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 const MCSection *TargetLoweringObjectFileELF::getStaticCtorSection(
362 unsigned Priority, const MCSymbol *KeySym) const {
363 // The default scheme is .ctor / .dtor, so we have to invert the priority
365 if (Priority == 65535)
366 return StaticCtorSection;
369 std::string Name = std::string(".init_array.") + utostr(Priority);
370 return getContext().getELFSection(Name, ELF::SHT_INIT_ARRAY,
371 ELF::SHF_ALLOC | ELF::SHF_WRITE,
372 SectionKind::getDataRel());
374 std::string Name = std::string(".ctors.") + utostr(65535 - Priority);
375 return getContext().getELFSection(Name, ELF::SHT_PROGBITS,
376 ELF::SHF_ALLOC |ELF::SHF_WRITE,
377 SectionKind::getDataRel());
381 const MCSection *TargetLoweringObjectFileELF::getStaticDtorSection(
382 unsigned Priority, const MCSymbol *KeySym) const {
383 // The default scheme is .ctor / .dtor, so we have to invert the priority
385 if (Priority == 65535)
386 return StaticDtorSection;
389 std::string Name = std::string(".fini_array.") + utostr(Priority);
390 return getContext().getELFSection(Name, ELF::SHT_FINI_ARRAY,
391 ELF::SHF_ALLOC | ELF::SHF_WRITE,
392 SectionKind::getDataRel());
394 std::string Name = std::string(".dtors.") + utostr(65535 - Priority);
395 return getContext().getELFSection(Name, ELF::SHT_PROGBITS,
396 ELF::SHF_ALLOC |ELF::SHF_WRITE,
397 SectionKind::getDataRel());
402 TargetLoweringObjectFileELF::InitializeELF(bool UseInitArray_) {
403 UseInitArray = UseInitArray_;
408 getContext().getELFSection(".init_array", ELF::SHT_INIT_ARRAY,
411 SectionKind::getDataRel());
413 getContext().getELFSection(".fini_array", ELF::SHT_FINI_ARRAY,
416 SectionKind::getDataRel());
419 //===----------------------------------------------------------------------===//
421 //===----------------------------------------------------------------------===//
423 /// getDepLibFromLinkerOpt - Extract the dependent library name from a linker
424 /// option string. Returns StringRef() if the option does not specify a library.
425 StringRef TargetLoweringObjectFileMachO::
426 getDepLibFromLinkerOpt(StringRef LinkerOption) const {
427 const char *LibCmd = "-l";
428 if (LinkerOption.startswith(LibCmd))
429 return LinkerOption.substr(strlen(LibCmd));
433 /// emitModuleFlags - Perform code emission for module flags.
434 void TargetLoweringObjectFileMachO::
435 emitModuleFlags(MCStreamer &Streamer,
436 ArrayRef<Module::ModuleFlagEntry> ModuleFlags,
437 Mangler &Mang, const TargetMachine &TM) const {
438 unsigned VersionVal = 0;
439 unsigned ImageInfoFlags = 0;
440 MDNode *LinkerOptions = nullptr;
441 StringRef SectionVal;
443 for (ArrayRef<Module::ModuleFlagEntry>::iterator
444 i = ModuleFlags.begin(), e = ModuleFlags.end(); i != e; ++i) {
445 const Module::ModuleFlagEntry &MFE = *i;
447 // Ignore flags with 'Require' behavior.
448 if (MFE.Behavior == Module::Require)
451 StringRef Key = MFE.Key->getString();
452 Value *Val = MFE.Val;
454 if (Key == "Objective-C Image Info Version") {
455 VersionVal = cast<ConstantInt>(Val)->getZExtValue();
456 } else if (Key == "Objective-C Garbage Collection" ||
457 Key == "Objective-C GC Only" ||
458 Key == "Objective-C Is Simulated") {
459 ImageInfoFlags |= cast<ConstantInt>(Val)->getZExtValue();
460 } else if (Key == "Objective-C Image Info Section") {
461 SectionVal = cast<MDString>(Val)->getString();
462 } else if (Key == "Linker Options") {
463 LinkerOptions = cast<MDNode>(Val);
467 // Emit the linker options if present.
469 for (unsigned i = 0, e = LinkerOptions->getNumOperands(); i != e; ++i) {
470 MDNode *MDOptions = cast<MDNode>(LinkerOptions->getOperand(i));
471 SmallVector<std::string, 4> StrOptions;
473 // Convert to strings.
474 for (unsigned ii = 0, ie = MDOptions->getNumOperands(); ii != ie; ++ii) {
475 MDString *MDOption = cast<MDString>(MDOptions->getOperand(ii));
476 StrOptions.push_back(MDOption->getString());
479 Streamer.EmitLinkerOptions(StrOptions);
483 // The section is mandatory. If we don't have it, then we don't have GC info.
484 if (SectionVal.empty()) return;
486 StringRef Segment, Section;
487 unsigned TAA = 0, StubSize = 0;
489 std::string ErrorCode =
490 MCSectionMachO::ParseSectionSpecifier(SectionVal, Segment, Section,
491 TAA, TAAParsed, StubSize);
492 if (!ErrorCode.empty())
493 // If invalid, report the error with report_fatal_error.
494 report_fatal_error("Invalid section specifier '" + Section + "': " +
498 const MCSectionMachO *S =
499 getContext().getMachOSection(Segment, Section, TAA, StubSize,
500 SectionKind::getDataNoRel());
501 Streamer.SwitchSection(S);
502 Streamer.EmitLabel(getContext().
503 GetOrCreateSymbol(StringRef("L_OBJC_IMAGE_INFO")));
504 Streamer.EmitIntValue(VersionVal, 4);
505 Streamer.EmitIntValue(ImageInfoFlags, 4);
506 Streamer.AddBlankLine();
509 static void checkMachOComdat(const GlobalValue *GV) {
510 const Comdat *C = GV->getComdat();
514 report_fatal_error("MachO doesn't support COMDATs, '" + C->getName() +
515 "' cannot be lowered.");
518 const MCSection *TargetLoweringObjectFileMachO::getExplicitSectionGlobal(
519 const GlobalValue *GV, SectionKind Kind, Mangler &Mang,
520 const TargetMachine &TM) const {
521 // Parse the section specifier and create it if valid.
522 StringRef Segment, Section;
523 unsigned TAA = 0, StubSize = 0;
526 checkMachOComdat(GV);
528 std::string ErrorCode =
529 MCSectionMachO::ParseSectionSpecifier(GV->getSection(), Segment, Section,
530 TAA, TAAParsed, StubSize);
531 if (!ErrorCode.empty()) {
532 // If invalid, report the error with report_fatal_error.
533 report_fatal_error("Global variable '" + GV->getName() +
534 "' has an invalid section specifier '" +
535 GV->getSection() + "': " + ErrorCode + ".");
539 const MCSectionMachO *S =
540 getContext().getMachOSection(Segment, Section, TAA, StubSize, Kind);
542 // If TAA wasn't set by ParseSectionSpecifier() above,
543 // use the value returned by getMachOSection() as a default.
545 TAA = S->getTypeAndAttributes();
547 // Okay, now that we got the section, verify that the TAA & StubSize agree.
548 // If the user declared multiple globals with different section flags, we need
549 // to reject it here.
550 if (S->getTypeAndAttributes() != TAA || S->getStubSize() != StubSize) {
551 // If invalid, report the error with report_fatal_error.
552 report_fatal_error("Global variable '" + GV->getName() +
553 "' section type or attributes does not match previous"
554 " section specifier");
560 bool TargetLoweringObjectFileMachO::isSectionAtomizableBySymbols(
561 const MCSection &Section) const {
562 const MCSectionMachO &SMO = static_cast<const MCSectionMachO&>(Section);
564 // Sections holding 1 byte strings are atomized based on the data
566 // Sections holding 2 byte strings require symbols in order to be
568 // There is no dedicated section for 4 byte strings.
569 if (SMO.getKind().isMergeable1ByteCString())
572 if (SMO.getSegmentName() == "__DATA" &&
573 SMO.getSectionName() == "__cfstring")
576 switch (SMO.getType()) {
580 // These sections are atomized at the element boundaries without using
582 case MachO::S_4BYTE_LITERALS:
583 case MachO::S_8BYTE_LITERALS:
584 case MachO::S_16BYTE_LITERALS:
585 case MachO::S_LITERAL_POINTERS:
586 case MachO::S_NON_LAZY_SYMBOL_POINTERS:
587 case MachO::S_LAZY_SYMBOL_POINTERS:
588 case MachO::S_MOD_INIT_FUNC_POINTERS:
589 case MachO::S_MOD_TERM_FUNC_POINTERS:
590 case MachO::S_INTERPOSING:
595 const MCSection *TargetLoweringObjectFileMachO::
596 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
597 Mangler &Mang, const TargetMachine &TM) const {
598 checkMachOComdat(GV);
600 // Handle thread local data.
601 if (Kind.isThreadBSS()) return TLSBSSSection;
602 if (Kind.isThreadData()) return TLSDataSection;
605 return GV->isWeakForLinker() ? TextCoalSection : TextSection;
607 // If this is weak/linkonce, put this in a coalescable section, either in text
608 // or data depending on if it is writable.
609 if (GV->isWeakForLinker()) {
610 if (Kind.isReadOnly())
611 return ConstTextCoalSection;
612 return DataCoalSection;
615 // FIXME: Alignment check should be handled by section classifier.
616 if (Kind.isMergeable1ByteCString() &&
617 TM.getSubtargetImpl()->getDataLayout()->getPreferredAlignment(
618 cast<GlobalVariable>(GV)) < 32)
619 return CStringSection;
621 // Do not put 16-bit arrays in the UString section if they have an
622 // externally visible label, this runs into issues with certain linker
624 if (Kind.isMergeable2ByteCString() && !GV->hasExternalLinkage() &&
625 TM.getSubtargetImpl()->getDataLayout()->getPreferredAlignment(
626 cast<GlobalVariable>(GV)) < 32)
627 return UStringSection;
629 if (Kind.isMergeableConst()) {
630 if (Kind.isMergeableConst4())
631 return FourByteConstantSection;
632 if (Kind.isMergeableConst8())
633 return EightByteConstantSection;
634 if (Kind.isMergeableConst16())
635 return SixteenByteConstantSection;
638 // Otherwise, if it is readonly, but not something we can specially optimize,
639 // just drop it in .const.
640 if (Kind.isReadOnly())
641 return ReadOnlySection;
643 // If this is marked const, put it into a const section. But if the dynamic
644 // linker needs to write to it, put it in the data segment.
645 if (Kind.isReadOnlyWithRel())
646 return ConstDataSection;
648 // Put zero initialized globals with strong external linkage in the
649 // DATA, __common section with the .zerofill directive.
650 if (Kind.isBSSExtern())
651 return DataCommonSection;
653 // Put zero initialized globals with local linkage in __DATA,__bss directive
654 // with the .zerofill directive (aka .lcomm).
655 if (Kind.isBSSLocal())
656 return DataBSSSection;
658 // Otherwise, just drop the variable in the normal data section.
663 TargetLoweringObjectFileMachO::getSectionForConstant(SectionKind Kind,
664 const Constant *C) const {
665 // If this constant requires a relocation, we have to put it in the data
666 // segment, not in the text segment.
667 if (Kind.isDataRel() || Kind.isReadOnlyWithRel())
668 return ConstDataSection;
670 if (Kind.isMergeableConst4())
671 return FourByteConstantSection;
672 if (Kind.isMergeableConst8())
673 return EightByteConstantSection;
674 if (Kind.isMergeableConst16())
675 return SixteenByteConstantSection;
676 return ReadOnlySection; // .const
679 const MCExpr *TargetLoweringObjectFileMachO::getTTypeGlobalReference(
680 const GlobalValue *GV, unsigned Encoding, Mangler &Mang,
681 const TargetMachine &TM, MachineModuleInfo *MMI,
682 MCStreamer &Streamer) const {
683 // The mach-o version of this method defaults to returning a stub reference.
685 if (Encoding & DW_EH_PE_indirect) {
686 MachineModuleInfoMachO &MachOMMI =
687 MMI->getObjFileInfo<MachineModuleInfoMachO>();
690 getSymbolWithGlobalValueBase(GV, "$non_lazy_ptr", Mang, TM);
692 // Add information about the stub reference to MachOMMI so that the stub
693 // gets emitted by the asmprinter.
694 MachineModuleInfoImpl::StubValueTy &StubSym =
695 GV->hasHiddenVisibility() ? MachOMMI.getHiddenGVStubEntry(SSym) :
696 MachOMMI.getGVStubEntry(SSym);
697 if (!StubSym.getPointer()) {
698 MCSymbol *Sym = TM.getSymbol(GV, Mang);
699 StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage());
702 return TargetLoweringObjectFile::
703 getTTypeReference(MCSymbolRefExpr::Create(SSym, getContext()),
704 Encoding & ~dwarf::DW_EH_PE_indirect, Streamer);
707 return TargetLoweringObjectFile::getTTypeGlobalReference(GV, Encoding, Mang,
711 MCSymbol *TargetLoweringObjectFileMachO::getCFIPersonalitySymbol(
712 const GlobalValue *GV, Mangler &Mang, const TargetMachine &TM,
713 MachineModuleInfo *MMI) const {
714 // The mach-o version of this method defaults to returning a stub reference.
715 MachineModuleInfoMachO &MachOMMI =
716 MMI->getObjFileInfo<MachineModuleInfoMachO>();
718 MCSymbol *SSym = getSymbolWithGlobalValueBase(GV, "$non_lazy_ptr", Mang, TM);
720 // Add information about the stub reference to MachOMMI so that the stub
721 // gets emitted by the asmprinter.
722 MachineModuleInfoImpl::StubValueTy &StubSym = MachOMMI.getGVStubEntry(SSym);
723 if (!StubSym.getPointer()) {
724 MCSymbol *Sym = TM.getSymbol(GV, Mang);
725 StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage());
731 //===----------------------------------------------------------------------===//
733 //===----------------------------------------------------------------------===//
736 getCOFFSectionFlags(SectionKind K) {
741 COFF::IMAGE_SCN_MEM_DISCARDABLE;
744 COFF::IMAGE_SCN_MEM_EXECUTE |
745 COFF::IMAGE_SCN_MEM_READ |
746 COFF::IMAGE_SCN_CNT_CODE;
749 COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA |
750 COFF::IMAGE_SCN_MEM_READ |
751 COFF::IMAGE_SCN_MEM_WRITE;
752 else if (K.isThreadLocal())
754 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
755 COFF::IMAGE_SCN_MEM_READ |
756 COFF::IMAGE_SCN_MEM_WRITE;
757 else if (K.isReadOnly())
759 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
760 COFF::IMAGE_SCN_MEM_READ;
761 else if (K.isWriteable())
763 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
764 COFF::IMAGE_SCN_MEM_READ |
765 COFF::IMAGE_SCN_MEM_WRITE;
770 static const GlobalValue *getComdatGVForCOFF(const GlobalValue *GV) {
771 const Comdat *C = GV->getComdat();
772 assert(C && "expected GV to have a Comdat!");
774 StringRef ComdatGVName = C->getName();
775 const GlobalValue *ComdatGV = GV->getParent()->getNamedValue(ComdatGVName);
777 report_fatal_error("Associative COMDAT symbol '" + ComdatGVName +
778 "' does not exist.");
780 if (ComdatGV->getComdat() != C)
781 report_fatal_error("Associative COMDAT symbol '" + ComdatGVName +
782 "' is not a key for it's COMDAT.");
787 static int getSelectionForCOFF(const GlobalValue *GV) {
788 if (const Comdat *C = GV->getComdat()) {
789 const GlobalValue *ComdatKey = getComdatGVForCOFF(GV);
790 if (const auto *GA = dyn_cast<GlobalAlias>(ComdatKey))
791 ComdatKey = GA->getBaseObject();
792 if (ComdatKey == GV) {
793 switch (C->getSelectionKind()) {
795 return COFF::IMAGE_COMDAT_SELECT_ANY;
796 case Comdat::ExactMatch:
797 return COFF::IMAGE_COMDAT_SELECT_EXACT_MATCH;
798 case Comdat::Largest:
799 return COFF::IMAGE_COMDAT_SELECT_LARGEST;
800 case Comdat::NoDuplicates:
801 return COFF::IMAGE_COMDAT_SELECT_NODUPLICATES;
802 case Comdat::SameSize:
803 return COFF::IMAGE_COMDAT_SELECT_SAME_SIZE;
806 return COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE;
808 } else if (GV->isWeakForLinker()) {
809 return COFF::IMAGE_COMDAT_SELECT_ANY;
814 const MCSection *TargetLoweringObjectFileCOFF::getExplicitSectionGlobal(
815 const GlobalValue *GV, SectionKind Kind, Mangler &Mang,
816 const TargetMachine &TM) const {
818 unsigned Characteristics = getCOFFSectionFlags(Kind);
819 StringRef Name = GV->getSection();
820 StringRef COMDATSymName = "";
821 if ((GV->isWeakForLinker() || GV->hasComdat()) && !Kind.isCommon()) {
822 Selection = getSelectionForCOFF(GV);
823 const GlobalValue *ComdatGV;
824 if (Selection == COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE)
825 ComdatGV = getComdatGVForCOFF(GV);
829 if (!ComdatGV->hasPrivateLinkage()) {
830 MCSymbol *Sym = TM.getSymbol(ComdatGV, Mang);
831 COMDATSymName = Sym->getName();
832 Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT;
837 return getContext().getCOFFSection(Name,
844 static const char *getCOFFSectionNameForUniqueGlobal(SectionKind Kind) {
849 if (Kind.isThreadLocal())
851 if (Kind.isWriteable())
857 const MCSection *TargetLoweringObjectFileCOFF::
858 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
859 Mangler &Mang, const TargetMachine &TM) const {
860 // If we have -ffunction-sections then we should emit the global value to a
861 // uniqued section specifically for it.
862 bool EmitUniquedSection;
864 EmitUniquedSection = TM.getFunctionSections();
866 EmitUniquedSection = TM.getDataSections();
868 // If this global is linkonce/weak and the target handles this by emitting it
869 // into a 'uniqued' section name, create and return the section now.
870 // Section names depend on the name of the symbol which is not feasible if the
871 // symbol has private linkage.
872 if ((GV->isWeakForLinker() || EmitUniquedSection || GV->hasComdat()) &&
874 const char *Name = getCOFFSectionNameForUniqueGlobal(Kind);
875 unsigned Characteristics = getCOFFSectionFlags(Kind);
877 Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT;
878 int Selection = getSelectionForCOFF(GV);
880 Selection = COFF::IMAGE_COMDAT_SELECT_NODUPLICATES;
881 const GlobalValue *ComdatGV;
883 ComdatGV = getComdatGVForCOFF(GV);
887 if (!ComdatGV->hasPrivateLinkage()) {
888 MCSymbol *Sym = TM.getSymbol(ComdatGV, Mang);
889 StringRef COMDATSymName = Sym->getName();
890 return getContext().getCOFFSection(Name, Characteristics, Kind,
891 COMDATSymName, Selection);
898 if (Kind.isThreadLocal())
899 return TLSDataSection;
901 if (Kind.isReadOnly())
902 return ReadOnlySection;
904 // Note: we claim that common symbols are put in BSSSection, but they are
905 // really emitted with the magic .comm directive, which creates a symbol table
906 // entry but not a section.
907 if (Kind.isBSS() || Kind.isCommon())
913 StringRef TargetLoweringObjectFileCOFF::
914 getDepLibFromLinkerOpt(StringRef LinkerOption) const {
915 const char *LibCmd = "/DEFAULTLIB:";
916 if (LinkerOption.startswith(LibCmd))
917 return LinkerOption.substr(strlen(LibCmd));
921 void TargetLoweringObjectFileCOFF::
922 emitModuleFlags(MCStreamer &Streamer,
923 ArrayRef<Module::ModuleFlagEntry> ModuleFlags,
924 Mangler &Mang, const TargetMachine &TM) const {
925 MDNode *LinkerOptions = nullptr;
927 // Look for the "Linker Options" flag, since it's the only one we support.
928 for (ArrayRef<Module::ModuleFlagEntry>::iterator
929 i = ModuleFlags.begin(), e = ModuleFlags.end(); i != e; ++i) {
930 const Module::ModuleFlagEntry &MFE = *i;
931 StringRef Key = MFE.Key->getString();
932 Value *Val = MFE.Val;
933 if (Key == "Linker Options") {
934 LinkerOptions = cast<MDNode>(Val);
941 // Emit the linker options to the linker .drectve section. According to the
942 // spec, this section is a space-separated string containing flags for linker.
943 const MCSection *Sec = getDrectveSection();
944 Streamer.SwitchSection(Sec);
945 for (unsigned i = 0, e = LinkerOptions->getNumOperands(); i != e; ++i) {
946 MDNode *MDOptions = cast<MDNode>(LinkerOptions->getOperand(i));
947 for (unsigned ii = 0, ie = MDOptions->getNumOperands(); ii != ie; ++ii) {
948 MDString *MDOption = cast<MDString>(MDOptions->getOperand(ii));
949 StringRef Op = MDOption->getString();
950 // Lead with a space for consistency with our dllexport implementation.
951 std::string Escaped(" ");
952 if (Op.find(" ") != StringRef::npos) {
953 // The PE-COFF spec says args with spaces must be quoted. It doesn't say
954 // how to escape quotes, but it probably uses this algorithm:
955 // http://msdn.microsoft.com/en-us/library/17w5ykft(v=vs.85).aspx
956 // FIXME: Reuse escaping code from Support/Windows/Program.inc
957 Escaped.push_back('\"');
959 Escaped.push_back('\"');
963 Streamer.EmitBytes(Escaped);
968 static const MCSection *getAssociativeCOFFSection(MCContext &Ctx,
969 const MCSection *Sec,
970 const MCSymbol *KeySym) {
971 // Return the normal section if we don't have to be associative.
975 // Make an associative section with the same name and kind as the normal
977 const MCSectionCOFF *SecCOFF = cast<MCSectionCOFF>(Sec);
978 unsigned Characteristics =
979 SecCOFF->getCharacteristics() | COFF::IMAGE_SCN_LNK_COMDAT;
980 return Ctx.getCOFFSection(SecCOFF->getSectionName(), Characteristics,
981 SecCOFF->getKind(), KeySym->getName(),
982 COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE);
985 const MCSection *TargetLoweringObjectFileCOFF::getStaticCtorSection(
986 unsigned Priority, const MCSymbol *KeySym) const {
987 return getAssociativeCOFFSection(getContext(), StaticCtorSection, KeySym);
990 const MCSection *TargetLoweringObjectFileCOFF::getStaticDtorSection(
991 unsigned Priority, const MCSymbol *KeySym) const {
992 return getAssociativeCOFFSection(getContext(), StaticDtorSection, KeySym);