }
49 
50     asDerived().flushTrivialFields(Args...);
51   }
52 
53   template <class... Ts> void visitTrivial(Ts... Args) {}
54 
55   template <class... Ts> void visitCXXDestructor(Ts... Args) {
56     llvm_unreachable("field of a C++ struct type is not expected");
57   }
58 
59   template <class... Ts> void flushTrivialFields(Ts... Args) {}
60 
61   uint64_t getFieldOffsetInBits(const FieldDecl *FD) {
62     return FD ? Ctx.getASTRecordLayout(FD->getParent())
63                     .getFieldOffset(FD->getFieldIndex())
64               : 0;
65   }
66 
67   CharUnits getFieldOffset(const FieldDecl *FD) {
68     return Ctx.toCharUnitsFromBits(getFieldOffsetInBits(FD));
69   }
70 
71   Derived &asDerived() { return static_cast<Derived &>(*this); }
72 
73   ASTContext &getContext() { return Ctx; }
74   ASTContext &Ctx;
75 };
76 
77 template <class Derived, bool IsMove>
78 struct CopyStructVisitor : StructVisitor<Derived>,
79                            CopiedTypeVisitor<Derived, IsMove> {
80   using StructVisitor<Derived>::asDerived;
81   using Super = CopiedTypeVisitor<Derived, IsMove>;
82 
83   CopyStructVisitor(ASTContext &Ctx) : StructVisitor<Derived>(Ctx) {}
84 
85   template <class... Ts>
86   void preVisit(QualType::PrimitiveCopyKind PCK, QualType FT,
87                 const FieldDecl *FD, CharUnits CurStructOffsset,
88                 Ts &&... Args) {
89     if (PCK)
90       asDerived().flushTrivialFields(std::forward<Ts>(Args)...);
91   }
92 
93   template <class... Ts>
94   void visitWithKind(QualType::PrimitiveCopyKind PCK, QualType FT,
95                      const FieldDecl *FD, CharUnits CurStructOffsset,
96                      Ts &&... Args) {
97     if (const auto *AT = asDerived().getContext().getAsArrayType(FT)) {
98       asDerived().visitArray(PCK, AT, FT.isVolatileQualified(), FD,
99                              CurStructOffsset, std::forward<Ts>(Args)...);
100       return;
101     }
102 
103     Super::visitWithKind(PCK, FT, FD, CurStructOffsset,
104                          std::forward<Ts>(Args)...);
105   }
106 
107   template <class... Ts>
108   void visitTrivial(QualType FT, const FieldDecl *FD, CharUnits CurStructOffset,
109                     Ts... Args) {
110     assert(!FT.isVolatileQualified() && "volatile field not expected");
111     ASTContext &Ctx = asDerived().getContext();
112     uint64_t FieldSize = getFieldSize(FD, FT, Ctx);
113 
114     // Ignore zero-sized fields.
115     if (FieldSize == 0)
116       return;
117 
118     uint64_t FStartInBits = asDerived().getFieldOffsetInBits(FD);
119     uint64_t FEndInBits = FStartInBits + FieldSize;
120     uint64_t RoundedFEnd = llvm::alignTo(FEndInBits, Ctx.getCharWidth());
121 
122     // Set Start if this is the first field of a sequence of trivial fields.
123     if (Start == End)
124       Start = CurStructOffset + Ctx.toCharUnitsFromBits(FStartInBits);
125     End = CurStructOffset + Ctx.toCharUnitsFromBits(RoundedFEnd);
126   }
127 
128   CharUnits Start = CharUnits::Zero(), End = CharUnits::Zero();
129 };
130 
131 // This function creates the mangled name of a special function of a non-trivial
132 // C struct. Since there is no ODR in C, the function is mangled based on the
133 // struct contents and not the name. The mangled name has the following
134 // structure:
135 //
136 // <function-name> ::= <prefix> <alignment-info> "_" <struct-field-info>
137 // <prefix> ::= "__destructor_" | "__default_constructor_" |
138 //              "__copy_constructor_" | "__move_constructor_" |
139 //              "__copy_assignment_" | "__move_assignment_"
140 // <alignment-info> ::= <dst-alignment> ["_" <src-alignment>]
141 // <struct-field-info> ::= <field-info>+
142 // <field-info> ::= <struct-or-scalar-field-info> | <array-field-info>
143 // <struct-or-scalar-field-info> ::= <struct-field-info> | <strong-field-info> |
144 //                                   <trivial-field-info>
145 // <array-field-info> ::= "_AB" <array-offset> "s" <element-size> "n"
146 //                        <num-elements> <innermost-element-info> "_AE"
147 // <innermost-element-info> ::= <struct-or-scalar-field-info>
148 // <strong-field-info> ::= "_s" ["b"] ["v"] <field-offset>
149 // <trivial-field-info> ::= "_t" ["v"] <field-offset> "_" <field-size>
150 
151 template <class Derived> struct GenFuncNameBase {
152   std::string getVolatileOffsetStr(bool IsVolatile, CharUnits Offset) {
153     std::string S;
154     if (IsVolatile)
155       S = "v";
156     S += llvm::to_string(Offset.getQuantity());
157     return S;
158   }
159 
160   void visitARCStrong(QualType FT, const FieldDecl *FD,
161                       CharUnits CurStructOffset) {
162     appendStr("_s");
163     if (FT->isBlockPointerType())
164       appendStr("b");
165     CharUnits FieldOffset = CurStructOffset + asDerived().getFieldOffset(FD);
166     appendStr(getVolatileOffsetStr(FT.isVolatileQualified(), FieldOffset));
167   }
168 
169   void visitARCWeak(QualType FT, const FieldDecl *FD,
170                     CharUnits CurStructOffset) {
171     appendStr("_w");
172     CharUnits FieldOffset = CurStructOffset + asDerived().getFieldOffset(FD);
173     appendStr(getVolatileOffsetStr(FT.isVolatileQualified(), FieldOffset));
174   }
175 
176   void visitStruct(QualType QT, const FieldDecl *FD,
177                    CharUnits CurStructOffset) {
178     CharUnits FieldOffset = CurStructOffset + asDerived().getFieldOffset(FD);
179     asDerived().visitStructFields(QT, FieldOffset);
180   }
181 
182   template <class FieldKind>
183   void visitArray(FieldKind FK, const ArrayType *AT, bool IsVolatile,
184                   const FieldDecl *FD, CharUnits CurStructOffset) {
185     // String for non-volatile trivial fields is emitted when
186     // flushTrivialFields is called.
187     if (!FK)
188       return asDerived().visitTrivial(QualType(AT, 0), FD, CurStructOffset);
189 
190     CharUnits FieldOffset = CurStructOffset + asDerived().getFieldOffset(FD);
191     ASTContext &Ctx = asDerived().getContext();
192     const ConstantArrayType *CAT = cast<ConstantArrayType>(AT);
193     unsigned NumElts = Ctx.getConstantArrayElementCount(CAT);
194     QualType EltTy = Ctx.getBaseElementType(CAT);
195     CharUnits EltSize = Ctx.getTypeSizeInChars(EltTy);
196     appendStr("_AB" + llvm::to_string(FieldOffset.getQuantity()) + "s" +
197               llvm::to_string(EltSize.getQuantity()) + "n" +
198               llvm::to_string(NumElts));
199     EltTy = IsVolatile ? EltTy.withVolatile() : EltTy;
200     asDerived().visitWithKind(FK, EltTy, nullptr, FieldOffset);
201     appendStr("_AE");
202   }
203 
204   void appendStr(StringRef Str) { Name += Str; }
205 
206   std::string getName(QualType QT, bool IsVolatile) {
207     QT = IsVolatile ? QT.withVolatile() : QT;
208     asDerived().visitStructFields(QT, CharUnits::Zero());
209     return Name;
210   }
211 
212   Derived &asDerived() { return static_cast<Derived &>(*this); }
213 
214   std::string Name;
215 };
216 
217 template <class Derived>
218 struct GenUnaryFuncName : StructVisitor<Derived>, GenFuncNameBase<Derived> {
219   GenUnaryFuncName(StringRef Prefix, CharUnits DstAlignment, ASTContext &Ctx)
220       : StructVisitor<Derived>(Ctx) {
221     this->appendStr(Prefix);
222     this->appendStr(llvm::to_string(DstAlignment.getQuantity()));
223   }
224 };
225 
226 // Helper function to create a null constant.
227 static llvm::Constant *getNullForVariable(Address Addr) {
228   llvm::Type *Ty = Addr.getElementType();
229   return llvm::ConstantPointerNull::get(cast<llvm::PointerType>(Ty));
230 }
231 
232 template <bool IsMove>
233 struct GenBinaryFuncName : CopyStructVisitor<GenBinaryFuncName<IsMove>, IsMove>,
234                            GenFuncNameBase<GenBinaryFuncName<IsMove>> {
235 
236   GenBinaryFuncName(StringRef Prefix, CharUnits DstAlignment,
237                     CharUnits SrcAlignment, ASTContext &Ctx)
238       : CopyStructVisitor<GenBinaryFuncName<IsMove>, IsMove>(Ctx) {
239     this->appendStr(Prefix);
240     this->appendStr(llvm::to_string(DstAlignment.getQuantity()));
241     this->appendStr("_" + llvm::to_string(SrcAlignment.getQuantity()));
242   }
243 
244   void flushTrivialFields() {
245     if (this->Start == this->End)
246       return;
247 
248     this->appendStr("_t" + llvm::to_string(this->Start.getQuantity()) + "w" +
249                     llvm::to_string((this->End - this->Start).getQuantity()));
250 
251     this->Start = this->End = CharUnits::Zero();
252   }
253 
254   void visitVolatileTrivial(QualType FT, const FieldDecl *FD,
255                             CharUnits CurStackOffset) {
256     // Because volatile fields can be bit-fields and are individually copied,
257     // their offset and width are in bits.
258     uint64_t OffsetInBits =
259         this->Ctx.toBits(CurStackOffset) + this->getFieldOffsetInBits(FD);
260     this->appendStr("_tv" + llvm::to_string(OffsetInBits) + "w" +
261                     llvm::to_string(getFieldSize(FD, FT, this->Ctx)));
262   }
263 };
264 
265 struct GenDefaultInitializeFuncName
266     : GenUnaryFuncName<GenDefaultInitializeFuncName>,
267       DefaultInitializedTypeVisitor<GenDefaultInitializeFuncName> {
268   using Super = DefaultInitializedTypeVisitor<GenDefaultInitializeFuncName>;
269   GenDefaultInitializeFuncName(CharUnits DstAlignment, ASTContext &Ctx)
270       : GenUnaryFuncName<GenDefaultInitializeFuncName>("__default_constructor_",
271                                                        DstAlignment, Ctx) {}
272   void visitWithKind(QualType::PrimitiveDefaultInitializeKind PDIK, QualType FT,
273                      const FieldDecl *FD, CharUnits CurStructOffset) {
274     if (const auto *AT = getContext().getAsArrayType(FT)) {
275       visitArray(PDIK, AT, FT.isVolatileQualified(), FD, CurStructOffset);
276       return;
277     }
278 
279     Super::visitWithKind(PDIK, FT, FD, CurStructOffset);
280   }
281 };
282 
283 struct GenDestructorFuncName : GenUnaryFuncName<GenDestructorFuncName>,
284                                DestructedTypeVisitor<GenDestructorFuncName> {
285   using Super = DestructedTypeVisitor<GenDestructorFuncName>;
286   GenDestructorFuncName(const char *Prefix, CharUnits DstAlignment,
287                         ASTContext &Ctx)
288       : GenUnaryFuncName<GenDestructorFuncName>(Prefix, DstAlignment,
289                                                 Ctx) {}
290   void visitWithKind(QualType::DestructionKind DK, QualType FT,
291                      const FieldDecl *FD, CharUnits CurStructOffset) {
292     if (const auto *AT = getContext().getAsArrayType(FT)) {
293       visitArray(DK, AT, FT.isVolatileQualified(), FD, CurStructOffset);
294       return;
295     }
296 
297     Super::visitWithKind(DK, FT, FD, CurStructOffset);
298   }
299 };
300 
301 // Helper function that creates CGFunctionInfo for an N-ary special function.
302 template <size_t N>
303 static const CGFunctionInfo &getFunctionInfo(CodeGenModule &CGM,
304                                              FunctionArgList &Args) {
305   ASTContext &Ctx = CGM.getContext();
306   llvm::SmallVector<ImplicitParamDecl *, N> Params;
307   QualType ParamTy = Ctx.getPointerType(Ctx.VoidPtrTy);
308 
309   for (unsigned I = 0; I < N; ++I)
310     Params.push_back(ImplicitParamDecl::Create(
311         Ctx, nullptr, SourceLocation(), &Ctx.Idents.get(ValNameStr[I]), ParamTy,
312         ImplicitParamDecl::Other));
313 
314   for (auto &P : Params)
315     Args.push_back(P);
316 
317   return CGM.getTypes().arrangeBuiltinFunctionDeclaration(Ctx.VoidTy, Args);
318 }
319 
320 // Template classes that are used as bases for classes that emit special
321 // functions.
322 template <class Derived> struct GenFuncBase {
323   template <size_t N>
324   void visitStruct(QualType FT, const FieldDecl *FD, CharUnits CurStackOffset,
325                    std::array<Address, N> Addrs) {
326     this->asDerived().callSpecialFunction(
327         FT, CurStackOffset + asDerived().getFieldOffset(FD), Addrs);
328   }
329 
330   template <class FieldKind, size_t N>
331   void visitArray(FieldKind FK, const ArrayType *AT, bool IsVolatile,
332                   const FieldDecl *FD, CharUnits CurStackOffset,
333                   std::array<Address, N> Addrs) {
334     // Non-volatile trivial fields are copied when flushTrivialFields is called.
335     if (!FK)
336       return asDerived().visitTrivial(QualType(AT, 0), FD, CurStackOffset,
337                                       Addrs);
338 
339     CodeGenFunction &CGF = *this->CGF;
340     ASTContext &Ctx = CGF.getContext();
341 
342     // Compute the end address.
343     QualType BaseEltQT;
344     std::array<Address, N> StartAddrs = Addrs;
345     for (unsigned I = 0; I < N; ++I)
346       StartAddrs[I] = getAddrWithOffset(Addrs[I], CurStackOffset, FD);
347     Address DstAddr = StartAddrs[DstIdx];
348     llvm::Value *NumElts = CGF.emitArrayLength(AT, BaseEltQT, DstAddr);
349     unsigned BaseEltSize = Ctx.getTypeSizeInChars(BaseEltQT).getQuantity();
350     llvm::Value *BaseEltSizeVal =
351         llvm::ConstantInt::get(NumElts->getType(), BaseEltSize);
352     llvm::Value *SizeInBytes =
353         CGF.Builder.CreateNUWMul(BaseEltSizeVal, NumElts);
354     Address BC = CGF.Builder.CreateBitCast(DstAddr, CGF.CGM.Int8PtrTy);
355     llvm::Value *DstArrayEnd =
356         CGF.Builder.CreateInBoundsGEP(BC.getPointer(), SizeInBytes);
357     DstArrayEnd = CGF.Builder.CreateBitCast(DstArrayEnd, CGF.CGM.Int8PtrPtrTy,
358                                             "dstarray.end");
359     llvm::BasicBlock *PreheaderBB = CGF.Builder.GetInsertBlock();
360 
361     // Create the header block and insert the phi instructions.
362     llvm::BasicBlock *HeaderBB = CGF.createBasicBlock("loop.header");
363     CGF.EmitBlock(HeaderBB);
364     llvm::PHINode *PHIs[N];
365 
366     for (unsigned I = 0; I < N; ++I) {
367       PHIs[I] = CGF.Builder.CreatePHI(CGF.CGM.Int8PtrPtrTy, 2, "addr.cur");
368       PHIs[I]->addIncoming(StartAddrs[I].getPointer(), PreheaderBB);
369     }
370 
371     // Create the exit and loop body blocks.
372     llvm::BasicBlock *ExitBB = CGF.createBasicBlock("loop.exit");
373     llvm::BasicBlock *LoopBB = CGF.createBasicBlock("loop.body");
374 
375     // Emit the comparison and conditional branch instruction that jumps to
376     // either the exit or the loop body.
377     llvm::Value *Done =
378         CGF.Builder.CreateICmpEQ(PHIs[DstIdx], DstArrayEnd, "done");
379     CGF.Builder.CreateCondBr(Done, ExitBB, LoopBB);
380 
381     // Visit the element of the array in the loop body.
382     CGF.EmitBlock(LoopBB);
383     QualType EltQT = AT->getElementType();
384     CharUnits EltSize = Ctx.getTypeSizeInChars(EltQT);
385     std::array<Address, N> NewAddrs = Addrs;
386 
387     for (unsigned I = 0; I < N; ++I)
388       NewAddrs[I] = Address(
389           PHIs[I], StartAddrs[I].getAlignment().alignmentAtOffset(EltSize));
390 
391     EltQT = IsVolatile ? EltQT.withVolatile() : EltQT;
392     this->asDerived().visitWithKind(FK, EltQT, nullptr, CharUnits::Zero(),
393                                     NewAddrs);
394 
395     LoopBB = CGF.Builder.GetInsertBlock();
396 
397     for (unsigned I = 0; I < N; ++I) {
398       // Instrs to update the destination and source addresses.
399       // Update phi instructions.
400       NewAddrs[I] = getAddrWithOffset(NewAddrs[I], EltSize);
401       PHIs[I]->addIncoming(NewAddrs[I].getPointer(), LoopBB);
402     }
403 
404     // Insert an unconditional branch to the header block.
405     CGF.Builder.CreateBr(HeaderBB);
406     CGF.EmitBlock(ExitBB);
407   }
408 
409   /// Return an address with the specified offset from the passed address.
410   Address getAddrWithOffset(Address Addr, CharUnits Offset) {
411     assert(Addr.isValid() && "invalid address");
412     if (Offset.getQuantity() == 0)
413       return Addr;
414     Addr = CGF->Builder.CreateBitCast(Addr, CGF->CGM.Int8PtrTy);
415     Addr = CGF->Builder.CreateConstInBoundsGEP(Addr, Offset.getQuantity(),
416                                                CharUnits::One());
417     return CGF->Builder.CreateBitCast(Addr, CGF->CGM.Int8PtrPtrTy);
418   }
419 
420   Address getAddrWithOffset(Address Addr, CharUnits StructFieldOffset,
421                             const FieldDecl *FD) {
422     return getAddrWithOffset(Addr, StructFieldOffset +
423                                        asDerived().getFieldOffset(FD));
424   }
425 
426   template <size_t N>
427   llvm::Function *
428   getFunction(StringRef FuncName, QualType QT, std::array<Address, N> Addrs,
429               std::array<CharUnits, N> Alignments, CodeGenModule &CGM) {
430     // If the special function already exists in the module, return it.
431     if (llvm::Function *F = CGM.getModule().getFunction(FuncName)) {
432       bool WrongType = false;
433       if (!F->getReturnType()->isVoidTy())
434         WrongType = true;
435       else {
436         for (const llvm::Argument &Arg : F->args())
437           if (Arg.getType() != CGM.Int8PtrPtrTy)
438             WrongType = true;
439       }
440 
441       if (WrongType) {
442         std::string FuncName = F->getName();
443         SourceLocation Loc = QT->castAs<RecordType>()->getDecl()->getLocation();
444         CGM.Error(Loc, "special function " + FuncName +
445                            " for non-trivial C struct has incorrect type");
446         return nullptr;
447       }
448       return F;
449     }
450 
451     ASTContext &Ctx = CGM.getContext();
452     FunctionArgList Args;
453     const CGFunctionInfo &FI = getFunctionInfo<N>(CGM, Args);
454     llvm::FunctionType *FuncTy = CGM.getTypes().GetFunctionType(FI);
455     llvm::Function *F =
456         llvm::Function::Create(FuncTy, llvm::GlobalValue::LinkOnceODRLinkage,
457                                FuncName, &CGM.getModule());
458     F->setVisibility(llvm::GlobalValue::HiddenVisibility);
459     CGM.SetLLVMFunctionAttributes(nullptr, FI, F);
460     CGM.SetLLVMFunctionAttributesForDefinition(nullptr, F);
461     IdentifierInfo *II = &Ctx.Idents.get(FuncName);
462     FunctionDecl *FD = FunctionDecl::Create(
463         Ctx, Ctx.getTranslationUnitDecl(), SourceLocation(), SourceLocation(),
464         II, Ctx.VoidTy, nullptr, SC_PrivateExtern, false, false);
465     CodeGenFunction NewCGF(CGM);
466     setCGF(&NewCGF);
467     CGF->StartFunction(FD, Ctx.VoidTy, F, FI, Args);
468 
469     for (unsigned I = 0; I < N; ++I) {
470       llvm::Value *V = CGF->Builder.CreateLoad(CGF->GetAddrOfLocalVar(Args[I]));
471       Addrs[I] = Address(V, Alignments[I]);
472     }
473 
474     asDerived().visitStructFields(QT, CharUnits::Zero(), Addrs);
475     CGF->FinishFunction();
476     return F;
477   }
478 
479   template <size_t N>
480   void callFunc(StringRef FuncName, QualType QT, std::array<Address, N> Addrs,
481                 CodeGenFunction &CallerCGF) {
482     std::array<CharUnits, N> Alignments;
483     llvm::Value *Ptrs[N];
484 
485     for (unsigned I = 0; I < N; ++I) {
486       Alignments[I] = Addrs[I].getAlignment();
487       Ptrs[I] =
488           CallerCGF.Builder.CreateBitCast(Addrs[I], CallerCGF.CGM.Int8PtrPtrTy)
489               .getPointer();
490     }
491 
492     if (llvm::Function *F =
493             getFunction(FuncName, QT, Addrs, Alignments, CallerCGF.CGM))
494       CallerCGF.EmitNounwindRuntimeCall(F, Ptrs);
495   }
496 
497   Derived &asDerived() { return static_cast<Derived &>(*this); }
498 
499   void setCGF(CodeGenFunction *F) { CGF = F; }
500 
501   CodeGenFunction *CGF = nullptr;
502 };
503 
504 template <class Derived, bool IsMove>
505 struct GenBinaryFunc : CopyStructVisitor<Derived, IsMove>,
506                        GenFuncBase<Derived> {
507   GenBinaryFunc(ASTContext &Ctx) : CopyStructVisitor<Derived, IsMove>(Ctx) {}
508 
509   void flushTrivialFields(std::array<Address, 2> Addrs) {
510     CharUnits Size = this->End - this->Start;
511 
512     if (Size.getQuantity() == 0)
513       return;
514 
515     Address DstAddr = this->getAddrWithOffset(Addrs[DstIdx], this->Start);
516     Address SrcAddr = this->getAddrWithOffset(Addrs[SrcIdx], this->Start);
517 
518     // Emit memcpy.
519     if (Size.getQuantity() >= 16 || !llvm::isPowerOf2_32(Size.getQuantity())) {
520       llvm::Value *SizeVal =
521           llvm::ConstantInt::get(this->CGF->SizeTy, Size.getQuantity());
522       DstAddr =
523           this->CGF->Builder.CreateElementBitCast(DstAddr, this->CGF->Int8Ty);
524       SrcAddr =
525           this->CGF->Builder.CreateElementBitCast(SrcAddr, this->CGF->Int8Ty);
526       this->CGF->Builder.CreateMemCpy(DstAddr, SrcAddr, SizeVal, false);
527     } else {
528       llvm::Type *Ty = llvm::Type::getIntNTy(
529           this->CGF->getLLVMContext(),
530           Size.getQuantity() * this->CGF->getContext().getCharWidth());
531       DstAddr = this->CGF->Builder.CreateElementBitCast(DstAddr, Ty);
532       SrcAddr = this->CGF->Builder.CreateElementBitCast(SrcAddr, Ty);
533       llvm::Value *SrcVal = this->CGF->Builder.CreateLoad(SrcAddr, false);
534       this->CGF->Builder.CreateStore(SrcVal, DstAddr, false);
535     }
536 
537     this->Start = this->End = CharUnits::Zero();
538   }
539 
540   template <class... Ts>
541   void visitVolatileTrivial(QualType FT, const FieldDecl *FD, CharUnits Offset,
542                             std::array<Address, 2> Addrs) {
543     LValue DstLV, SrcLV;
544     if (FD) {
545       QualType RT = QualType(FD->getParent()->getTypeForDecl(), 0);
546       llvm::PointerType *PtrTy = this->CGF->ConvertType(RT)->getPointerTo();
547       Address DstAddr = this->getAddrWithOffset(Addrs[DstIdx], Offset);
548       LValue DstBase = this->CGF->MakeAddrLValue(
549           this->CGF->Builder.CreateBitCast(DstAddr, PtrTy), FT);
550       DstLV = this->CGF->EmitLValueForField(DstBase, FD);
551       Address SrcAddr = this->getAddrWithOffset(Addrs[SrcIdx], Offset);
552       LValue SrcBase = this->CGF->MakeAddrLValue(
553           this->CGF->Builder.CreateBitCast(SrcAddr, PtrTy), FT);
554       SrcLV = this->CGF->EmitLValueForField(SrcBase, FD);
555     } else {
556       llvm::PointerType *Ty = this->CGF->ConvertType(FT)->getPointerTo();
557       Address DstAddr = this->CGF->Builder.CreateBitCast(Addrs[DstIdx], Ty);
558       Address SrcAddr = this->CGF->Builder.CreateBitCast(Addrs[SrcIdx], Ty);
559       DstLV = this->CGF->MakeAddrLValue(DstAddr, FT);
560       SrcLV = this->CGF->MakeAddrLValue(SrcAddr, FT);
561     }
562     RValue SrcVal = this->CGF->EmitLoadOfLValue(SrcLV, SourceLocation());
563     this->CGF->EmitStoreThroughLValue(SrcVal, DstLV);
564   }
565 };
566 
567 // These classes that emit the special functions for a non-trivial struct.
568 struct GenDestructor : StructVisitor<GenDestructor>,
569                        GenFuncBase<GenDestructor>,
570                        DestructedTypeVisitor<GenDestructor> {
571   using Super = DestructedTypeVisitor<GenDestructor>;
572   GenDestructor(ASTContext &Ctx) : StructVisitor<GenDestructor>(Ctx) {}
573 
574   void visitWithKind(QualType::DestructionKind DK, QualType FT,
575                      const FieldDecl *FD, CharUnits CurStructOffset,
576                      std::array<Address, 1> Addrs) {
577     if (const auto *AT = getContext().getAsArrayType(FT)) {
578       visitArray(DK, AT, FT.isVolatileQualified(), FD, CurStructOffset, Addrs);
579       return;
580     }
581 
582     Super::visitWithKind(DK, FT, FD, CurStructOffset, Addrs);
583   }
584 
585   void visitARCStrong(QualType QT, const FieldDecl *FD,
586                       CharUnits CurStackOffset, std::array<Address, 1> Addrs) {
587     CGF->destroyARCStrongImprecise(
588         *CGF, getAddrWithOffset(Addrs[DstIdx], CurStackOffset, FD), QT);
589   }
590 
591   void visitARCWeak(QualType QT, const FieldDecl *FD, CharUnits CurStackOffset,
592                     std::array<Address, 1> Addrs) {
593     CGF->destroyARCWeak(
594         *CGF, getAddrWithOffset(Addrs[DstIdx], CurStackOffset, FD), QT);
595   }
596 
597   void callSpecialFunction(QualType FT, CharUnits Offset,
598                            std::array<Address, 1> Addrs) {
599     CGF->callCStructDestructor(
600         CGF->MakeAddrLValue(getAddrWithOffset(Addrs[DstIdx], Offset), FT));
601   }
602 };
603 
604 struct GenDefaultInitialize
605     : StructVisitor<GenDefaultInitialize>,
606       GenFuncBase<GenDefaultInitialize>,
607       DefaultInitializedTypeVisitor<GenDefaultInitialize> {
608   using Super = DefaultInitializedTypeVisitor<GenDefaultInitialize>;
609   typedef GenFuncBase<GenDefaultInitialize> GenFuncBaseTy;
610 
611   GenDefaultInitialize(ASTContext &Ctx)
612       : StructVisitor<GenDefaultInitialize>(Ctx) {}
613 
614   void visitWithKind(QualType::PrimitiveDefaultInitializeKind PDIK, QualType FT,
615                      const FieldDecl *FD, CharUnits CurStructOffset,
616                      std::array<Address, 1> Addrs) {
617     if (const auto *AT = getContext().getAsArrayType(FT)) {
618       visitArray(PDIK, AT, FT.isVolatileQualified(), FD, CurStructOffset,
619                  Addrs);
620       return;
621     }
622 
623     Super::visitWithKind(PDIK, FT, FD, CurStructOffset, Addrs);
624   }
625 
626   void visitARCStrong(QualType QT, const FieldDecl *FD,
627                       CharUnits CurStackOffset, std::array<Address, 1> Addrs) {
628     CGF->EmitNullInitialization(
629         getAddrWithOffset(Addrs[DstIdx], CurStackOffset, FD), QT);
630   }
631 
632   void visitARCWeak(QualType QT, const FieldDecl *FD, CharUnits CurStackOffset,
633                     std::array<Address, 1> Addrs) {
634     CGF->EmitNullInitialization(
635         getAddrWithOffset(Addrs[DstIdx], CurStackOffset, FD), QT);
636   }
637 
638   template <class FieldKind, size_t... Is>
639   void visitArray(FieldKind FK, const ArrayType *AT, bool IsVolatile,
640                   const FieldDecl *FD, CharUnits CurStackOffset,
641                   std::array<Address, 1> Addrs) {
642     if (!FK)
643       return visitTrivial(QualType(AT, 0), FD, CurStackOffset, Addrs);
644 
645     ASTContext &Ctx = getContext();
646     CharUnits Size = Ctx.getTypeSizeInChars(QualType(AT, 0));
647     QualType EltTy = Ctx.getBaseElementType(QualType(AT, 0));
648 
649     if (Size < CharUnits::fromQuantity(16) || EltTy->getAs<RecordType>()) {
650       GenFuncBaseTy::visitArray(FK, AT, IsVolatile, FD, CurStackOffset, Addrs);
651       return;
652     }
653 
654     llvm::Constant *SizeVal = CGF->Builder.getInt64(Size.getQuantity());
655     Address DstAddr = getAddrWithOffset(Addrs[DstIdx], CurStackOffset, FD);
656     Address Loc = CGF->Builder.CreateElementBitCast(DstAddr, CGF->Int8Ty);
657     CGF->Builder.CreateMemSet(Loc, CGF->Builder.getInt8(0), SizeVal,
658                               IsVolatile);
659   }
660 
661   void callSpecialFunction(QualType FT, CharUnits Offset,
662                            std::array<Address, 1> Addrs) {
663     CGF->callCStructDefaultConstructor(
664         CGF->MakeAddrLValue(getAddrWithOffset(Addrs[DstIdx], Offset), FT));
665   }
666 };
667 
668 struct GenCopyConstructor : GenBinaryFunc<GenCopyConstructor, false> {
669   GenCopyConstructor(ASTContext &Ctx)
670       : GenBinaryFunc<GenCopyConstructor, false>(Ctx) {}
671 
672   void visitARCStrong(QualType QT, const FieldDecl *FD,
673                       CharUnits CurStackOffset, std::array<Address, 2> Addrs) {
674     Addrs[DstIdx] = getAddrWithOffset(Addrs[DstIdx], CurStackOffset, FD);
675     Addrs[SrcIdx] = getAddrWithOffset(Addrs[SrcIdx], CurStackOffset, FD);
676     llvm::Value *SrcVal = CGF->EmitLoadOfScalar(
677         Addrs[SrcIdx], QT.isVolatileQualified(), QT, SourceLocation());
678     llvm::Value *Val = CGF->EmitARCRetain(QT, SrcVal);
679     CGF->EmitStoreOfScalar(Val, CGF->MakeAddrLValue(Addrs[DstIdx], QT), true);
680   }
681 
682   void visitARCWeak(QualType QT, const FieldDecl *FD, CharUnits CurStackOffset,
683                     std::array<Address, 2> Addrs) {
684     Addrs[DstIdx] = getAddrWithOffset(Addrs[DstIdx], CurStackOffset, FD);
685     Addrs[SrcIdx] = getAddrWithOffset(Addrs[SrcIdx], CurStackOffset, FD);
686     CGF->EmitARCCopyWeak(Addrs[DstIdx], Addrs[SrcIdx]);
687   }
688 
689   void callSpecialFunction(QualType FT, CharUnits Offset,
690                            std::array<Address, 2> Addrs) {
691     CGF->callCStructCopyConstructor(CGF->MakeAddrLValue(Addrs[DstIdx], FT),
692                                     CGF->MakeAddrLValue(Addrs[SrcIdx], FT));
693   }
694 };
695 
696 struct GenMoveConstructor : GenBinaryFunc<GenMoveConstructor, true> {
697   GenMoveConstructor(ASTContext &Ctx)
698       : GenBinaryFunc<GenMoveConstructor, true>(Ctx) {}
699 
700   void visitARCStrong(QualType QT, const FieldDecl *FD,
701                       CharUnits CurStackOffset, std::array<Address, 2> Addrs) {
702     Addrs[DstIdx] = getAddrWithOffset(Addrs[DstIdx], CurStackOffset, FD);
703     Addrs[SrcIdx] = getAddrWithOffset(Addrs[SrcIdx], CurStackOffset, FD);
704     LValue SrcLV = CGF->MakeAddrLValue(Addrs[SrcIdx], QT);
705     llvm::Value *SrcVal =
706         CGF->EmitLoadOfLValue(SrcLV, SourceLocation()).getScalarVal();
707     CGF->EmitStoreOfScalar(getNullForVariable(SrcLV.getAddress()), SrcLV);
708     CGF->EmitStoreOfScalar(SrcVal, CGF->MakeAddrLValue(Addrs[DstIdx], QT),
709                            /* isInitialization */ true);
710   }
711 
712   void visitARCWeak(QualType QT, const FieldDecl *FD, CharUnits CurStackOffset,
713                     std::array<Address, 2> Addrs) {
714     Addrs[DstIdx] = getAddrWithOffset(Addrs[DstIdx], CurStackOffset, FD);
715     Addrs[SrcIdx] = getAddrWithOffset(Addrs[SrcIdx], CurStackOffset, FD);
716     CGF->EmitARCMoveWeak(Addrs[DstIdx], Addrs[SrcIdx]);
717   }
718 
719   void callSpecialFunction(QualType FT, CharUnits Offset,
720                            std::array<Address, 2> Addrs) {
721     CGF->callCStructMoveConstructor(CGF->MakeAddrLValue(Addrs[DstIdx], FT),
722                                     CGF->MakeAddrLValue(Addrs[SrcIdx], FT));
723   }
724 };
725 
726 struct GenCopyAssignment : GenBinaryFunc<GenCopyAssignment, false> {
727   GenCopyAssignment(ASTContext &Ctx)
728       : GenBinaryFunc<GenCopyAssignment, false>(Ctx) {}
729 
730   void visitARCStrong(QualType QT, const FieldDecl *FD,
731                       CharUnits CurStackOffset, std::array<Address, 2> Addrs) {
732     Addrs[DstIdx] = getAddrWithOffset(Addrs[DstIdx], CurStackOffset, FD);
733     Addrs[SrcIdx] = getAddrWithOffset(Addrs[SrcIdx], CurStackOffset, FD);
734     llvm::Value *SrcVal = CGF->EmitLoadOfScalar(
735         Addrs[SrcIdx], QT.isVolatileQualified(), QT, SourceLocation());
736     CGF->EmitARCStoreStrong(CGF->MakeAddrLValue(Addrs[DstIdx], QT), SrcVal,
737                             false);
738   }
739 
740   void visitARCWeak(QualType QT, const FieldDecl *FD, CharUnits CurStackOffset,
741                     std::array<Address, 2> Addrs) {
742     Addrs[DstIdx] = getAddrWithOffset(Addrs[DstIdx], CurStackOffset, FD);
743     Addrs[SrcIdx] = getAddrWithOffset(Addrs[SrcIdx], CurStackOffset, FD);
744     CGF->emitARCCopyAssignWeak(QT, Addrs[DstIdx], Addrs[SrcIdx]);
745   }
746 
747   void callSpecialFunction(QualType FT, CharUnits Offset,
748                            std::array<Address, 2> Addrs) {
749     CGF->callCStructCopyAssignmentOperator(
750         CGF->MakeAddrLValue(Addrs[DstIdx], FT),
751         CGF->MakeAddrLValue(Addrs[SrcIdx], FT));
752   }
753 };
754 
755 struct GenMoveAssignment : GenBinaryFunc<GenMoveAssignment, true> {
756   GenMoveAssignment(ASTContext &Ctx)
757       : GenBinaryFunc<GenMoveAssignment, true>(Ctx) {}
758 
759   void visitARCStrong(QualType QT, const FieldDecl *FD,
760                       CharUnits CurStackOffset, std::array<Address, 2> Addrs) {
761     Addrs[DstIdx] = getAddrWithOffset(Addrs[DstIdx], CurStackOffset, FD);
762     Addrs[SrcIdx] = getAddrWithOffset(Addrs[SrcIdx], CurStackOffset, FD);
763     LValue SrcLV = CGF->MakeAddrLValue(Addrs[SrcIdx], QT);
764     llvm::Value *SrcVal =
765         CGF->EmitLoadOfLValue(SrcLV, SourceLocation()).getScalarVal();
766     CGF->EmitStoreOfScalar(getNullForVariable(SrcLV.getAddress()), SrcLV);
767     LValue DstLV = CGF->MakeAddrLValue(Addrs[DstIdx], QT);
768     llvm::Value *DstVal =
769         CGF->EmitLoadOfLValue(DstLV, SourceLocation()).getScalarVal();
770     CGF->EmitStoreOfScalar(SrcVal, DstLV);
771     CGF->EmitARCRelease(DstVal, ARCImpreciseLifetime);
772   }
773 
774   void visitARCWeak(QualType QT, const FieldDecl *FD, CharUnits CurStackOffset,
775                     std::array<Address, 2> Addrs) {
776     Addrs[DstIdx] = getAddrWithOffset(Addrs[DstIdx], CurStackOffset, FD);
777     Addrs[SrcIdx] = getAddrWithOffset(Addrs[SrcIdx], CurStackOffset, FD);
778     CGF->emitARCMoveAssignWeak(QT, Addrs[DstIdx], Addrs[SrcIdx]);
779   }
780 
781   void callSpecialFunction(QualType FT, CharUnits Offset,
782                            std::array<Address, 2> Addrs) {
783     CGF->callCStructMoveAssignmentOperator(
784         CGF->MakeAddrLValue(Addrs[DstIdx], FT),
785         CGF->MakeAddrLValue(Addrs[SrcIdx], FT));
786   }
787 };
788 
789 } // namespace
790 
791 void CodeGenFunction::destroyNonTrivialCStruct(CodeGenFunction &CGF,
792                                                Address Addr, QualType Type) {
793   CGF.callCStructDestructor(CGF.MakeAddrLValue(Addr, Type));
794 }
795 
796 // Default-initialize a variable that is a non-trivial struct or an array of
797 // such structure.
798 void CodeGenFunction::defaultInitNonTrivialCStructVar(LValue Dst) {
799   GenDefaultInitialize Gen(getContext());
800   Address DstPtr = Builder.CreateBitCast(Dst.getAddress(), CGM.Int8PtrPtrTy);
801   Gen.setCGF(this);
802   QualType QT = Dst.getType();
803   QT = Dst.isVolatile() ? QT.withVolatile() : QT;
804   Gen.visit(QT, nullptr, CharUnits::Zero(), std::array<Address, 1>({{DstPtr}}));
805 }
806 
807 template <class G, size_t N>
808 static void callSpecialFunction(G &&Gen, StringRef FuncName, QualType QT,
809                                 bool IsVolatile, CodeGenFunction &CGF,
810                                 std::array<Address, N> Addrs) {
811   for (unsigned I = 0; I < N; ++I)
812     Addrs[I] = CGF.Builder.CreateBitCast(Addrs[I], CGF.CGM.Int8PtrPtrTy);
813   QT = IsVolatile ? QT.withVolatile() : QT;
814   Gen.callFunc(FuncName, QT, Addrs, CGF);
815 }
816 
817 // Functions to emit calls to the special functions of a non-trivial C struct.
818 void CodeGenFunction::callCStructDefaultConstructor(LValue Dst) {
819   bool IsVolatile = Dst.isVolatile();
820   Address DstPtr = Dst.getAddress();
821   QualType QT = Dst.getType();
822   GenDefaultInitializeFuncName GenName(DstPtr.getAlignment(), getContext());
823   std::string FuncName = GenName.getName(QT, IsVolatile);
824   callSpecialFunction(GenDefaultInitialize(getContext()), FuncName, QT,
825                       IsVolatile, *this, std::array<Address, 1>({{DstPtr}}));
826 }
827 
828 std::string
829 CodeGenFunction::getNonTrivialCopyConstructorStr(QualType QT,
830                                                  CharUnits Alignment,
831                                                  bool IsVolatile,
832                                                  ASTContext &Ctx) {
833   GenBinaryFuncName<false> GenName("", Alignment, Alignment, Ctx);
834   return GenName.getName(QT, IsVolatile);
835 }
836 
837 std::string
838 CodeGenFunction::getNonTrivialDestructorStr(QualType QT, CharUnits Alignment,
839                                             bool IsVolatile, ASTContext &Ctx) {
840   GenDestructorFuncName GenName("", Alignment, Ctx);
841   return GenName.getName(QT, IsVolatile);
842 }
843 
844 void CodeGenFunction::callCStructDestructor(LValue Dst) {
845   bool IsVolatile = Dst.isVolatile();
846   Address DstPtr = Dst.getAddress();
847   QualType QT = Dst.getType();
848   GenDestructorFuncName GenName("__destructor_", DstPtr.getAlignment(),
849                                 getContext());
850   std::string FuncName = GenName.getName(QT, IsVolatile);
851   callSpecialFunction(GenDestructor(getContext()), FuncName, QT, IsVolatile,
852                       *this, std::array<Address, 1>({{DstPtr}}));
853 }
854 
855 void CodeGenFunction::callCStructCopyConstructor(LValue Dst, LValue Src) {
856   bool IsVolatile = Dst.isVolatile() || Src.isVolatile();
857   Address DstPtr = Dst.getAddress(), SrcPtr = Src.getAddress();
858   QualType QT = Dst.getType();
859   GenBinaryFuncName<false> GenName("__copy_constructor_", DstPtr.getAlignment(),
860                                    SrcPtr.getAlignment(), getContext());
861   std::string FuncName = GenName.getName(QT, IsVolatile);
862   callSpecialFunction(GenCopyConstructor(getContext()), FuncName, QT,
863                       IsVolatile, *this,
864                       std::array<Address, 2>({{DstPtr, SrcPtr}}));
865 }
866 
867 void CodeGenFunction::callCStructCopyAssignmentOperator(LValue Dst, LValue Src
868 
869 ) {
870   bool IsVolatile = Dst.isVolatile() || Src.isVolatile();
871   Address DstPtr = Dst.getAddress(), SrcPtr = Src.getAddress();
872   QualType QT = Dst.getType();
873   GenBinaryFuncName<false> GenName("__copy_assignment_", DstPtr.getAlignment(),
874                                    SrcPtr.getAlignment(), getContext());
875   std::string FuncName = GenName.getName(QT, IsVolatile);
876   callSpecialFunction(GenCopyAssignment(getContext()), FuncName, QT, IsVolatile,
877                       *this, std::array<Address, 2>({{DstPtr, SrcPtr}}));
878 }
879 
880 void CodeGenFunction::callCStructMoveConstructor(LValue Dst, LValue Src) {
881   bool IsVolatile = Dst.isVolatile() || Src.isVolatile();
882   Address DstPtr = Dst.getAddress(), SrcPtr = Src.getAddress();
883   QualType QT = Dst.getType();
884   GenBinaryFuncName<true> GenName("__move_constructor_", DstPtr.getAlignment(),
885                                   SrcPtr.getAlignment(), getContext());
886   std::string FuncName = GenName.getName(QT, IsVolatile);
887   callSpecialFunction(GenMoveConstructor(getContext()), FuncName, QT,
888                       IsVolatile, *this,
889                       std::array<Address, 2>({{DstPtr, SrcPtr}}));
890 }
891 
892 void CodeGenFunction::callCStructMoveAssignmentOperator(LValue Dst, LValue Src
893 
894 ) {
895   bool IsVolatile = Dst.isVolatile() || Src.isVolatile();
896   Address DstPtr = Dst.getAddress(), SrcPtr = Src.getAddress();
897   QualType QT = Dst.getType();
898   GenBinaryFuncName<true> GenName("__move_assignment_", DstPtr.getAlignment(),
899                                   SrcPtr.getAlignment(), getContext());
900   std::string FuncName = GenName.getName(QT, IsVolatile);
901   callSpecialFunction(GenMoveAssignment(getContext()), FuncName, QT, IsVolatile,
902                       *this, std::array<Address, 2>({{DstPtr, SrcPtr}}));
903 }
904