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() == "__TEXT" &&
588 SMO.getSectionName() == "__objc_classname" &&
589 SMO.getType() == MachO::S_CSTRING_LITERALS)
592 if (SMO.getSegmentName() == "__TEXT" &&
593 SMO.getSectionName() == "__objc_methname" &&
594 SMO.getType() == MachO::S_CSTRING_LITERALS)
597 if (SMO.getSegmentName() == "__TEXT" &&
598 SMO.getSectionName() == "__objc_methtype" &&
599 SMO.getType() == MachO::S_CSTRING_LITERALS)
602 if (SMO.getSegmentName() == "__DATA" &&
603 SMO.getSectionName() == "__cfstring")
606 // no_dead_strip sections are not atomized in practice.
607 if (SMO.hasAttribute(MachO::S_ATTR_NO_DEAD_STRIP))
610 switch (SMO.getType()) {
614 // These sections are atomized at the element boundaries without using
616 case MachO::S_4BYTE_LITERALS:
617 case MachO::S_8BYTE_LITERALS:
618 case MachO::S_16BYTE_LITERALS:
619 case MachO::S_LITERAL_POINTERS:
620 case MachO::S_NON_LAZY_SYMBOL_POINTERS:
621 case MachO::S_LAZY_SYMBOL_POINTERS:
622 case MachO::S_MOD_INIT_FUNC_POINTERS:
623 case MachO::S_MOD_TERM_FUNC_POINTERS:
624 case MachO::S_INTERPOSING:
629 const MCSection *TargetLoweringObjectFileMachO::
630 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
631 Mangler &Mang, const TargetMachine &TM) const {
632 checkMachOComdat(GV);
634 // Handle thread local data.
635 if (Kind.isThreadBSS()) return TLSBSSSection;
636 if (Kind.isThreadData()) return TLSDataSection;
639 return GV->isWeakForLinker() ? TextCoalSection : TextSection;
641 // If this is weak/linkonce, put this in a coalescable section, either in text
642 // or data depending on if it is writable.
643 if (GV->isWeakForLinker()) {
644 if (Kind.isReadOnly())
645 return ConstTextCoalSection;
646 return DataCoalSection;
649 // FIXME: Alignment check should be handled by section classifier.
650 if (Kind.isMergeable1ByteCString() &&
651 TM.getSubtargetImpl()->getDataLayout()->getPreferredAlignment(
652 cast<GlobalVariable>(GV)) < 32)
653 return CStringSection;
655 // Do not put 16-bit arrays in the UString section if they have an
656 // externally visible label, this runs into issues with certain linker
658 if (Kind.isMergeable2ByteCString() && !GV->hasExternalLinkage() &&
659 TM.getSubtargetImpl()->getDataLayout()->getPreferredAlignment(
660 cast<GlobalVariable>(GV)) < 32)
661 return UStringSection;
663 // With MachO only variables whose corresponding symbol starts with 'l' or
664 // 'L' can be merged, so we only try merging GVs with private linkage.
665 if (GV->hasPrivateLinkage() && Kind.isMergeableConst()) {
666 if (Kind.isMergeableConst4())
667 return FourByteConstantSection;
668 if (Kind.isMergeableConst8())
669 return EightByteConstantSection;
670 if (Kind.isMergeableConst16())
671 return SixteenByteConstantSection;
674 // Otherwise, if it is readonly, but not something we can specially optimize,
675 // just drop it in .const.
676 if (Kind.isReadOnly())
677 return ReadOnlySection;
679 // If this is marked const, put it into a const section. But if the dynamic
680 // linker needs to write to it, put it in the data segment.
681 if (Kind.isReadOnlyWithRel())
682 return ConstDataSection;
684 // Put zero initialized globals with strong external linkage in the
685 // DATA, __common section with the .zerofill directive.
686 if (Kind.isBSSExtern())
687 return DataCommonSection;
689 // Put zero initialized globals with local linkage in __DATA,__bss directive
690 // with the .zerofill directive (aka .lcomm).
691 if (Kind.isBSSLocal())
692 return DataBSSSection;
694 // Otherwise, just drop the variable in the normal data section.
699 TargetLoweringObjectFileMachO::getSectionForConstant(SectionKind Kind,
700 const Constant *C) const {
701 // If this constant requires a relocation, we have to put it in the data
702 // segment, not in the text segment.
703 if (Kind.isDataRel() || Kind.isReadOnlyWithRel())
704 return ConstDataSection;
706 if (Kind.isMergeableConst4())
707 return FourByteConstantSection;
708 if (Kind.isMergeableConst8())
709 return EightByteConstantSection;
710 if (Kind.isMergeableConst16())
711 return SixteenByteConstantSection;
712 return ReadOnlySection; // .const
715 const MCExpr *TargetLoweringObjectFileMachO::getTTypeGlobalReference(
716 const GlobalValue *GV, unsigned Encoding, Mangler &Mang,
717 const TargetMachine &TM, MachineModuleInfo *MMI,
718 MCStreamer &Streamer) const {
719 // The mach-o version of this method defaults to returning a stub reference.
721 if (Encoding & DW_EH_PE_indirect) {
722 MachineModuleInfoMachO &MachOMMI =
723 MMI->getObjFileInfo<MachineModuleInfoMachO>();
726 getSymbolWithGlobalValueBase(GV, "$non_lazy_ptr", Mang, TM);
728 // Add information about the stub reference to MachOMMI so that the stub
729 // gets emitted by the asmprinter.
730 MachineModuleInfoImpl::StubValueTy &StubSym =
731 GV->hasHiddenVisibility() ? MachOMMI.getHiddenGVStubEntry(SSym) :
732 MachOMMI.getGVStubEntry(SSym);
733 if (!StubSym.getPointer()) {
734 MCSymbol *Sym = TM.getSymbol(GV, Mang);
735 StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage());
738 return TargetLoweringObjectFile::
739 getTTypeReference(MCSymbolRefExpr::Create(SSym, getContext()),
740 Encoding & ~dwarf::DW_EH_PE_indirect, Streamer);
743 return TargetLoweringObjectFile::getTTypeGlobalReference(GV, Encoding, Mang,
747 MCSymbol *TargetLoweringObjectFileMachO::getCFIPersonalitySymbol(
748 const GlobalValue *GV, Mangler &Mang, const TargetMachine &TM,
749 MachineModuleInfo *MMI) const {
750 // The mach-o version of this method defaults to returning a stub reference.
751 MachineModuleInfoMachO &MachOMMI =
752 MMI->getObjFileInfo<MachineModuleInfoMachO>();
754 MCSymbol *SSym = getSymbolWithGlobalValueBase(GV, "$non_lazy_ptr", Mang, TM);
756 // Add information about the stub reference to MachOMMI so that the stub
757 // gets emitted by the asmprinter.
758 MachineModuleInfoImpl::StubValueTy &StubSym = MachOMMI.getGVStubEntry(SSym);
759 if (!StubSym.getPointer()) {
760 MCSymbol *Sym = TM.getSymbol(GV, Mang);
761 StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage());
767 //===----------------------------------------------------------------------===//
769 //===----------------------------------------------------------------------===//
772 getCOFFSectionFlags(SectionKind K) {
777 COFF::IMAGE_SCN_MEM_DISCARDABLE;
780 COFF::IMAGE_SCN_MEM_EXECUTE |
781 COFF::IMAGE_SCN_MEM_READ |
782 COFF::IMAGE_SCN_CNT_CODE;
785 COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA |
786 COFF::IMAGE_SCN_MEM_READ |
787 COFF::IMAGE_SCN_MEM_WRITE;
788 else if (K.isThreadLocal())
790 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
791 COFF::IMAGE_SCN_MEM_READ |
792 COFF::IMAGE_SCN_MEM_WRITE;
793 else if (K.isReadOnly() || K.isReadOnlyWithRel())
795 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
796 COFF::IMAGE_SCN_MEM_READ;
797 else if (K.isWriteable())
799 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
800 COFF::IMAGE_SCN_MEM_READ |
801 COFF::IMAGE_SCN_MEM_WRITE;
806 static const GlobalValue *getComdatGVForCOFF(const GlobalValue *GV) {
807 const Comdat *C = GV->getComdat();
808 assert(C && "expected GV to have a Comdat!");
810 StringRef ComdatGVName = C->getName();
811 const GlobalValue *ComdatGV = GV->getParent()->getNamedValue(ComdatGVName);
813 report_fatal_error("Associative COMDAT symbol '" + ComdatGVName +
814 "' does not exist.");
816 if (ComdatGV->getComdat() != C)
817 report_fatal_error("Associative COMDAT symbol '" + ComdatGVName +
818 "' is not a key for its COMDAT.");
823 static int getSelectionForCOFF(const GlobalValue *GV) {
824 if (const Comdat *C = GV->getComdat()) {
825 const GlobalValue *ComdatKey = getComdatGVForCOFF(GV);
826 if (const auto *GA = dyn_cast<GlobalAlias>(ComdatKey))
827 ComdatKey = GA->getBaseObject();
828 if (ComdatKey == GV) {
829 switch (C->getSelectionKind()) {
831 return COFF::IMAGE_COMDAT_SELECT_ANY;
832 case Comdat::ExactMatch:
833 return COFF::IMAGE_COMDAT_SELECT_EXACT_MATCH;
834 case Comdat::Largest:
835 return COFF::IMAGE_COMDAT_SELECT_LARGEST;
836 case Comdat::NoDuplicates:
837 return COFF::IMAGE_COMDAT_SELECT_NODUPLICATES;
838 case Comdat::SameSize:
839 return COFF::IMAGE_COMDAT_SELECT_SAME_SIZE;
842 return COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE;
844 } else if (GV->isWeakForLinker()) {
845 return COFF::IMAGE_COMDAT_SELECT_ANY;
850 const MCSection *TargetLoweringObjectFileCOFF::getExplicitSectionGlobal(
851 const GlobalValue *GV, SectionKind Kind, Mangler &Mang,
852 const TargetMachine &TM) const {
854 unsigned Characteristics = getCOFFSectionFlags(Kind);
855 StringRef Name = GV->getSection();
856 StringRef COMDATSymName = "";
857 if ((GV->isWeakForLinker() || GV->hasComdat()) && !Kind.isCommon()) {
858 Selection = getSelectionForCOFF(GV);
859 const GlobalValue *ComdatGV;
860 if (Selection == COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE)
861 ComdatGV = getComdatGVForCOFF(GV);
865 if (!ComdatGV->hasPrivateLinkage()) {
866 MCSymbol *Sym = TM.getSymbol(ComdatGV, Mang);
867 COMDATSymName = Sym->getName();
868 Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT;
873 return getContext().getCOFFSection(Name,
880 static const char *getCOFFSectionNameForUniqueGlobal(SectionKind Kind) {
885 if (Kind.isThreadLocal())
887 if (Kind.isReadOnly() || Kind.isReadOnlyWithRel())
893 const MCSection *TargetLoweringObjectFileCOFF::
894 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
895 Mangler &Mang, const TargetMachine &TM) const {
896 // If we have -ffunction-sections then we should emit the global value to a
897 // uniqued section specifically for it.
898 bool EmitUniquedSection;
900 EmitUniquedSection = TM.getFunctionSections();
902 EmitUniquedSection = TM.getDataSections();
904 // If this global is linkonce/weak and the target handles this by emitting it
905 // into a 'uniqued' section name, create and return the section now.
906 // Section names depend on the name of the symbol which is not feasible if the
907 // symbol has private linkage.
908 if ((GV->isWeakForLinker() || EmitUniquedSection || GV->hasComdat()) &&
910 const char *Name = getCOFFSectionNameForUniqueGlobal(Kind);
911 unsigned Characteristics = getCOFFSectionFlags(Kind);
913 Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT;
914 int Selection = getSelectionForCOFF(GV);
916 Selection = COFF::IMAGE_COMDAT_SELECT_NODUPLICATES;
917 const GlobalValue *ComdatGV;
919 ComdatGV = getComdatGVForCOFF(GV);
923 if (!ComdatGV->hasPrivateLinkage()) {
924 MCSymbol *Sym = TM.getSymbol(ComdatGV, Mang);
925 StringRef COMDATSymName = Sym->getName();
926 return getContext().getCOFFSection(Name, Characteristics, Kind,
927 COMDATSymName, Selection);
934 if (Kind.isThreadLocal())
935 return TLSDataSection;
937 if (Kind.isReadOnly() || Kind.isReadOnlyWithRel())
938 return ReadOnlySection;
940 // Note: we claim that common symbols are put in BSSSection, but they are
941 // really emitted with the magic .comm directive, which creates a symbol table
942 // entry but not a section.
943 if (Kind.isBSS() || Kind.isCommon())
949 StringRef TargetLoweringObjectFileCOFF::
950 getDepLibFromLinkerOpt(StringRef LinkerOption) const {
951 const char *LibCmd = "/DEFAULTLIB:";
952 if (LinkerOption.startswith(LibCmd))
953 return LinkerOption.substr(strlen(LibCmd));
957 void TargetLoweringObjectFileCOFF::
958 emitModuleFlags(MCStreamer &Streamer,
959 ArrayRef<Module::ModuleFlagEntry> ModuleFlags,
960 Mangler &Mang, const TargetMachine &TM) const {
961 MDNode *LinkerOptions = nullptr;
963 // Look for the "Linker Options" flag, since it's the only one we support.
964 for (ArrayRef<Module::ModuleFlagEntry>::iterator
965 i = ModuleFlags.begin(), e = ModuleFlags.end(); i != e; ++i) {
966 const Module::ModuleFlagEntry &MFE = *i;
967 StringRef Key = MFE.Key->getString();
968 Value *Val = MFE.Val;
969 if (Key == "Linker Options") {
970 LinkerOptions = cast<MDNode>(Val);
977 // Emit the linker options to the linker .drectve section. According to the
978 // spec, this section is a space-separated string containing flags for linker.
979 const MCSection *Sec = getDrectveSection();
980 Streamer.SwitchSection(Sec);
981 for (unsigned i = 0, e = LinkerOptions->getNumOperands(); i != e; ++i) {
982 MDNode *MDOptions = cast<MDNode>(LinkerOptions->getOperand(i));
983 for (unsigned ii = 0, ie = MDOptions->getNumOperands(); ii != ie; ++ii) {
984 MDString *MDOption = cast<MDString>(MDOptions->getOperand(ii));
985 StringRef Op = MDOption->getString();
986 // Lead with a space for consistency with our dllexport implementation.
987 std::string Escaped(" ");
988 if (Op.find(" ") != StringRef::npos) {
989 // The PE-COFF spec says args with spaces must be quoted. It doesn't say
990 // how to escape quotes, but it probably uses this algorithm:
991 // http://msdn.microsoft.com/en-us/library/17w5ykft(v=vs.85).aspx
992 // FIXME: Reuse escaping code from Support/Windows/Program.inc
993 Escaped.push_back('\"');
995 Escaped.push_back('\"');
999 Streamer.EmitBytes(Escaped);
1004 const MCSection *TargetLoweringObjectFileCOFF::getStaticCtorSection(
1005 unsigned Priority, const MCSymbol *KeySym) const {
1006 return getContext().getAssociativeCOFFSection(
1007 cast<MCSectionCOFF>(StaticCtorSection), KeySym);
1010 const MCSection *TargetLoweringObjectFileCOFF::getStaticDtorSection(
1011 unsigned Priority, const MCSymbol *KeySym) const {
1012 return getContext().getAssociativeCOFFSection(
1013 cast<MCSectionCOFF>(StaticDtorSection), KeySym);