1 //===- llvm/CodeGen/TargetLoweringObjectFileImpl.cpp - Object File Info ---===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements classes used to handle lowerings specific to common
11 // object file formats.
13 //===----------------------------------------------------------------------===//
15 #include "llvm/CodeGen/TargetLoweringObjectFileImpl.h"
16 #include "llvm/ADT/SmallString.h"
17 #include "llvm/ADT/SmallVector.h"
18 #include "llvm/ADT/StringExtras.h"
19 #include "llvm/ADT/StringRef.h"
20 #include "llvm/ADT/Triple.h"
21 #include "llvm/BinaryFormat/COFF.h"
22 #include "llvm/BinaryFormat/Dwarf.h"
23 #include "llvm/BinaryFormat/ELF.h"
24 #include "llvm/BinaryFormat/MachO.h"
25 #include "llvm/CodeGen/MachineModuleInfo.h"
26 #include "llvm/CodeGen/MachineModuleInfoImpls.h"
27 #include "llvm/IR/Comdat.h"
28 #include "llvm/IR/Constants.h"
29 #include "llvm/IR/DataLayout.h"
30 #include "llvm/IR/DerivedTypes.h"
31 #include "llvm/IR/Function.h"
32 #include "llvm/IR/GlobalAlias.h"
33 #include "llvm/IR/GlobalObject.h"
34 #include "llvm/IR/GlobalValue.h"
35 #include "llvm/IR/GlobalVariable.h"
36 #include "llvm/IR/Mangler.h"
37 #include "llvm/IR/Metadata.h"
38 #include "llvm/IR/Module.h"
39 #include "llvm/IR/Type.h"
40 #include "llvm/MC/MCAsmInfo.h"
41 #include "llvm/MC/MCContext.h"
42 #include "llvm/MC/MCExpr.h"
43 #include "llvm/MC/MCSectionCOFF.h"
44 #include "llvm/MC/MCSectionELF.h"
45 #include "llvm/MC/MCSectionMachO.h"
46 #include "llvm/MC/MCSectionWasm.h"
47 #include "llvm/MC/MCStreamer.h"
48 #include "llvm/MC/MCSymbol.h"
49 #include "llvm/MC/MCSymbolELF.h"
50 #include "llvm/MC/MCValue.h"
51 #include "llvm/MC/SectionKind.h"
52 #include "llvm/ProfileData/InstrProf.h"
53 #include "llvm/Support/Casting.h"
54 #include "llvm/Support/CodeGen.h"
55 #include "llvm/Support/Format.h"
56 #include "llvm/Support/ErrorHandling.h"
57 #include "llvm/Support/raw_ostream.h"
58 #include "llvm/Target/TargetMachine.h"
63 using namespace dwarf;
65 static void GetObjCImageInfo(Module &M, unsigned &Version, unsigned &Flags,
67 SmallVector<Module::ModuleFlagEntry, 8> ModuleFlags;
68 M.getModuleFlagsMetadata(ModuleFlags);
70 for (const auto &MFE: ModuleFlags) {
71 // Ignore flags with 'Require' behaviour.
72 if (MFE.Behavior == Module::Require)
75 StringRef Key = MFE.Key->getString();
76 if (Key == "Objective-C Image Info Version") {
77 Version = mdconst::extract<ConstantInt>(MFE.Val)->getZExtValue();
78 } else if (Key == "Objective-C Garbage Collection" ||
79 Key == "Objective-C GC Only" ||
80 Key == "Objective-C Is Simulated" ||
81 Key == "Objective-C Class Properties" ||
82 Key == "Objective-C Image Swift Version") {
83 Flags |= mdconst::extract<ConstantInt>(MFE.Val)->getZExtValue();
84 } else if (Key == "Objective-C Image Info Section") {
85 Section = cast<MDString>(MFE.Val)->getString();
90 //===----------------------------------------------------------------------===//
92 //===----------------------------------------------------------------------===//
94 void TargetLoweringObjectFileELF::Initialize(MCContext &Ctx,
95 const TargetMachine &TgtM) {
96 TargetLoweringObjectFile::Initialize(Ctx, TgtM);
99 CodeModel::Model CM = TgtM.getCodeModel();
101 switch (TgtM.getTargetTriple().getArch()) {
105 case Triple::thumbeb:
106 if (Ctx.getAsmInfo()->getExceptionHandlingType() == ExceptionHandling::ARM)
108 // Fallthrough if not using EHABI
112 PersonalityEncoding = isPositionIndependent()
113 ? dwarf::DW_EH_PE_indirect |
114 dwarf::DW_EH_PE_pcrel |
115 dwarf::DW_EH_PE_sdata4
116 : dwarf::DW_EH_PE_absptr;
117 LSDAEncoding = isPositionIndependent()
118 ? dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4
119 : dwarf::DW_EH_PE_absptr;
120 TTypeEncoding = isPositionIndependent()
121 ? dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
122 dwarf::DW_EH_PE_sdata4
123 : dwarf::DW_EH_PE_absptr;
126 if (isPositionIndependent()) {
127 PersonalityEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
128 ((CM == CodeModel::Small || CM == CodeModel::Medium)
129 ? dwarf::DW_EH_PE_sdata4 : dwarf::DW_EH_PE_sdata8);
130 LSDAEncoding = dwarf::DW_EH_PE_pcrel |
131 (CM == CodeModel::Small
132 ? dwarf::DW_EH_PE_sdata4 : dwarf::DW_EH_PE_sdata8);
133 TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
134 ((CM == CodeModel::Small || CM == CodeModel::Medium)
135 ? dwarf::DW_EH_PE_sdata8 : dwarf::DW_EH_PE_sdata4);
137 PersonalityEncoding =
138 (CM == CodeModel::Small || CM == CodeModel::Medium)
139 ? dwarf::DW_EH_PE_udata4 : dwarf::DW_EH_PE_absptr;
140 LSDAEncoding = (CM == CodeModel::Small)
141 ? dwarf::DW_EH_PE_udata4 : dwarf::DW_EH_PE_absptr;
142 TTypeEncoding = (CM == CodeModel::Small)
143 ? dwarf::DW_EH_PE_udata4 : dwarf::DW_EH_PE_absptr;
146 case Triple::hexagon:
147 PersonalityEncoding = dwarf::DW_EH_PE_absptr;
148 LSDAEncoding = dwarf::DW_EH_PE_absptr;
149 TTypeEncoding = dwarf::DW_EH_PE_absptr;
150 if (isPositionIndependent()) {
151 PersonalityEncoding |= dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel;
152 LSDAEncoding |= dwarf::DW_EH_PE_pcrel;
153 TTypeEncoding |= dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel;
156 case Triple::aarch64:
157 case Triple::aarch64_be:
158 // The small model guarantees static code/data size < 4GB, but not where it
159 // will be in memory. Most of these could end up >2GB away so even a signed
160 // pc-relative 32-bit address is insufficient, theoretically.
161 if (isPositionIndependent()) {
162 PersonalityEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
163 dwarf::DW_EH_PE_sdata8;
164 LSDAEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata8;
165 TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
166 dwarf::DW_EH_PE_sdata8;
168 PersonalityEncoding = dwarf::DW_EH_PE_absptr;
169 LSDAEncoding = dwarf::DW_EH_PE_absptr;
170 TTypeEncoding = dwarf::DW_EH_PE_absptr;
174 LSDAEncoding = dwarf::DW_EH_PE_absptr;
175 PersonalityEncoding = dwarf::DW_EH_PE_absptr;
176 TTypeEncoding = dwarf::DW_EH_PE_absptr;
181 case Triple::mips64el:
182 // MIPS uses indirect pointer to refer personality functions and types, so
183 // that the eh_frame section can be read-only. DW.ref.personality will be
184 // generated for relocation.
185 PersonalityEncoding = dwarf::DW_EH_PE_indirect;
186 // FIXME: The N64 ABI probably ought to use DW_EH_PE_sdata8 but we can't
187 // identify N64 from just a triple.
188 TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
189 dwarf::DW_EH_PE_sdata4;
190 // We don't support PC-relative LSDA references in GAS so we use the default
191 // DW_EH_PE_absptr for those.
193 // FreeBSD must be explicit about the data size and using pcrel since it's
194 // assembler/linker won't do the automatic conversion that the Linux tools
196 if (TgtM.getTargetTriple().isOSFreeBSD()) {
197 PersonalityEncoding |= dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
198 LSDAEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
202 case Triple::ppc64le:
203 PersonalityEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
204 dwarf::DW_EH_PE_udata8;
205 LSDAEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata8;
206 TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
207 dwarf::DW_EH_PE_udata8;
209 case Triple::sparcel:
211 if (isPositionIndependent()) {
212 LSDAEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
213 PersonalityEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
214 dwarf::DW_EH_PE_sdata4;
215 TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
216 dwarf::DW_EH_PE_sdata4;
218 LSDAEncoding = dwarf::DW_EH_PE_absptr;
219 PersonalityEncoding = dwarf::DW_EH_PE_absptr;
220 TTypeEncoding = dwarf::DW_EH_PE_absptr;
223 case Triple::sparcv9:
224 LSDAEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
225 if (isPositionIndependent()) {
226 PersonalityEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
227 dwarf::DW_EH_PE_sdata4;
228 TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
229 dwarf::DW_EH_PE_sdata4;
231 PersonalityEncoding = dwarf::DW_EH_PE_absptr;
232 TTypeEncoding = dwarf::DW_EH_PE_absptr;
235 case Triple::systemz:
236 // All currently-defined code models guarantee that 4-byte PC-relative
237 // values will be in range.
238 if (isPositionIndependent()) {
239 PersonalityEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
240 dwarf::DW_EH_PE_sdata4;
241 LSDAEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
242 TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
243 dwarf::DW_EH_PE_sdata4;
245 PersonalityEncoding = dwarf::DW_EH_PE_absptr;
246 LSDAEncoding = dwarf::DW_EH_PE_absptr;
247 TTypeEncoding = dwarf::DW_EH_PE_absptr;
255 void TargetLoweringObjectFileELF::emitModuleMetadata(MCStreamer &Streamer,
257 auto &C = getContext();
259 if (NamedMDNode *LinkerOptions = M.getNamedMetadata("llvm.linker.options")) {
260 auto *S = C.getELFSection(".linker-options", ELF::SHT_LLVM_LINKER_OPTIONS,
263 Streamer.SwitchSection(S);
265 for (const auto &Operand : LinkerOptions->operands()) {
266 if (cast<MDNode>(Operand)->getNumOperands() != 2)
267 report_fatal_error("invalid llvm.linker.options");
268 for (const auto &Option : cast<MDNode>(Operand)->operands()) {
269 Streamer.EmitBytes(cast<MDString>(Option)->getString());
270 Streamer.EmitIntValue(0, 1);
275 unsigned Version = 0;
279 GetObjCImageInfo(M, Version, Flags, Section);
280 if (!Section.empty()) {
281 auto *S = C.getELFSection(Section, ELF::SHT_PROGBITS, ELF::SHF_ALLOC);
282 Streamer.SwitchSection(S);
283 Streamer.EmitLabel(C.getOrCreateSymbol(StringRef("OBJC_IMAGE_INFO")));
284 Streamer.EmitIntValue(Version, 4);
285 Streamer.EmitIntValue(Flags, 4);
286 Streamer.AddBlankLine();
289 SmallVector<Module::ModuleFlagEntry, 8> ModuleFlags;
290 M.getModuleFlagsMetadata(ModuleFlags);
292 MDNode *CFGProfile = nullptr;
294 for (const auto &MFE : ModuleFlags) {
295 StringRef Key = MFE.Key->getString();
296 if (Key == "CG Profile") {
297 CFGProfile = cast<MDNode>(MFE.Val);
305 auto GetSym = [this](const MDOperand &MDO) -> MCSymbol * {
308 auto V = cast<ValueAsMetadata>(MDO);
309 const Function *F = cast<Function>(V->getValue());
310 return TM->getSymbol(F);
313 for (const auto &Edge : CFGProfile->operands()) {
314 MDNode *E = cast<MDNode>(Edge);
315 const MCSymbol *From = GetSym(E->getOperand(0));
316 const MCSymbol *To = GetSym(E->getOperand(1));
317 // Skip null functions. This can happen if functions are dead stripped after
318 // the CGProfile pass has been run.
321 uint64_t Count = cast<ConstantAsMetadata>(E->getOperand(2))
325 Streamer.emitCGProfileEntry(
326 MCSymbolRefExpr::create(From, MCSymbolRefExpr::VK_None, C),
327 MCSymbolRefExpr::create(To, MCSymbolRefExpr::VK_None, C), Count);
331 MCSymbol *TargetLoweringObjectFileELF::getCFIPersonalitySymbol(
332 const GlobalValue *GV, const TargetMachine &TM,
333 MachineModuleInfo *MMI) const {
334 unsigned Encoding = getPersonalityEncoding();
335 if ((Encoding & 0x80) == DW_EH_PE_indirect)
336 return getContext().getOrCreateSymbol(StringRef("DW.ref.") +
337 TM.getSymbol(GV)->getName());
338 if ((Encoding & 0x70) == DW_EH_PE_absptr)
339 return TM.getSymbol(GV);
340 report_fatal_error("We do not support this DWARF encoding yet!");
343 void TargetLoweringObjectFileELF::emitPersonalityValue(
344 MCStreamer &Streamer, const DataLayout &DL, const MCSymbol *Sym) const {
345 SmallString<64> NameData("DW.ref.");
346 NameData += Sym->getName();
348 cast<MCSymbolELF>(getContext().getOrCreateSymbol(NameData));
349 Streamer.EmitSymbolAttribute(Label, MCSA_Hidden);
350 Streamer.EmitSymbolAttribute(Label, MCSA_Weak);
351 unsigned Flags = ELF::SHF_ALLOC | ELF::SHF_WRITE | ELF::SHF_GROUP;
352 MCSection *Sec = getContext().getELFNamedSection(".data", Label->getName(),
353 ELF::SHT_PROGBITS, Flags, 0);
354 unsigned Size = DL.getPointerSize();
355 Streamer.SwitchSection(Sec);
356 Streamer.EmitValueToAlignment(DL.getPointerABIAlignment(0));
357 Streamer.EmitSymbolAttribute(Label, MCSA_ELF_TypeObject);
358 const MCExpr *E = MCConstantExpr::create(Size, getContext());
359 Streamer.emitELFSize(Label, E);
360 Streamer.EmitLabel(Label);
362 Streamer.EmitSymbolValue(Sym, Size);
365 const MCExpr *TargetLoweringObjectFileELF::getTTypeGlobalReference(
366 const GlobalValue *GV, unsigned Encoding, const TargetMachine &TM,
367 MachineModuleInfo *MMI, MCStreamer &Streamer) const {
368 if (Encoding & DW_EH_PE_indirect) {
369 MachineModuleInfoELF &ELFMMI = MMI->getObjFileInfo<MachineModuleInfoELF>();
371 MCSymbol *SSym = getSymbolWithGlobalValueBase(GV, ".DW.stub", TM);
373 // Add information about the stub reference to ELFMMI so that the stub
374 // gets emitted by the asmprinter.
375 MachineModuleInfoImpl::StubValueTy &StubSym = ELFMMI.getGVStubEntry(SSym);
376 if (!StubSym.getPointer()) {
377 MCSymbol *Sym = TM.getSymbol(GV);
378 StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage());
381 return TargetLoweringObjectFile::
382 getTTypeReference(MCSymbolRefExpr::create(SSym, getContext()),
383 Encoding & ~DW_EH_PE_indirect, Streamer);
386 return TargetLoweringObjectFile::getTTypeGlobalReference(GV, Encoding, TM,
390 static SectionKind getELFKindForNamedSection(StringRef Name, SectionKind K) {
391 // N.B.: The defaults used in here are not the same ones used in MC.
392 // We follow gcc, MC follows gas. For example, given ".section .eh_frame",
393 // both gas and MC will produce a section with no flags. Given
394 // section(".eh_frame") gcc will produce:
396 // .section .eh_frame,"a",@progbits
398 if (Name == getInstrProfSectionName(IPSK_covmap, Triple::ELF,
399 /*AddSegmentInfo=*/false))
400 return SectionKind::getMetadata();
402 if (Name.empty() || Name[0] != '.') return K;
404 // Default implementation based on some magic section names.
405 if (Name == ".bss" ||
406 Name.startswith(".bss.") ||
407 Name.startswith(".gnu.linkonce.b.") ||
408 Name.startswith(".llvm.linkonce.b.") ||
410 Name.startswith(".sbss.") ||
411 Name.startswith(".gnu.linkonce.sb.") ||
412 Name.startswith(".llvm.linkonce.sb."))
413 return SectionKind::getBSS();
415 if (Name == ".tdata" ||
416 Name.startswith(".tdata.") ||
417 Name.startswith(".gnu.linkonce.td.") ||
418 Name.startswith(".llvm.linkonce.td."))
419 return SectionKind::getThreadData();
421 if (Name == ".tbss" ||
422 Name.startswith(".tbss.") ||
423 Name.startswith(".gnu.linkonce.tb.") ||
424 Name.startswith(".llvm.linkonce.tb."))
425 return SectionKind::getThreadBSS();
430 static unsigned getELFSectionType(StringRef Name, SectionKind K) {
431 // Use SHT_NOTE for section whose name starts with ".note" to allow
432 // emitting ELF notes from C variable declaration.
433 // See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77609
434 if (Name.startswith(".note"))
435 return ELF::SHT_NOTE;
437 if (Name == ".init_array")
438 return ELF::SHT_INIT_ARRAY;
440 if (Name == ".fini_array")
441 return ELF::SHT_FINI_ARRAY;
443 if (Name == ".preinit_array")
444 return ELF::SHT_PREINIT_ARRAY;
446 if (K.isBSS() || K.isThreadBSS())
447 return ELF::SHT_NOBITS;
449 return ELF::SHT_PROGBITS;
452 static unsigned getELFSectionFlags(SectionKind K) {
456 Flags |= ELF::SHF_ALLOC;
459 Flags |= ELF::SHF_EXECINSTR;
461 if (K.isExecuteOnly())
462 Flags |= ELF::SHF_ARM_PURECODE;
465 Flags |= ELF::SHF_WRITE;
467 if (K.isThreadLocal())
468 Flags |= ELF::SHF_TLS;
470 if (K.isMergeableCString() || K.isMergeableConst())
471 Flags |= ELF::SHF_MERGE;
473 if (K.isMergeableCString())
474 Flags |= ELF::SHF_STRINGS;
479 static const Comdat *getELFComdat(const GlobalValue *GV) {
480 const Comdat *C = GV->getComdat();
484 if (C->getSelectionKind() != Comdat::Any)
485 report_fatal_error("ELF COMDATs only support SelectionKind::Any, '" +
486 C->getName() + "' cannot be lowered.");
491 static const MCSymbolELF *getAssociatedSymbol(const GlobalObject *GO,
492 const TargetMachine &TM) {
493 MDNode *MD = GO->getMetadata(LLVMContext::MD_associated);
497 const MDOperand &Op = MD->getOperand(0);
501 auto *VM = dyn_cast<ValueAsMetadata>(Op);
503 report_fatal_error("MD_associated operand is not ValueAsMetadata");
505 GlobalObject *OtherGO = dyn_cast<GlobalObject>(VM->getValue());
506 return OtherGO ? dyn_cast<MCSymbolELF>(TM.getSymbol(OtherGO)) : nullptr;
509 static unsigned getEntrySizeForKind(SectionKind Kind) {
510 if (Kind.isMergeable1ByteCString())
512 else if (Kind.isMergeable2ByteCString())
514 else if (Kind.isMergeable4ByteCString())
516 else if (Kind.isMergeableConst4())
518 else if (Kind.isMergeableConst8())
520 else if (Kind.isMergeableConst16())
522 else if (Kind.isMergeableConst32())
525 // We shouldn't have mergeable C strings or mergeable constants that we
526 // didn't handle above.
527 assert(!Kind.isMergeableCString() && "unknown string width");
528 assert(!Kind.isMergeableConst() && "unknown data width");
533 MCSection *TargetLoweringObjectFileELF::getExplicitSectionGlobal(
534 const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const {
535 StringRef SectionName = GO->getSection();
537 // Check if '#pragma clang section' name is applicable.
538 // Note that pragma directive overrides -ffunction-section, -fdata-section
539 // and so section name is exactly as user specified and not uniqued.
540 const GlobalVariable *GV = dyn_cast<GlobalVariable>(GO);
541 if (GV && GV->hasImplicitSection()) {
542 auto Attrs = GV->getAttributes();
543 if (Attrs.hasAttribute("bss-section") && Kind.isBSS()) {
544 SectionName = Attrs.getAttribute("bss-section").getValueAsString();
545 } else if (Attrs.hasAttribute("rodata-section") && Kind.isReadOnly()) {
546 SectionName = Attrs.getAttribute("rodata-section").getValueAsString();
547 } else if (Attrs.hasAttribute("data-section") && Kind.isData()) {
548 SectionName = Attrs.getAttribute("data-section").getValueAsString();
551 const Function *F = dyn_cast<Function>(GO);
552 if (F && F->hasFnAttribute("implicit-section-name")) {
553 SectionName = F->getFnAttribute("implicit-section-name").getValueAsString();
556 // Infer section flags from the section name if we can.
557 Kind = getELFKindForNamedSection(SectionName, Kind);
559 StringRef Group = "";
560 unsigned Flags = getELFSectionFlags(Kind);
561 if (const Comdat *C = getELFComdat(GO)) {
562 Group = C->getName();
563 Flags |= ELF::SHF_GROUP;
566 // A section can have at most one associated section. Put each global with
567 // MD_associated in a unique section.
568 unsigned UniqueID = MCContext::GenericSectionID;
569 const MCSymbolELF *AssociatedSymbol = getAssociatedSymbol(GO, TM);
570 if (AssociatedSymbol) {
571 UniqueID = NextUniqueID++;
572 Flags |= ELF::SHF_LINK_ORDER;
575 MCSectionELF *Section = getContext().getELFSection(
576 SectionName, getELFSectionType(SectionName, Kind), Flags,
577 getEntrySizeForKind(Kind), Group, UniqueID, AssociatedSymbol);
578 // Make sure that we did not get some other section with incompatible sh_link.
579 // This should not be possible due to UniqueID code above.
580 assert(Section->getAssociatedSymbol() == AssociatedSymbol &&
581 "Associated symbol mismatch between sections");
585 /// Return the section prefix name used by options FunctionsSections and
587 static StringRef getSectionPrefixForGlobal(SectionKind Kind) {
590 if (Kind.isReadOnly())
594 if (Kind.isThreadData())
596 if (Kind.isThreadBSS())
600 assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
601 return ".data.rel.ro";
604 static MCSectionELF *selectELFSectionForGlobal(
605 MCContext &Ctx, const GlobalObject *GO, SectionKind Kind, Mangler &Mang,
606 const TargetMachine &TM, bool EmitUniqueSection, unsigned Flags,
607 unsigned *NextUniqueID, const MCSymbolELF *AssociatedSymbol) {
609 StringRef Group = "";
610 if (const Comdat *C = getELFComdat(GO)) {
611 Flags |= ELF::SHF_GROUP;
612 Group = C->getName();
615 // Get the section entry size based on the kind.
616 unsigned EntrySize = getEntrySizeForKind(Kind);
618 SmallString<128> Name;
619 if (Kind.isMergeableCString()) {
620 // We also need alignment here.
621 // FIXME: this is getting the alignment of the character, not the
622 // alignment of the global!
623 unsigned Align = GO->getParent()->getDataLayout().getPreferredAlignment(
624 cast<GlobalVariable>(GO));
626 std::string SizeSpec = ".rodata.str" + utostr(EntrySize) + ".";
627 Name = SizeSpec + utostr(Align);
628 } else if (Kind.isMergeableConst()) {
629 Name = ".rodata.cst";
630 Name += utostr(EntrySize);
632 Name = getSectionPrefixForGlobal(Kind);
635 if (const auto *F = dyn_cast<Function>(GO)) {
636 const auto &OptionalPrefix = F->getSectionPrefix();
638 Name += *OptionalPrefix;
641 unsigned UniqueID = MCContext::GenericSectionID;
642 if (EmitUniqueSection) {
643 if (TM.getUniqueSectionNames()) {
645 TM.getNameWithPrefix(Name, GO, Mang, true /*MayAlwaysUsePrivate*/);
647 UniqueID = *NextUniqueID;
651 // Use 0 as the unique ID for execute-only text.
652 if (Kind.isExecuteOnly())
654 return Ctx.getELFSection(Name, getELFSectionType(Name, Kind), Flags,
655 EntrySize, Group, UniqueID, AssociatedSymbol);
658 MCSection *TargetLoweringObjectFileELF::SelectSectionForGlobal(
659 const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const {
660 unsigned Flags = getELFSectionFlags(Kind);
662 // If we have -ffunction-section or -fdata-section then we should emit the
663 // global value to a uniqued section specifically for it.
664 bool EmitUniqueSection = false;
665 if (!(Flags & ELF::SHF_MERGE) && !Kind.isCommon()) {
667 EmitUniqueSection = TM.getFunctionSections();
669 EmitUniqueSection = TM.getDataSections();
671 EmitUniqueSection |= GO->hasComdat();
673 const MCSymbolELF *AssociatedSymbol = getAssociatedSymbol(GO, TM);
674 if (AssociatedSymbol) {
675 EmitUniqueSection = true;
676 Flags |= ELF::SHF_LINK_ORDER;
679 MCSectionELF *Section = selectELFSectionForGlobal(
680 getContext(), GO, Kind, getMangler(), TM, EmitUniqueSection, Flags,
681 &NextUniqueID, AssociatedSymbol);
682 assert(Section->getAssociatedSymbol() == AssociatedSymbol);
686 MCSection *TargetLoweringObjectFileELF::getSectionForJumpTable(
687 const Function &F, const TargetMachine &TM) const {
688 // If the function can be removed, produce a unique section so that
689 // the table doesn't prevent the removal.
690 const Comdat *C = F.getComdat();
691 bool EmitUniqueSection = TM.getFunctionSections() || C;
692 if (!EmitUniqueSection)
693 return ReadOnlySection;
695 return selectELFSectionForGlobal(getContext(), &F, SectionKind::getReadOnly(),
696 getMangler(), TM, EmitUniqueSection,
697 ELF::SHF_ALLOC, &NextUniqueID,
698 /* AssociatedSymbol */ nullptr);
701 bool TargetLoweringObjectFileELF::shouldPutJumpTableInFunctionSection(
702 bool UsesLabelDifference, const Function &F) const {
703 // We can always create relative relocations, so use another section
704 // that can be marked non-executable.
708 /// Given a mergeable constant with the specified size and relocation
709 /// information, return a section that it should be placed in.
710 MCSection *TargetLoweringObjectFileELF::getSectionForConstant(
711 const DataLayout &DL, SectionKind Kind, const Constant *C,
712 unsigned &Align) const {
713 if (Kind.isMergeableConst4() && MergeableConst4Section)
714 return MergeableConst4Section;
715 if (Kind.isMergeableConst8() && MergeableConst8Section)
716 return MergeableConst8Section;
717 if (Kind.isMergeableConst16() && MergeableConst16Section)
718 return MergeableConst16Section;
719 if (Kind.isMergeableConst32() && MergeableConst32Section)
720 return MergeableConst32Section;
721 if (Kind.isReadOnly())
722 return ReadOnlySection;
724 assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
725 return DataRelROSection;
728 static MCSectionELF *getStaticStructorSection(MCContext &Ctx, bool UseInitArray,
729 bool IsCtor, unsigned Priority,
730 const MCSymbol *KeySym) {
733 unsigned Flags = ELF::SHF_ALLOC | ELF::SHF_WRITE;
734 StringRef COMDAT = KeySym ? KeySym->getName() : "";
737 Flags |= ELF::SHF_GROUP;
741 Type = ELF::SHT_INIT_ARRAY;
742 Name = ".init_array";
744 Type = ELF::SHT_FINI_ARRAY;
745 Name = ".fini_array";
747 if (Priority != 65535) {
749 Name += utostr(Priority);
752 // The default scheme is .ctor / .dtor, so we have to invert the priority
758 if (Priority != 65535)
759 raw_string_ostream(Name) << format(".%05u", 65535 - Priority);
760 Type = ELF::SHT_PROGBITS;
763 return Ctx.getELFSection(Name, Type, Flags, 0, COMDAT);
766 MCSection *TargetLoweringObjectFileELF::getStaticCtorSection(
767 unsigned Priority, const MCSymbol *KeySym) const {
768 return getStaticStructorSection(getContext(), UseInitArray, true, Priority,
772 MCSection *TargetLoweringObjectFileELF::getStaticDtorSection(
773 unsigned Priority, const MCSymbol *KeySym) const {
774 return getStaticStructorSection(getContext(), UseInitArray, false, Priority,
778 const MCExpr *TargetLoweringObjectFileELF::lowerRelativeReference(
779 const GlobalValue *LHS, const GlobalValue *RHS,
780 const TargetMachine &TM) const {
781 // We may only use a PLT-relative relocation to refer to unnamed_addr
783 if (!LHS->hasGlobalUnnamedAddr() || !LHS->getValueType()->isFunctionTy())
786 // Basic sanity checks.
787 if (LHS->getType()->getPointerAddressSpace() != 0 ||
788 RHS->getType()->getPointerAddressSpace() != 0 || LHS->isThreadLocal() ||
789 RHS->isThreadLocal())
792 return MCBinaryExpr::createSub(
793 MCSymbolRefExpr::create(TM.getSymbol(LHS), PLTRelativeVariantKind,
795 MCSymbolRefExpr::create(TM.getSymbol(RHS), getContext()), getContext());
798 MCSection *TargetLoweringObjectFileELF::getSectionForCommandLines() const {
799 // Use ".GCC.command.line" since this feature is to support clang's
800 // -frecord-gcc-switches which in turn attempts to mimic GCC's switch of the
802 return getContext().getELFSection(".GCC.command.line", ELF::SHT_PROGBITS,
803 ELF::SHF_MERGE | ELF::SHF_STRINGS, 1, "");
807 TargetLoweringObjectFileELF::InitializeELF(bool UseInitArray_) {
808 UseInitArray = UseInitArray_;
809 MCContext &Ctx = getContext();
811 StaticCtorSection = Ctx.getELFSection(".ctors", ELF::SHT_PROGBITS,
812 ELF::SHF_ALLOC | ELF::SHF_WRITE);
814 StaticDtorSection = Ctx.getELFSection(".dtors", ELF::SHT_PROGBITS,
815 ELF::SHF_ALLOC | ELF::SHF_WRITE);
819 StaticCtorSection = Ctx.getELFSection(".init_array", ELF::SHT_INIT_ARRAY,
820 ELF::SHF_WRITE | ELF::SHF_ALLOC);
821 StaticDtorSection = Ctx.getELFSection(".fini_array", ELF::SHT_FINI_ARRAY,
822 ELF::SHF_WRITE | ELF::SHF_ALLOC);
825 //===----------------------------------------------------------------------===//
827 //===----------------------------------------------------------------------===//
829 TargetLoweringObjectFileMachO::TargetLoweringObjectFileMachO()
830 : TargetLoweringObjectFile() {
831 SupportIndirectSymViaGOTPCRel = true;
834 void TargetLoweringObjectFileMachO::Initialize(MCContext &Ctx,
835 const TargetMachine &TM) {
836 TargetLoweringObjectFile::Initialize(Ctx, TM);
837 if (TM.getRelocationModel() == Reloc::Static) {
838 StaticCtorSection = Ctx.getMachOSection("__TEXT", "__constructor", 0,
839 SectionKind::getData());
840 StaticDtorSection = Ctx.getMachOSection("__TEXT", "__destructor", 0,
841 SectionKind::getData());
843 StaticCtorSection = Ctx.getMachOSection("__DATA", "__mod_init_func",
844 MachO::S_MOD_INIT_FUNC_POINTERS,
845 SectionKind::getData());
846 StaticDtorSection = Ctx.getMachOSection("__DATA", "__mod_term_func",
847 MachO::S_MOD_TERM_FUNC_POINTERS,
848 SectionKind::getData());
851 PersonalityEncoding =
852 dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
853 LSDAEncoding = dwarf::DW_EH_PE_pcrel;
855 dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
858 void TargetLoweringObjectFileMachO::emitModuleMetadata(MCStreamer &Streamer,
860 // Emit the linker options if present.
861 if (auto *LinkerOptions = M.getNamedMetadata("llvm.linker.options")) {
862 for (const auto &Option : LinkerOptions->operands()) {
863 SmallVector<std::string, 4> StrOptions;
864 for (const auto &Piece : cast<MDNode>(Option)->operands())
865 StrOptions.push_back(cast<MDString>(Piece)->getString());
866 Streamer.EmitLinkerOptions(StrOptions);
870 unsigned VersionVal = 0;
871 unsigned ImageInfoFlags = 0;
872 StringRef SectionVal;
874 GetObjCImageInfo(M, VersionVal, ImageInfoFlags, SectionVal);
876 // The section is mandatory. If we don't have it, then we don't have GC info.
877 if (SectionVal.empty())
880 StringRef Segment, Section;
881 unsigned TAA = 0, StubSize = 0;
883 std::string ErrorCode =
884 MCSectionMachO::ParseSectionSpecifier(SectionVal, Segment, Section,
885 TAA, TAAParsed, StubSize);
886 if (!ErrorCode.empty())
887 // If invalid, report the error with report_fatal_error.
888 report_fatal_error("Invalid section specifier '" + Section + "': " +
892 MCSectionMachO *S = getContext().getMachOSection(
893 Segment, Section, TAA, StubSize, SectionKind::getData());
894 Streamer.SwitchSection(S);
895 Streamer.EmitLabel(getContext().
896 getOrCreateSymbol(StringRef("L_OBJC_IMAGE_INFO")));
897 Streamer.EmitIntValue(VersionVal, 4);
898 Streamer.EmitIntValue(ImageInfoFlags, 4);
899 Streamer.AddBlankLine();
902 static void checkMachOComdat(const GlobalValue *GV) {
903 const Comdat *C = GV->getComdat();
907 report_fatal_error("MachO doesn't support COMDATs, '" + C->getName() +
908 "' cannot be lowered.");
911 MCSection *TargetLoweringObjectFileMachO::getExplicitSectionGlobal(
912 const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const {
913 // Parse the section specifier and create it if valid.
914 StringRef Segment, Section;
915 unsigned TAA = 0, StubSize = 0;
918 checkMachOComdat(GO);
920 std::string ErrorCode =
921 MCSectionMachO::ParseSectionSpecifier(GO->getSection(), Segment, Section,
922 TAA, TAAParsed, StubSize);
923 if (!ErrorCode.empty()) {
924 // If invalid, report the error with report_fatal_error.
925 report_fatal_error("Global variable '" + GO->getName() +
926 "' has an invalid section specifier '" +
927 GO->getSection() + "': " + ErrorCode + ".");
932 getContext().getMachOSection(Segment, Section, TAA, StubSize, Kind);
934 // If TAA wasn't set by ParseSectionSpecifier() above,
935 // use the value returned by getMachOSection() as a default.
937 TAA = S->getTypeAndAttributes();
939 // Okay, now that we got the section, verify that the TAA & StubSize agree.
940 // If the user declared multiple globals with different section flags, we need
941 // to reject it here.
942 if (S->getTypeAndAttributes() != TAA || S->getStubSize() != StubSize) {
943 // If invalid, report the error with report_fatal_error.
944 report_fatal_error("Global variable '" + GO->getName() +
945 "' section type or attributes does not match previous"
946 " section specifier");
952 MCSection *TargetLoweringObjectFileMachO::SelectSectionForGlobal(
953 const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const {
954 checkMachOComdat(GO);
956 // Handle thread local data.
957 if (Kind.isThreadBSS()) return TLSBSSSection;
958 if (Kind.isThreadData()) return TLSDataSection;
961 return GO->isWeakForLinker() ? TextCoalSection : TextSection;
963 // If this is weak/linkonce, put this in a coalescable section, either in text
964 // or data depending on if it is writable.
965 if (GO->isWeakForLinker()) {
966 if (Kind.isReadOnly())
967 return ConstTextCoalSection;
968 if (Kind.isReadOnlyWithRel())
969 return ConstDataCoalSection;
970 return DataCoalSection;
973 // FIXME: Alignment check should be handled by section classifier.
974 if (Kind.isMergeable1ByteCString() &&
975 GO->getParent()->getDataLayout().getPreferredAlignment(
976 cast<GlobalVariable>(GO)) < 32)
977 return CStringSection;
979 // Do not put 16-bit arrays in the UString section if they have an
980 // externally visible label, this runs into issues with certain linker
982 if (Kind.isMergeable2ByteCString() && !GO->hasExternalLinkage() &&
983 GO->getParent()->getDataLayout().getPreferredAlignment(
984 cast<GlobalVariable>(GO)) < 32)
985 return UStringSection;
987 // With MachO only variables whose corresponding symbol starts with 'l' or
988 // 'L' can be merged, so we only try merging GVs with private linkage.
989 if (GO->hasPrivateLinkage() && Kind.isMergeableConst()) {
990 if (Kind.isMergeableConst4())
991 return FourByteConstantSection;
992 if (Kind.isMergeableConst8())
993 return EightByteConstantSection;
994 if (Kind.isMergeableConst16())
995 return SixteenByteConstantSection;
998 // Otherwise, if it is readonly, but not something we can specially optimize,
999 // just drop it in .const.
1000 if (Kind.isReadOnly())
1001 return ReadOnlySection;
1003 // If this is marked const, put it into a const section. But if the dynamic
1004 // linker needs to write to it, put it in the data segment.
1005 if (Kind.isReadOnlyWithRel())
1006 return ConstDataSection;
1008 // Put zero initialized globals with strong external linkage in the
1009 // DATA, __common section with the .zerofill directive.
1010 if (Kind.isBSSExtern())
1011 return DataCommonSection;
1013 // Put zero initialized globals with local linkage in __DATA,__bss directive
1014 // with the .zerofill directive (aka .lcomm).
1015 if (Kind.isBSSLocal())
1016 return DataBSSSection;
1018 // Otherwise, just drop the variable in the normal data section.
1022 MCSection *TargetLoweringObjectFileMachO::getSectionForConstant(
1023 const DataLayout &DL, SectionKind Kind, const Constant *C,
1024 unsigned &Align) const {
1025 // If this constant requires a relocation, we have to put it in the data
1026 // segment, not in the text segment.
1027 if (Kind.isData() || Kind.isReadOnlyWithRel())
1028 return ConstDataSection;
1030 if (Kind.isMergeableConst4())
1031 return FourByteConstantSection;
1032 if (Kind.isMergeableConst8())
1033 return EightByteConstantSection;
1034 if (Kind.isMergeableConst16())
1035 return SixteenByteConstantSection;
1036 return ReadOnlySection; // .const
1039 const MCExpr *TargetLoweringObjectFileMachO::getTTypeGlobalReference(
1040 const GlobalValue *GV, unsigned Encoding, const TargetMachine &TM,
1041 MachineModuleInfo *MMI, MCStreamer &Streamer) const {
1042 // The mach-o version of this method defaults to returning a stub reference.
1044 if (Encoding & DW_EH_PE_indirect) {
1045 MachineModuleInfoMachO &MachOMMI =
1046 MMI->getObjFileInfo<MachineModuleInfoMachO>();
1048 MCSymbol *SSym = getSymbolWithGlobalValueBase(GV, "$non_lazy_ptr", TM);
1050 // Add information about the stub reference to MachOMMI so that the stub
1051 // gets emitted by the asmprinter.
1052 MachineModuleInfoImpl::StubValueTy &StubSym = MachOMMI.getGVStubEntry(SSym);
1053 if (!StubSym.getPointer()) {
1054 MCSymbol *Sym = TM.getSymbol(GV);
1055 StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage());
1058 return TargetLoweringObjectFile::
1059 getTTypeReference(MCSymbolRefExpr::create(SSym, getContext()),
1060 Encoding & ~DW_EH_PE_indirect, Streamer);
1063 return TargetLoweringObjectFile::getTTypeGlobalReference(GV, Encoding, TM,
1067 MCSymbol *TargetLoweringObjectFileMachO::getCFIPersonalitySymbol(
1068 const GlobalValue *GV, const TargetMachine &TM,
1069 MachineModuleInfo *MMI) const {
1070 // The mach-o version of this method defaults to returning a stub reference.
1071 MachineModuleInfoMachO &MachOMMI =
1072 MMI->getObjFileInfo<MachineModuleInfoMachO>();
1074 MCSymbol *SSym = getSymbolWithGlobalValueBase(GV, "$non_lazy_ptr", TM);
1076 // Add information about the stub reference to MachOMMI so that the stub
1077 // gets emitted by the asmprinter.
1078 MachineModuleInfoImpl::StubValueTy &StubSym = MachOMMI.getGVStubEntry(SSym);
1079 if (!StubSym.getPointer()) {
1080 MCSymbol *Sym = TM.getSymbol(GV);
1081 StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage());
1087 const MCExpr *TargetLoweringObjectFileMachO::getIndirectSymViaGOTPCRel(
1088 const MCSymbol *Sym, const MCValue &MV, int64_t Offset,
1089 MachineModuleInfo *MMI, MCStreamer &Streamer) const {
1090 // Although MachO 32-bit targets do not explicitly have a GOTPCREL relocation
1091 // as 64-bit do, we replace the GOT equivalent by accessing the final symbol
1092 // through a non_lazy_ptr stub instead. One advantage is that it allows the
1093 // computation of deltas to final external symbols. Example:
1099 // .long _extgotequiv-_delta
1101 // is transformed to:
1104 // .long L_extfoo$non_lazy_ptr-(_delta+0)
1106 // .section __IMPORT,__pointers,non_lazy_symbol_pointers
1107 // L_extfoo$non_lazy_ptr:
1108 // .indirect_symbol _extfoo
1111 // The indirect symbol table (and sections of non_lazy_symbol_pointers type)
1112 // may point to both local (same translation unit) and global (other
1113 // translation units) symbols. Example:
1115 // .section __DATA,__pointers,non_lazy_symbol_pointers
1117 // .indirect_symbol _myGlobal
1120 // .indirect_symbol _myLocal
1123 // If the symbol is local, instead of the symbol's index, the assembler
1124 // places the constant INDIRECT_SYMBOL_LOCAL into the indirect symbol table.
1125 // Then the linker will notice the constant in the table and will look at the
1126 // content of the symbol.
1127 MachineModuleInfoMachO &MachOMMI =
1128 MMI->getObjFileInfo<MachineModuleInfoMachO>();
1129 MCContext &Ctx = getContext();
1131 // The offset must consider the original displacement from the base symbol
1132 // since 32-bit targets don't have a GOTPCREL to fold the PC displacement.
1133 Offset = -MV.getConstant();
1134 const MCSymbol *BaseSym = &MV.getSymB()->getSymbol();
1136 // Access the final symbol via sym$non_lazy_ptr and generate the appropriated
1137 // non_lazy_ptr stubs.
1138 SmallString<128> Name;
1139 StringRef Suffix = "$non_lazy_ptr";
1140 Name += MMI->getModule()->getDataLayout().getPrivateGlobalPrefix();
1141 Name += Sym->getName();
1143 MCSymbol *Stub = Ctx.getOrCreateSymbol(Name);
1145 MachineModuleInfoImpl::StubValueTy &StubSym = MachOMMI.getGVStubEntry(Stub);
1146 if (!StubSym.getPointer()) {
1147 bool IsIndirectLocal = Sym->isDefined() && !Sym->isExternal();
1148 // With the assumption that IsIndirectLocal == GV->hasLocalLinkage().
1149 StubSym = MachineModuleInfoImpl::StubValueTy(const_cast<MCSymbol *>(Sym),
1153 const MCExpr *BSymExpr =
1154 MCSymbolRefExpr::create(BaseSym, MCSymbolRefExpr::VK_None, Ctx);
1156 MCSymbolRefExpr::create(Stub, MCSymbolRefExpr::VK_None, Ctx);
1159 return MCBinaryExpr::createSub(LHS, BSymExpr, Ctx);
1162 MCBinaryExpr::createAdd(BSymExpr, MCConstantExpr::create(Offset, Ctx), Ctx);
1163 return MCBinaryExpr::createSub(LHS, RHS, Ctx);
1166 static bool canUsePrivateLabel(const MCAsmInfo &AsmInfo,
1167 const MCSection &Section) {
1168 if (!AsmInfo.isSectionAtomizableBySymbols(Section))
1171 // If it is not dead stripped, it is safe to use private labels.
1172 const MCSectionMachO &SMO = cast<MCSectionMachO>(Section);
1173 if (SMO.hasAttribute(MachO::S_ATTR_NO_DEAD_STRIP))
1179 void TargetLoweringObjectFileMachO::getNameWithPrefix(
1180 SmallVectorImpl<char> &OutName, const GlobalValue *GV,
1181 const TargetMachine &TM) const {
1182 bool CannotUsePrivateLabel = true;
1183 if (auto *GO = GV->getBaseObject()) {
1184 SectionKind GOKind = TargetLoweringObjectFile::getKindForGlobal(GO, TM);
1185 const MCSection *TheSection = SectionForGlobal(GO, GOKind, TM);
1186 CannotUsePrivateLabel =
1187 !canUsePrivateLabel(*TM.getMCAsmInfo(), *TheSection);
1189 getMangler().getNameWithPrefix(OutName, GV, CannotUsePrivateLabel);
1192 //===----------------------------------------------------------------------===//
1194 //===----------------------------------------------------------------------===//
1197 getCOFFSectionFlags(SectionKind K, const TargetMachine &TM) {
1199 bool isThumb = TM.getTargetTriple().getArch() == Triple::thumb;
1203 COFF::IMAGE_SCN_MEM_DISCARDABLE;
1204 else if (K.isText())
1206 COFF::IMAGE_SCN_MEM_EXECUTE |
1207 COFF::IMAGE_SCN_MEM_READ |
1208 COFF::IMAGE_SCN_CNT_CODE |
1209 (isThumb ? COFF::IMAGE_SCN_MEM_16BIT : (COFF::SectionCharacteristics)0);
1212 COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA |
1213 COFF::IMAGE_SCN_MEM_READ |
1214 COFF::IMAGE_SCN_MEM_WRITE;
1215 else if (K.isThreadLocal())
1217 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
1218 COFF::IMAGE_SCN_MEM_READ |
1219 COFF::IMAGE_SCN_MEM_WRITE;
1220 else if (K.isReadOnly() || K.isReadOnlyWithRel())
1222 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
1223 COFF::IMAGE_SCN_MEM_READ;
1224 else if (K.isWriteable())
1226 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
1227 COFF::IMAGE_SCN_MEM_READ |
1228 COFF::IMAGE_SCN_MEM_WRITE;
1233 static const GlobalValue *getComdatGVForCOFF(const GlobalValue *GV) {
1234 const Comdat *C = GV->getComdat();
1235 assert(C && "expected GV to have a Comdat!");
1237 StringRef ComdatGVName = C->getName();
1238 const GlobalValue *ComdatGV = GV->getParent()->getNamedValue(ComdatGVName);
1240 report_fatal_error("Associative COMDAT symbol '" + ComdatGVName +
1241 "' does not exist.");
1243 if (ComdatGV->getComdat() != C)
1244 report_fatal_error("Associative COMDAT symbol '" + ComdatGVName +
1245 "' is not a key for its COMDAT.");
1250 static int getSelectionForCOFF(const GlobalValue *GV) {
1251 if (const Comdat *C = GV->getComdat()) {
1252 const GlobalValue *ComdatKey = getComdatGVForCOFF(GV);
1253 if (const auto *GA = dyn_cast<GlobalAlias>(ComdatKey))
1254 ComdatKey = GA->getBaseObject();
1255 if (ComdatKey == GV) {
1256 switch (C->getSelectionKind()) {
1258 return COFF::IMAGE_COMDAT_SELECT_ANY;
1259 case Comdat::ExactMatch:
1260 return COFF::IMAGE_COMDAT_SELECT_EXACT_MATCH;
1261 case Comdat::Largest:
1262 return COFF::IMAGE_COMDAT_SELECT_LARGEST;
1263 case Comdat::NoDuplicates:
1264 return COFF::IMAGE_COMDAT_SELECT_NODUPLICATES;
1265 case Comdat::SameSize:
1266 return COFF::IMAGE_COMDAT_SELECT_SAME_SIZE;
1269 return COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE;
1275 MCSection *TargetLoweringObjectFileCOFF::getExplicitSectionGlobal(
1276 const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const {
1278 unsigned Characteristics = getCOFFSectionFlags(Kind, TM);
1279 StringRef Name = GO->getSection();
1280 StringRef COMDATSymName = "";
1281 if (GO->hasComdat()) {
1282 Selection = getSelectionForCOFF(GO);
1283 const GlobalValue *ComdatGV;
1284 if (Selection == COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE)
1285 ComdatGV = getComdatGVForCOFF(GO);
1289 if (!ComdatGV->hasPrivateLinkage()) {
1290 MCSymbol *Sym = TM.getSymbol(ComdatGV);
1291 COMDATSymName = Sym->getName();
1292 Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT;
1298 return getContext().getCOFFSection(Name, Characteristics, Kind, COMDATSymName,
1302 static StringRef getCOFFSectionNameForUniqueGlobal(SectionKind Kind) {
1307 if (Kind.isThreadLocal())
1309 if (Kind.isReadOnly() || Kind.isReadOnlyWithRel())
1314 MCSection *TargetLoweringObjectFileCOFF::SelectSectionForGlobal(
1315 const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const {
1316 // If we have -ffunction-sections then we should emit the global value to a
1317 // uniqued section specifically for it.
1318 bool EmitUniquedSection;
1320 EmitUniquedSection = TM.getFunctionSections();
1322 EmitUniquedSection = TM.getDataSections();
1324 if ((EmitUniquedSection && !Kind.isCommon()) || GO->hasComdat()) {
1325 SmallString<256> Name = getCOFFSectionNameForUniqueGlobal(Kind);
1327 unsigned Characteristics = getCOFFSectionFlags(Kind, TM);
1329 Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT;
1330 int Selection = getSelectionForCOFF(GO);
1332 Selection = COFF::IMAGE_COMDAT_SELECT_NODUPLICATES;
1333 const GlobalValue *ComdatGV;
1334 if (GO->hasComdat())
1335 ComdatGV = getComdatGVForCOFF(GO);
1339 unsigned UniqueID = MCContext::GenericSectionID;
1340 if (EmitUniquedSection)
1341 UniqueID = NextUniqueID++;
1343 if (!ComdatGV->hasPrivateLinkage()) {
1344 MCSymbol *Sym = TM.getSymbol(ComdatGV);
1345 StringRef COMDATSymName = Sym->getName();
1347 // Append "$symbol" to the section name *before* IR-level mangling is
1348 // applied when targetting mingw. This is what GCC does, and the ld.bfd
1349 // COFF linker will not properly handle comdats otherwise.
1350 if (getTargetTriple().isWindowsGNUEnvironment())
1351 raw_svector_ostream(Name) << '$' << ComdatGV->getName();
1353 return getContext().getCOFFSection(Name, Characteristics, Kind,
1354 COMDATSymName, Selection, UniqueID);
1356 SmallString<256> TmpData;
1357 getMangler().getNameWithPrefix(TmpData, GO, /*CannotUsePrivateLabel=*/true);
1358 return getContext().getCOFFSection(Name, Characteristics, Kind, TmpData,
1359 Selection, UniqueID);
1366 if (Kind.isThreadLocal())
1367 return TLSDataSection;
1369 if (Kind.isReadOnly() || Kind.isReadOnlyWithRel())
1370 return ReadOnlySection;
1372 // Note: we claim that common symbols are put in BSSSection, but they are
1373 // really emitted with the magic .comm directive, which creates a symbol table
1374 // entry but not a section.
1375 if (Kind.isBSS() || Kind.isCommon())
1381 void TargetLoweringObjectFileCOFF::getNameWithPrefix(
1382 SmallVectorImpl<char> &OutName, const GlobalValue *GV,
1383 const TargetMachine &TM) const {
1384 bool CannotUsePrivateLabel = false;
1385 if (GV->hasPrivateLinkage() &&
1386 ((isa<Function>(GV) && TM.getFunctionSections()) ||
1387 (isa<GlobalVariable>(GV) && TM.getDataSections())))
1388 CannotUsePrivateLabel = true;
1390 getMangler().getNameWithPrefix(OutName, GV, CannotUsePrivateLabel);
1393 MCSection *TargetLoweringObjectFileCOFF::getSectionForJumpTable(
1394 const Function &F, const TargetMachine &TM) const {
1395 // If the function can be removed, produce a unique section so that
1396 // the table doesn't prevent the removal.
1397 const Comdat *C = F.getComdat();
1398 bool EmitUniqueSection = TM.getFunctionSections() || C;
1399 if (!EmitUniqueSection)
1400 return ReadOnlySection;
1402 // FIXME: we should produce a symbol for F instead.
1403 if (F.hasPrivateLinkage())
1404 return ReadOnlySection;
1406 MCSymbol *Sym = TM.getSymbol(&F);
1407 StringRef COMDATSymName = Sym->getName();
1409 SectionKind Kind = SectionKind::getReadOnly();
1410 StringRef SecName = getCOFFSectionNameForUniqueGlobal(Kind);
1411 unsigned Characteristics = getCOFFSectionFlags(Kind, TM);
1412 Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT;
1413 unsigned UniqueID = NextUniqueID++;
1415 return getContext().getCOFFSection(
1416 SecName, Characteristics, Kind, COMDATSymName,
1417 COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE, UniqueID);
1420 void TargetLoweringObjectFileCOFF::emitModuleMetadata(MCStreamer &Streamer,
1422 if (NamedMDNode *LinkerOptions = M.getNamedMetadata("llvm.linker.options")) {
1423 // Emit the linker options to the linker .drectve section. According to the
1424 // spec, this section is a space-separated string containing flags for
1426 MCSection *Sec = getDrectveSection();
1427 Streamer.SwitchSection(Sec);
1428 for (const auto &Option : LinkerOptions->operands()) {
1429 for (const auto &Piece : cast<MDNode>(Option)->operands()) {
1430 // Lead with a space for consistency with our dllexport implementation.
1431 std::string Directive(" ");
1432 Directive.append(cast<MDString>(Piece)->getString());
1433 Streamer.EmitBytes(Directive);
1438 unsigned Version = 0;
1442 GetObjCImageInfo(M, Version, Flags, Section);
1443 if (Section.empty())
1446 auto &C = getContext();
1447 auto *S = C.getCOFFSection(
1448 Section, COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | COFF::IMAGE_SCN_MEM_READ,
1449 SectionKind::getReadOnly());
1450 Streamer.SwitchSection(S);
1451 Streamer.EmitLabel(C.getOrCreateSymbol(StringRef("OBJC_IMAGE_INFO")));
1452 Streamer.EmitIntValue(Version, 4);
1453 Streamer.EmitIntValue(Flags, 4);
1454 Streamer.AddBlankLine();
1457 void TargetLoweringObjectFileCOFF::Initialize(MCContext &Ctx,
1458 const TargetMachine &TM) {
1459 TargetLoweringObjectFile::Initialize(Ctx, TM);
1460 const Triple &T = TM.getTargetTriple();
1461 if (T.isKnownWindowsMSVCEnvironment() || T.isWindowsItaniumEnvironment()) {
1463 Ctx.getCOFFSection(".CRT$XCU", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
1464 COFF::IMAGE_SCN_MEM_READ,
1465 SectionKind::getReadOnly());
1467 Ctx.getCOFFSection(".CRT$XTX", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
1468 COFF::IMAGE_SCN_MEM_READ,
1469 SectionKind::getReadOnly());
1471 StaticCtorSection = Ctx.getCOFFSection(
1472 ".ctors", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
1473 COFF::IMAGE_SCN_MEM_READ | COFF::IMAGE_SCN_MEM_WRITE,
1474 SectionKind::getData());
1475 StaticDtorSection = Ctx.getCOFFSection(
1476 ".dtors", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
1477 COFF::IMAGE_SCN_MEM_READ | COFF::IMAGE_SCN_MEM_WRITE,
1478 SectionKind::getData());
1482 static MCSectionCOFF *getCOFFStaticStructorSection(MCContext &Ctx,
1483 const Triple &T, bool IsCtor,
1485 const MCSymbol *KeySym,
1486 MCSectionCOFF *Default) {
1487 if (T.isKnownWindowsMSVCEnvironment() || T.isWindowsItaniumEnvironment()) {
1488 // If the priority is the default, use .CRT$XCU, possibly associative.
1489 if (Priority == 65535)
1490 return Ctx.getAssociativeCOFFSection(Default, KeySym, 0);
1492 // Otherwise, we need to compute a new section name. Low priorities should
1493 // run earlier. The linker will sort sections ASCII-betically, and we need a
1494 // string that sorts between .CRT$XCA and .CRT$XCU. In the general case, we
1495 // make a name like ".CRT$XCT12345", since that runs before .CRT$XCU. Really
1496 // low priorities need to sort before 'L', since the CRT uses that
1497 // internally, so we use ".CRT$XCA00001" for them.
1498 SmallString<24> Name;
1499 raw_svector_ostream OS(Name);
1500 OS << ".CRT$XC" << (Priority < 200 ? 'A' : 'T') << format("%05u", Priority);
1501 MCSectionCOFF *Sec = Ctx.getCOFFSection(
1502 Name, COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | COFF::IMAGE_SCN_MEM_READ,
1503 SectionKind::getReadOnly());
1504 return Ctx.getAssociativeCOFFSection(Sec, KeySym, 0);
1507 std::string Name = IsCtor ? ".ctors" : ".dtors";
1508 if (Priority != 65535)
1509 raw_string_ostream(Name) << format(".%05u", 65535 - Priority);
1511 return Ctx.getAssociativeCOFFSection(
1512 Ctx.getCOFFSection(Name, COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
1513 COFF::IMAGE_SCN_MEM_READ |
1514 COFF::IMAGE_SCN_MEM_WRITE,
1515 SectionKind::getData()),
1519 MCSection *TargetLoweringObjectFileCOFF::getStaticCtorSection(
1520 unsigned Priority, const MCSymbol *KeySym) const {
1521 return getCOFFStaticStructorSection(getContext(), getTargetTriple(), true,
1523 cast<MCSectionCOFF>(StaticCtorSection));
1526 MCSection *TargetLoweringObjectFileCOFF::getStaticDtorSection(
1527 unsigned Priority, const MCSymbol *KeySym) const {
1528 return getCOFFStaticStructorSection(getContext(), getTargetTriple(), false,
1530 cast<MCSectionCOFF>(StaticDtorSection));
1533 void TargetLoweringObjectFileCOFF::emitLinkerFlagsForGlobal(
1534 raw_ostream &OS, const GlobalValue *GV) const {
1535 emitLinkerFlagsForGlobalCOFF(OS, GV, getTargetTriple(), getMangler());
1538 void TargetLoweringObjectFileCOFF::emitLinkerFlagsForUsed(
1539 raw_ostream &OS, const GlobalValue *GV) const {
1540 emitLinkerFlagsForUsedCOFF(OS, GV, getTargetTriple(), getMangler());
1543 const MCExpr *TargetLoweringObjectFileCOFF::lowerRelativeReference(
1544 const GlobalValue *LHS, const GlobalValue *RHS,
1545 const TargetMachine &TM) const {
1546 const Triple &T = TM.getTargetTriple();
1547 if (!T.isKnownWindowsMSVCEnvironment() &&
1548 !T.isWindowsItaniumEnvironment() &&
1549 !T.isWindowsCoreCLREnvironment())
1552 // Our symbols should exist in address space zero, cowardly no-op if
1554 if (LHS->getType()->getPointerAddressSpace() != 0 ||
1555 RHS->getType()->getPointerAddressSpace() != 0)
1558 // Both ptrtoint instructions must wrap global objects:
1559 // - Only global variables are eligible for image relative relocations.
1560 // - The subtrahend refers to the special symbol __ImageBase, a GlobalVariable.
1561 // We expect __ImageBase to be a global variable without a section, externally
1564 // It should look something like this: @__ImageBase = external constant i8
1565 if (!isa<GlobalObject>(LHS) || !isa<GlobalVariable>(RHS) ||
1566 LHS->isThreadLocal() || RHS->isThreadLocal() ||
1567 RHS->getName() != "__ImageBase" || !RHS->hasExternalLinkage() ||
1568 cast<GlobalVariable>(RHS)->hasInitializer() || RHS->hasSection())
1571 return MCSymbolRefExpr::create(TM.getSymbol(LHS),
1572 MCSymbolRefExpr::VK_COFF_IMGREL32,
1576 static std::string APIntToHexString(const APInt &AI) {
1577 unsigned Width = (AI.getBitWidth() / 8) * 2;
1578 std::string HexString = utohexstr(AI.getLimitedValue(), /*LowerCase=*/true);
1579 unsigned Size = HexString.size();
1580 assert(Width >= Size && "hex string is too large!");
1581 HexString.insert(HexString.begin(), Width - Size, '0');
1586 static std::string scalarConstantToHexString(const Constant *C) {
1587 Type *Ty = C->getType();
1588 if (isa<UndefValue>(C)) {
1589 return APIntToHexString(APInt::getNullValue(Ty->getPrimitiveSizeInBits()));
1590 } else if (const auto *CFP = dyn_cast<ConstantFP>(C)) {
1591 return APIntToHexString(CFP->getValueAPF().bitcastToAPInt());
1592 } else if (const auto *CI = dyn_cast<ConstantInt>(C)) {
1593 return APIntToHexString(CI->getValue());
1595 unsigned NumElements;
1596 if (isa<VectorType>(Ty))
1597 NumElements = Ty->getVectorNumElements();
1599 NumElements = Ty->getArrayNumElements();
1600 std::string HexString;
1601 for (int I = NumElements - 1, E = -1; I != E; --I)
1602 HexString += scalarConstantToHexString(C->getAggregateElement(I));
1607 MCSection *TargetLoweringObjectFileCOFF::getSectionForConstant(
1608 const DataLayout &DL, SectionKind Kind, const Constant *C,
1609 unsigned &Align) const {
1610 if (Kind.isMergeableConst() && C &&
1611 getContext().getAsmInfo()->hasCOFFComdatConstants()) {
1612 // This creates comdat sections with the given symbol name, but unless
1613 // AsmPrinter::GetCPISymbol actually makes the symbol global, the symbol
1614 // will be created with a null storage class, which makes GNU binutils
1616 const unsigned Characteristics = COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
1617 COFF::IMAGE_SCN_MEM_READ |
1618 COFF::IMAGE_SCN_LNK_COMDAT;
1619 std::string COMDATSymName;
1620 if (Kind.isMergeableConst4()) {
1622 COMDATSymName = "__real@" + scalarConstantToHexString(C);
1625 } else if (Kind.isMergeableConst8()) {
1627 COMDATSymName = "__real@" + scalarConstantToHexString(C);
1630 } else if (Kind.isMergeableConst16()) {
1631 // FIXME: These may not be appropriate for non-x86 architectures.
1633 COMDATSymName = "__xmm@" + scalarConstantToHexString(C);
1636 } else if (Kind.isMergeableConst32()) {
1638 COMDATSymName = "__ymm@" + scalarConstantToHexString(C);
1643 if (!COMDATSymName.empty())
1644 return getContext().getCOFFSection(".rdata", Characteristics, Kind,
1646 COFF::IMAGE_COMDAT_SELECT_ANY);
1649 return TargetLoweringObjectFile::getSectionForConstant(DL, Kind, C, Align);
1653 //===----------------------------------------------------------------------===//
1655 //===----------------------------------------------------------------------===//
1657 static const Comdat *getWasmComdat(const GlobalValue *GV) {
1658 const Comdat *C = GV->getComdat();
1662 if (C->getSelectionKind() != Comdat::Any)
1663 report_fatal_error("WebAssembly COMDATs only support "
1664 "SelectionKind::Any, '" + C->getName() + "' cannot be "
1670 static SectionKind getWasmKindForNamedSection(StringRef Name, SectionKind K) {
1671 // If we're told we have function data, then use that.
1673 return SectionKind::getText();
1675 // Otherwise, ignore whatever section type the generic impl detected and use
1676 // a plain data section.
1677 return SectionKind::getData();
1680 MCSection *TargetLoweringObjectFileWasm::getExplicitSectionGlobal(
1681 const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const {
1682 // We don't support explict section names for functions in the wasm object
1683 // format. Each function has to be in its own unique section.
1684 if (isa<Function>(GO)) {
1685 return SelectSectionForGlobal(GO, Kind, TM);
1688 StringRef Name = GO->getSection();
1690 Kind = getWasmKindForNamedSection(Name, Kind);
1692 StringRef Group = "";
1693 if (const Comdat *C = getWasmComdat(GO)) {
1694 Group = C->getName();
1697 return getContext().getWasmSection(Name, Kind, Group,
1698 MCContext::GenericSectionID);
1701 static MCSectionWasm *selectWasmSectionForGlobal(
1702 MCContext &Ctx, const GlobalObject *GO, SectionKind Kind, Mangler &Mang,
1703 const TargetMachine &TM, bool EmitUniqueSection, unsigned *NextUniqueID) {
1704 StringRef Group = "";
1705 if (const Comdat *C = getWasmComdat(GO)) {
1706 Group = C->getName();
1709 bool UniqueSectionNames = TM.getUniqueSectionNames();
1710 SmallString<128> Name = getSectionPrefixForGlobal(Kind);
1712 if (const auto *F = dyn_cast<Function>(GO)) {
1713 const auto &OptionalPrefix = F->getSectionPrefix();
1715 Name += *OptionalPrefix;
1718 if (EmitUniqueSection && UniqueSectionNames) {
1719 Name.push_back('.');
1720 TM.getNameWithPrefix(Name, GO, Mang, true);
1722 unsigned UniqueID = MCContext::GenericSectionID;
1723 if (EmitUniqueSection && !UniqueSectionNames) {
1724 UniqueID = *NextUniqueID;
1727 return Ctx.getWasmSection(Name, Kind, Group, UniqueID);
1730 MCSection *TargetLoweringObjectFileWasm::SelectSectionForGlobal(
1731 const GlobalObject *GO, SectionKind Kind, const TargetMachine &TM) const {
1733 if (Kind.isCommon())
1734 report_fatal_error("mergable sections not supported yet on wasm");
1736 // If we have -ffunction-section or -fdata-section then we should emit the
1737 // global value to a uniqued section specifically for it.
1738 bool EmitUniqueSection = false;
1740 EmitUniqueSection = TM.getFunctionSections();
1742 EmitUniqueSection = TM.getDataSections();
1743 EmitUniqueSection |= GO->hasComdat();
1745 return selectWasmSectionForGlobal(getContext(), GO, Kind, getMangler(), TM,
1746 EmitUniqueSection, &NextUniqueID);
1749 bool TargetLoweringObjectFileWasm::shouldPutJumpTableInFunctionSection(
1750 bool UsesLabelDifference, const Function &F) const {
1751 // We can always create relative relocations, so use another section
1752 // that can be marked non-executable.
1756 const MCExpr *TargetLoweringObjectFileWasm::lowerRelativeReference(
1757 const GlobalValue *LHS, const GlobalValue *RHS,
1758 const TargetMachine &TM) const {
1759 // We may only use a PLT-relative relocation to refer to unnamed_addr
1761 if (!LHS->hasGlobalUnnamedAddr() || !LHS->getValueType()->isFunctionTy())
1764 // Basic sanity checks.
1765 if (LHS->getType()->getPointerAddressSpace() != 0 ||
1766 RHS->getType()->getPointerAddressSpace() != 0 || LHS->isThreadLocal() ||
1767 RHS->isThreadLocal())
1770 return MCBinaryExpr::createSub(
1771 MCSymbolRefExpr::create(TM.getSymbol(LHS), MCSymbolRefExpr::VK_None,
1773 MCSymbolRefExpr::create(TM.getSymbol(RHS), getContext()), getContext());
1776 void TargetLoweringObjectFileWasm::InitializeWasm() {
1778 getContext().getWasmSection(".init_array", SectionKind::getData());
1780 // We don't use PersonalityEncoding and LSDAEncoding because we don't emit
1781 // .cfi directives. We use TTypeEncoding to encode typeinfo global variables.
1782 TTypeEncoding = dwarf::DW_EH_PE_absptr;
1785 MCSection *TargetLoweringObjectFileWasm::getStaticCtorSection(
1786 unsigned Priority, const MCSymbol *KeySym) const {
1787 return Priority == UINT16_MAX ?
1789 getContext().getWasmSection(".init_array." + utostr(Priority),
1790 SectionKind::getData());
1793 MCSection *TargetLoweringObjectFileWasm::getStaticDtorSection(
1794 unsigned Priority, const MCSymbol *KeySym) const {
1795 llvm_unreachable("@llvm.global_dtors should have been lowered already");