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/Constants.h"
17 #include "llvm/DerivedTypes.h"
18 #include "llvm/Function.h"
19 #include "llvm/GlobalVariable.h"
20 #include "llvm/Module.h"
21 #include "llvm/CodeGen/MachineModuleInfoImpls.h"
22 #include "llvm/MC/MCContext.h"
23 #include "llvm/MC/MCExpr.h"
24 #include "llvm/MC/MCSectionMachO.h"
25 #include "llvm/MC/MCSectionELF.h"
26 #include "llvm/MC/MCSectionCOFF.h"
27 #include "llvm/MC/MCStreamer.h"
28 #include "llvm/MC/MCSymbol.h"
29 #include "llvm/Target/Mangler.h"
30 #include "llvm/Target/TargetData.h"
31 #include "llvm/Target/TargetMachine.h"
32 #include "llvm/Target/TargetOptions.h"
33 #include "llvm/Support/Dwarf.h"
34 #include "llvm/Support/ELF.h"
35 #include "llvm/Support/ErrorHandling.h"
36 #include "llvm/Support/raw_ostream.h"
37 #include "llvm/ADT/SmallString.h"
38 #include "llvm/ADT/StringExtras.h"
39 #include "llvm/ADT/Triple.h"
41 using namespace dwarf;
43 //===----------------------------------------------------------------------===//
45 //===----------------------------------------------------------------------===//
48 TargetLoweringObjectFileELF::getCFIPersonalitySymbol(const GlobalValue *GV,
50 MachineModuleInfo *MMI) const {
51 unsigned Encoding = getPersonalityEncoding();
52 switch (Encoding & 0x70) {
54 report_fatal_error("We do not support this DWARF encoding yet!");
55 case dwarf::DW_EH_PE_absptr:
56 return Mang->getSymbol(GV);
57 case dwarf::DW_EH_PE_pcrel: {
58 return getContext().GetOrCreateSymbol(StringRef("DW.ref.") +
59 Mang->getSymbol(GV)->getName());
64 void TargetLoweringObjectFileELF::emitPersonalityValue(MCStreamer &Streamer,
65 const TargetMachine &TM,
66 const MCSymbol *Sym) const {
67 SmallString<64> NameData("DW.ref.");
68 NameData += Sym->getName();
69 MCSymbol *Label = getContext().GetOrCreateSymbol(NameData);
70 Streamer.EmitSymbolAttribute(Label, MCSA_Hidden);
71 Streamer.EmitSymbolAttribute(Label, MCSA_Weak);
72 StringRef Prefix = ".data.";
73 NameData.insert(NameData.begin(), Prefix.begin(), Prefix.end());
74 unsigned Flags = ELF::SHF_ALLOC | ELF::SHF_WRITE | ELF::SHF_GROUP;
75 const MCSection *Sec = getContext().getELFSection(NameData,
78 SectionKind::getDataRel(),
80 unsigned Size = TM.getTargetData()->getPointerSize();
81 Streamer.SwitchSection(Sec);
82 Streamer.EmitValueToAlignment(TM.getTargetData()->getPointerABIAlignment());
83 Streamer.EmitSymbolAttribute(Label, MCSA_ELF_TypeObject);
84 const MCExpr *E = MCConstantExpr::Create(Size, getContext());
85 Streamer.EmitELFSize(Label, E);
86 Streamer.EmitLabel(Label);
88 Streamer.EmitSymbolValue(Sym, Size);
92 getELFKindForNamedSection(StringRef Name, SectionKind K) {
93 // N.B.: The defaults used in here are no the same ones used in MC.
94 // We follow gcc, MC follows gas. For example, given ".section .eh_frame",
95 // both gas and MC will produce a section with no flags. Given
96 // section(".eh_frame") gcc will produce
97 // .section .eh_frame,"a",@progbits
98 if (Name.empty() || Name[0] != '.') return K;
100 // Some lame default implementation based on some magic section names.
101 if (Name == ".bss" ||
102 Name.startswith(".bss.") ||
103 Name.startswith(".gnu.linkonce.b.") ||
104 Name.startswith(".llvm.linkonce.b.") ||
106 Name.startswith(".sbss.") ||
107 Name.startswith(".gnu.linkonce.sb.") ||
108 Name.startswith(".llvm.linkonce.sb."))
109 return SectionKind::getBSS();
111 if (Name == ".tdata" ||
112 Name.startswith(".tdata.") ||
113 Name.startswith(".gnu.linkonce.td.") ||
114 Name.startswith(".llvm.linkonce.td."))
115 return SectionKind::getThreadData();
117 if (Name == ".tbss" ||
118 Name.startswith(".tbss.") ||
119 Name.startswith(".gnu.linkonce.tb.") ||
120 Name.startswith(".llvm.linkonce.tb."))
121 return SectionKind::getThreadBSS();
127 static unsigned getELFSectionType(StringRef Name, SectionKind K) {
129 if (Name == ".init_array")
130 return ELF::SHT_INIT_ARRAY;
132 if (Name == ".fini_array")
133 return ELF::SHT_FINI_ARRAY;
135 if (Name == ".preinit_array")
136 return ELF::SHT_PREINIT_ARRAY;
138 if (K.isBSS() || K.isThreadBSS())
139 return ELF::SHT_NOBITS;
141 return ELF::SHT_PROGBITS;
146 getELFSectionFlags(SectionKind K) {
150 Flags |= ELF::SHF_ALLOC;
153 Flags |= ELF::SHF_EXECINSTR;
156 Flags |= ELF::SHF_WRITE;
158 if (K.isThreadLocal())
159 Flags |= ELF::SHF_TLS;
161 // K.isMergeableConst() is left out to honour PR4650
162 if (K.isMergeableCString() || K.isMergeableConst4() ||
163 K.isMergeableConst8() || K.isMergeableConst16())
164 Flags |= ELF::SHF_MERGE;
166 if (K.isMergeableCString())
167 Flags |= ELF::SHF_STRINGS;
173 const MCSection *TargetLoweringObjectFileELF::
174 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
175 Mangler *Mang, const TargetMachine &TM) const {
176 StringRef SectionName = GV->getSection();
178 // Infer section flags from the section name if we can.
179 Kind = getELFKindForNamedSection(SectionName, Kind);
181 return getContext().getELFSection(SectionName,
182 getELFSectionType(SectionName, Kind),
183 getELFSectionFlags(Kind), Kind);
186 /// getSectionPrefixForGlobal - Return the section prefix name used by options
187 /// FunctionsSections and DataSections.
188 static const char *getSectionPrefixForGlobal(SectionKind Kind) {
189 if (Kind.isText()) return ".text.";
190 if (Kind.isReadOnly()) return ".rodata.";
191 if (Kind.isBSS()) return ".bss.";
193 if (Kind.isThreadData()) return ".tdata.";
194 if (Kind.isThreadBSS()) return ".tbss.";
196 if (Kind.isDataNoRel()) return ".data.";
197 if (Kind.isDataRelLocal()) return ".data.rel.local.";
198 if (Kind.isDataRel()) return ".data.rel.";
199 if (Kind.isReadOnlyWithRelLocal()) return ".data.rel.ro.local.";
201 assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
202 return ".data.rel.ro.";
206 const MCSection *TargetLoweringObjectFileELF::
207 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
208 Mangler *Mang, const TargetMachine &TM) const {
209 // If we have -ffunction-section or -fdata-section then we should emit the
210 // global value to a uniqued section specifically for it.
211 bool EmitUniquedSection;
213 EmitUniquedSection = TM.getFunctionSections();
215 EmitUniquedSection = TM.getDataSections();
217 // If this global is linkonce/weak and the target handles this by emitting it
218 // into a 'uniqued' section name, create and return the section now.
219 if ((GV->isWeakForLinker() || EmitUniquedSection) &&
222 Prefix = getSectionPrefixForGlobal(Kind);
224 SmallString<128> Name(Prefix, Prefix+strlen(Prefix));
225 MCSymbol *Sym = Mang->getSymbol(GV);
226 Name.append(Sym->getName().begin(), Sym->getName().end());
227 StringRef Group = "";
228 unsigned Flags = getELFSectionFlags(Kind);
229 if (GV->isWeakForLinker()) {
230 Group = Sym->getName();
231 Flags |= ELF::SHF_GROUP;
234 return getContext().getELFSection(Name.str(),
235 getELFSectionType(Name.str(), Kind),
236 Flags, Kind, 0, Group);
239 if (Kind.isText()) return TextSection;
241 if (Kind.isMergeable1ByteCString() ||
242 Kind.isMergeable2ByteCString() ||
243 Kind.isMergeable4ByteCString()) {
245 // We also need alignment here.
246 // FIXME: this is getting the alignment of the character, not the
247 // alignment of the global!
249 TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV));
251 const char *SizeSpec = ".rodata.str1.";
252 if (Kind.isMergeable2ByteCString())
253 SizeSpec = ".rodata.str2.";
254 else if (Kind.isMergeable4ByteCString())
255 SizeSpec = ".rodata.str4.";
257 assert(Kind.isMergeable1ByteCString() && "unknown string width");
260 std::string Name = SizeSpec + utostr(Align);
261 return getContext().getELFSection(Name, ELF::SHT_PROGBITS,
268 if (Kind.isMergeableConst()) {
269 if (Kind.isMergeableConst4() && MergeableConst4Section)
270 return MergeableConst4Section;
271 if (Kind.isMergeableConst8() && MergeableConst8Section)
272 return MergeableConst8Section;
273 if (Kind.isMergeableConst16() && MergeableConst16Section)
274 return MergeableConst16Section;
275 return ReadOnlySection; // .const
278 if (Kind.isReadOnly()) return ReadOnlySection;
280 if (Kind.isThreadData()) return TLSDataSection;
281 if (Kind.isThreadBSS()) return TLSBSSSection;
283 // Note: we claim that common symbols are put in BSSSection, but they are
284 // really emitted with the magic .comm directive, which creates a symbol table
285 // entry but not a section.
286 if (Kind.isBSS() || Kind.isCommon()) return BSSSection;
288 if (Kind.isDataNoRel()) return DataSection;
289 if (Kind.isDataRelLocal()) return DataRelLocalSection;
290 if (Kind.isDataRel()) return DataRelSection;
291 if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection;
293 assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
294 return DataRelROSection;
297 /// getSectionForConstant - Given a mergeable constant with the
298 /// specified size and relocation information, return a section that it
299 /// should be placed in.
300 const MCSection *TargetLoweringObjectFileELF::
301 getSectionForConstant(SectionKind Kind) const {
302 if (Kind.isMergeableConst4() && MergeableConst4Section)
303 return MergeableConst4Section;
304 if (Kind.isMergeableConst8() && MergeableConst8Section)
305 return MergeableConst8Section;
306 if (Kind.isMergeableConst16() && MergeableConst16Section)
307 return MergeableConst16Section;
308 if (Kind.isReadOnly())
309 return ReadOnlySection;
311 if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection;
312 assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
313 return DataRelROSection;
316 const MCExpr *TargetLoweringObjectFileELF::
317 getExprForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang,
318 MachineModuleInfo *MMI,
319 unsigned Encoding, MCStreamer &Streamer) const {
321 if (Encoding & dwarf::DW_EH_PE_indirect) {
322 MachineModuleInfoELF &ELFMMI = MMI->getObjFileInfo<MachineModuleInfoELF>();
324 SmallString<128> Name;
325 Mang->getNameWithPrefix(Name, GV, true);
328 // Add information about the stub reference to ELFMMI so that the stub
329 // gets emitted by the asmprinter.
330 MCSymbol *SSym = getContext().GetOrCreateSymbol(Name.str());
331 MachineModuleInfoImpl::StubValueTy &StubSym = ELFMMI.getGVStubEntry(SSym);
332 if (StubSym.getPointer() == 0) {
333 MCSymbol *Sym = Mang->getSymbol(GV);
334 StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage());
337 return TargetLoweringObjectFile::
338 getExprForDwarfReference(SSym, Encoding & ~dwarf::DW_EH_PE_indirect, Streamer);
341 return TargetLoweringObjectFile::
342 getExprForDwarfGlobalReference(GV, Mang, MMI, Encoding, Streamer);
346 TargetLoweringObjectFileELF::getStaticCtorSection(unsigned Priority) const {
347 // The default scheme is .ctor / .dtor, so we have to invert the priority
349 if (Priority == 65535)
350 return StaticCtorSection;
352 std::string Name = std::string(".ctors.") + utostr(65535 - Priority);
353 return getContext().getELFSection(Name, ELF::SHT_PROGBITS,
354 ELF::SHF_ALLOC |ELF::SHF_WRITE,
355 SectionKind::getDataRel());
359 TargetLoweringObjectFileELF::getStaticDtorSection(unsigned Priority) const {
360 // The default scheme is .ctor / .dtor, so we have to invert the priority
362 if (Priority == 65535)
363 return StaticDtorSection;
365 std::string Name = std::string(".dtors.") + utostr(65535 - Priority);
366 return getContext().getELFSection(Name, ELF::SHT_PROGBITS,
367 ELF::SHF_ALLOC |ELF::SHF_WRITE,
368 SectionKind::getDataRel());
371 //===----------------------------------------------------------------------===//
373 //===----------------------------------------------------------------------===//
375 /// emitModuleFlags - Emit the module flags that specify the garbage collection
377 void TargetLoweringObjectFileMachO::
378 emitModuleFlags(MCStreamer &Streamer,
379 ArrayRef<Module::ModuleFlagEntry> ModuleFlags,
380 Mangler *Mang, const TargetMachine &TM) const {
381 unsigned VersionVal = 0;
382 unsigned GCFlags = 0;
383 StringRef SectionVal;
385 for (ArrayRef<Module::ModuleFlagEntry>::iterator
386 i = ModuleFlags.begin(), e = ModuleFlags.end(); i != e; ++i) {
387 const Module::ModuleFlagEntry &MFE = *i;
389 // Ignore flags with 'Require' behavior.
390 if (MFE.Behavior == Module::Require)
393 StringRef Key = MFE.Key->getString();
394 Value *Val = MFE.Val;
396 if (Key == "Objective-C Image Info Version")
397 VersionVal = cast<ConstantInt>(Val)->getZExtValue();
398 else if (Key == "Objective-C Garbage Collection" ||
399 Key == "Objective-C GC Only")
400 GCFlags |= cast<ConstantInt>(Val)->getZExtValue();
401 else if (Key == "Objective-C Image Info Section")
402 SectionVal = cast<MDString>(Val)->getString();
405 // The section is mandatory. If we don't have it, then we don't have GC info.
406 if (SectionVal.empty()) return;
408 StringRef Segment, Section;
409 unsigned TAA = 0, StubSize = 0;
411 std::string ErrorCode =
412 MCSectionMachO::ParseSectionSpecifier(SectionVal, Segment, Section,
413 TAA, TAAParsed, StubSize);
414 if (!ErrorCode.empty())
415 // If invalid, report the error with report_fatal_error.
416 report_fatal_error("Invalid section specifier '" + Section + "': " +
420 const MCSectionMachO *S =
421 getContext().getMachOSection(Segment, Section, TAA, StubSize,
422 SectionKind::getDataNoRel());
423 Streamer.SwitchSection(S);
424 Streamer.EmitLabel(getContext().
425 GetOrCreateSymbol(StringRef("L_OBJC_IMAGE_INFO")));
426 Streamer.EmitIntValue(VersionVal, 4);
427 Streamer.EmitIntValue(GCFlags, 4);
428 Streamer.AddBlankLine();
431 const MCSection *TargetLoweringObjectFileMachO::
432 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
433 Mangler *Mang, const TargetMachine &TM) const {
434 // Parse the section specifier and create it if valid.
435 StringRef Segment, Section;
436 unsigned TAA = 0, StubSize = 0;
438 std::string ErrorCode =
439 MCSectionMachO::ParseSectionSpecifier(GV->getSection(), Segment, Section,
440 TAA, TAAParsed, StubSize);
441 if (!ErrorCode.empty()) {
442 // If invalid, report the error with report_fatal_error.
443 report_fatal_error("Global variable '" + GV->getName() +
444 "' has an invalid section specifier '" +
445 GV->getSection() + "': " + ErrorCode + ".");
449 const MCSectionMachO *S =
450 getContext().getMachOSection(Segment, Section, TAA, StubSize, Kind);
452 // If TAA wasn't set by ParseSectionSpecifier() above,
453 // use the value returned by getMachOSection() as a default.
455 TAA = S->getTypeAndAttributes();
457 // Okay, now that we got the section, verify that the TAA & StubSize agree.
458 // If the user declared multiple globals with different section flags, we need
459 // to reject it here.
460 if (S->getTypeAndAttributes() != TAA || S->getStubSize() != StubSize) {
461 // If invalid, report the error with report_fatal_error.
462 report_fatal_error("Global variable '" + GV->getName() +
463 "' section type or attributes does not match previous"
464 " section specifier");
470 const MCSection *TargetLoweringObjectFileMachO::
471 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
472 Mangler *Mang, const TargetMachine &TM) const {
474 // Handle thread local data.
475 if (Kind.isThreadBSS()) return TLSBSSSection;
476 if (Kind.isThreadData()) return TLSDataSection;
479 return GV->isWeakForLinker() ? TextCoalSection : TextSection;
481 // If this is weak/linkonce, put this in a coalescable section, either in text
482 // or data depending on if it is writable.
483 if (GV->isWeakForLinker()) {
484 if (Kind.isReadOnly())
485 return ConstTextCoalSection;
486 return DataCoalSection;
489 // FIXME: Alignment check should be handled by section classifier.
490 if (Kind.isMergeable1ByteCString() &&
491 TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)) < 32)
492 return CStringSection;
494 // Do not put 16-bit arrays in the UString section if they have an
495 // externally visible label, this runs into issues with certain linker
497 if (Kind.isMergeable2ByteCString() && !GV->hasExternalLinkage() &&
498 TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)) < 32)
499 return UStringSection;
501 if (Kind.isMergeableConst()) {
502 if (Kind.isMergeableConst4())
503 return FourByteConstantSection;
504 if (Kind.isMergeableConst8())
505 return EightByteConstantSection;
506 if (Kind.isMergeableConst16() && SixteenByteConstantSection)
507 return SixteenByteConstantSection;
510 // Otherwise, if it is readonly, but not something we can specially optimize,
511 // just drop it in .const.
512 if (Kind.isReadOnly())
513 return ReadOnlySection;
515 // If this is marked const, put it into a const section. But if the dynamic
516 // linker needs to write to it, put it in the data segment.
517 if (Kind.isReadOnlyWithRel())
518 return ConstDataSection;
520 // Put zero initialized globals with strong external linkage in the
521 // DATA, __common section with the .zerofill directive.
522 if (Kind.isBSSExtern())
523 return DataCommonSection;
525 // Put zero initialized globals with local linkage in __DATA,__bss directive
526 // with the .zerofill directive (aka .lcomm).
527 if (Kind.isBSSLocal())
528 return DataBSSSection;
530 // Otherwise, just drop the variable in the normal data section.
535 TargetLoweringObjectFileMachO::getSectionForConstant(SectionKind Kind) const {
536 // If this constant requires a relocation, we have to put it in the data
537 // segment, not in the text segment.
538 if (Kind.isDataRel() || Kind.isReadOnlyWithRel())
539 return ConstDataSection;
541 if (Kind.isMergeableConst4())
542 return FourByteConstantSection;
543 if (Kind.isMergeableConst8())
544 return EightByteConstantSection;
545 if (Kind.isMergeableConst16() && SixteenByteConstantSection)
546 return SixteenByteConstantSection;
547 return ReadOnlySection; // .const
550 /// shouldEmitUsedDirectiveFor - This hook allows targets to selectively decide
551 /// not to emit the UsedDirective for some symbols in llvm.used.
552 // FIXME: REMOVE this (rdar://7071300)
553 bool TargetLoweringObjectFileMachO::
554 shouldEmitUsedDirectiveFor(const GlobalValue *GV, Mangler *Mang) const {
555 /// On Darwin, internally linked data beginning with "L" or "l" does not have
556 /// the directive emitted (this occurs in ObjC metadata).
557 if (!GV) return false;
559 // Check whether the mangled name has the "Private" or "LinkerPrivate" prefix.
560 if (GV->hasLocalLinkage() && !isa<Function>(GV)) {
561 // FIXME: ObjC metadata is currently emitted as internal symbols that have
562 // \1L and \0l prefixes on them. Fix them to be Private/LinkerPrivate and
563 // this horrible hack can go away.
564 MCSymbol *Sym = Mang->getSymbol(GV);
565 if (Sym->getName()[0] == 'L' || Sym->getName()[0] == 'l')
572 const MCExpr *TargetLoweringObjectFileMachO::
573 getExprForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang,
574 MachineModuleInfo *MMI, unsigned Encoding,
575 MCStreamer &Streamer) const {
576 // The mach-o version of this method defaults to returning a stub reference.
578 if (Encoding & DW_EH_PE_indirect) {
579 MachineModuleInfoMachO &MachOMMI =
580 MMI->getObjFileInfo<MachineModuleInfoMachO>();
582 SmallString<128> Name;
583 Mang->getNameWithPrefix(Name, GV, true);
584 Name += "$non_lazy_ptr";
586 // Add information about the stub reference to MachOMMI so that the stub
587 // gets emitted by the asmprinter.
588 MCSymbol *SSym = getContext().GetOrCreateSymbol(Name.str());
589 MachineModuleInfoImpl::StubValueTy &StubSym =
590 GV->hasHiddenVisibility() ? MachOMMI.getHiddenGVStubEntry(SSym) :
591 MachOMMI.getGVStubEntry(SSym);
592 if (StubSym.getPointer() == 0) {
593 MCSymbol *Sym = Mang->getSymbol(GV);
594 StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage());
597 return TargetLoweringObjectFile::
598 getExprForDwarfReference(SSym, Encoding & ~dwarf::DW_EH_PE_indirect, Streamer);
601 return TargetLoweringObjectFile::
602 getExprForDwarfGlobalReference(GV, Mang, MMI, Encoding, Streamer);
605 MCSymbol *TargetLoweringObjectFileMachO::
606 getCFIPersonalitySymbol(const GlobalValue *GV, Mangler *Mang,
607 MachineModuleInfo *MMI) const {
608 // The mach-o version of this method defaults to returning a stub reference.
609 MachineModuleInfoMachO &MachOMMI =
610 MMI->getObjFileInfo<MachineModuleInfoMachO>();
612 SmallString<128> Name;
613 Mang->getNameWithPrefix(Name, GV, true);
614 Name += "$non_lazy_ptr";
616 // Add information about the stub reference to MachOMMI so that the stub
617 // gets emitted by the asmprinter.
618 MCSymbol *SSym = getContext().GetOrCreateSymbol(Name.str());
619 MachineModuleInfoImpl::StubValueTy &StubSym = MachOMMI.getGVStubEntry(SSym);
620 if (StubSym.getPointer() == 0) {
621 MCSymbol *Sym = Mang->getSymbol(GV);
622 StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage());
628 //===----------------------------------------------------------------------===//
630 //===----------------------------------------------------------------------===//
633 getCOFFSectionFlags(SectionKind K) {
638 COFF::IMAGE_SCN_MEM_DISCARDABLE;
641 COFF::IMAGE_SCN_MEM_EXECUTE |
642 COFF::IMAGE_SCN_MEM_READ |
643 COFF::IMAGE_SCN_CNT_CODE;
646 COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA |
647 COFF::IMAGE_SCN_MEM_READ |
648 COFF::IMAGE_SCN_MEM_WRITE;
649 else if (K.isThreadLocal())
651 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
652 COFF::IMAGE_SCN_MEM_READ |
653 COFF::IMAGE_SCN_MEM_WRITE;
654 else if (K.isReadOnly())
656 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
657 COFF::IMAGE_SCN_MEM_READ;
658 else if (K.isWriteable())
660 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
661 COFF::IMAGE_SCN_MEM_READ |
662 COFF::IMAGE_SCN_MEM_WRITE;
667 const MCSection *TargetLoweringObjectFileCOFF::
668 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
669 Mangler *Mang, const TargetMachine &TM) const {
670 return getContext().getCOFFSection(GV->getSection(),
671 getCOFFSectionFlags(Kind),
675 static const char *getCOFFSectionPrefixForUniqueGlobal(SectionKind Kind) {
680 if (Kind.isThreadLocal())
682 if (Kind.isWriteable())
688 const MCSection *TargetLoweringObjectFileCOFF::
689 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
690 Mangler *Mang, const TargetMachine &TM) const {
692 // If this global is linkonce/weak and the target handles this by emitting it
693 // into a 'uniqued' section name, create and return the section now.
694 if (GV->isWeakForLinker()) {
695 const char *Prefix = getCOFFSectionPrefixForUniqueGlobal(Kind);
696 SmallString<128> Name(Prefix, Prefix+strlen(Prefix));
697 MCSymbol *Sym = Mang->getSymbol(GV);
698 Name.append(Sym->getName().begin() + 1, Sym->getName().end());
700 unsigned Characteristics = getCOFFSectionFlags(Kind);
702 Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT;
704 return getContext().getCOFFSection(Name.str(), Characteristics,
705 COFF::IMAGE_COMDAT_SELECT_ANY, Kind);
709 return getTextSection();
711 if (Kind.isThreadLocal())
712 return getTLSDataSection();
714 return getDataSection();