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/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/Support/Dwarf.h"
35 #include "llvm/Support/ELF.h"
36 #include "llvm/Support/ErrorHandling.h"
37 #include "llvm/Support/raw_ostream.h"
38 #include "llvm/Target/TargetLowering.h"
39 #include "llvm/Target/TargetMachine.h"
40 #include "llvm/Target/TargetSubtargetInfo.h"
42 using namespace dwarf;
44 //===----------------------------------------------------------------------===//
46 //===----------------------------------------------------------------------===//
48 MCSymbol *TargetLoweringObjectFileELF::getCFIPersonalitySymbol(
49 const GlobalValue *GV, Mangler &Mang, const TargetMachine &TM,
50 MachineModuleInfo *MMI) const {
51 unsigned Encoding = getPersonalityEncoding();
52 if ((Encoding & 0x80) == dwarf::DW_EH_PE_indirect)
53 return getContext().GetOrCreateSymbol(StringRef("DW.ref.") +
54 TM.getSymbol(GV, Mang)->getName());
55 if ((Encoding & 0x70) == dwarf::DW_EH_PE_absptr)
56 return TM.getSymbol(GV, Mang);
57 report_fatal_error("We do not support this DWARF encoding yet!");
60 void TargetLoweringObjectFileELF::emitPersonalityValue(MCStreamer &Streamer,
61 const TargetMachine &TM,
62 const MCSymbol *Sym) const {
63 SmallString<64> NameData("DW.ref.");
64 NameData += Sym->getName();
65 MCSymbol *Label = getContext().GetOrCreateSymbol(NameData);
66 Streamer.EmitSymbolAttribute(Label, MCSA_Hidden);
67 Streamer.EmitSymbolAttribute(Label, MCSA_Weak);
68 StringRef Prefix = ".data.";
69 NameData.insert(NameData.begin(), Prefix.begin(), Prefix.end());
70 unsigned Flags = ELF::SHF_ALLOC | ELF::SHF_WRITE | ELF::SHF_GROUP;
71 const MCSection *Sec = getContext().getELFSection(NameData,
74 SectionKind::getDataRel(),
76 unsigned Size = TM.getSubtargetImpl()->getDataLayout()->getPointerSize();
77 Streamer.SwitchSection(Sec);
78 Streamer.EmitValueToAlignment(
79 TM.getSubtargetImpl()->getDataLayout()->getPointerABIAlignment());
80 Streamer.EmitSymbolAttribute(Label, MCSA_ELF_TypeObject);
81 const MCExpr *E = MCConstantExpr::Create(Size, getContext());
82 Streamer.EmitELFSize(Label, E);
83 Streamer.EmitLabel(Label);
85 Streamer.EmitSymbolValue(Sym, Size);
88 const MCExpr *TargetLoweringObjectFileELF::getTTypeGlobalReference(
89 const GlobalValue *GV, unsigned Encoding, Mangler &Mang,
90 const TargetMachine &TM, MachineModuleInfo *MMI,
91 MCStreamer &Streamer) const {
93 if (Encoding & dwarf::DW_EH_PE_indirect) {
94 MachineModuleInfoELF &ELFMMI = MMI->getObjFileInfo<MachineModuleInfoELF>();
96 MCSymbol *SSym = getSymbolWithGlobalValueBase(GV, ".DW.stub", Mang, TM);
98 // Add information about the stub reference to ELFMMI so that the stub
99 // gets emitted by the asmprinter.
100 MachineModuleInfoImpl::StubValueTy &StubSym = ELFMMI.getGVStubEntry(SSym);
101 if (!StubSym.getPointer()) {
102 MCSymbol *Sym = TM.getSymbol(GV, Mang);
103 StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage());
106 return TargetLoweringObjectFile::
107 getTTypeReference(MCSymbolRefExpr::Create(SSym, getContext()),
108 Encoding & ~dwarf::DW_EH_PE_indirect, Streamer);
111 return TargetLoweringObjectFile::
112 getTTypeGlobalReference(GV, Encoding, Mang, TM, MMI, Streamer);
116 getELFKindForNamedSection(StringRef Name, SectionKind K) {
117 // N.B.: The defaults used in here are no the same ones used in MC.
118 // We follow gcc, MC follows gas. For example, given ".section .eh_frame",
119 // both gas and MC will produce a section with no flags. Given
120 // section(".eh_frame") gcc will produce:
122 // .section .eh_frame,"a",@progbits
123 if (Name.empty() || Name[0] != '.') return K;
125 // Some lame default implementation based on some magic section names.
126 if (Name == ".bss" ||
127 Name.startswith(".bss.") ||
128 Name.startswith(".gnu.linkonce.b.") ||
129 Name.startswith(".llvm.linkonce.b.") ||
131 Name.startswith(".sbss.") ||
132 Name.startswith(".gnu.linkonce.sb.") ||
133 Name.startswith(".llvm.linkonce.sb."))
134 return SectionKind::getBSS();
136 if (Name == ".tdata" ||
137 Name.startswith(".tdata.") ||
138 Name.startswith(".gnu.linkonce.td.") ||
139 Name.startswith(".llvm.linkonce.td."))
140 return SectionKind::getThreadData();
142 if (Name == ".tbss" ||
143 Name.startswith(".tbss.") ||
144 Name.startswith(".gnu.linkonce.tb.") ||
145 Name.startswith(".llvm.linkonce.tb."))
146 return SectionKind::getThreadBSS();
152 static unsigned getELFSectionType(StringRef Name, SectionKind K) {
154 if (Name == ".init_array")
155 return ELF::SHT_INIT_ARRAY;
157 if (Name == ".fini_array")
158 return ELF::SHT_FINI_ARRAY;
160 if (Name == ".preinit_array")
161 return ELF::SHT_PREINIT_ARRAY;
163 if (K.isBSS() || K.isThreadBSS())
164 return ELF::SHT_NOBITS;
166 return ELF::SHT_PROGBITS;
171 getELFSectionFlags(SectionKind K) {
175 Flags |= ELF::SHF_ALLOC;
178 Flags |= ELF::SHF_EXECINSTR;
181 Flags |= ELF::SHF_WRITE;
183 if (K.isThreadLocal())
184 Flags |= ELF::SHF_TLS;
186 // K.isMergeableConst() is left out to honour PR4650
187 if (K.isMergeableCString() || K.isMergeableConst4() ||
188 K.isMergeableConst8() || K.isMergeableConst16())
189 Flags |= ELF::SHF_MERGE;
191 if (K.isMergeableCString())
192 Flags |= ELF::SHF_STRINGS;
197 static const Comdat *getELFComdat(const GlobalValue *GV) {
198 const Comdat *C = GV->getComdat();
202 if (C->getSelectionKind() != Comdat::Any)
203 report_fatal_error("ELF COMDATs only support SelectionKind::Any, '" +
204 C->getName() + "' cannot be lowered.");
209 const MCSection *TargetLoweringObjectFileELF::getExplicitSectionGlobal(
210 const GlobalValue *GV, SectionKind Kind, Mangler &Mang,
211 const TargetMachine &TM) const {
212 StringRef SectionName = GV->getSection();
214 // Infer section flags from the section name if we can.
215 Kind = getELFKindForNamedSection(SectionName, Kind);
217 StringRef Group = "";
218 unsigned Flags = getELFSectionFlags(Kind);
219 if (const Comdat *C = getELFComdat(GV)) {
220 Group = C->getName();
221 Flags |= ELF::SHF_GROUP;
223 return getContext().getELFSection(SectionName,
224 getELFSectionType(SectionName, Kind), Flags,
225 Kind, /*EntrySize=*/0, Group);
228 /// getSectionPrefixForGlobal - Return the section prefix name used by options
229 /// FunctionsSections and DataSections.
230 static StringRef getSectionPrefixForGlobal(SectionKind Kind) {
231 if (Kind.isText()) return ".text.";
232 if (Kind.isReadOnly()) return ".rodata.";
233 if (Kind.isBSS()) return ".bss.";
235 if (Kind.isThreadData()) return ".tdata.";
236 if (Kind.isThreadBSS()) return ".tbss.";
238 if (Kind.isDataNoRel()) return ".data.";
239 if (Kind.isDataRelLocal()) return ".data.rel.local.";
240 if (Kind.isDataRel()) return ".data.rel.";
241 if (Kind.isReadOnlyWithRelLocal()) return ".data.rel.ro.local.";
243 assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
244 return ".data.rel.ro.";
247 const MCSection *TargetLoweringObjectFileELF::
248 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
249 Mangler &Mang, const TargetMachine &TM) const {
250 // If we have -ffunction-section or -fdata-section then we should emit the
251 // global value to a uniqued section specifically for it.
252 bool EmitUniquedSection;
254 EmitUniquedSection = TM.getFunctionSections();
256 EmitUniquedSection = TM.getDataSections();
258 // If this global is linkonce/weak and the target handles this by emitting it
259 // into a 'uniqued' section name, create and return the section now.
260 if ((GV->isWeakForLinker() || EmitUniquedSection || GV->hasComdat()) &&
262 StringRef Prefix = getSectionPrefixForGlobal(Kind);
264 SmallString<128> Name(Prefix);
265 TM.getNameWithPrefix(Name, GV, Mang, true);
267 StringRef Group = "";
268 unsigned Flags = getELFSectionFlags(Kind);
269 if (GV->isWeakForLinker() || GV->hasComdat()) {
270 if (const Comdat *C = getELFComdat(GV))
271 Group = C->getName();
273 Group = Name.substr(Prefix.size());
274 Flags |= ELF::SHF_GROUP;
277 return getContext().getELFSection(Name.str(),
278 getELFSectionType(Name.str(), Kind),
279 Flags, Kind, 0, Group);
282 if (Kind.isText()) return TextSection;
284 if (Kind.isMergeable1ByteCString() ||
285 Kind.isMergeable2ByteCString() ||
286 Kind.isMergeable4ByteCString()) {
288 // We also need alignment here.
289 // FIXME: this is getting the alignment of the character, not the
290 // alignment of the global!
292 TM.getSubtargetImpl()->getDataLayout()->getPreferredAlignment(
293 cast<GlobalVariable>(GV));
295 const char *SizeSpec = ".rodata.str1.";
296 if (Kind.isMergeable2ByteCString())
297 SizeSpec = ".rodata.str2.";
298 else if (Kind.isMergeable4ByteCString())
299 SizeSpec = ".rodata.str4.";
301 assert(Kind.isMergeable1ByteCString() && "unknown string width");
304 std::string Name = SizeSpec + utostr(Align);
305 return getContext().getELFSection(Name, ELF::SHT_PROGBITS,
312 if (Kind.isMergeableConst()) {
313 if (Kind.isMergeableConst4() && MergeableConst4Section)
314 return MergeableConst4Section;
315 if (Kind.isMergeableConst8() && MergeableConst8Section)
316 return MergeableConst8Section;
317 if (Kind.isMergeableConst16() && MergeableConst16Section)
318 return MergeableConst16Section;
319 return ReadOnlySection; // .const
322 if (Kind.isReadOnly()) return ReadOnlySection;
324 if (Kind.isThreadData()) return TLSDataSection;
325 if (Kind.isThreadBSS()) return TLSBSSSection;
327 // Note: we claim that common symbols are put in BSSSection, but they are
328 // really emitted with the magic .comm directive, which creates a symbol table
329 // entry but not a section.
330 if (Kind.isBSS() || Kind.isCommon()) return BSSSection;
332 if (Kind.isDataNoRel()) return DataSection;
333 if (Kind.isDataRelLocal()) return DataRelLocalSection;
334 if (Kind.isDataRel()) return DataRelSection;
335 if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection;
337 assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
338 return DataRelROSection;
341 /// getSectionForConstant - Given a mergeable constant with the
342 /// specified size and relocation information, return a section that it
343 /// should be placed in.
345 TargetLoweringObjectFileELF::getSectionForConstant(SectionKind Kind,
346 const Constant *C) const {
347 if (Kind.isMergeableConst4() && MergeableConst4Section)
348 return MergeableConst4Section;
349 if (Kind.isMergeableConst8() && MergeableConst8Section)
350 return MergeableConst8Section;
351 if (Kind.isMergeableConst16() && MergeableConst16Section)
352 return MergeableConst16Section;
353 if (Kind.isReadOnly())
354 return ReadOnlySection;
356 if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection;
357 assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
358 return DataRelROSection;
361 static const MCSectionELF *getStaticStructorSection(MCContext &Ctx,
365 const MCSymbol *KeySym) {
368 unsigned Flags = ELF::SHF_ALLOC | ELF::SHF_WRITE;
369 SectionKind Kind = SectionKind::getDataRel();
370 StringRef COMDAT = KeySym ? KeySym->getName() : "";
373 Flags |= ELF::SHF_GROUP;
377 Type = ELF::SHT_INIT_ARRAY;
378 Name = ".init_array";
380 Type = ELF::SHT_FINI_ARRAY;
381 Name = ".fini_array";
383 if (Priority != 65535) {
385 Name += utostr(Priority);
388 // The default scheme is .ctor / .dtor, so we have to invert the priority
394 if (Priority != 65535) {
396 Name += utostr(65535 - Priority);
398 Type = ELF::SHT_PROGBITS;
401 return Ctx.getELFSection(Name, Type, Flags, Kind, 0, COMDAT);
404 const MCSection *TargetLoweringObjectFileELF::getStaticCtorSection(
405 unsigned Priority, const MCSymbol *KeySym) const {
406 return getStaticStructorSection(getContext(), UseInitArray, true, Priority,
410 const MCSection *TargetLoweringObjectFileELF::getStaticDtorSection(
411 unsigned Priority, const MCSymbol *KeySym) const {
412 return getStaticStructorSection(getContext(), UseInitArray, false, Priority,
417 TargetLoweringObjectFileELF::InitializeELF(bool UseInitArray_) {
418 UseInitArray = UseInitArray_;
423 getContext().getELFSection(".init_array", ELF::SHT_INIT_ARRAY,
426 SectionKind::getDataRel());
428 getContext().getELFSection(".fini_array", ELF::SHT_FINI_ARRAY,
431 SectionKind::getDataRel());
434 //===----------------------------------------------------------------------===//
436 //===----------------------------------------------------------------------===//
438 /// getDepLibFromLinkerOpt - Extract the dependent library name from a linker
439 /// option string. Returns StringRef() if the option does not specify a library.
440 StringRef TargetLoweringObjectFileMachO::
441 getDepLibFromLinkerOpt(StringRef LinkerOption) const {
442 const char *LibCmd = "-l";
443 if (LinkerOption.startswith(LibCmd))
444 return LinkerOption.substr(strlen(LibCmd));
448 /// emitModuleFlags - Perform code emission for module flags.
449 void TargetLoweringObjectFileMachO::
450 emitModuleFlags(MCStreamer &Streamer,
451 ArrayRef<Module::ModuleFlagEntry> ModuleFlags,
452 Mangler &Mang, const TargetMachine &TM) const {
453 unsigned VersionVal = 0;
454 unsigned ImageInfoFlags = 0;
455 MDNode *LinkerOptions = nullptr;
456 StringRef SectionVal;
458 for (ArrayRef<Module::ModuleFlagEntry>::iterator
459 i = ModuleFlags.begin(), e = ModuleFlags.end(); i != e; ++i) {
460 const Module::ModuleFlagEntry &MFE = *i;
462 // Ignore flags with 'Require' behavior.
463 if (MFE.Behavior == Module::Require)
466 StringRef Key = MFE.Key->getString();
467 Value *Val = MFE.Val;
469 if (Key == "Objective-C Image Info Version") {
470 VersionVal = cast<ConstantInt>(Val)->getZExtValue();
471 } else if (Key == "Objective-C Garbage Collection" ||
472 Key == "Objective-C GC Only" ||
473 Key == "Objective-C Is Simulated") {
474 ImageInfoFlags |= cast<ConstantInt>(Val)->getZExtValue();
475 } else if (Key == "Objective-C Image Info Section") {
476 SectionVal = cast<MDString>(Val)->getString();
477 } else if (Key == "Linker Options") {
478 LinkerOptions = cast<MDNode>(Val);
482 // Emit the linker options if present.
484 for (unsigned i = 0, e = LinkerOptions->getNumOperands(); i != e; ++i) {
485 MDNode *MDOptions = cast<MDNode>(LinkerOptions->getOperand(i));
486 SmallVector<std::string, 4> StrOptions;
488 // Convert to strings.
489 for (unsigned ii = 0, ie = MDOptions->getNumOperands(); ii != ie; ++ii) {
490 MDString *MDOption = cast<MDString>(MDOptions->getOperand(ii));
491 StrOptions.push_back(MDOption->getString());
494 Streamer.EmitLinkerOptions(StrOptions);
498 // The section is mandatory. If we don't have it, then we don't have GC info.
499 if (SectionVal.empty()) return;
501 StringRef Segment, Section;
502 unsigned TAA = 0, StubSize = 0;
504 std::string ErrorCode =
505 MCSectionMachO::ParseSectionSpecifier(SectionVal, Segment, Section,
506 TAA, TAAParsed, StubSize);
507 if (!ErrorCode.empty())
508 // If invalid, report the error with report_fatal_error.
509 report_fatal_error("Invalid section specifier '" + Section + "': " +
513 const MCSectionMachO *S =
514 getContext().getMachOSection(Segment, Section, TAA, StubSize,
515 SectionKind::getDataNoRel());
516 Streamer.SwitchSection(S);
517 Streamer.EmitLabel(getContext().
518 GetOrCreateSymbol(StringRef("L_OBJC_IMAGE_INFO")));
519 Streamer.EmitIntValue(VersionVal, 4);
520 Streamer.EmitIntValue(ImageInfoFlags, 4);
521 Streamer.AddBlankLine();
524 static void checkMachOComdat(const GlobalValue *GV) {
525 const Comdat *C = GV->getComdat();
529 report_fatal_error("MachO doesn't support COMDATs, '" + C->getName() +
530 "' cannot be lowered.");
533 const MCSection *TargetLoweringObjectFileMachO::getExplicitSectionGlobal(
534 const GlobalValue *GV, SectionKind Kind, Mangler &Mang,
535 const TargetMachine &TM) const {
536 // Parse the section specifier and create it if valid.
537 StringRef Segment, Section;
538 unsigned TAA = 0, StubSize = 0;
541 checkMachOComdat(GV);
543 std::string ErrorCode =
544 MCSectionMachO::ParseSectionSpecifier(GV->getSection(), Segment, Section,
545 TAA, TAAParsed, StubSize);
546 if (!ErrorCode.empty()) {
547 // If invalid, report the error with report_fatal_error.
548 report_fatal_error("Global variable '" + GV->getName() +
549 "' has an invalid section specifier '" +
550 GV->getSection() + "': " + ErrorCode + ".");
554 const MCSectionMachO *S =
555 getContext().getMachOSection(Segment, Section, TAA, StubSize, Kind);
557 // If TAA wasn't set by ParseSectionSpecifier() above,
558 // use the value returned by getMachOSection() as a default.
560 TAA = S->getTypeAndAttributes();
562 // Okay, now that we got the section, verify that the TAA & StubSize agree.
563 // If the user declared multiple globals with different section flags, we need
564 // to reject it here.
565 if (S->getTypeAndAttributes() != TAA || S->getStubSize() != StubSize) {
566 // If invalid, report the error with report_fatal_error.
567 report_fatal_error("Global variable '" + GV->getName() +
568 "' section type or attributes does not match previous"
569 " section specifier");
575 bool TargetLoweringObjectFileMachO::isSectionAtomizableBySymbols(
576 const MCSection &Section) const {
577 const MCSectionMachO &SMO = static_cast<const MCSectionMachO&>(Section);
579 // Sections holding 1 byte strings are atomized based on the data
581 // Sections holding 2 byte strings require symbols in order to be
583 // There is no dedicated section for 4 byte strings.
584 if (SMO.getKind().isMergeable1ByteCString())
587 if (SMO.getSegmentName() == "__DATA" &&
588 SMO.getSectionName() == "__cfstring")
591 switch (SMO.getType()) {
595 // These sections are atomized at the element boundaries without using
597 case MachO::S_4BYTE_LITERALS:
598 case MachO::S_8BYTE_LITERALS:
599 case MachO::S_16BYTE_LITERALS:
600 case MachO::S_LITERAL_POINTERS:
601 case MachO::S_NON_LAZY_SYMBOL_POINTERS:
602 case MachO::S_LAZY_SYMBOL_POINTERS:
603 case MachO::S_MOD_INIT_FUNC_POINTERS:
604 case MachO::S_MOD_TERM_FUNC_POINTERS:
605 case MachO::S_INTERPOSING:
610 const MCSection *TargetLoweringObjectFileMachO::
611 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
612 Mangler &Mang, const TargetMachine &TM) const {
613 checkMachOComdat(GV);
615 // Handle thread local data.
616 if (Kind.isThreadBSS()) return TLSBSSSection;
617 if (Kind.isThreadData()) return TLSDataSection;
620 return GV->isWeakForLinker() ? TextCoalSection : TextSection;
622 // If this is weak/linkonce, put this in a coalescable section, either in text
623 // or data depending on if it is writable.
624 if (GV->isWeakForLinker()) {
625 if (Kind.isReadOnly())
626 return ConstTextCoalSection;
627 return DataCoalSection;
630 // FIXME: Alignment check should be handled by section classifier.
631 if (Kind.isMergeable1ByteCString() &&
632 TM.getSubtargetImpl()->getDataLayout()->getPreferredAlignment(
633 cast<GlobalVariable>(GV)) < 32)
634 return CStringSection;
636 // Do not put 16-bit arrays in the UString section if they have an
637 // externally visible label, this runs into issues with certain linker
639 if (Kind.isMergeable2ByteCString() && !GV->hasExternalLinkage() &&
640 TM.getSubtargetImpl()->getDataLayout()->getPreferredAlignment(
641 cast<GlobalVariable>(GV)) < 32)
642 return UStringSection;
644 // With MachO only variables whose corresponding symbol starts with 'l' or
645 // 'L' can be merged, so we only try merging GVs with private linkage.
646 if (GV->hasPrivateLinkage() && Kind.isMergeableConst()) {
647 if (Kind.isMergeableConst4())
648 return FourByteConstantSection;
649 if (Kind.isMergeableConst8())
650 return EightByteConstantSection;
651 if (Kind.isMergeableConst16())
652 return SixteenByteConstantSection;
655 // Otherwise, if it is readonly, but not something we can specially optimize,
656 // just drop it in .const.
657 if (Kind.isReadOnly())
658 return ReadOnlySection;
660 // If this is marked const, put it into a const section. But if the dynamic
661 // linker needs to write to it, put it in the data segment.
662 if (Kind.isReadOnlyWithRel())
663 return ConstDataSection;
665 // Put zero initialized globals with strong external linkage in the
666 // DATA, __common section with the .zerofill directive.
667 if (Kind.isBSSExtern())
668 return DataCommonSection;
670 // Put zero initialized globals with local linkage in __DATA,__bss directive
671 // with the .zerofill directive (aka .lcomm).
672 if (Kind.isBSSLocal())
673 return DataBSSSection;
675 // Otherwise, just drop the variable in the normal data section.
680 TargetLoweringObjectFileMachO::getSectionForConstant(SectionKind Kind,
681 const Constant *C) const {
682 // If this constant requires a relocation, we have to put it in the data
683 // segment, not in the text segment.
684 if (Kind.isDataRel() || Kind.isReadOnlyWithRel())
685 return ConstDataSection;
687 if (Kind.isMergeableConst4())
688 return FourByteConstantSection;
689 if (Kind.isMergeableConst8())
690 return EightByteConstantSection;
691 if (Kind.isMergeableConst16())
692 return SixteenByteConstantSection;
693 return ReadOnlySection; // .const
696 const MCExpr *TargetLoweringObjectFileMachO::getTTypeGlobalReference(
697 const GlobalValue *GV, unsigned Encoding, Mangler &Mang,
698 const TargetMachine &TM, MachineModuleInfo *MMI,
699 MCStreamer &Streamer) const {
700 // The mach-o version of this method defaults to returning a stub reference.
702 if (Encoding & DW_EH_PE_indirect) {
703 MachineModuleInfoMachO &MachOMMI =
704 MMI->getObjFileInfo<MachineModuleInfoMachO>();
707 getSymbolWithGlobalValueBase(GV, "$non_lazy_ptr", Mang, TM);
709 // Add information about the stub reference to MachOMMI so that the stub
710 // gets emitted by the asmprinter.
711 MachineModuleInfoImpl::StubValueTy &StubSym =
712 GV->hasHiddenVisibility() ? MachOMMI.getHiddenGVStubEntry(SSym) :
713 MachOMMI.getGVStubEntry(SSym);
714 if (!StubSym.getPointer()) {
715 MCSymbol *Sym = TM.getSymbol(GV, Mang);
716 StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage());
719 return TargetLoweringObjectFile::
720 getTTypeReference(MCSymbolRefExpr::Create(SSym, getContext()),
721 Encoding & ~dwarf::DW_EH_PE_indirect, Streamer);
724 return TargetLoweringObjectFile::getTTypeGlobalReference(GV, Encoding, Mang,
728 MCSymbol *TargetLoweringObjectFileMachO::getCFIPersonalitySymbol(
729 const GlobalValue *GV, Mangler &Mang, const TargetMachine &TM,
730 MachineModuleInfo *MMI) const {
731 // The mach-o version of this method defaults to returning a stub reference.
732 MachineModuleInfoMachO &MachOMMI =
733 MMI->getObjFileInfo<MachineModuleInfoMachO>();
735 MCSymbol *SSym = getSymbolWithGlobalValueBase(GV, "$non_lazy_ptr", Mang, TM);
737 // Add information about the stub reference to MachOMMI so that the stub
738 // gets emitted by the asmprinter.
739 MachineModuleInfoImpl::StubValueTy &StubSym = MachOMMI.getGVStubEntry(SSym);
740 if (!StubSym.getPointer()) {
741 MCSymbol *Sym = TM.getSymbol(GV, Mang);
742 StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage());
748 //===----------------------------------------------------------------------===//
750 //===----------------------------------------------------------------------===//
753 getCOFFSectionFlags(SectionKind K) {
758 COFF::IMAGE_SCN_MEM_DISCARDABLE;
761 COFF::IMAGE_SCN_MEM_EXECUTE |
762 COFF::IMAGE_SCN_MEM_READ |
763 COFF::IMAGE_SCN_CNT_CODE;
766 COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA |
767 COFF::IMAGE_SCN_MEM_READ |
768 COFF::IMAGE_SCN_MEM_WRITE;
769 else if (K.isThreadLocal())
771 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
772 COFF::IMAGE_SCN_MEM_READ |
773 COFF::IMAGE_SCN_MEM_WRITE;
774 else if (K.isReadOnly())
776 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
777 COFF::IMAGE_SCN_MEM_READ;
778 else if (K.isWriteable())
780 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
781 COFF::IMAGE_SCN_MEM_READ |
782 COFF::IMAGE_SCN_MEM_WRITE;
787 static const GlobalValue *getComdatGVForCOFF(const GlobalValue *GV) {
788 const Comdat *C = GV->getComdat();
789 assert(C && "expected GV to have a Comdat!");
791 StringRef ComdatGVName = C->getName();
792 const GlobalValue *ComdatGV = GV->getParent()->getNamedValue(ComdatGVName);
794 report_fatal_error("Associative COMDAT symbol '" + ComdatGVName +
795 "' does not exist.");
797 if (ComdatGV->getComdat() != C)
798 report_fatal_error("Associative COMDAT symbol '" + ComdatGVName +
799 "' is not a key for its COMDAT.");
804 static int getSelectionForCOFF(const GlobalValue *GV) {
805 if (const Comdat *C = GV->getComdat()) {
806 const GlobalValue *ComdatKey = getComdatGVForCOFF(GV);
807 if (const auto *GA = dyn_cast<GlobalAlias>(ComdatKey))
808 ComdatKey = GA->getBaseObject();
809 if (ComdatKey == GV) {
810 switch (C->getSelectionKind()) {
812 return COFF::IMAGE_COMDAT_SELECT_ANY;
813 case Comdat::ExactMatch:
814 return COFF::IMAGE_COMDAT_SELECT_EXACT_MATCH;
815 case Comdat::Largest:
816 return COFF::IMAGE_COMDAT_SELECT_LARGEST;
817 case Comdat::NoDuplicates:
818 return COFF::IMAGE_COMDAT_SELECT_NODUPLICATES;
819 case Comdat::SameSize:
820 return COFF::IMAGE_COMDAT_SELECT_SAME_SIZE;
823 return COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE;
825 } else if (GV->isWeakForLinker()) {
826 return COFF::IMAGE_COMDAT_SELECT_ANY;
831 const MCSection *TargetLoweringObjectFileCOFF::getExplicitSectionGlobal(
832 const GlobalValue *GV, SectionKind Kind, Mangler &Mang,
833 const TargetMachine &TM) const {
835 unsigned Characteristics = getCOFFSectionFlags(Kind);
836 StringRef Name = GV->getSection();
837 StringRef COMDATSymName = "";
838 if ((GV->isWeakForLinker() || GV->hasComdat()) && !Kind.isCommon()) {
839 Selection = getSelectionForCOFF(GV);
840 const GlobalValue *ComdatGV;
841 if (Selection == COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE)
842 ComdatGV = getComdatGVForCOFF(GV);
846 if (!ComdatGV->hasPrivateLinkage()) {
847 MCSymbol *Sym = TM.getSymbol(ComdatGV, Mang);
848 COMDATSymName = Sym->getName();
849 Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT;
854 return getContext().getCOFFSection(Name,
861 static const char *getCOFFSectionNameForUniqueGlobal(SectionKind Kind) {
866 if (Kind.isThreadLocal())
868 if (Kind.isWriteable())
874 const MCSection *TargetLoweringObjectFileCOFF::
875 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
876 Mangler &Mang, const TargetMachine &TM) const {
877 // If we have -ffunction-sections then we should emit the global value to a
878 // uniqued section specifically for it.
879 bool EmitUniquedSection;
881 EmitUniquedSection = TM.getFunctionSections();
883 EmitUniquedSection = TM.getDataSections();
885 // If this global is linkonce/weak and the target handles this by emitting it
886 // into a 'uniqued' section name, create and return the section now.
887 // Section names depend on the name of the symbol which is not feasible if the
888 // symbol has private linkage.
889 if ((GV->isWeakForLinker() || EmitUniquedSection || GV->hasComdat()) &&
891 const char *Name = getCOFFSectionNameForUniqueGlobal(Kind);
892 unsigned Characteristics = getCOFFSectionFlags(Kind);
894 Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT;
895 int Selection = getSelectionForCOFF(GV);
897 Selection = COFF::IMAGE_COMDAT_SELECT_NODUPLICATES;
898 const GlobalValue *ComdatGV;
900 ComdatGV = getComdatGVForCOFF(GV);
904 if (!ComdatGV->hasPrivateLinkage()) {
905 MCSymbol *Sym = TM.getSymbol(ComdatGV, Mang);
906 StringRef COMDATSymName = Sym->getName();
907 return getContext().getCOFFSection(Name, Characteristics, Kind,
908 COMDATSymName, Selection);
915 if (Kind.isThreadLocal())
916 return TLSDataSection;
918 if (Kind.isReadOnly())
919 return ReadOnlySection;
921 // Note: we claim that common symbols are put in BSSSection, but they are
922 // really emitted with the magic .comm directive, which creates a symbol table
923 // entry but not a section.
924 if (Kind.isBSS() || Kind.isCommon())
930 StringRef TargetLoweringObjectFileCOFF::
931 getDepLibFromLinkerOpt(StringRef LinkerOption) const {
932 const char *LibCmd = "/DEFAULTLIB:";
933 if (LinkerOption.startswith(LibCmd))
934 return LinkerOption.substr(strlen(LibCmd));
938 void TargetLoweringObjectFileCOFF::
939 emitModuleFlags(MCStreamer &Streamer,
940 ArrayRef<Module::ModuleFlagEntry> ModuleFlags,
941 Mangler &Mang, const TargetMachine &TM) const {
942 MDNode *LinkerOptions = nullptr;
944 // Look for the "Linker Options" flag, since it's the only one we support.
945 for (ArrayRef<Module::ModuleFlagEntry>::iterator
946 i = ModuleFlags.begin(), e = ModuleFlags.end(); i != e; ++i) {
947 const Module::ModuleFlagEntry &MFE = *i;
948 StringRef Key = MFE.Key->getString();
949 Value *Val = MFE.Val;
950 if (Key == "Linker Options") {
951 LinkerOptions = cast<MDNode>(Val);
958 // Emit the linker options to the linker .drectve section. According to the
959 // spec, this section is a space-separated string containing flags for linker.
960 const MCSection *Sec = getDrectveSection();
961 Streamer.SwitchSection(Sec);
962 for (unsigned i = 0, e = LinkerOptions->getNumOperands(); i != e; ++i) {
963 MDNode *MDOptions = cast<MDNode>(LinkerOptions->getOperand(i));
964 for (unsigned ii = 0, ie = MDOptions->getNumOperands(); ii != ie; ++ii) {
965 MDString *MDOption = cast<MDString>(MDOptions->getOperand(ii));
966 StringRef Op = MDOption->getString();
967 // Lead with a space for consistency with our dllexport implementation.
968 std::string Escaped(" ");
969 if (Op.find(" ") != StringRef::npos) {
970 // The PE-COFF spec says args with spaces must be quoted. It doesn't say
971 // how to escape quotes, but it probably uses this algorithm:
972 // http://msdn.microsoft.com/en-us/library/17w5ykft(v=vs.85).aspx
973 // FIXME: Reuse escaping code from Support/Windows/Program.inc
974 Escaped.push_back('\"');
976 Escaped.push_back('\"');
980 Streamer.EmitBytes(Escaped);
985 const MCSection *TargetLoweringObjectFileCOFF::getStaticCtorSection(
986 unsigned Priority, const MCSymbol *KeySym) const {
987 return getContext().getAssociativeCOFFSection(
988 cast<MCSectionCOFF>(StaticCtorSection), KeySym);
991 const MCSection *TargetLoweringObjectFileCOFF::getStaticDtorSection(
992 unsigned Priority, const MCSymbol *KeySym) const {
993 return getContext().getAssociativeCOFFSection(
994 cast<MCSectionCOFF>(StaticDtorSection), KeySym);