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/MCExpr.h"
22 #include "llvm/MC/MCSectionMachO.h"
23 #include "llvm/MC/MCSectionELF.h"
24 #include "llvm/MC/MCSymbol.h"
25 #include "llvm/Target/Mangler.h"
26 #include "llvm/Target/TargetData.h"
27 #include "llvm/Target/TargetMachine.h"
28 #include "llvm/Target/TargetOptions.h"
29 #include "llvm/Support/ErrorHandling.h"
30 #include "llvm/Support/raw_ostream.h"
31 #include "llvm/ADT/SmallString.h"
32 #include "llvm/ADT/StringExtras.h"
35 //===----------------------------------------------------------------------===//
37 //===----------------------------------------------------------------------===//
39 TargetLoweringObjectFile::TargetLoweringObjectFile() : Ctx(0) {
44 StaticCtorSection = 0;
45 StaticDtorSection = 0;
49 DwarfAbbrevSection = 0;
52 DwarfFrameSection = 0;
53 DwarfPubNamesSection = 0;
54 DwarfPubTypesSection = 0;
55 DwarfDebugInlineSection = 0;
58 DwarfARangesSection = 0;
59 DwarfRangesSection = 0;
60 DwarfMacroInfoSection = 0;
63 TargetLoweringObjectFile::~TargetLoweringObjectFile() {
66 static bool isSuitableForBSS(const GlobalVariable *GV) {
67 Constant *C = GV->getInitializer();
69 // Must have zero initializer.
70 if (!C->isNullValue())
73 // Leave constant zeros in readonly constant sections, so they can be shared.
77 // If the global has an explicit section specified, don't put it in BSS.
78 if (!GV->getSection().empty())
81 // If -nozero-initialized-in-bss is specified, don't ever use BSS.
85 // Otherwise, put it in BSS!
89 /// IsNullTerminatedString - Return true if the specified constant (which is
90 /// known to have a type that is an array of 1/2/4 byte elements) ends with a
91 /// nul value and contains no other nuls in it.
92 static bool IsNullTerminatedString(const Constant *C) {
93 const ArrayType *ATy = cast<ArrayType>(C->getType());
95 // First check: is we have constant array of i8 terminated with zero
96 if (const ConstantArray *CVA = dyn_cast<ConstantArray>(C)) {
97 if (ATy->getNumElements() == 0) return false;
100 dyn_cast<ConstantInt>(CVA->getOperand(ATy->getNumElements()-1));
101 if (Null == 0 || Null->getZExtValue() != 0)
102 return false; // Not null terminated.
104 // Verify that the null doesn't occur anywhere else in the string.
105 for (unsigned i = 0, e = ATy->getNumElements()-1; i != e; ++i)
106 // Reject constantexpr elements etc.
107 if (!isa<ConstantInt>(CVA->getOperand(i)) ||
108 CVA->getOperand(i) == Null)
113 // Another possibility: [1 x i8] zeroinitializer
114 if (isa<ConstantAggregateZero>(C))
115 return ATy->getNumElements() == 1;
120 /// getKindForGlobal - This is a top-level target-independent classifier for
121 /// a global variable. Given an global variable and information from TM, it
122 /// classifies the global in a variety of ways that make various target
123 /// implementations simpler. The target implementation is free to ignore this
124 /// extra info of course.
125 SectionKind TargetLoweringObjectFile::getKindForGlobal(const GlobalValue *GV,
126 const TargetMachine &TM){
127 assert(!GV->isDeclaration() && !GV->hasAvailableExternallyLinkage() &&
128 "Can only be used for global definitions");
130 Reloc::Model ReloModel = TM.getRelocationModel();
132 // Early exit - functions should be always in text sections.
133 const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV);
135 return SectionKind::getText();
137 // Handle thread-local data first.
138 if (GVar->isThreadLocal()) {
139 if (isSuitableForBSS(GVar))
140 return SectionKind::getThreadBSS();
141 return SectionKind::getThreadData();
144 // Variable can be easily put to BSS section.
145 if (isSuitableForBSS(GVar))
146 return SectionKind::getBSS();
148 Constant *C = GVar->getInitializer();
150 // If the global is marked constant, we can put it into a mergable section,
151 // a mergable string section, or general .data if it contains relocations.
152 if (GVar->isConstant()) {
153 // If the initializer for the global contains something that requires a
154 // relocation, then we may have to drop this into a wriable data section
155 // even though it is marked const.
156 switch (C->getRelocationInfo()) {
157 default: assert(0 && "unknown relocation info kind");
158 case Constant::NoRelocation:
159 // If initializer is a null-terminated string, put it in a "cstring"
160 // section of the right width.
161 if (const ArrayType *ATy = dyn_cast<ArrayType>(C->getType())) {
162 if (const IntegerType *ITy =
163 dyn_cast<IntegerType>(ATy->getElementType())) {
164 if ((ITy->getBitWidth() == 8 || ITy->getBitWidth() == 16 ||
165 ITy->getBitWidth() == 32) &&
166 IsNullTerminatedString(C)) {
167 if (ITy->getBitWidth() == 8)
168 return SectionKind::getMergeable1ByteCString();
169 if (ITy->getBitWidth() == 16)
170 return SectionKind::getMergeable2ByteCString();
172 assert(ITy->getBitWidth() == 32 && "Unknown width");
173 return SectionKind::getMergeable4ByteCString();
178 // Otherwise, just drop it into a mergable constant section. If we have
179 // a section for this size, use it, otherwise use the arbitrary sized
181 switch (TM.getTargetData()->getTypeAllocSize(C->getType())) {
182 case 4: return SectionKind::getMergeableConst4();
183 case 8: return SectionKind::getMergeableConst8();
184 case 16: return SectionKind::getMergeableConst16();
185 default: return SectionKind::getMergeableConst();
188 case Constant::LocalRelocation:
189 // In static relocation model, the linker will resolve all addresses, so
190 // the relocation entries will actually be constants by the time the app
191 // starts up. However, we can't put this into a mergable section, because
192 // the linker doesn't take relocations into consideration when it tries to
193 // merge entries in the section.
194 if (ReloModel == Reloc::Static)
195 return SectionKind::getReadOnly();
197 // Otherwise, the dynamic linker needs to fix it up, put it in the
198 // writable data.rel.local section.
199 return SectionKind::getReadOnlyWithRelLocal();
201 case Constant::GlobalRelocations:
202 // In static relocation model, the linker will resolve all addresses, so
203 // the relocation entries will actually be constants by the time the app
204 // starts up. However, we can't put this into a mergable section, because
205 // the linker doesn't take relocations into consideration when it tries to
206 // merge entries in the section.
207 if (ReloModel == Reloc::Static)
208 return SectionKind::getReadOnly();
210 // Otherwise, the dynamic linker needs to fix it up, put it in the
211 // writable data.rel section.
212 return SectionKind::getReadOnlyWithRel();
216 // Okay, this isn't a constant. If the initializer for the global is going
217 // to require a runtime relocation by the dynamic linker, put it into a more
218 // specific section to improve startup time of the app. This coalesces these
219 // globals together onto fewer pages, improving the locality of the dynamic
221 if (ReloModel == Reloc::Static)
222 return SectionKind::getDataNoRel();
224 switch (C->getRelocationInfo()) {
225 default: assert(0 && "unknown relocation info kind");
226 case Constant::NoRelocation:
227 return SectionKind::getDataNoRel();
228 case Constant::LocalRelocation:
229 return SectionKind::getDataRelLocal();
230 case Constant::GlobalRelocations:
231 return SectionKind::getDataRel();
235 /// SectionForGlobal - This method computes the appropriate section to emit
236 /// the specified global variable or function definition. This should not
237 /// be passed external (or available externally) globals.
238 const MCSection *TargetLoweringObjectFile::
239 SectionForGlobal(const GlobalValue *GV, SectionKind Kind, Mangler *Mang,
240 const TargetMachine &TM) const {
241 // Select section name.
242 if (GV->hasSection())
243 return getExplicitSectionGlobal(GV, Kind, Mang, TM);
246 // Use default section depending on the 'type' of global
247 return SelectSectionForGlobal(GV, Kind, Mang, TM);
251 // Lame default implementation. Calculate the section name for global.
253 TargetLoweringObjectFile::SelectSectionForGlobal(const GlobalValue *GV,
256 const TargetMachine &TM) const{
257 assert(!Kind.isThreadLocal() && "Doesn't support TLS");
260 return getTextSection();
262 if (Kind.isBSS() && BSSSection != 0)
265 if (Kind.isReadOnly() && ReadOnlySection != 0)
266 return ReadOnlySection;
268 return getDataSection();
271 /// getSectionForConstant - Given a mergable constant with the
272 /// specified size and relocation information, return a section that it
273 /// should be placed in.
275 TargetLoweringObjectFile::getSectionForConstant(SectionKind Kind) const {
276 if (Kind.isReadOnly() && ReadOnlySection != 0)
277 return ReadOnlySection;
282 /// getSymbolForDwarfGlobalReference - Return an MCExpr to use for a
283 /// pc-relative reference to the specified global variable from exception
284 /// handling information. In addition to the symbol, this returns
287 /// IsIndirect - True if the returned symbol is actually a stub that contains
288 /// the address of the symbol, false if the symbol is the global itself.
290 /// IsPCRel - True if the symbol reference is already pc-relative, false if
291 /// the caller needs to subtract off the address of the reference from the
294 const MCExpr *TargetLoweringObjectFile::
295 getSymbolForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang,
296 MachineModuleInfo *MMI,
297 bool &IsIndirect, bool &IsPCRel) const {
298 // The generic implementation of this just returns a direct reference to the
303 // FIXME: Use GetGlobalValueSymbol.
304 SmallString<128> Name;
305 Mang->getNameWithPrefix(Name, GV, false);
306 return MCSymbolRefExpr::Create(Name.str(), getContext());
310 //===----------------------------------------------------------------------===//
312 //===----------------------------------------------------------------------===//
313 typedef StringMap<const MCSectionELF*> ELFUniqueMapTy;
315 TargetLoweringObjectFileELF::~TargetLoweringObjectFileELF() {
316 // If we have the section uniquing map, free it.
317 delete (ELFUniqueMapTy*)UniquingMap;
320 const MCSection *TargetLoweringObjectFileELF::
321 getELFSection(StringRef Section, unsigned Type, unsigned Flags,
322 SectionKind Kind, bool IsExplicit) const {
323 if (UniquingMap == 0)
324 UniquingMap = new ELFUniqueMapTy();
325 ELFUniqueMapTy &Map = *(ELFUniqueMapTy*)UniquingMap;
327 // Do the lookup, if we have a hit, return it.
328 const MCSectionELF *&Entry = Map[Section];
329 if (Entry) return Entry;
331 return Entry = MCSectionELF::Create(Section, Type, Flags, Kind, IsExplicit,
335 void TargetLoweringObjectFileELF::Initialize(MCContext &Ctx,
336 const TargetMachine &TM) {
337 if (UniquingMap != 0)
338 ((ELFUniqueMapTy*)UniquingMap)->clear();
339 TargetLoweringObjectFile::Initialize(Ctx, TM);
342 getELFSection(".bss", MCSectionELF::SHT_NOBITS,
343 MCSectionELF::SHF_WRITE | MCSectionELF::SHF_ALLOC,
344 SectionKind::getBSS());
347 getELFSection(".text", MCSectionELF::SHT_PROGBITS,
348 MCSectionELF::SHF_EXECINSTR | MCSectionELF::SHF_ALLOC,
349 SectionKind::getText());
352 getELFSection(".data", MCSectionELF::SHT_PROGBITS,
353 MCSectionELF::SHF_WRITE | MCSectionELF::SHF_ALLOC,
354 SectionKind::getDataRel());
357 getELFSection(".rodata", MCSectionELF::SHT_PROGBITS,
358 MCSectionELF::SHF_ALLOC,
359 SectionKind::getReadOnly());
362 getELFSection(".tdata", MCSectionELF::SHT_PROGBITS,
363 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_TLS |
364 MCSectionELF::SHF_WRITE, SectionKind::getThreadData());
367 getELFSection(".tbss", MCSectionELF::SHT_NOBITS,
368 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_TLS |
369 MCSectionELF::SHF_WRITE, SectionKind::getThreadBSS());
372 getELFSection(".data.rel", MCSectionELF::SHT_PROGBITS,
373 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
374 SectionKind::getDataRel());
376 DataRelLocalSection =
377 getELFSection(".data.rel.local", MCSectionELF::SHT_PROGBITS,
378 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
379 SectionKind::getDataRelLocal());
382 getELFSection(".data.rel.ro", MCSectionELF::SHT_PROGBITS,
383 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
384 SectionKind::getReadOnlyWithRel());
386 DataRelROLocalSection =
387 getELFSection(".data.rel.ro.local", MCSectionELF::SHT_PROGBITS,
388 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
389 SectionKind::getReadOnlyWithRelLocal());
391 MergeableConst4Section =
392 getELFSection(".rodata.cst4", MCSectionELF::SHT_PROGBITS,
393 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_MERGE,
394 SectionKind::getMergeableConst4());
396 MergeableConst8Section =
397 getELFSection(".rodata.cst8", MCSectionELF::SHT_PROGBITS,
398 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_MERGE,
399 SectionKind::getMergeableConst8());
401 MergeableConst16Section =
402 getELFSection(".rodata.cst16", MCSectionELF::SHT_PROGBITS,
403 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_MERGE,
404 SectionKind::getMergeableConst16());
407 getELFSection(".ctors", MCSectionELF::SHT_PROGBITS,
408 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
409 SectionKind::getDataRel());
412 getELFSection(".dtors", MCSectionELF::SHT_PROGBITS,
413 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
414 SectionKind::getDataRel());
416 // Exception Handling Sections.
418 // FIXME: We're emitting LSDA info into a readonly section on ELF, even though
419 // it contains relocatable pointers. In PIC mode, this is probably a big
420 // runtime hit for C++ apps. Either the contents of the LSDA need to be
421 // adjusted or this should be a data section.
423 getELFSection(".gcc_except_table", MCSectionELF::SHT_PROGBITS,
424 MCSectionELF::SHF_ALLOC, SectionKind::getReadOnly());
426 getELFSection(".eh_frame", MCSectionELF::SHT_PROGBITS,
427 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
428 SectionKind::getDataRel());
430 // Debug Info Sections.
432 getELFSection(".debug_abbrev", MCSectionELF::SHT_PROGBITS, 0,
433 SectionKind::getMetadata());
435 getELFSection(".debug_info", MCSectionELF::SHT_PROGBITS, 0,
436 SectionKind::getMetadata());
438 getELFSection(".debug_line", MCSectionELF::SHT_PROGBITS, 0,
439 SectionKind::getMetadata());
441 getELFSection(".debug_frame", MCSectionELF::SHT_PROGBITS, 0,
442 SectionKind::getMetadata());
443 DwarfPubNamesSection =
444 getELFSection(".debug_pubnames", MCSectionELF::SHT_PROGBITS, 0,
445 SectionKind::getMetadata());
446 DwarfPubTypesSection =
447 getELFSection(".debug_pubtypes", MCSectionELF::SHT_PROGBITS, 0,
448 SectionKind::getMetadata());
450 getELFSection(".debug_str", MCSectionELF::SHT_PROGBITS, 0,
451 SectionKind::getMetadata());
453 getELFSection(".debug_loc", MCSectionELF::SHT_PROGBITS, 0,
454 SectionKind::getMetadata());
455 DwarfARangesSection =
456 getELFSection(".debug_aranges", MCSectionELF::SHT_PROGBITS, 0,
457 SectionKind::getMetadata());
459 getELFSection(".debug_ranges", MCSectionELF::SHT_PROGBITS, 0,
460 SectionKind::getMetadata());
461 DwarfMacroInfoSection =
462 getELFSection(".debug_macinfo", MCSectionELF::SHT_PROGBITS, 0,
463 SectionKind::getMetadata());
468 getELFKindForNamedSection(const char *Name, SectionKind K) {
469 if (Name[0] != '.') return K;
471 // Some lame default implementation based on some magic section names.
472 if (strcmp(Name, ".bss") == 0 ||
473 strncmp(Name, ".bss.", 5) == 0 ||
474 strncmp(Name, ".gnu.linkonce.b.", 16) == 0 ||
475 strncmp(Name, ".llvm.linkonce.b.", 17) == 0 ||
476 strcmp(Name, ".sbss") == 0 ||
477 strncmp(Name, ".sbss.", 6) == 0 ||
478 strncmp(Name, ".gnu.linkonce.sb.", 17) == 0 ||
479 strncmp(Name, ".llvm.linkonce.sb.", 18) == 0)
480 return SectionKind::getBSS();
482 if (strcmp(Name, ".tdata") == 0 ||
483 strncmp(Name, ".tdata.", 7) == 0 ||
484 strncmp(Name, ".gnu.linkonce.td.", 17) == 0 ||
485 strncmp(Name, ".llvm.linkonce.td.", 18) == 0)
486 return SectionKind::getThreadData();
488 if (strcmp(Name, ".tbss") == 0 ||
489 strncmp(Name, ".tbss.", 6) == 0 ||
490 strncmp(Name, ".gnu.linkonce.tb.", 17) == 0 ||
491 strncmp(Name, ".llvm.linkonce.tb.", 18) == 0)
492 return SectionKind::getThreadBSS();
498 static unsigned getELFSectionType(StringRef Name, SectionKind K) {
500 if (Name == ".init_array")
501 return MCSectionELF::SHT_INIT_ARRAY;
503 if (Name == ".fini_array")
504 return MCSectionELF::SHT_FINI_ARRAY;
506 if (Name == ".preinit_array")
507 return MCSectionELF::SHT_PREINIT_ARRAY;
509 if (K.isBSS() || K.isThreadBSS())
510 return MCSectionELF::SHT_NOBITS;
512 return MCSectionELF::SHT_PROGBITS;
517 getELFSectionFlags(SectionKind K) {
521 Flags |= MCSectionELF::SHF_ALLOC;
524 Flags |= MCSectionELF::SHF_EXECINSTR;
527 Flags |= MCSectionELF::SHF_WRITE;
529 if (K.isThreadLocal())
530 Flags |= MCSectionELF::SHF_TLS;
532 // K.isMergeableConst() is left out to honour PR4650
533 if (K.isMergeableCString() || K.isMergeableConst4() ||
534 K.isMergeableConst8() || K.isMergeableConst16())
535 Flags |= MCSectionELF::SHF_MERGE;
537 if (K.isMergeableCString())
538 Flags |= MCSectionELF::SHF_STRINGS;
544 const MCSection *TargetLoweringObjectFileELF::
545 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
546 Mangler *Mang, const TargetMachine &TM) const {
547 const char *SectionName = GV->getSection().c_str();
549 // Infer section flags from the section name if we can.
550 Kind = getELFKindForNamedSection(SectionName, Kind);
552 return getELFSection(SectionName,
553 getELFSectionType(SectionName, Kind),
554 getELFSectionFlags(Kind), Kind, true);
557 static const char *getSectionPrefixForUniqueGlobal(SectionKind Kind) {
558 if (Kind.isText()) return ".gnu.linkonce.t.";
559 if (Kind.isReadOnly()) return ".gnu.linkonce.r.";
561 if (Kind.isThreadData()) return ".gnu.linkonce.td.";
562 if (Kind.isThreadBSS()) return ".gnu.linkonce.tb.";
564 if (Kind.isBSS()) return ".gnu.linkonce.b.";
565 if (Kind.isDataNoRel()) return ".gnu.linkonce.d.";
566 if (Kind.isDataRelLocal()) return ".gnu.linkonce.d.rel.local.";
567 if (Kind.isDataRel()) return ".gnu.linkonce.d.rel.";
568 if (Kind.isReadOnlyWithRelLocal()) return ".gnu.linkonce.d.rel.ro.local.";
570 assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
571 return ".gnu.linkonce.d.rel.ro.";
574 const MCSection *TargetLoweringObjectFileELF::
575 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
576 Mangler *Mang, const TargetMachine &TM) const {
578 // If this global is linkonce/weak and the target handles this by emitting it
579 // into a 'uniqued' section name, create and return the section now.
580 if (GV->isWeakForLinker()) {
581 const char *Prefix = getSectionPrefixForUniqueGlobal(Kind);
582 SmallString<128> Name, MangledName;
583 Name.append(Prefix, Prefix+strlen(Prefix));
584 Mang->getNameWithPrefix(Name, GV, false);
586 raw_svector_ostream OS(MangledName);
587 MCSymbol::printMangledName(Name, OS, 0);
590 return getELFSection(MangledName.str(),
591 getELFSectionType(MangledName.str(), Kind),
592 getELFSectionFlags(Kind),
596 if (Kind.isText()) return TextSection;
598 if (Kind.isMergeable1ByteCString() ||
599 Kind.isMergeable2ByteCString() ||
600 Kind.isMergeable4ByteCString()) {
602 // We also need alignment here.
603 // FIXME: this is getting the alignment of the character, not the
604 // alignment of the global!
606 TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV));
608 const char *SizeSpec = ".rodata.str1.";
609 if (Kind.isMergeable2ByteCString())
610 SizeSpec = ".rodata.str2.";
611 else if (Kind.isMergeable4ByteCString())
612 SizeSpec = ".rodata.str4.";
614 assert(Kind.isMergeable1ByteCString() && "unknown string width");
617 std::string Name = SizeSpec + utostr(Align);
618 return getELFSection(Name.c_str(), MCSectionELF::SHT_PROGBITS,
619 MCSectionELF::SHF_ALLOC |
620 MCSectionELF::SHF_MERGE |
621 MCSectionELF::SHF_STRINGS,
625 if (Kind.isMergeableConst()) {
626 if (Kind.isMergeableConst4() && MergeableConst4Section)
627 return MergeableConst4Section;
628 if (Kind.isMergeableConst8() && MergeableConst8Section)
629 return MergeableConst8Section;
630 if (Kind.isMergeableConst16() && MergeableConst16Section)
631 return MergeableConst16Section;
632 return ReadOnlySection; // .const
635 if (Kind.isReadOnly()) return ReadOnlySection;
637 if (Kind.isThreadData()) return TLSDataSection;
638 if (Kind.isThreadBSS()) return TLSBSSSection;
640 if (Kind.isBSS()) return BSSSection;
642 if (Kind.isDataNoRel()) return DataSection;
643 if (Kind.isDataRelLocal()) return DataRelLocalSection;
644 if (Kind.isDataRel()) return DataRelSection;
645 if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection;
647 assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
648 return DataRelROSection;
651 /// getSectionForConstant - Given a mergeable constant with the
652 /// specified size and relocation information, return a section that it
653 /// should be placed in.
654 const MCSection *TargetLoweringObjectFileELF::
655 getSectionForConstant(SectionKind Kind) const {
656 if (Kind.isMergeableConst4() && MergeableConst4Section)
657 return MergeableConst4Section;
658 if (Kind.isMergeableConst8() && MergeableConst8Section)
659 return MergeableConst8Section;
660 if (Kind.isMergeableConst16() && MergeableConst16Section)
661 return MergeableConst16Section;
662 if (Kind.isReadOnly())
663 return ReadOnlySection;
665 if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection;
666 assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
667 return DataRelROSection;
670 //===----------------------------------------------------------------------===//
672 //===----------------------------------------------------------------------===//
674 typedef StringMap<const MCSectionMachO*> MachOUniqueMapTy;
676 TargetLoweringObjectFileMachO::~TargetLoweringObjectFileMachO() {
677 // If we have the MachO uniquing map, free it.
678 delete (MachOUniqueMapTy*)UniquingMap;
682 const MCSectionMachO *TargetLoweringObjectFileMachO::
683 getMachOSection(StringRef Segment, StringRef Section,
684 unsigned TypeAndAttributes,
685 unsigned Reserved2, SectionKind Kind) const {
686 // We unique sections by their segment/section pair. The returned section
687 // may not have the same flags as the requested section, if so this should be
688 // diagnosed by the client as an error.
690 // Create the map if it doesn't already exist.
691 if (UniquingMap == 0)
692 UniquingMap = new MachOUniqueMapTy();
693 MachOUniqueMapTy &Map = *(MachOUniqueMapTy*)UniquingMap;
695 // Form the name to look up.
696 SmallString<64> Name;
701 // Do the lookup, if we have a hit, return it.
702 const MCSectionMachO *&Entry = Map[Name.str()];
703 if (Entry) return Entry;
705 // Otherwise, return a new section.
706 return Entry = MCSectionMachO::Create(Segment, Section, TypeAndAttributes,
707 Reserved2, Kind, getContext());
711 void TargetLoweringObjectFileMachO::Initialize(MCContext &Ctx,
712 const TargetMachine &TM) {
713 if (UniquingMap != 0)
714 ((MachOUniqueMapTy*)UniquingMap)->clear();
715 TargetLoweringObjectFile::Initialize(Ctx, TM);
718 = getMachOSection("__TEXT", "__text",
719 MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
720 SectionKind::getText());
722 = getMachOSection("__DATA", "__data", 0, SectionKind::getDataRel());
724 CStringSection // .cstring
725 = getMachOSection("__TEXT", "__cstring", MCSectionMachO::S_CSTRING_LITERALS,
726 SectionKind::getMergeable1ByteCString());
728 = getMachOSection("__TEXT","__ustring", 0,
729 SectionKind::getMergeable2ByteCString());
730 FourByteConstantSection // .literal4
731 = getMachOSection("__TEXT", "__literal4", MCSectionMachO::S_4BYTE_LITERALS,
732 SectionKind::getMergeableConst4());
733 EightByteConstantSection // .literal8
734 = getMachOSection("__TEXT", "__literal8", MCSectionMachO::S_8BYTE_LITERALS,
735 SectionKind::getMergeableConst8());
737 // ld_classic doesn't support .literal16 in 32-bit mode, and ld64 falls back
738 // to using it in -static mode.
739 SixteenByteConstantSection = 0;
740 if (TM.getRelocationModel() != Reloc::Static &&
741 TM.getTargetData()->getPointerSize() == 32)
742 SixteenByteConstantSection = // .literal16
743 getMachOSection("__TEXT", "__literal16",MCSectionMachO::S_16BYTE_LITERALS,
744 SectionKind::getMergeableConst16());
746 ReadOnlySection // .const
747 = getMachOSection("__TEXT", "__const", 0, SectionKind::getReadOnly());
750 = getMachOSection("__TEXT", "__textcoal_nt",
751 MCSectionMachO::S_COALESCED |
752 MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
753 SectionKind::getText());
755 = getMachOSection("__TEXT", "__const_coal", MCSectionMachO::S_COALESCED,
756 SectionKind::getText());
758 = getMachOSection("__DATA","__const_coal", MCSectionMachO::S_COALESCED,
759 SectionKind::getText());
760 ConstDataSection // .const_data
761 = getMachOSection("__DATA", "__const", 0,
762 SectionKind::getReadOnlyWithRel());
764 = getMachOSection("__DATA","__datacoal_nt", MCSectionMachO::S_COALESCED,
765 SectionKind::getDataRel());
768 LazySymbolPointerSection
769 = getMachOSection("__DATA", "__la_symbol_ptr",
770 MCSectionMachO::S_LAZY_SYMBOL_POINTERS,
771 SectionKind::getMetadata());
772 NonLazySymbolPointerSection
773 = getMachOSection("__DATA", "__nl_symbol_ptr",
774 MCSectionMachO::S_NON_LAZY_SYMBOL_POINTERS,
775 SectionKind::getMetadata());
777 if (TM.getRelocationModel() == Reloc::Static) {
779 = getMachOSection("__TEXT", "__constructor", 0,SectionKind::getDataRel());
781 = getMachOSection("__TEXT", "__destructor", 0, SectionKind::getDataRel());
784 = getMachOSection("__DATA", "__mod_init_func",
785 MCSectionMachO::S_MOD_INIT_FUNC_POINTERS,
786 SectionKind::getDataRel());
788 = getMachOSection("__DATA", "__mod_term_func",
789 MCSectionMachO::S_MOD_TERM_FUNC_POINTERS,
790 SectionKind::getDataRel());
793 // Exception Handling.
794 LSDASection = getMachOSection("__DATA", "__gcc_except_tab", 0,
795 SectionKind::getDataRel());
797 getMachOSection("__TEXT", "__eh_frame",
798 MCSectionMachO::S_COALESCED |
799 MCSectionMachO::S_ATTR_NO_TOC |
800 MCSectionMachO::S_ATTR_STRIP_STATIC_SYMS |
801 MCSectionMachO::S_ATTR_LIVE_SUPPORT,
802 SectionKind::getReadOnly());
804 // Debug Information.
806 getMachOSection("__DWARF", "__debug_abbrev", MCSectionMachO::S_ATTR_DEBUG,
807 SectionKind::getMetadata());
809 getMachOSection("__DWARF", "__debug_info", MCSectionMachO::S_ATTR_DEBUG,
810 SectionKind::getMetadata());
812 getMachOSection("__DWARF", "__debug_line", MCSectionMachO::S_ATTR_DEBUG,
813 SectionKind::getMetadata());
815 getMachOSection("__DWARF", "__debug_frame", MCSectionMachO::S_ATTR_DEBUG,
816 SectionKind::getMetadata());
817 DwarfPubNamesSection =
818 getMachOSection("__DWARF", "__debug_pubnames", MCSectionMachO::S_ATTR_DEBUG,
819 SectionKind::getMetadata());
820 DwarfPubTypesSection =
821 getMachOSection("__DWARF", "__debug_pubtypes", MCSectionMachO::S_ATTR_DEBUG,
822 SectionKind::getMetadata());
824 getMachOSection("__DWARF", "__debug_str", MCSectionMachO::S_ATTR_DEBUG,
825 SectionKind::getMetadata());
827 getMachOSection("__DWARF", "__debug_loc", MCSectionMachO::S_ATTR_DEBUG,
828 SectionKind::getMetadata());
829 DwarfARangesSection =
830 getMachOSection("__DWARF", "__debug_aranges", MCSectionMachO::S_ATTR_DEBUG,
831 SectionKind::getMetadata());
833 getMachOSection("__DWARF", "__debug_ranges", MCSectionMachO::S_ATTR_DEBUG,
834 SectionKind::getMetadata());
835 DwarfMacroInfoSection =
836 getMachOSection("__DWARF", "__debug_macinfo", MCSectionMachO::S_ATTR_DEBUG,
837 SectionKind::getMetadata());
838 DwarfDebugInlineSection =
839 getMachOSection("__DWARF", "__debug_inlined", MCSectionMachO::S_ATTR_DEBUG,
840 SectionKind::getMetadata());
843 const MCSection *TargetLoweringObjectFileMachO::
844 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
845 Mangler *Mang, const TargetMachine &TM) const {
846 // Parse the section specifier and create it if valid.
847 StringRef Segment, Section;
848 unsigned TAA, StubSize;
849 std::string ErrorCode =
850 MCSectionMachO::ParseSectionSpecifier(GV->getSection(), Segment, Section,
852 if (!ErrorCode.empty()) {
853 // If invalid, report the error with llvm_report_error.
854 llvm_report_error("Global variable '" + GV->getNameStr() +
855 "' has an invalid section specifier '" + GV->getSection()+
856 "': " + ErrorCode + ".");
857 // Fall back to dropping it into the data section.
862 const MCSectionMachO *S =
863 getMachOSection(Segment, Section, TAA, StubSize, Kind);
865 // Okay, now that we got the section, verify that the TAA & StubSize agree.
866 // If the user declared multiple globals with different section flags, we need
867 // to reject it here.
868 if (S->getTypeAndAttributes() != TAA || S->getStubSize() != StubSize) {
869 // If invalid, report the error with llvm_report_error.
870 llvm_report_error("Global variable '" + GV->getNameStr() +
871 "' section type or attributes does not match previous"
872 " section specifier");
878 const MCSection *TargetLoweringObjectFileMachO::
879 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
880 Mangler *Mang, const TargetMachine &TM) const {
881 assert(!Kind.isThreadLocal() && "Darwin doesn't support TLS");
884 return GV->isWeakForLinker() ? TextCoalSection : TextSection;
886 // If this is weak/linkonce, put this in a coalescable section, either in text
887 // or data depending on if it is writable.
888 if (GV->isWeakForLinker()) {
889 if (Kind.isReadOnly())
890 return ConstTextCoalSection;
891 return DataCoalSection;
894 // FIXME: Alignment check should be handled by section classifier.
895 if (Kind.isMergeable1ByteCString() ||
896 Kind.isMergeable2ByteCString()) {
897 if (TM.getTargetData()->getPreferredAlignment(
898 cast<GlobalVariable>(GV)) < 32) {
899 if (Kind.isMergeable1ByteCString())
900 return CStringSection;
901 assert(Kind.isMergeable2ByteCString());
902 return UStringSection;
906 if (Kind.isMergeableConst()) {
907 if (Kind.isMergeableConst4())
908 return FourByteConstantSection;
909 if (Kind.isMergeableConst8())
910 return EightByteConstantSection;
911 if (Kind.isMergeableConst16() && SixteenByteConstantSection)
912 return SixteenByteConstantSection;
915 // Otherwise, if it is readonly, but not something we can specially optimize,
916 // just drop it in .const.
917 if (Kind.isReadOnly())
918 return ReadOnlySection;
920 // If this is marked const, put it into a const section. But if the dynamic
921 // linker needs to write to it, put it in the data segment.
922 if (Kind.isReadOnlyWithRel())
923 return ConstDataSection;
925 // Otherwise, just drop the variable in the normal data section.
930 TargetLoweringObjectFileMachO::getSectionForConstant(SectionKind Kind) const {
931 // If this constant requires a relocation, we have to put it in the data
932 // segment, not in the text segment.
933 if (Kind.isDataRel() || Kind.isReadOnlyWithRel())
934 return ConstDataSection;
936 if (Kind.isMergeableConst4())
937 return FourByteConstantSection;
938 if (Kind.isMergeableConst8())
939 return EightByteConstantSection;
940 if (Kind.isMergeableConst16() && SixteenByteConstantSection)
941 return SixteenByteConstantSection;
942 return ReadOnlySection; // .const
945 /// shouldEmitUsedDirectiveFor - This hook allows targets to selectively decide
946 /// not to emit the UsedDirective for some symbols in llvm.used.
947 // FIXME: REMOVE this (rdar://7071300)
948 bool TargetLoweringObjectFileMachO::
949 shouldEmitUsedDirectiveFor(const GlobalValue *GV, Mangler *Mang) const {
950 /// On Darwin, internally linked data beginning with "L" or "l" does not have
951 /// the directive emitted (this occurs in ObjC metadata).
952 if (!GV) return false;
954 // Check whether the mangled name has the "Private" or "LinkerPrivate" prefix.
955 if (GV->hasLocalLinkage() && !isa<Function>(GV)) {
956 // FIXME: ObjC metadata is currently emitted as internal symbols that have
957 // \1L and \0l prefixes on them. Fix them to be Private/LinkerPrivate and
958 // this horrible hack can go away.
959 SmallString<64> Name;
960 Mang->getNameWithPrefix(Name, GV, false);
961 if (Name[0] == 'L' || Name[0] == 'l')
968 const MCExpr *TargetLoweringObjectFileMachO::
969 getSymbolForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang,
970 MachineModuleInfo *MMI,
971 bool &IsIndirect, bool &IsPCRel) const {
972 // The mach-o version of this method defaults to returning a stub reference.
976 SmallString<128> Name;
977 Mang->getNameWithPrefix(Name, GV, true);
978 Name += "$non_lazy_ptr";
979 return MCSymbolRefExpr::Create(Name.str(), getContext());
983 //===----------------------------------------------------------------------===//
985 //===----------------------------------------------------------------------===//
987 typedef StringMap<const MCSectionCOFF*> COFFUniqueMapTy;
989 TargetLoweringObjectFileCOFF::~TargetLoweringObjectFileCOFF() {
990 delete (COFFUniqueMapTy*)UniquingMap;
994 const MCSection *TargetLoweringObjectFileCOFF::
995 getCOFFSection(StringRef Name, bool isDirective, SectionKind Kind) const {
996 // Create the map if it doesn't already exist.
997 if (UniquingMap == 0)
998 UniquingMap = new MachOUniqueMapTy();
999 COFFUniqueMapTy &Map = *(COFFUniqueMapTy*)UniquingMap;
1001 // Do the lookup, if we have a hit, return it.
1002 const MCSectionCOFF *&Entry = Map[Name];
1003 if (Entry) return Entry;
1005 return Entry = MCSectionCOFF::Create(Name, isDirective, Kind, getContext());
1008 void TargetLoweringObjectFileCOFF::Initialize(MCContext &Ctx,
1009 const TargetMachine &TM) {
1010 if (UniquingMap != 0)
1011 ((COFFUniqueMapTy*)UniquingMap)->clear();
1012 TargetLoweringObjectFile::Initialize(Ctx, TM);
1013 TextSection = getCOFFSection("\t.text", true, SectionKind::getText());
1014 DataSection = getCOFFSection("\t.data", true, SectionKind::getDataRel());
1016 getCOFFSection(".ctors", false, SectionKind::getDataRel());
1018 getCOFFSection(".dtors", false, SectionKind::getDataRel());
1020 // FIXME: We're emitting LSDA info into a readonly section on COFF, even
1021 // though it contains relocatable pointers. In PIC mode, this is probably a
1022 // big runtime hit for C++ apps. Either the contents of the LSDA need to be
1023 // adjusted or this should be a data section.
1025 getCOFFSection(".gcc_except_table", false, SectionKind::getReadOnly());
1027 getCOFFSection(".eh_frame", false, SectionKind::getDataRel());
1030 // FIXME: Don't use 'directive' mode here.
1031 DwarfAbbrevSection =
1032 getCOFFSection("\t.section\t.debug_abbrev,\"dr\"",
1033 true, SectionKind::getMetadata());
1035 getCOFFSection("\t.section\t.debug_info,\"dr\"",
1036 true, SectionKind::getMetadata());
1038 getCOFFSection("\t.section\t.debug_line,\"dr\"",
1039 true, SectionKind::getMetadata());
1041 getCOFFSection("\t.section\t.debug_frame,\"dr\"",
1042 true, SectionKind::getMetadata());
1043 DwarfPubNamesSection =
1044 getCOFFSection("\t.section\t.debug_pubnames,\"dr\"",
1045 true, SectionKind::getMetadata());
1046 DwarfPubTypesSection =
1047 getCOFFSection("\t.section\t.debug_pubtypes,\"dr\"",
1048 true, SectionKind::getMetadata());
1050 getCOFFSection("\t.section\t.debug_str,\"dr\"",
1051 true, SectionKind::getMetadata());
1053 getCOFFSection("\t.section\t.debug_loc,\"dr\"",
1054 true, SectionKind::getMetadata());
1055 DwarfARangesSection =
1056 getCOFFSection("\t.section\t.debug_aranges,\"dr\"",
1057 true, SectionKind::getMetadata());
1058 DwarfRangesSection =
1059 getCOFFSection("\t.section\t.debug_ranges,\"dr\"",
1060 true, SectionKind::getMetadata());
1061 DwarfMacroInfoSection =
1062 getCOFFSection("\t.section\t.debug_macinfo,\"dr\"",
1063 true, SectionKind::getMetadata());
1066 const MCSection *TargetLoweringObjectFileCOFF::
1067 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
1068 Mangler *Mang, const TargetMachine &TM) const {
1069 return getCOFFSection(GV->getSection().c_str(), false, Kind);
1072 static const char *getCOFFSectionPrefixForUniqueGlobal(SectionKind Kind) {
1074 return ".text$linkonce";
1075 if (Kind.isWriteable())
1076 return ".data$linkonce";
1077 return ".rdata$linkonce";
1081 const MCSection *TargetLoweringObjectFileCOFF::
1082 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
1083 Mangler *Mang, const TargetMachine &TM) const {
1084 assert(!Kind.isThreadLocal() && "Doesn't support TLS");
1086 // If this global is linkonce/weak and the target handles this by emitting it
1087 // into a 'uniqued' section name, create and return the section now.
1088 if (GV->isWeakForLinker()) {
1089 const char *Prefix = getCOFFSectionPrefixForUniqueGlobal(Kind);
1090 SmallString<128> Name(Prefix, Prefix+strlen(Prefix));
1091 Mang->getNameWithPrefix(Name, GV, false);
1092 return getCOFFSection(Name.str(), false, Kind);
1096 return getTextSection();
1098 return getDataSection();