1 //===-- llvm/Target/TargetLoweringObjectFile.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/Target/TargetLoweringObjectFile.h"
16 #include "llvm/Constants.h"
17 #include "llvm/DerivedTypes.h"
18 #include "llvm/Function.h"
19 #include "llvm/GlobalVariable.h"
20 #include "llvm/MC/MCContext.h"
21 #include "llvm/MC/MCSectionMachO.h"
22 #include "llvm/MC/MCSectionELF.h"
23 #include "llvm/Target/TargetData.h"
24 #include "llvm/Target/TargetMachine.h"
25 #include "llvm/Target/TargetOptions.h"
26 #include "llvm/Support/Mangler.h"
27 #include "llvm/ADT/SmallString.h"
28 #include "llvm/ADT/StringExtras.h"
31 //===----------------------------------------------------------------------===//
33 //===----------------------------------------------------------------------===//
35 TargetLoweringObjectFile::TargetLoweringObjectFile() : Ctx(0) {
40 StaticCtorSection = 0;
41 StaticDtorSection = 0;
45 DwarfAbbrevSection = 0;
48 DwarfFrameSection = 0;
49 DwarfPubNamesSection = 0;
50 DwarfPubTypesSection = 0;
51 DwarfDebugInlineSection = 0;
54 DwarfARangesSection = 0;
55 DwarfRangesSection = 0;
56 DwarfMacroInfoSection = 0;
59 TargetLoweringObjectFile::~TargetLoweringObjectFile() {
62 static bool isSuitableForBSS(const GlobalVariable *GV) {
63 Constant *C = GV->getInitializer();
65 // Must have zero initializer.
66 if (!C->isNullValue())
69 // Leave constant zeros in readonly constant sections, so they can be shared.
73 // If the global has an explicit section specified, don't put it in BSS.
74 if (!GV->getSection().empty())
77 // If -nozero-initialized-in-bss is specified, don't ever use BSS.
81 // Otherwise, put it in BSS!
85 /// IsNullTerminatedString - Return true if the specified constant (which is
86 /// known to have a type that is an array of 1/2/4 byte elements) ends with a
87 /// nul value and contains no other nuls in it.
88 static bool IsNullTerminatedString(const Constant *C) {
89 const ArrayType *ATy = cast<ArrayType>(C->getType());
91 // First check: is we have constant array of i8 terminated with zero
92 if (const ConstantArray *CVA = dyn_cast<ConstantArray>(C)) {
93 if (ATy->getNumElements() == 0) return false;
96 dyn_cast<ConstantInt>(CVA->getOperand(ATy->getNumElements()-1));
97 if (Null == 0 || Null->getZExtValue() != 0)
98 return false; // Not null terminated.
100 // Verify that the null doesn't occur anywhere else in the string.
101 for (unsigned i = 0, e = ATy->getNumElements()-1; i != e; ++i)
102 // Reject constantexpr elements etc.
103 if (!isa<ConstantInt>(CVA->getOperand(i)) ||
104 CVA->getOperand(i) == Null)
109 // Another possibility: [1 x i8] zeroinitializer
110 if (isa<ConstantAggregateZero>(C))
111 return ATy->getNumElements() == 1;
116 /// getKindForGlobal - This is a top-level target-independent classifier for
117 /// a global variable. Given an global variable and information from TM, it
118 /// classifies the global in a variety of ways that make various target
119 /// implementations simpler. The target implementation is free to ignore this
120 /// extra info of course.
121 SectionKind TargetLoweringObjectFile::getKindForGlobal(const GlobalValue *GV,
122 const TargetMachine &TM){
123 assert(!GV->isDeclaration() && !GV->hasAvailableExternallyLinkage() &&
124 "Can only be used for global definitions");
126 Reloc::Model ReloModel = TM.getRelocationModel();
128 // Early exit - functions should be always in text sections.
129 const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV);
131 return SectionKind::getText();
133 // Handle thread-local data first.
134 if (GVar->isThreadLocal()) {
135 if (isSuitableForBSS(GVar))
136 return SectionKind::getThreadBSS();
137 return SectionKind::getThreadData();
140 // Variable can be easily put to BSS section.
141 if (isSuitableForBSS(GVar))
142 return SectionKind::getBSS();
144 Constant *C = GVar->getInitializer();
146 // If the global is marked constant, we can put it into a mergable section,
147 // a mergable string section, or general .data if it contains relocations.
148 if (GVar->isConstant()) {
149 // If the initializer for the global contains something that requires a
150 // relocation, then we may have to drop this into a wriable data section
151 // even though it is marked const.
152 switch (C->getRelocationInfo()) {
153 default: llvm_unreachable("unknown relocation info kind");
154 case Constant::NoRelocation:
155 // If initializer is a null-terminated string, put it in a "cstring"
156 // section of the right width.
157 if (const ArrayType *ATy = dyn_cast<ArrayType>(C->getType())) {
158 if (const IntegerType *ITy =
159 dyn_cast<IntegerType>(ATy->getElementType())) {
160 if ((ITy->getBitWidth() == 8 || ITy->getBitWidth() == 16 ||
161 ITy->getBitWidth() == 32) &&
162 IsNullTerminatedString(C)) {
163 if (ITy->getBitWidth() == 8)
164 return SectionKind::getMergeable1ByteCString();
165 if (ITy->getBitWidth() == 16)
166 return SectionKind::getMergeable2ByteCString();
168 assert(ITy->getBitWidth() == 32 && "Unknown width");
169 return SectionKind::getMergeable4ByteCString();
174 // Otherwise, just drop it into a mergable constant section. If we have
175 // a section for this size, use it, otherwise use the arbitrary sized
177 switch (TM.getTargetData()->getTypeAllocSize(C->getType())) {
178 case 4: return SectionKind::getMergeableConst4();
179 case 8: return SectionKind::getMergeableConst8();
180 case 16: return SectionKind::getMergeableConst16();
181 default: return SectionKind::getMergeableConst();
184 case Constant::LocalRelocation:
185 // In static relocation model, the linker will resolve all addresses, so
186 // the relocation entries will actually be constants by the time the app
187 // starts up. However, we can't put this into a mergable section, because
188 // the linker doesn't take relocations into consideration when it tries to
189 // merge entries in the section.
190 if (ReloModel == Reloc::Static)
191 return SectionKind::getReadOnly();
193 // Otherwise, the dynamic linker needs to fix it up, put it in the
194 // writable data.rel.local section.
195 return SectionKind::getReadOnlyWithRelLocal();
197 case Constant::GlobalRelocations:
198 // In static relocation model, the linker will resolve all addresses, so
199 // the relocation entries will actually be constants by the time the app
200 // starts up. However, we can't put this into a mergable section, because
201 // the linker doesn't take relocations into consideration when it tries to
202 // merge entries in the section.
203 if (ReloModel == Reloc::Static)
204 return SectionKind::getReadOnly();
206 // Otherwise, the dynamic linker needs to fix it up, put it in the
207 // writable data.rel section.
208 return SectionKind::getReadOnlyWithRel();
212 // Okay, this isn't a constant. If the initializer for the global is going
213 // to require a runtime relocation by the dynamic linker, put it into a more
214 // specific section to improve startup time of the app. This coalesces these
215 // globals together onto fewer pages, improving the locality of the dynamic
217 if (ReloModel == Reloc::Static)
218 return SectionKind::getDataNoRel();
220 switch (C->getRelocationInfo()) {
221 default: llvm_unreachable("unknown relocation info kind");
222 case Constant::NoRelocation:
223 return SectionKind::getDataNoRel();
224 case Constant::LocalRelocation:
225 return SectionKind::getDataRelLocal();
226 case Constant::GlobalRelocations:
227 return SectionKind::getDataRel();
231 /// SectionForGlobal - This method computes the appropriate section to emit
232 /// the specified global variable or function definition. This should not
233 /// be passed external (or available externally) globals.
234 const MCSection *TargetLoweringObjectFile::
235 SectionForGlobal(const GlobalValue *GV, SectionKind Kind, Mangler *Mang,
236 const TargetMachine &TM) const {
237 // Select section name.
238 if (GV->hasSection())
239 return getExplicitSectionGlobal(GV, Kind, Mang, TM);
242 // Use default section depending on the 'type' of global
243 return SelectSectionForGlobal(GV, Kind, Mang, TM);
247 // Lame default implementation. Calculate the section name for global.
249 TargetLoweringObjectFile::SelectSectionForGlobal(const GlobalValue *GV,
252 const TargetMachine &TM) const{
253 assert(!Kind.isThreadLocal() && "Doesn't support TLS");
256 return getTextSection();
258 if (Kind.isBSS() && BSSSection != 0)
261 if (Kind.isReadOnly() && ReadOnlySection != 0)
262 return ReadOnlySection;
264 return getDataSection();
267 /// getSectionForConstant - Given a mergable constant with the
268 /// specified size and relocation information, return a section that it
269 /// should be placed in.
271 TargetLoweringObjectFile::getSectionForConstant(SectionKind Kind) const {
272 if (Kind.isReadOnly() && ReadOnlySection != 0)
273 return ReadOnlySection;
280 //===----------------------------------------------------------------------===//
282 //===----------------------------------------------------------------------===//
283 typedef StringMap<const MCSectionELF*> ELFUniqueMapTy;
285 TargetLoweringObjectFileELF::~TargetLoweringObjectFileELF() {
286 // If we have the section uniquing map, free it.
287 delete (ELFUniqueMapTy*)UniquingMap;
290 const MCSection *TargetLoweringObjectFileELF::
291 getELFSection(StringRef Section, unsigned Type, unsigned Flags,
292 SectionKind Kind, bool IsExplicit) const {
293 if (UniquingMap == 0)
294 UniquingMap = new ELFUniqueMapTy();
295 ELFUniqueMapTy &Map = *(ELFUniqueMapTy*)UniquingMap;
297 // Do the lookup, if we have a hit, return it.
298 const MCSectionELF *&Entry = Map[Section];
299 if (Entry) return Entry;
301 return Entry = MCSectionELF::Create(Section, Type, Flags, Kind, IsExplicit,
305 void TargetLoweringObjectFileELF::Initialize(MCContext &Ctx,
306 const TargetMachine &TM) {
307 TargetLoweringObjectFile::Initialize(Ctx, TM);
310 getELFSection(".bss", MCSectionELF::SHT_NOBITS,
311 MCSectionELF::SHF_WRITE | MCSectionELF::SHF_ALLOC,
312 SectionKind::getBSS());
315 getELFSection(".text", MCSectionELF::SHT_PROGBITS,
316 MCSectionELF::SHF_EXECINSTR | MCSectionELF::SHF_ALLOC,
317 SectionKind::getText());
320 getELFSection(".data", MCSectionELF::SHT_PROGBITS,
321 MCSectionELF::SHF_WRITE | MCSectionELF::SHF_ALLOC,
322 SectionKind::getDataRel());
325 getELFSection(".rodata", MCSectionELF::SHT_PROGBITS,
326 MCSectionELF::SHF_ALLOC,
327 SectionKind::getReadOnly());
330 getELFSection(".tdata", MCSectionELF::SHT_PROGBITS,
331 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_TLS |
332 MCSectionELF::SHF_WRITE, SectionKind::getThreadData());
335 getELFSection(".tbss", MCSectionELF::SHT_NOBITS,
336 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_TLS |
337 MCSectionELF::SHF_WRITE, SectionKind::getThreadBSS());
340 getELFSection(".data.rel", MCSectionELF::SHT_PROGBITS,
341 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
342 SectionKind::getDataRel());
344 DataRelLocalSection =
345 getELFSection(".data.rel.local", MCSectionELF::SHT_PROGBITS,
346 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
347 SectionKind::getDataRelLocal());
350 getELFSection(".data.rel.ro", MCSectionELF::SHT_PROGBITS,
351 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
352 SectionKind::getReadOnlyWithRel());
354 DataRelROLocalSection =
355 getELFSection(".data.rel.ro.local", MCSectionELF::SHT_PROGBITS,
356 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
357 SectionKind::getReadOnlyWithRelLocal());
359 MergeableConst4Section =
360 getELFSection(".rodata.cst4", MCSectionELF::SHT_PROGBITS,
361 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_MERGE,
362 SectionKind::getMergeableConst4());
364 MergeableConst8Section =
365 getELFSection(".rodata.cst8", MCSectionELF::SHT_PROGBITS,
366 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_MERGE,
367 SectionKind::getMergeableConst8());
369 MergeableConst16Section =
370 getELFSection(".rodata.cst16", MCSectionELF::SHT_PROGBITS,
371 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_MERGE,
372 SectionKind::getMergeableConst16());
375 getELFSection(".ctors", MCSectionELF::SHT_PROGBITS,
376 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
377 SectionKind::getDataRel());
380 getELFSection(".dtors", MCSectionELF::SHT_PROGBITS,
381 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
382 SectionKind::getDataRel());
384 // Exception Handling Sections.
386 // FIXME: We're emitting LSDA info into a readonly section on ELF, even though
387 // it contains relocatable pointers. In PIC mode, this is probably a big
388 // runtime hit for C++ apps. Either the contents of the LSDA need to be
389 // adjusted or this should be a data section.
391 getELFSection(".gcc_except_table", MCSectionELF::SHT_PROGBITS,
392 MCSectionELF::SHF_ALLOC, SectionKind::getReadOnly());
394 getELFSection(".eh_frame", MCSectionELF::SHT_PROGBITS,
395 MCSectionELF::SHF_ALLOC, SectionKind::getDataRel());
397 // Debug Info Sections.
399 getELFSection(".debug_abbrev", MCSectionELF::SHT_PROGBITS, 0,
400 SectionKind::getMetadata());
402 getELFSection(".debug_info", MCSectionELF::SHT_PROGBITS, 0,
403 SectionKind::getMetadata());
405 getELFSection(".debug_line", MCSectionELF::SHT_PROGBITS, 0,
406 SectionKind::getMetadata());
408 getELFSection(".debug_frame", MCSectionELF::SHT_PROGBITS, 0,
409 SectionKind::getMetadata());
410 DwarfPubNamesSection =
411 getELFSection(".debug_pubnames", MCSectionELF::SHT_PROGBITS, 0,
412 SectionKind::getMetadata());
413 DwarfPubTypesSection =
414 getELFSection(".debug_pubtypes", MCSectionELF::SHT_PROGBITS, 0,
415 SectionKind::getMetadata());
417 getELFSection(".debug_str", MCSectionELF::SHT_PROGBITS, 0,
418 SectionKind::getMetadata());
420 getELFSection(".debug_loc", MCSectionELF::SHT_PROGBITS, 0,
421 SectionKind::getMetadata());
422 DwarfARangesSection =
423 getELFSection(".debug_aranges", MCSectionELF::SHT_PROGBITS, 0,
424 SectionKind::getMetadata());
426 getELFSection(".debug_ranges", MCSectionELF::SHT_PROGBITS, 0,
427 SectionKind::getMetadata());
428 DwarfMacroInfoSection =
429 getELFSection(".debug_macinfo", MCSectionELF::SHT_PROGBITS, 0,
430 SectionKind::getMetadata());
435 getELFKindForNamedSection(const char *Name, SectionKind K) {
436 if (Name[0] != '.') return K;
438 // Some lame default implementation based on some magic section names.
439 if (strncmp(Name, ".gnu.linkonce.b.", 16) == 0 ||
440 strncmp(Name, ".llvm.linkonce.b.", 17) == 0 ||
441 strncmp(Name, ".gnu.linkonce.sb.", 17) == 0 ||
442 strncmp(Name, ".llvm.linkonce.sb.", 18) == 0)
443 return SectionKind::getBSS();
445 if (strcmp(Name, ".tdata") == 0 ||
446 strncmp(Name, ".tdata.", 7) == 0 ||
447 strncmp(Name, ".gnu.linkonce.td.", 17) == 0 ||
448 strncmp(Name, ".llvm.linkonce.td.", 18) == 0)
449 return SectionKind::getThreadData();
451 if (strcmp(Name, ".tbss") == 0 ||
452 strncmp(Name, ".tbss.", 6) == 0 ||
453 strncmp(Name, ".gnu.linkonce.tb.", 17) == 0 ||
454 strncmp(Name, ".llvm.linkonce.tb.", 18) == 0)
455 return SectionKind::getThreadBSS();
462 getELFSectionType(const char *Name, SectionKind K) {
464 if (strcmp(Name, ".init_array") == 0)
465 return MCSectionELF::SHT_INIT_ARRAY;
467 if (strcmp(Name, ".fini_array") == 0)
468 return MCSectionELF::SHT_FINI_ARRAY;
470 if (strcmp(Name, ".preinit_array") == 0)
471 return MCSectionELF::SHT_PREINIT_ARRAY;
473 if (K.isBSS() || K.isThreadBSS())
474 return MCSectionELF::SHT_NOBITS;
476 return MCSectionELF::SHT_PROGBITS;
481 getELFSectionFlags(SectionKind K) {
485 Flags |= MCSectionELF::SHF_ALLOC;
488 Flags |= MCSectionELF::SHF_WRITE;
490 if (K.isThreadLocal())
491 Flags |= MCSectionELF::SHF_TLS;
493 // K.isMergeableConst() is left out to honour PR4650
494 if (K.isMergeableCString() || K.isMergeableConst4() ||
495 K.isMergeableConst8() || K.isMergeableConst16())
496 Flags |= MCSectionELF::SHF_MERGE;
498 if (K.isMergeableCString())
499 Flags |= MCSectionELF::SHF_STRINGS;
505 const MCSection *TargetLoweringObjectFileELF::
506 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
507 Mangler *Mang, const TargetMachine &TM) const {
508 const char *SectionName = GV->getSection().c_str();
510 // Infer section flags from the section name if we can.
511 Kind = getELFKindForNamedSection(SectionName, Kind);
513 return getELFSection(SectionName,
514 getELFSectionType(SectionName, Kind),
515 getELFSectionFlags(Kind), Kind, true);
518 static const char *getSectionPrefixForUniqueGlobal(SectionKind Kind) {
519 if (Kind.isText()) return ".gnu.linkonce.t.";
520 if (Kind.isReadOnly()) return ".gnu.linkonce.r.";
522 if (Kind.isThreadData()) return ".gnu.linkonce.td.";
523 if (Kind.isThreadBSS()) return ".gnu.linkonce.tb.";
525 if (Kind.isBSS()) return ".gnu.linkonce.b.";
526 if (Kind.isDataNoRel()) return ".gnu.linkonce.d.";
527 if (Kind.isDataRelLocal()) return ".gnu.linkonce.d.rel.local.";
528 if (Kind.isDataRel()) return ".gnu.linkonce.d.rel.";
529 if (Kind.isReadOnlyWithRelLocal()) return ".gnu.linkonce.d.rel.ro.local.";
531 assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
532 return ".gnu.linkonce.d.rel.ro.";
535 const MCSection *TargetLoweringObjectFileELF::
536 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
537 Mangler *Mang, const TargetMachine &TM) const {
539 // If this global is linkonce/weak and the target handles this by emitting it
540 // into a 'uniqued' section name, create and return the section now.
541 if (GV->isWeakForLinker()) {
542 const char *Prefix = getSectionPrefixForUniqueGlobal(Kind);
543 std::string Name = Mang->makeNameProper(GV->getNameStr());
545 return getELFSection((Prefix+Name).c_str(),
546 getELFSectionType((Prefix+Name).c_str(), Kind),
547 getELFSectionFlags(Kind),
551 if (Kind.isText()) return TextSection;
553 if (Kind.isMergeable1ByteCString() ||
554 Kind.isMergeable2ByteCString() ||
555 Kind.isMergeable4ByteCString()) {
557 // We also need alignment here.
558 // FIXME: this is getting the alignment of the character, not the
559 // alignment of the global!
561 TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV));
563 const char *SizeSpec = ".rodata.str1.";
564 if (Kind.isMergeable2ByteCString())
565 SizeSpec = ".rodata.str2.";
566 else if (Kind.isMergeable4ByteCString())
567 SizeSpec = ".rodata.str4.";
569 assert(Kind.isMergeable1ByteCString() && "unknown string width");
572 std::string Name = SizeSpec + utostr(Align);
573 return getELFSection(Name.c_str(), MCSectionELF::SHT_PROGBITS,
574 MCSectionELF::SHF_ALLOC |
575 MCSectionELF::SHF_MERGE |
576 MCSectionELF::SHF_STRINGS,
580 if (Kind.isMergeableConst()) {
581 if (Kind.isMergeableConst4())
582 return MergeableConst4Section;
583 if (Kind.isMergeableConst8())
584 return MergeableConst8Section;
585 if (Kind.isMergeableConst16())
586 return MergeableConst16Section;
587 return ReadOnlySection; // .const
590 if (Kind.isReadOnly()) return ReadOnlySection;
592 if (Kind.isThreadData()) return TLSDataSection;
593 if (Kind.isThreadBSS()) return TLSBSSSection;
595 if (Kind.isBSS()) return BSSSection;
597 if (Kind.isDataNoRel()) return DataSection;
598 if (Kind.isDataRelLocal()) return DataRelLocalSection;
599 if (Kind.isDataRel()) return DataRelSection;
600 if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection;
602 assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
603 return DataRelROSection;
606 /// getSectionForConstant - Given a mergeable constant with the
607 /// specified size and relocation information, return a section that it
608 /// should be placed in.
609 const MCSection *TargetLoweringObjectFileELF::
610 getSectionForConstant(SectionKind Kind) const {
611 if (Kind.isMergeableConst4())
612 return MergeableConst4Section;
613 if (Kind.isMergeableConst8())
614 return MergeableConst8Section;
615 if (Kind.isMergeableConst16())
616 return MergeableConst16Section;
617 if (Kind.isReadOnly())
618 return ReadOnlySection;
620 if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection;
621 assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
622 return DataRelROSection;
625 //===----------------------------------------------------------------------===//
627 //===----------------------------------------------------------------------===//
629 typedef StringMap<const MCSectionMachO*> MachOUniqueMapTy;
631 TargetLoweringObjectFileMachO::~TargetLoweringObjectFileMachO() {
632 // If we have the MachO uniquing map, free it.
633 delete (MachOUniqueMapTy*)UniquingMap;
637 const MCSectionMachO *TargetLoweringObjectFileMachO::
638 getMachOSection(const StringRef &Segment, const StringRef &Section,
639 unsigned TypeAndAttributes,
640 unsigned Reserved2, SectionKind Kind) const {
641 // We unique sections by their segment/section pair. The returned section
642 // may not have the same flags as the requested section, if so this should be
643 // diagnosed by the client as an error.
645 // Create the map if it doesn't already exist.
646 if (UniquingMap == 0)
647 UniquingMap = new MachOUniqueMapTy();
648 MachOUniqueMapTy &Map = *(MachOUniqueMapTy*)UniquingMap;
650 // Form the name to look up.
651 SmallString<64> Name;
652 Name.append(Segment.begin(), Segment.end());
654 Name.append(Section.begin(), Section.end());
656 // Do the lookup, if we have a hit, return it.
657 const MCSectionMachO *&Entry = Map[StringRef(Name.data(), Name.size())];
658 if (Entry) return Entry;
660 // Otherwise, return a new section.
661 return Entry = MCSectionMachO::Create(Segment, Section, TypeAndAttributes,
662 Reserved2, Kind, getContext());
666 void TargetLoweringObjectFileMachO::Initialize(MCContext &Ctx,
667 const TargetMachine &TM) {
668 TargetLoweringObjectFile::Initialize(Ctx, TM);
671 = getMachOSection("__TEXT", "__text",
672 MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
673 SectionKind::getText());
675 = getMachOSection("__DATA", "__data", 0, SectionKind::getDataRel());
677 CStringSection // .cstring
678 = getMachOSection("__TEXT", "__cstring", MCSectionMachO::S_CSTRING_LITERALS,
679 SectionKind::getMergeable1ByteCString());
681 = getMachOSection("__TEXT","__ustring", 0,
682 SectionKind::getMergeable2ByteCString());
683 FourByteConstantSection // .literal4
684 = getMachOSection("__TEXT", "__literal4", MCSectionMachO::S_4BYTE_LITERALS,
685 SectionKind::getMergeableConst4());
686 EightByteConstantSection // .literal8
687 = getMachOSection("__TEXT", "__literal8", MCSectionMachO::S_8BYTE_LITERALS,
688 SectionKind::getMergeableConst8());
690 // ld_classic doesn't support .literal16 in 32-bit mode, and ld64 falls back
691 // to using it in -static mode.
692 SixteenByteConstantSection = 0;
693 if (TM.getRelocationModel() != Reloc::Static &&
694 TM.getTargetData()->getPointerSize() == 32)
695 SixteenByteConstantSection = // .literal16
696 getMachOSection("__TEXT", "__literal16",MCSectionMachO::S_16BYTE_LITERALS,
697 SectionKind::getMergeableConst16());
699 ReadOnlySection // .const
700 = getMachOSection("__TEXT", "__const", 0, SectionKind::getReadOnly());
703 = getMachOSection("__TEXT", "__textcoal_nt",
704 MCSectionMachO::S_COALESCED |
705 MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
706 SectionKind::getText());
708 = getMachOSection("__TEXT", "__const_coal", MCSectionMachO::S_COALESCED,
709 SectionKind::getText());
711 = getMachOSection("__DATA","__const_coal", MCSectionMachO::S_COALESCED,
712 SectionKind::getText());
713 ConstDataSection // .const_data
714 = getMachOSection("__DATA", "__const", 0,
715 SectionKind::getReadOnlyWithRel());
717 = getMachOSection("__DATA","__datacoal_nt", MCSectionMachO::S_COALESCED,
718 SectionKind::getDataRel());
721 LazySymbolPointerSection
722 = getMachOSection("__DATA", "__la_symbol_ptr",
723 MCSectionMachO::S_LAZY_SYMBOL_POINTERS,
724 SectionKind::getMetadata());
725 NonLazySymbolPointerSection
726 = getMachOSection("__DATA", "__nl_symbol_ptr",
727 MCSectionMachO::S_NON_LAZY_SYMBOL_POINTERS,
728 SectionKind::getMetadata());
730 if (TM.getRelocationModel() == Reloc::Static) {
732 = getMachOSection("__TEXT", "__constructor", 0,SectionKind::getDataRel());
734 = getMachOSection("__TEXT", "__destructor", 0, SectionKind::getDataRel());
737 = getMachOSection("__DATA", "__mod_init_func",
738 MCSectionMachO::S_MOD_INIT_FUNC_POINTERS,
739 SectionKind::getDataRel());
741 = getMachOSection("__DATA", "__mod_term_func",
742 MCSectionMachO::S_MOD_TERM_FUNC_POINTERS,
743 SectionKind::getDataRel());
746 // Exception Handling.
747 LSDASection = getMachOSection("__DATA", "__gcc_except_tab", 0,
748 SectionKind::getDataRel());
750 getMachOSection("__TEXT", "__eh_frame",
751 MCSectionMachO::S_COALESCED |
752 MCSectionMachO::S_ATTR_NO_TOC |
753 MCSectionMachO::S_ATTR_STRIP_STATIC_SYMS |
754 MCSectionMachO::S_ATTR_LIVE_SUPPORT,
755 SectionKind::getReadOnly());
757 // Debug Information.
759 getMachOSection("__DWARF", "__debug_abbrev", MCSectionMachO::S_ATTR_DEBUG,
760 SectionKind::getMetadata());
762 getMachOSection("__DWARF", "__debug_info", MCSectionMachO::S_ATTR_DEBUG,
763 SectionKind::getMetadata());
765 getMachOSection("__DWARF", "__debug_line", MCSectionMachO::S_ATTR_DEBUG,
766 SectionKind::getMetadata());
768 getMachOSection("__DWARF", "__debug_frame", MCSectionMachO::S_ATTR_DEBUG,
769 SectionKind::getMetadata());
770 DwarfPubNamesSection =
771 getMachOSection("__DWARF", "__debug_pubnames", MCSectionMachO::S_ATTR_DEBUG,
772 SectionKind::getMetadata());
773 DwarfPubTypesSection =
774 getMachOSection("__DWARF", "__debug_pubtypes", MCSectionMachO::S_ATTR_DEBUG,
775 SectionKind::getMetadata());
777 getMachOSection("__DWARF", "__debug_str", MCSectionMachO::S_ATTR_DEBUG,
778 SectionKind::getMetadata());
780 getMachOSection("__DWARF", "__debug_loc", MCSectionMachO::S_ATTR_DEBUG,
781 SectionKind::getMetadata());
782 DwarfARangesSection =
783 getMachOSection("__DWARF", "__debug_aranges", MCSectionMachO::S_ATTR_DEBUG,
784 SectionKind::getMetadata());
786 getMachOSection("__DWARF", "__debug_ranges", MCSectionMachO::S_ATTR_DEBUG,
787 SectionKind::getMetadata());
788 DwarfMacroInfoSection =
789 getMachOSection("__DWARF", "__debug_macinfo", MCSectionMachO::S_ATTR_DEBUG,
790 SectionKind::getMetadata());
791 DwarfDebugInlineSection =
792 getMachOSection("__DWARF", "__debug_inlined", MCSectionMachO::S_ATTR_DEBUG,
793 SectionKind::getMetadata());
796 const MCSection *TargetLoweringObjectFileMachO::
797 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
798 Mangler *Mang, const TargetMachine &TM) const {
799 // Parse the section specifier and create it if valid.
800 StringRef Segment, Section;
801 unsigned TAA, StubSize;
802 std::string ErrorCode =
803 MCSectionMachO::ParseSectionSpecifier(GV->getSection(), Segment, Section,
805 if (!ErrorCode.empty()) {
806 // If invalid, report the error with llvm_report_error.
807 llvm_report_error("Global variable '" + GV->getNameStr() +
808 "' has an invalid section specifier '" + GV->getSection()+
809 "': " + ErrorCode + ".");
810 // Fall back to dropping it into the data section.
815 const MCSectionMachO *S =
816 getMachOSection(Segment, Section, TAA, StubSize, Kind);
818 // Okay, now that we got the section, verify that the TAA & StubSize agree.
819 // If the user declared multiple globals with different section flags, we need
820 // to reject it here.
821 if (S->getTypeAndAttributes() != TAA || S->getStubSize() != StubSize) {
822 // If invalid, report the error with llvm_report_error.
823 llvm_report_error("Global variable '" + GV->getNameStr() +
824 "' section type or attributes does not match previous"
825 " section specifier");
831 const MCSection *TargetLoweringObjectFileMachO::
832 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
833 Mangler *Mang, const TargetMachine &TM) const {
834 assert(!Kind.isThreadLocal() && "Darwin doesn't support TLS");
837 return GV->isWeakForLinker() ? TextCoalSection : TextSection;
839 // If this is weak/linkonce, put this in a coalescable section, either in text
840 // or data depending on if it is writable.
841 if (GV->isWeakForLinker()) {
842 if (Kind.isReadOnly())
843 return ConstTextCoalSection;
844 return DataCoalSection;
847 // FIXME: Alignment check should be handled by section classifier.
848 if (Kind.isMergeable1ByteCString() ||
849 Kind.isMergeable2ByteCString()) {
850 if (TM.getTargetData()->getPreferredAlignment(
851 cast<GlobalVariable>(GV)) < 32) {
852 if (Kind.isMergeable1ByteCString())
853 return CStringSection;
854 assert(Kind.isMergeable2ByteCString());
855 return UStringSection;
859 if (Kind.isMergeableConst()) {
860 if (Kind.isMergeableConst4())
861 return FourByteConstantSection;
862 if (Kind.isMergeableConst8())
863 return EightByteConstantSection;
864 if (Kind.isMergeableConst16() && SixteenByteConstantSection)
865 return SixteenByteConstantSection;
868 // Otherwise, if it is readonly, but not something we can specially optimize,
869 // just drop it in .const.
870 if (Kind.isReadOnly())
871 return ReadOnlySection;
873 // If this is marked const, put it into a const section. But if the dynamic
874 // linker needs to write to it, put it in the data segment.
875 if (Kind.isReadOnlyWithRel())
876 return ConstDataSection;
878 // Otherwise, just drop the variable in the normal data section.
883 TargetLoweringObjectFileMachO::getSectionForConstant(SectionKind Kind) const {
884 // If this constant requires a relocation, we have to put it in the data
885 // segment, not in the text segment.
886 if (Kind.isDataRel())
887 return ConstDataSection;
889 if (Kind.isMergeableConst4())
890 return FourByteConstantSection;
891 if (Kind.isMergeableConst8())
892 return EightByteConstantSection;
893 if (Kind.isMergeableConst16() && SixteenByteConstantSection)
894 return SixteenByteConstantSection;
895 return ReadOnlySection; // .const
898 /// shouldEmitUsedDirectiveFor - This hook allows targets to selectively decide
899 /// not to emit the UsedDirective for some symbols in llvm.used.
900 // FIXME: REMOVE this (rdar://7071300)
901 bool TargetLoweringObjectFileMachO::
902 shouldEmitUsedDirectiveFor(const GlobalValue *GV, Mangler *Mang) const {
903 /// On Darwin, internally linked data beginning with "L" or "l" does not have
904 /// the directive emitted (this occurs in ObjC metadata).
905 if (!GV) return false;
907 // Check whether the mangled name has the "Private" or "LinkerPrivate" prefix.
908 if (GV->hasLocalLinkage() && !isa<Function>(GV)) {
909 // FIXME: ObjC metadata is currently emitted as internal symbols that have
910 // \1L and \0l prefixes on them. Fix them to be Private/LinkerPrivate and
911 // this horrible hack can go away.
912 const std::string &Name = Mang->getMangledName(GV);
913 if (Name[0] == 'L' || Name[0] == 'l')
921 //===----------------------------------------------------------------------===//
923 //===----------------------------------------------------------------------===//
925 typedef StringMap<const MCSectionCOFF*> COFFUniqueMapTy;
927 TargetLoweringObjectFileCOFF::~TargetLoweringObjectFileCOFF() {
928 delete (COFFUniqueMapTy*)UniquingMap;
932 const MCSection *TargetLoweringObjectFileCOFF::
933 getCOFFSection(const char *Name, bool isDirective, SectionKind Kind) const {
934 // Create the map if it doesn't already exist.
935 if (UniquingMap == 0)
936 UniquingMap = new MachOUniqueMapTy();
937 COFFUniqueMapTy &Map = *(COFFUniqueMapTy*)UniquingMap;
939 // Do the lookup, if we have a hit, return it.
940 const MCSectionCOFF *&Entry = Map[Name];
941 if (Entry) return Entry;
943 return Entry = MCSectionCOFF::Create(Name, isDirective, Kind, getContext());
946 void TargetLoweringObjectFileCOFF::Initialize(MCContext &Ctx,
947 const TargetMachine &TM) {
948 TargetLoweringObjectFile::Initialize(Ctx, TM);
949 TextSection = getCOFFSection("\t.text", true, SectionKind::getText());
950 DataSection = getCOFFSection("\t.data", true, SectionKind::getDataRel());
952 getCOFFSection(".ctors", false, SectionKind::getDataRel());
954 getCOFFSection(".dtors", false, SectionKind::getDataRel());
958 // FIXME: Don't use 'directive' mode here.
960 getCOFFSection("\t.section\t.debug_abbrev,\"dr\"",
961 true, SectionKind::getMetadata());
963 getCOFFSection("\t.section\t.debug_info,\"dr\"",
964 true, SectionKind::getMetadata());
966 getCOFFSection("\t.section\t.debug_line,\"dr\"",
967 true, SectionKind::getMetadata());
969 getCOFFSection("\t.section\t.debug_frame,\"dr\"",
970 true, SectionKind::getMetadata());
971 DwarfPubNamesSection =
972 getCOFFSection("\t.section\t.debug_pubnames,\"dr\"",
973 true, SectionKind::getMetadata());
974 DwarfPubTypesSection =
975 getCOFFSection("\t.section\t.debug_pubtypes,\"dr\"",
976 true, SectionKind::getMetadata());
978 getCOFFSection("\t.section\t.debug_str,\"dr\"",
979 true, SectionKind::getMetadata());
981 getCOFFSection("\t.section\t.debug_loc,\"dr\"",
982 true, SectionKind::getMetadata());
983 DwarfARangesSection =
984 getCOFFSection("\t.section\t.debug_aranges,\"dr\"",
985 true, SectionKind::getMetadata());
987 getCOFFSection("\t.section\t.debug_ranges,\"dr\"",
988 true, SectionKind::getMetadata());
989 DwarfMacroInfoSection =
990 getCOFFSection("\t.section\t.debug_macinfo,\"dr\"",
991 true, SectionKind::getMetadata());
994 const MCSection *TargetLoweringObjectFileCOFF::
995 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
996 Mangler *Mang, const TargetMachine &TM) const {
997 return getCOFFSection(GV->getSection().c_str(), false, Kind);
1000 static const char *getCOFFSectionPrefixForUniqueGlobal(SectionKind Kind) {
1002 return ".text$linkonce";
1003 if (Kind.isWriteable())
1004 return ".data$linkonce";
1005 return ".rdata$linkonce";
1009 const MCSection *TargetLoweringObjectFileCOFF::
1010 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
1011 Mangler *Mang, const TargetMachine &TM) const {
1012 assert(!Kind.isThreadLocal() && "Doesn't support TLS");
1014 // If this global is linkonce/weak and the target handles this by emitting it
1015 // into a 'uniqued' section name, create and return the section now.
1016 if (GV->isWeakForLinker()) {
1017 const char *Prefix = getCOFFSectionPrefixForUniqueGlobal(Kind);
1018 std::string Name = Mang->makeNameProper(GV->getNameStr());
1019 return getCOFFSection((Prefix+Name).c_str(), false, Kind);
1023 return getTextSection();
1025 return getDataSection();