1 //===-- llvm/CodeGen/TargetLoweringObjectFileImpl.cpp - Object File Info --===//
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 implements classes used to handle lowerings specific to common
11 // object file formats.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "llvm/CodeGen/TargetLoweringObjectFileImpl.h"
16 #include "llvm/ADT/SmallString.h"
17 #include "llvm/ADT/StringExtras.h"
18 #include "llvm/ADT/Triple.h"
19 #include "llvm/CodeGen/MachineModuleInfoImpls.h"
20 #include "llvm/IR/Constants.h"
21 #include "llvm/IR/DataLayout.h"
22 #include "llvm/IR/DerivedTypes.h"
23 #include "llvm/IR/Function.h"
24 #include "llvm/IR/GlobalVariable.h"
25 #include "llvm/IR/Mangler.h"
26 #include "llvm/IR/Module.h"
27 #include "llvm/MC/MCContext.h"
28 #include "llvm/MC/MCExpr.h"
29 #include "llvm/MC/MCSectionCOFF.h"
30 #include "llvm/MC/MCSectionELF.h"
31 #include "llvm/MC/MCSectionMachO.h"
32 #include "llvm/MC/MCStreamer.h"
33 #include "llvm/MC/MCSymbol.h"
34 #include "llvm/MC/MCValue.h"
35 #include "llvm/Support/Dwarf.h"
36 #include "llvm/Support/ELF.h"
37 #include "llvm/Support/ErrorHandling.h"
38 #include "llvm/Support/raw_ostream.h"
39 #include "llvm/Target/TargetLowering.h"
40 #include "llvm/Target/TargetMachine.h"
41 #include "llvm/Target/TargetSubtargetInfo.h"
42 using namespace llvm;
43 using namespace dwarf;
44 
45 //===----------------------------------------------------------------------===//
46 //                                  ELF
47 //===----------------------------------------------------------------------===//
48 
getCFIPersonalitySymbol(const GlobalValue * GV,Mangler & Mang,const TargetMachine & TM,MachineModuleInfo * MMI) const49 MCSymbol *TargetLoweringObjectFileELF::getCFIPersonalitySymbol(
50     const GlobalValue *GV, Mangler &Mang, const TargetMachine &TM,
51     MachineModuleInfo *MMI) const {
52   unsigned Encoding = getPersonalityEncoding();
53   if ((Encoding & 0x80) == dwarf::DW_EH_PE_indirect)
54     return getContext().GetOrCreateSymbol(StringRef("DW.ref.") +
55                                           TM.getSymbol(GV, Mang)->getName());
56   if ((Encoding & 0x70) == dwarf::DW_EH_PE_absptr)
57     return TM.getSymbol(GV, Mang);
58   report_fatal_error("We do not support this DWARF encoding yet!");
59 }
60 
emitPersonalityValue(MCStreamer & Streamer,const TargetMachine & TM,const MCSymbol * Sym) const61 void TargetLoweringObjectFileELF::emitPersonalityValue(MCStreamer &Streamer,
62                                                        const TargetMachine &TM,
63                                                        const MCSymbol *Sym) const {
64   SmallString<64> NameData("DW.ref.");
65   NameData += Sym->getName();
66   MCSymbol *Label = getContext().GetOrCreateSymbol(NameData);
67   Streamer.EmitSymbolAttribute(Label, MCSA_Hidden);
68   Streamer.EmitSymbolAttribute(Label, MCSA_Weak);
69   StringRef Prefix = ".data.";
70   NameData.insert(NameData.begin(), Prefix.begin(), Prefix.end());
71   unsigned Flags = ELF::SHF_ALLOC | ELF::SHF_WRITE | ELF::SHF_GROUP;
72   const MCSection *Sec = getContext().getELFSection(NameData,
73                                                     ELF::SHT_PROGBITS,
74                                                     Flags,
75                                                     0, Label->getName());
76   unsigned Size = TM.getDataLayout()->getPointerSize();
77   Streamer.SwitchSection(Sec);
78   Streamer.EmitValueToAlignment(TM.getDataLayout()->getPointerABIAlignment());
79   Streamer.EmitSymbolAttribute(Label, MCSA_ELF_TypeObject);
80   const MCExpr *E = MCConstantExpr::Create(Size, getContext());
81   Streamer.EmitELFSize(Label, E);
82   Streamer.EmitLabel(Label);
83 
84   Streamer.EmitSymbolValue(Sym, Size);
85 }
86 
getTTypeGlobalReference(const GlobalValue * GV,unsigned Encoding,Mangler & Mang,const TargetMachine & TM,MachineModuleInfo * MMI,MCStreamer & Streamer) const87 const MCExpr *TargetLoweringObjectFileELF::getTTypeGlobalReference(
88     const GlobalValue *GV, unsigned Encoding, Mangler &Mang,
89     const TargetMachine &TM, MachineModuleInfo *MMI,
90     MCStreamer &Streamer) const {
91 
92   if (Encoding & dwarf::DW_EH_PE_indirect) {
93     MachineModuleInfoELF &ELFMMI = MMI->getObjFileInfo<MachineModuleInfoELF>();
94 
95     MCSymbol *SSym = getSymbolWithGlobalValueBase(GV, ".DW.stub", Mang, TM);
96 
97     // Add information about the stub reference to ELFMMI so that the stub
98     // gets emitted by the asmprinter.
99     MachineModuleInfoImpl::StubValueTy &StubSym = ELFMMI.getGVStubEntry(SSym);
100     if (!StubSym.getPointer()) {
101       MCSymbol *Sym = TM.getSymbol(GV, Mang);
102       StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage());
103     }
104 
105     return TargetLoweringObjectFile::
106       getTTypeReference(MCSymbolRefExpr::Create(SSym, getContext()),
107                         Encoding & ~dwarf::DW_EH_PE_indirect, Streamer);
108   }
109 
110   return TargetLoweringObjectFile::
111     getTTypeGlobalReference(GV, Encoding, Mang, TM, MMI, Streamer);
112 }
113 
114 static SectionKind
getELFKindForNamedSection(StringRef Name,SectionKind K)115 getELFKindForNamedSection(StringRef Name, SectionKind K) {
116   // N.B.: The defaults used in here are no the same ones used in MC.
117   // We follow gcc, MC follows gas. For example, given ".section .eh_frame",
118   // both gas and MC will produce a section with no flags. Given
119   // section(".eh_frame") gcc will produce:
120   //
121   //   .section   .eh_frame,"a",@progbits
122   if (Name.empty() || Name[0] != '.') return K;
123 
124   // Some lame default implementation based on some magic section names.
125   if (Name == ".bss" ||
126       Name.startswith(".bss.") ||
127       Name.startswith(".gnu.linkonce.b.") ||
128       Name.startswith(".llvm.linkonce.b.") ||
129       Name == ".sbss" ||
130       Name.startswith(".sbss.") ||
131       Name.startswith(".gnu.linkonce.sb.") ||
132       Name.startswith(".llvm.linkonce.sb."))
133     return SectionKind::getBSS();
134 
135   if (Name == ".tdata" ||
136       Name.startswith(".tdata.") ||
137       Name.startswith(".gnu.linkonce.td.") ||
138       Name.startswith(".llvm.linkonce.td."))
139     return SectionKind::getThreadData();
140 
141   if (Name == ".tbss" ||
142       Name.startswith(".tbss.") ||
143       Name.startswith(".gnu.linkonce.tb.") ||
144       Name.startswith(".llvm.linkonce.tb."))
145     return SectionKind::getThreadBSS();
146 
147   return K;
148 }
149 
150 
getELFSectionType(StringRef Name,SectionKind K)151 static unsigned getELFSectionType(StringRef Name, SectionKind K) {
152 
153   if (Name == ".init_array")
154     return ELF::SHT_INIT_ARRAY;
155 
156   if (Name == ".fini_array")
157     return ELF::SHT_FINI_ARRAY;
158 
159   if (Name == ".preinit_array")
160     return ELF::SHT_PREINIT_ARRAY;
161 
162   if (K.isBSS() || K.isThreadBSS())
163     return ELF::SHT_NOBITS;
164 
165   return ELF::SHT_PROGBITS;
166 }
167 
getELFSectionFlags(SectionKind K)168 static unsigned getELFSectionFlags(SectionKind K) {
169   unsigned Flags = 0;
170 
171   if (!K.isMetadata())
172     Flags |= ELF::SHF_ALLOC;
173 
174   if (K.isText())
175     Flags |= ELF::SHF_EXECINSTR;
176 
177   if (K.isWriteable())
178     Flags |= ELF::SHF_WRITE;
179 
180   if (K.isThreadLocal())
181     Flags |= ELF::SHF_TLS;
182 
183   if (K.isMergeableCString() || K.isMergeableConst())
184     Flags |= ELF::SHF_MERGE;
185 
186   if (K.isMergeableCString())
187     Flags |= ELF::SHF_STRINGS;
188 
189   return Flags;
190 }
191 
getELFComdat(const GlobalValue * GV)192 static const Comdat *getELFComdat(const GlobalValue *GV) {
193   const Comdat *C = GV->getComdat();
194   if (!C)
195     return nullptr;
196 
197   if (C->getSelectionKind() != Comdat::Any)
198     report_fatal_error("ELF COMDATs only support SelectionKind::Any, '" +
199                        C->getName() + "' cannot be lowered.");
200 
201   return C;
202 }
203 
getExplicitSectionGlobal(const GlobalValue * GV,SectionKind Kind,Mangler & Mang,const TargetMachine & TM) const204 const MCSection *TargetLoweringObjectFileELF::getExplicitSectionGlobal(
205     const GlobalValue *GV, SectionKind Kind, Mangler &Mang,
206     const TargetMachine &TM) const {
207   StringRef SectionName = GV->getSection();
208 
209   // Infer section flags from the section name if we can.
210   Kind = getELFKindForNamedSection(SectionName, Kind);
211 
212   StringRef Group = "";
213   unsigned Flags = getELFSectionFlags(Kind);
214   if (const Comdat *C = getELFComdat(GV)) {
215     Group = C->getName();
216     Flags |= ELF::SHF_GROUP;
217   }
218   return getContext().getELFSection(SectionName,
219                                     getELFSectionType(SectionName, Kind), Flags,
220                                     /*EntrySize=*/0, Group);
221 }
222 
223 /// Return the section prefix name used by options FunctionsSections and
224 /// DataSections.
getSectionPrefixForGlobal(SectionKind Kind)225 static StringRef getSectionPrefixForGlobal(SectionKind Kind) {
226   if (Kind.isText())
227     return ".text";
228   if (Kind.isReadOnly())
229     return ".rodata";
230   if (Kind.isBSS())
231     return ".bss";
232   if (Kind.isThreadData())
233     return ".tdata";
234   if (Kind.isThreadBSS())
235     return ".tbss";
236   if (Kind.isDataNoRel())
237     return ".data";
238   if (Kind.isDataRelLocal())
239     return ".data.rel.local";
240   if (Kind.isDataRel())
241     return ".data.rel";
242   if (Kind.isReadOnlyWithRelLocal())
243     return ".data.rel.ro.local";
244   assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
245   return ".data.rel.ro";
246 }
247 
248 static const MCSectionELF *
selectELFSectionForGlobal(MCContext & Ctx,const GlobalValue * GV,SectionKind Kind,Mangler & Mang,const TargetMachine & TM,bool EmitUniqueSection,unsigned Flags,unsigned * NextUniqueID)249 selectELFSectionForGlobal(MCContext &Ctx, const GlobalValue *GV,
250                           SectionKind Kind, Mangler &Mang,
251                           const TargetMachine &TM, bool EmitUniqueSection,
252                           unsigned Flags, unsigned *NextUniqueID) {
253   unsigned EntrySize = 0;
254   if (Kind.isMergeableCString()) {
255     if (Kind.isMergeable2ByteCString()) {
256       EntrySize = 2;
257     } else if (Kind.isMergeable4ByteCString()) {
258       EntrySize = 4;
259     } else {
260       EntrySize = 1;
261       assert(Kind.isMergeable1ByteCString() && "unknown string width");
262     }
263   } else if (Kind.isMergeableConst()) {
264     if (Kind.isMergeableConst4()) {
265       EntrySize = 4;
266     } else if (Kind.isMergeableConst8()) {
267       EntrySize = 8;
268     } else {
269       assert(Kind.isMergeableConst16() && "unknown data width");
270       EntrySize = 16;
271     }
272   }
273 
274   StringRef Group = "";
275   if (const Comdat *C = getELFComdat(GV)) {
276     Flags |= ELF::SHF_GROUP;
277     Group = C->getName();
278   }
279 
280   bool UniqueSectionNames = TM.getUniqueSectionNames();
281   SmallString<128> Name;
282   if (Kind.isMergeableCString()) {
283     // We also need alignment here.
284     // FIXME: this is getting the alignment of the character, not the
285     // alignment of the global!
286     unsigned Align =
287         TM.getDataLayout()->getPreferredAlignment(cast<GlobalVariable>(GV));
288 
289     std::string SizeSpec = ".rodata.str" + utostr(EntrySize) + ".";
290     Name = SizeSpec + utostr(Align);
291   } else if (Kind.isMergeableConst()) {
292     Name = ".rodata.cst";
293     Name += utostr(EntrySize);
294   } else {
295     Name = getSectionPrefixForGlobal(Kind);
296   }
297 
298   if (EmitUniqueSection && UniqueSectionNames) {
299     Name.push_back('.');
300     TM.getNameWithPrefix(Name, GV, Mang, true);
301   }
302   unsigned UniqueID = ~0;
303   if (EmitUniqueSection && !UniqueSectionNames) {
304     UniqueID = *NextUniqueID;
305     (*NextUniqueID)++;
306   }
307   return Ctx.getELFSection(Name, getELFSectionType(Name, Kind), Flags,
308                            EntrySize, Group, UniqueID);
309 }
310 
SelectSectionForGlobal(const GlobalValue * GV,SectionKind Kind,Mangler & Mang,const TargetMachine & TM) const311 const MCSection *TargetLoweringObjectFileELF::SelectSectionForGlobal(
312     const GlobalValue *GV, SectionKind Kind, Mangler &Mang,
313     const TargetMachine &TM) const {
314   unsigned Flags = getELFSectionFlags(Kind);
315 
316   // If we have -ffunction-section or -fdata-section then we should emit the
317   // global value to a uniqued section specifically for it.
318   bool EmitUniqueSection = false;
319   if (!(Flags & ELF::SHF_MERGE) && !Kind.isCommon()) {
320     if (Kind.isText())
321       EmitUniqueSection = TM.getFunctionSections();
322     else
323       EmitUniqueSection = TM.getDataSections();
324   }
325   EmitUniqueSection |= GV->hasComdat();
326 
327   return selectELFSectionForGlobal(getContext(), GV, Kind, Mang, TM,
328                                    EmitUniqueSection, Flags, &NextUniqueID);
329 }
330 
getSectionForJumpTable(const Function & F,Mangler & Mang,const TargetMachine & TM) const331 const MCSection *TargetLoweringObjectFileELF::getSectionForJumpTable(
332     const Function &F, Mangler &Mang, const TargetMachine &TM) const {
333   // If the function can be removed, produce a unique section so that
334   // the table doesn't prevent the removal.
335   const Comdat *C = F.getComdat();
336   bool EmitUniqueSection = TM.getFunctionSections() || C;
337   if (!EmitUniqueSection)
338     return ReadOnlySection;
339 
340   return selectELFSectionForGlobal(getContext(), &F, SectionKind::getReadOnly(),
341                                    Mang, TM, EmitUniqueSection, ELF::SHF_ALLOC,
342                                    &NextUniqueID);
343 }
344 
shouldPutJumpTableInFunctionSection(bool UsesLabelDifference,const Function & F) const345 bool TargetLoweringObjectFileELF::shouldPutJumpTableInFunctionSection(
346     bool UsesLabelDifference, const Function &F) const {
347   // We can always create relative relocations, so use another section
348   // that can be marked non-executable.
349   return false;
350 }
351 
352 /// getSectionForConstant - Given a mergeable constant with the
353 /// specified size and relocation information, return a section that it
354 /// should be placed in.
355 const MCSection *
getSectionForConstant(SectionKind Kind,const Constant * C) const356 TargetLoweringObjectFileELF::getSectionForConstant(SectionKind Kind,
357                                                    const Constant *C) const {
358   if (Kind.isMergeableConst4() && MergeableConst4Section)
359     return MergeableConst4Section;
360   if (Kind.isMergeableConst8() && MergeableConst8Section)
361     return MergeableConst8Section;
362   if (Kind.isMergeableConst16() && MergeableConst16Section)
363     return MergeableConst16Section;
364   if (Kind.isReadOnly())
365     return ReadOnlySection;
366 
367   if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection;
368   assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
369   return DataRelROSection;
370 }
371 
getStaticStructorSection(MCContext & Ctx,bool UseInitArray,bool IsCtor,unsigned Priority,const MCSymbol * KeySym)372 static const MCSectionELF *getStaticStructorSection(MCContext &Ctx,
373                                                     bool UseInitArray,
374                                                     bool IsCtor,
375                                                     unsigned Priority,
376                                                     const MCSymbol *KeySym) {
377   std::string Name;
378   unsigned Type;
379   unsigned Flags = ELF::SHF_ALLOC | ELF::SHF_WRITE;
380   StringRef COMDAT = KeySym ? KeySym->getName() : "";
381 
382   if (KeySym)
383     Flags |= ELF::SHF_GROUP;
384 
385   if (UseInitArray) {
386     if (IsCtor) {
387       Type = ELF::SHT_INIT_ARRAY;
388       Name = ".init_array";
389     } else {
390       Type = ELF::SHT_FINI_ARRAY;
391       Name = ".fini_array";
392     }
393     if (Priority != 65535) {
394       Name += '.';
395       Name += utostr(Priority);
396     }
397   } else {
398     // The default scheme is .ctor / .dtor, so we have to invert the priority
399     // numbering.
400     if (IsCtor)
401       Name = ".ctors";
402     else
403       Name = ".dtors";
404     if (Priority != 65535) {
405       Name += '.';
406       Name += utostr(65535 - Priority);
407     }
408     Type = ELF::SHT_PROGBITS;
409   }
410 
411   return Ctx.getELFSection(Name, Type, Flags, 0, COMDAT);
412 }
413 
getStaticCtorSection(unsigned Priority,const MCSymbol * KeySym) const414 const MCSection *TargetLoweringObjectFileELF::getStaticCtorSection(
415     unsigned Priority, const MCSymbol *KeySym) const {
416   return getStaticStructorSection(getContext(), UseInitArray, true, Priority,
417                                   KeySym);
418 }
419 
getStaticDtorSection(unsigned Priority,const MCSymbol * KeySym) const420 const MCSection *TargetLoweringObjectFileELF::getStaticDtorSection(
421     unsigned Priority, const MCSymbol *KeySym) const {
422   return getStaticStructorSection(getContext(), UseInitArray, false, Priority,
423                                   KeySym);
424 }
425 
426 void
InitializeELF(bool UseInitArray_)427 TargetLoweringObjectFileELF::InitializeELF(bool UseInitArray_) {
428   UseInitArray = UseInitArray_;
429   if (!UseInitArray)
430     return;
431 
432   StaticCtorSection = getContext().getELFSection(
433       ".init_array", ELF::SHT_INIT_ARRAY, ELF::SHF_WRITE | ELF::SHF_ALLOC);
434   StaticDtorSection = getContext().getELFSection(
435       ".fini_array", ELF::SHT_FINI_ARRAY, ELF::SHF_WRITE | ELF::SHF_ALLOC);
436 }
437 
438 //===----------------------------------------------------------------------===//
439 //                                 MachO
440 //===----------------------------------------------------------------------===//
441 
TargetLoweringObjectFileMachO()442 TargetLoweringObjectFileMachO::TargetLoweringObjectFileMachO()
443   : TargetLoweringObjectFile() {
444   SupportIndirectSymViaGOTPCRel = true;
445 }
446 
447 /// getDepLibFromLinkerOpt - Extract the dependent library name from a linker
448 /// option string. Returns StringRef() if the option does not specify a library.
449 StringRef TargetLoweringObjectFileMachO::
getDepLibFromLinkerOpt(StringRef LinkerOption) const450 getDepLibFromLinkerOpt(StringRef LinkerOption) const {
451   const char *LibCmd = "-l";
452   if (LinkerOption.startswith(LibCmd))
453     return LinkerOption.substr(strlen(LibCmd));
454   return StringRef();
455 }
456 
457 /// emitModuleFlags - Perform code emission for module flags.
458 void TargetLoweringObjectFileMachO::
emitModuleFlags(MCStreamer & Streamer,ArrayRef<Module::ModuleFlagEntry> ModuleFlags,Mangler & Mang,const TargetMachine & TM) const459 emitModuleFlags(MCStreamer &Streamer,
460                 ArrayRef<Module::ModuleFlagEntry> ModuleFlags,
461                 Mangler &Mang, const TargetMachine &TM) const {
462   unsigned VersionVal = 0;
463   unsigned ImageInfoFlags = 0;
464   MDNode *LinkerOptions = nullptr;
465   StringRef SectionVal;
466 
467   for (ArrayRef<Module::ModuleFlagEntry>::iterator
468          i = ModuleFlags.begin(), e = ModuleFlags.end(); i != e; ++i) {
469     const Module::ModuleFlagEntry &MFE = *i;
470 
471     // Ignore flags with 'Require' behavior.
472     if (MFE.Behavior == Module::Require)
473       continue;
474 
475     StringRef Key = MFE.Key->getString();
476     Metadata *Val = MFE.Val;
477 
478     if (Key == "Objective-C Image Info Version") {
479       VersionVal = mdconst::extract<ConstantInt>(Val)->getZExtValue();
480     } else if (Key == "Objective-C Garbage Collection" ||
481                Key == "Objective-C GC Only" ||
482                Key == "Objective-C Is Simulated" ||
483                Key == "Objective-C Image Swift Version") {
484       ImageInfoFlags |= mdconst::extract<ConstantInt>(Val)->getZExtValue();
485     } else if (Key == "Objective-C Image Info Section") {
486       SectionVal = cast<MDString>(Val)->getString();
487     } else if (Key == "Linker Options") {
488       LinkerOptions = cast<MDNode>(Val);
489     }
490   }
491 
492   // Emit the linker options if present.
493   if (LinkerOptions) {
494     for (unsigned i = 0, e = LinkerOptions->getNumOperands(); i != e; ++i) {
495       MDNode *MDOptions = cast<MDNode>(LinkerOptions->getOperand(i));
496       SmallVector<std::string, 4> StrOptions;
497 
498       // Convert to strings.
499       for (unsigned ii = 0, ie = MDOptions->getNumOperands(); ii != ie; ++ii) {
500         MDString *MDOption = cast<MDString>(MDOptions->getOperand(ii));
501         StrOptions.push_back(MDOption->getString());
502       }
503 
504       Streamer.EmitLinkerOptions(StrOptions);
505     }
506   }
507 
508   // The section is mandatory. If we don't have it, then we don't have GC info.
509   if (SectionVal.empty()) return;
510 
511   StringRef Segment, Section;
512   unsigned TAA = 0, StubSize = 0;
513   bool TAAParsed;
514   std::string ErrorCode =
515     MCSectionMachO::ParseSectionSpecifier(SectionVal, Segment, Section,
516                                           TAA, TAAParsed, StubSize);
517   if (!ErrorCode.empty())
518     // If invalid, report the error with report_fatal_error.
519     report_fatal_error("Invalid section specifier '" + Section + "': " +
520                        ErrorCode + ".");
521 
522   // Get the section.
523   const MCSectionMachO *S =
524     getContext().getMachOSection(Segment, Section, TAA, StubSize,
525                                  SectionKind::getDataNoRel());
526   Streamer.SwitchSection(S);
527   Streamer.EmitLabel(getContext().
528                      GetOrCreateSymbol(StringRef("L_OBJC_IMAGE_INFO")));
529   Streamer.EmitIntValue(VersionVal, 4);
530   Streamer.EmitIntValue(ImageInfoFlags, 4);
531   Streamer.AddBlankLine();
532 }
533 
checkMachOComdat(const GlobalValue * GV)534 static void checkMachOComdat(const GlobalValue *GV) {
535   const Comdat *C = GV->getComdat();
536   if (!C)
537     return;
538 
539   report_fatal_error("MachO doesn't support COMDATs, '" + C->getName() +
540                      "' cannot be lowered.");
541 }
542 
getExplicitSectionGlobal(const GlobalValue * GV,SectionKind Kind,Mangler & Mang,const TargetMachine & TM) const543 const MCSection *TargetLoweringObjectFileMachO::getExplicitSectionGlobal(
544     const GlobalValue *GV, SectionKind Kind, Mangler &Mang,
545     const TargetMachine &TM) const {
546   // Parse the section specifier and create it if valid.
547   StringRef Segment, Section;
548   unsigned TAA = 0, StubSize = 0;
549   bool TAAParsed;
550 
551   checkMachOComdat(GV);
552 
553   std::string ErrorCode =
554     MCSectionMachO::ParseSectionSpecifier(GV->getSection(), Segment, Section,
555                                           TAA, TAAParsed, StubSize);
556   if (!ErrorCode.empty()) {
557     // If invalid, report the error with report_fatal_error.
558     report_fatal_error("Global variable '" + GV->getName() +
559                        "' has an invalid section specifier '" +
560                        GV->getSection() + "': " + ErrorCode + ".");
561   }
562 
563   // Get the section.
564   const MCSectionMachO *S =
565     getContext().getMachOSection(Segment, Section, TAA, StubSize, Kind);
566 
567   // If TAA wasn't set by ParseSectionSpecifier() above,
568   // use the value returned by getMachOSection() as a default.
569   if (!TAAParsed)
570     TAA = S->getTypeAndAttributes();
571 
572   // Okay, now that we got the section, verify that the TAA & StubSize agree.
573   // If the user declared multiple globals with different section flags, we need
574   // to reject it here.
575   if (S->getTypeAndAttributes() != TAA || S->getStubSize() != StubSize) {
576     // If invalid, report the error with report_fatal_error.
577     report_fatal_error("Global variable '" + GV->getName() +
578                        "' section type or attributes does not match previous"
579                        " section specifier");
580   }
581 
582   return S;
583 }
584 
585 const MCSection *TargetLoweringObjectFileMachO::
SelectSectionForGlobal(const GlobalValue * GV,SectionKind Kind,Mangler & Mang,const TargetMachine & TM) const586 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
587                        Mangler &Mang, const TargetMachine &TM) const {
588   checkMachOComdat(GV);
589 
590   // Handle thread local data.
591   if (Kind.isThreadBSS()) return TLSBSSSection;
592   if (Kind.isThreadData()) return TLSDataSection;
593 
594   if (Kind.isText())
595     return GV->isWeakForLinker() ? TextCoalSection : TextSection;
596 
597   // If this is weak/linkonce, put this in a coalescable section, either in text
598   // or data depending on if it is writable.
599   if (GV->isWeakForLinker()) {
600     if (Kind.isReadOnly())
601       return ConstTextCoalSection;
602     return DataCoalSection;
603   }
604 
605   // FIXME: Alignment check should be handled by section classifier.
606   if (Kind.isMergeable1ByteCString() &&
607       TM.getDataLayout()->getPreferredAlignment(cast<GlobalVariable>(GV)) < 32)
608     return CStringSection;
609 
610   // Do not put 16-bit arrays in the UString section if they have an
611   // externally visible label, this runs into issues with certain linker
612   // versions.
613   if (Kind.isMergeable2ByteCString() && !GV->hasExternalLinkage() &&
614       TM.getDataLayout()->getPreferredAlignment(cast<GlobalVariable>(GV)) < 32)
615     return UStringSection;
616 
617   // With MachO only variables whose corresponding symbol starts with 'l' or
618   // 'L' can be merged, so we only try merging GVs with private linkage.
619   if (GV->hasPrivateLinkage() && Kind.isMergeableConst()) {
620     if (Kind.isMergeableConst4())
621       return FourByteConstantSection;
622     if (Kind.isMergeableConst8())
623       return EightByteConstantSection;
624     if (Kind.isMergeableConst16())
625       return SixteenByteConstantSection;
626   }
627 
628   // Otherwise, if it is readonly, but not something we can specially optimize,
629   // just drop it in .const.
630   if (Kind.isReadOnly())
631     return ReadOnlySection;
632 
633   // If this is marked const, put it into a const section.  But if the dynamic
634   // linker needs to write to it, put it in the data segment.
635   if (Kind.isReadOnlyWithRel())
636     return ConstDataSection;
637 
638   // Put zero initialized globals with strong external linkage in the
639   // DATA, __common section with the .zerofill directive.
640   if (Kind.isBSSExtern())
641     return DataCommonSection;
642 
643   // Put zero initialized globals with local linkage in __DATA,__bss directive
644   // with the .zerofill directive (aka .lcomm).
645   if (Kind.isBSSLocal())
646     return DataBSSSection;
647 
648   // Otherwise, just drop the variable in the normal data section.
649   return DataSection;
650 }
651 
652 const MCSection *
getSectionForConstant(SectionKind Kind,const Constant * C) const653 TargetLoweringObjectFileMachO::getSectionForConstant(SectionKind Kind,
654                                                      const Constant *C) const {
655   // If this constant requires a relocation, we have to put it in the data
656   // segment, not in the text segment.
657   if (Kind.isDataRel() || Kind.isReadOnlyWithRel())
658     return ConstDataSection;
659 
660   if (Kind.isMergeableConst4())
661     return FourByteConstantSection;
662   if (Kind.isMergeableConst8())
663     return EightByteConstantSection;
664   if (Kind.isMergeableConst16())
665     return SixteenByteConstantSection;
666   return ReadOnlySection;  // .const
667 }
668 
getTTypeGlobalReference(const GlobalValue * GV,unsigned Encoding,Mangler & Mang,const TargetMachine & TM,MachineModuleInfo * MMI,MCStreamer & Streamer) const669 const MCExpr *TargetLoweringObjectFileMachO::getTTypeGlobalReference(
670     const GlobalValue *GV, unsigned Encoding, Mangler &Mang,
671     const TargetMachine &TM, MachineModuleInfo *MMI,
672     MCStreamer &Streamer) const {
673   // The mach-o version of this method defaults to returning a stub reference.
674 
675   if (Encoding & DW_EH_PE_indirect) {
676     MachineModuleInfoMachO &MachOMMI =
677       MMI->getObjFileInfo<MachineModuleInfoMachO>();
678 
679     MCSymbol *SSym =
680         getSymbolWithGlobalValueBase(GV, "$non_lazy_ptr", Mang, TM);
681 
682     // Add information about the stub reference to MachOMMI so that the stub
683     // gets emitted by the asmprinter.
684     MachineModuleInfoImpl::StubValueTy &StubSym =
685       GV->hasHiddenVisibility() ? MachOMMI.getHiddenGVStubEntry(SSym) :
686                                   MachOMMI.getGVStubEntry(SSym);
687     if (!StubSym.getPointer()) {
688       MCSymbol *Sym = TM.getSymbol(GV, Mang);
689       StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage());
690     }
691 
692     return TargetLoweringObjectFile::
693       getTTypeReference(MCSymbolRefExpr::Create(SSym, getContext()),
694                         Encoding & ~dwarf::DW_EH_PE_indirect, Streamer);
695   }
696 
697   return TargetLoweringObjectFile::getTTypeGlobalReference(GV, Encoding, Mang,
698                                                            TM, MMI, Streamer);
699 }
700 
getCFIPersonalitySymbol(const GlobalValue * GV,Mangler & Mang,const TargetMachine & TM,MachineModuleInfo * MMI) const701 MCSymbol *TargetLoweringObjectFileMachO::getCFIPersonalitySymbol(
702     const GlobalValue *GV, Mangler &Mang, const TargetMachine &TM,
703     MachineModuleInfo *MMI) const {
704   // The mach-o version of this method defaults to returning a stub reference.
705   MachineModuleInfoMachO &MachOMMI =
706     MMI->getObjFileInfo<MachineModuleInfoMachO>();
707 
708   MCSymbol *SSym = getSymbolWithGlobalValueBase(GV, "$non_lazy_ptr", Mang, TM);
709 
710   // Add information about the stub reference to MachOMMI so that the stub
711   // gets emitted by the asmprinter.
712   MachineModuleInfoImpl::StubValueTy &StubSym = MachOMMI.getGVStubEntry(SSym);
713   if (!StubSym.getPointer()) {
714     MCSymbol *Sym = TM.getSymbol(GV, Mang);
715     StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage());
716   }
717 
718   return SSym;
719 }
720 
getIndirectSymViaGOTPCRel(const MCSymbol * Sym,const MCValue & MV,int64_t Offset,MachineModuleInfo * MMI,MCStreamer & Streamer) const721 const MCExpr *TargetLoweringObjectFileMachO::getIndirectSymViaGOTPCRel(
722     const MCSymbol *Sym, const MCValue &MV, int64_t Offset,
723     MachineModuleInfo *MMI, MCStreamer &Streamer) const {
724   // Although MachO 32-bit targets do not explictly have a GOTPCREL relocation
725   // as 64-bit do, we replace the GOT equivalent by accessing the final symbol
726   // through a non_lazy_ptr stub instead. One advantage is that it allows the
727   // computation of deltas to final external symbols. Example:
728   //
729   //    _extgotequiv:
730   //       .long   _extfoo
731   //
732   //    _delta:
733   //       .long   _extgotequiv-_delta
734   //
735   // is transformed to:
736   //
737   //    _delta:
738   //       .long   L_extfoo$non_lazy_ptr-(_delta+0)
739   //
740   //       .section        __IMPORT,__pointers,non_lazy_symbol_pointers
741   //    L_extfoo$non_lazy_ptr:
742   //       .indirect_symbol        _extfoo
743   //       .long   0
744   //
745   MachineModuleInfoMachO &MachOMMI =
746     MMI->getObjFileInfo<MachineModuleInfoMachO>();
747   MCContext &Ctx = getContext();
748 
749   // The offset must consider the original displacement from the base symbol
750   // since 32-bit targets don't have a GOTPCREL to fold the PC displacement.
751   Offset = -MV.getConstant();
752   const MCSymbol *BaseSym = &MV.getSymB()->getSymbol();
753 
754   // Access the final symbol via sym$non_lazy_ptr and generate the appropriated
755   // non_lazy_ptr stubs.
756   SmallString<128> Name;
757   StringRef Suffix = "$non_lazy_ptr";
758   Name += DL->getPrivateGlobalPrefix();
759   Name += Sym->getName();
760   Name += Suffix;
761   MCSymbol *Stub = Ctx.GetOrCreateSymbol(Name);
762 
763   MachineModuleInfoImpl::StubValueTy &StubSym = MachOMMI.getGVStubEntry(Stub);
764   if (!StubSym.getPointer())
765     StubSym = MachineModuleInfoImpl::
766       StubValueTy(const_cast<MCSymbol *>(Sym), true /* access indirectly */);
767 
768   const MCExpr *BSymExpr =
769     MCSymbolRefExpr::Create(BaseSym, MCSymbolRefExpr::VK_None, Ctx);
770   const MCExpr *LHS =
771     MCSymbolRefExpr::Create(Stub, MCSymbolRefExpr::VK_None, Ctx);
772 
773   if (!Offset)
774     return MCBinaryExpr::CreateSub(LHS, BSymExpr, Ctx);
775 
776   const MCExpr *RHS =
777     MCBinaryExpr::CreateAdd(BSymExpr, MCConstantExpr::Create(Offset, Ctx), Ctx);
778   return MCBinaryExpr::CreateSub(LHS, RHS, Ctx);
779 }
780 
781 //===----------------------------------------------------------------------===//
782 //                                  COFF
783 //===----------------------------------------------------------------------===//
784 
785 static unsigned
getCOFFSectionFlags(SectionKind K)786 getCOFFSectionFlags(SectionKind K) {
787   unsigned Flags = 0;
788 
789   if (K.isMetadata())
790     Flags |=
791       COFF::IMAGE_SCN_MEM_DISCARDABLE;
792   else if (K.isText())
793     Flags |=
794       COFF::IMAGE_SCN_MEM_EXECUTE |
795       COFF::IMAGE_SCN_MEM_READ |
796       COFF::IMAGE_SCN_CNT_CODE;
797   else if (K.isBSS())
798     Flags |=
799       COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA |
800       COFF::IMAGE_SCN_MEM_READ |
801       COFF::IMAGE_SCN_MEM_WRITE;
802   else if (K.isThreadLocal())
803     Flags |=
804       COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
805       COFF::IMAGE_SCN_MEM_READ |
806       COFF::IMAGE_SCN_MEM_WRITE;
807   else if (K.isReadOnly() || K.isReadOnlyWithRel())
808     Flags |=
809       COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
810       COFF::IMAGE_SCN_MEM_READ;
811   else if (K.isWriteable())
812     Flags |=
813       COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
814       COFF::IMAGE_SCN_MEM_READ |
815       COFF::IMAGE_SCN_MEM_WRITE;
816 
817   return Flags;
818 }
819 
getComdatGVForCOFF(const GlobalValue * GV)820 static const GlobalValue *getComdatGVForCOFF(const GlobalValue *GV) {
821   const Comdat *C = GV->getComdat();
822   assert(C && "expected GV to have a Comdat!");
823 
824   StringRef ComdatGVName = C->getName();
825   const GlobalValue *ComdatGV = GV->getParent()->getNamedValue(ComdatGVName);
826   if (!ComdatGV)
827     report_fatal_error("Associative COMDAT symbol '" + ComdatGVName +
828                        "' does not exist.");
829 
830   if (ComdatGV->getComdat() != C)
831     report_fatal_error("Associative COMDAT symbol '" + ComdatGVName +
832                        "' is not a key for its COMDAT.");
833 
834   return ComdatGV;
835 }
836 
getSelectionForCOFF(const GlobalValue * GV)837 static int getSelectionForCOFF(const GlobalValue *GV) {
838   if (const Comdat *C = GV->getComdat()) {
839     const GlobalValue *ComdatKey = getComdatGVForCOFF(GV);
840     if (const auto *GA = dyn_cast<GlobalAlias>(ComdatKey))
841       ComdatKey = GA->getBaseObject();
842     if (ComdatKey == GV) {
843       switch (C->getSelectionKind()) {
844       case Comdat::Any:
845         return COFF::IMAGE_COMDAT_SELECT_ANY;
846       case Comdat::ExactMatch:
847         return COFF::IMAGE_COMDAT_SELECT_EXACT_MATCH;
848       case Comdat::Largest:
849         return COFF::IMAGE_COMDAT_SELECT_LARGEST;
850       case Comdat::NoDuplicates:
851         return COFF::IMAGE_COMDAT_SELECT_NODUPLICATES;
852       case Comdat::SameSize:
853         return COFF::IMAGE_COMDAT_SELECT_SAME_SIZE;
854       }
855     } else {
856       return COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE;
857     }
858   } else if (GV->isWeakForLinker()) {
859     return COFF::IMAGE_COMDAT_SELECT_ANY;
860   }
861   return 0;
862 }
863 
getExplicitSectionGlobal(const GlobalValue * GV,SectionKind Kind,Mangler & Mang,const TargetMachine & TM) const864 const MCSection *TargetLoweringObjectFileCOFF::getExplicitSectionGlobal(
865     const GlobalValue *GV, SectionKind Kind, Mangler &Mang,
866     const TargetMachine &TM) const {
867   int Selection = 0;
868   unsigned Characteristics = getCOFFSectionFlags(Kind);
869   StringRef Name = GV->getSection();
870   StringRef COMDATSymName = "";
871   if (GV->hasComdat()) {
872     Selection = getSelectionForCOFF(GV);
873     const GlobalValue *ComdatGV;
874     if (Selection == COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE)
875       ComdatGV = getComdatGVForCOFF(GV);
876     else
877       ComdatGV = GV;
878 
879     if (!ComdatGV->hasPrivateLinkage()) {
880       MCSymbol *Sym = TM.getSymbol(ComdatGV, Mang);
881       COMDATSymName = Sym->getName();
882       Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT;
883     } else {
884       Selection = 0;
885     }
886   }
887   return getContext().getCOFFSection(Name,
888                                      Characteristics,
889                                      Kind,
890                                      COMDATSymName,
891                                      Selection);
892 }
893 
getCOFFSectionNameForUniqueGlobal(SectionKind Kind)894 static const char *getCOFFSectionNameForUniqueGlobal(SectionKind Kind) {
895   if (Kind.isText())
896     return ".text";
897   if (Kind.isBSS())
898     return ".bss";
899   if (Kind.isThreadLocal())
900     return ".tls$";
901   if (Kind.isReadOnly() || Kind.isReadOnlyWithRel())
902     return ".rdata";
903   return ".data";
904 }
905 
906 
907 const MCSection *TargetLoweringObjectFileCOFF::
SelectSectionForGlobal(const GlobalValue * GV,SectionKind Kind,Mangler & Mang,const TargetMachine & TM) const908 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
909                        Mangler &Mang, const TargetMachine &TM) const {
910   // If we have -ffunction-sections then we should emit the global value to a
911   // uniqued section specifically for it.
912   bool EmitUniquedSection;
913   if (Kind.isText())
914     EmitUniquedSection = TM.getFunctionSections();
915   else
916     EmitUniquedSection = TM.getDataSections();
917 
918   if ((EmitUniquedSection && !Kind.isCommon()) || GV->hasComdat()) {
919     const char *Name = getCOFFSectionNameForUniqueGlobal(Kind);
920     unsigned Characteristics = getCOFFSectionFlags(Kind);
921 
922     Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT;
923     int Selection = getSelectionForCOFF(GV);
924     if (!Selection)
925       Selection = COFF::IMAGE_COMDAT_SELECT_NODUPLICATES;
926     const GlobalValue *ComdatGV;
927     if (GV->hasComdat())
928       ComdatGV = getComdatGVForCOFF(GV);
929     else
930       ComdatGV = GV;
931 
932     if (!ComdatGV->hasPrivateLinkage()) {
933       MCSymbol *Sym = TM.getSymbol(ComdatGV, Mang);
934       StringRef COMDATSymName = Sym->getName();
935       return getContext().getCOFFSection(Name, Characteristics, Kind,
936                                          COMDATSymName, Selection);
937     } else {
938       SmallString<256> TmpData;
939       getNameWithPrefix(TmpData, GV, /*CannotUsePrivateLabel=*/true, Mang, TM);
940       return getContext().getCOFFSection(Name, Characteristics, Kind, TmpData,
941                                          Selection);
942     }
943   }
944 
945   if (Kind.isText())
946     return TextSection;
947 
948   if (Kind.isThreadLocal())
949     return TLSDataSection;
950 
951   if (Kind.isReadOnly() || Kind.isReadOnlyWithRel())
952     return ReadOnlySection;
953 
954   // Note: we claim that common symbols are put in BSSSection, but they are
955   // really emitted with the magic .comm directive, which creates a symbol table
956   // entry but not a section.
957   if (Kind.isBSS() || Kind.isCommon())
958     return BSSSection;
959 
960   return DataSection;
961 }
962 
getNameWithPrefix(SmallVectorImpl<char> & OutName,const GlobalValue * GV,bool CannotUsePrivateLabel,Mangler & Mang,const TargetMachine & TM) const963 void TargetLoweringObjectFileCOFF::getNameWithPrefix(
964     SmallVectorImpl<char> &OutName, const GlobalValue *GV,
965     bool CannotUsePrivateLabel, Mangler &Mang, const TargetMachine &TM) const {
966   if (GV->hasPrivateLinkage() &&
967       ((isa<Function>(GV) && TM.getFunctionSections()) ||
968        (isa<GlobalVariable>(GV) && TM.getDataSections())))
969     CannotUsePrivateLabel = true;
970 
971   Mang.getNameWithPrefix(OutName, GV, CannotUsePrivateLabel);
972 }
973 
getSectionForJumpTable(const Function & F,Mangler & Mang,const TargetMachine & TM) const974 const MCSection *TargetLoweringObjectFileCOFF::getSectionForJumpTable(
975     const Function &F, Mangler &Mang, const TargetMachine &TM) const {
976   // If the function can be removed, produce a unique section so that
977   // the table doesn't prevent the removal.
978   const Comdat *C = F.getComdat();
979   bool EmitUniqueSection = TM.getFunctionSections() || C;
980   if (!EmitUniqueSection)
981     return ReadOnlySection;
982 
983   // FIXME: we should produce a symbol for F instead.
984   if (F.hasPrivateLinkage())
985     return ReadOnlySection;
986 
987   MCSymbol *Sym = TM.getSymbol(&F, Mang);
988   StringRef COMDATSymName = Sym->getName();
989 
990   SectionKind Kind = SectionKind::getReadOnly();
991   const char *Name = getCOFFSectionNameForUniqueGlobal(Kind);
992   unsigned Characteristics = getCOFFSectionFlags(Kind);
993   Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT;
994 
995   return getContext().getCOFFSection(Name, Characteristics, Kind, COMDATSymName,
996                                      COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE);
997 }
998 
999 StringRef TargetLoweringObjectFileCOFF::
getDepLibFromLinkerOpt(StringRef LinkerOption) const1000 getDepLibFromLinkerOpt(StringRef LinkerOption) const {
1001   const char *LibCmd = "/DEFAULTLIB:";
1002   if (LinkerOption.startswith(LibCmd))
1003     return LinkerOption.substr(strlen(LibCmd));
1004   return StringRef();
1005 }
1006 
1007 void TargetLoweringObjectFileCOFF::
emitModuleFlags(MCStreamer & Streamer,ArrayRef<Module::ModuleFlagEntry> ModuleFlags,Mangler & Mang,const TargetMachine & TM) const1008 emitModuleFlags(MCStreamer &Streamer,
1009                 ArrayRef<Module::ModuleFlagEntry> ModuleFlags,
1010                 Mangler &Mang, const TargetMachine &TM) const {
1011   MDNode *LinkerOptions = nullptr;
1012 
1013   // Look for the "Linker Options" flag, since it's the only one we support.
1014   for (ArrayRef<Module::ModuleFlagEntry>::iterator
1015        i = ModuleFlags.begin(), e = ModuleFlags.end(); i != e; ++i) {
1016     const Module::ModuleFlagEntry &MFE = *i;
1017     StringRef Key = MFE.Key->getString();
1018     Metadata *Val = MFE.Val;
1019     if (Key == "Linker Options") {
1020       LinkerOptions = cast<MDNode>(Val);
1021       break;
1022     }
1023   }
1024   if (!LinkerOptions)
1025     return;
1026 
1027   // Emit the linker options to the linker .drectve section.  According to the
1028   // spec, this section is a space-separated string containing flags for linker.
1029   const MCSection *Sec = getDrectveSection();
1030   Streamer.SwitchSection(Sec);
1031   for (unsigned i = 0, e = LinkerOptions->getNumOperands(); i != e; ++i) {
1032     MDNode *MDOptions = cast<MDNode>(LinkerOptions->getOperand(i));
1033     for (unsigned ii = 0, ie = MDOptions->getNumOperands(); ii != ie; ++ii) {
1034       MDString *MDOption = cast<MDString>(MDOptions->getOperand(ii));
1035       // Lead with a space for consistency with our dllexport implementation.
1036       std::string Directive(" ");
1037       Directive.append(MDOption->getString());
1038       Streamer.EmitBytes(Directive);
1039     }
1040   }
1041 }
1042 
getStaticCtorSection(unsigned Priority,const MCSymbol * KeySym) const1043 const MCSection *TargetLoweringObjectFileCOFF::getStaticCtorSection(
1044     unsigned Priority, const MCSymbol *KeySym) const {
1045   return getContext().getAssociativeCOFFSection(
1046       cast<MCSectionCOFF>(StaticCtorSection), KeySym);
1047 }
1048 
getStaticDtorSection(unsigned Priority,const MCSymbol * KeySym) const1049 const MCSection *TargetLoweringObjectFileCOFF::getStaticDtorSection(
1050     unsigned Priority, const MCSymbol *KeySym) const {
1051   return getContext().getAssociativeCOFFSection(
1052       cast<MCSectionCOFF>(StaticDtorSection), KeySym);
1053 }
1054