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 // Variables with common linkage always get classified as common.
145 if (GVar->hasCommonLinkage())
146 return SectionKind::getCommon();
148 // Variable can be easily put to BSS section.
149 if (isSuitableForBSS(GVar)) {
150 if (GVar->hasLocalLinkage())
151 return SectionKind::getBSSLocal();
152 else if (GVar->hasExternalLinkage())
153 return SectionKind::getBSSExtern();
154 return SectionKind::getBSS();
157 Constant *C = GVar->getInitializer();
159 // If the global is marked constant, we can put it into a mergable section,
160 // a mergable string section, or general .data if it contains relocations.
161 if (GVar->isConstant()) {
162 // If the initializer for the global contains something that requires a
163 // relocation, then we may have to drop this into a wriable data section
164 // even though it is marked const.
165 switch (C->getRelocationInfo()) {
166 default: assert(0 && "unknown relocation info kind");
167 case Constant::NoRelocation:
168 // If initializer is a null-terminated string, put it in a "cstring"
169 // section of the right width.
170 if (const ArrayType *ATy = dyn_cast<ArrayType>(C->getType())) {
171 if (const IntegerType *ITy =
172 dyn_cast<IntegerType>(ATy->getElementType())) {
173 if ((ITy->getBitWidth() == 8 || ITy->getBitWidth() == 16 ||
174 ITy->getBitWidth() == 32) &&
175 IsNullTerminatedString(C)) {
176 if (ITy->getBitWidth() == 8)
177 return SectionKind::getMergeable1ByteCString();
178 if (ITy->getBitWidth() == 16)
179 return SectionKind::getMergeable2ByteCString();
181 assert(ITy->getBitWidth() == 32 && "Unknown width");
182 return SectionKind::getMergeable4ByteCString();
187 // Otherwise, just drop it into a mergable constant section. If we have
188 // a section for this size, use it, otherwise use the arbitrary sized
190 switch (TM.getTargetData()->getTypeAllocSize(C->getType())) {
191 case 4: return SectionKind::getMergeableConst4();
192 case 8: return SectionKind::getMergeableConst8();
193 case 16: return SectionKind::getMergeableConst16();
194 default: return SectionKind::getMergeableConst();
197 case Constant::LocalRelocation:
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.local section.
208 return SectionKind::getReadOnlyWithRelLocal();
210 case Constant::GlobalRelocations:
211 // In static relocation model, the linker will resolve all addresses, so
212 // the relocation entries will actually be constants by the time the app
213 // starts up. However, we can't put this into a mergable section, because
214 // the linker doesn't take relocations into consideration when it tries to
215 // merge entries in the section.
216 if (ReloModel == Reloc::Static)
217 return SectionKind::getReadOnly();
219 // Otherwise, the dynamic linker needs to fix it up, put it in the
220 // writable data.rel section.
221 return SectionKind::getReadOnlyWithRel();
225 // Okay, this isn't a constant. If the initializer for the global is going
226 // to require a runtime relocation by the dynamic linker, put it into a more
227 // specific section to improve startup time of the app. This coalesces these
228 // globals together onto fewer pages, improving the locality of the dynamic
230 if (ReloModel == Reloc::Static)
231 return SectionKind::getDataNoRel();
233 switch (C->getRelocationInfo()) {
234 default: assert(0 && "unknown relocation info kind");
235 case Constant::NoRelocation:
236 return SectionKind::getDataNoRel();
237 case Constant::LocalRelocation:
238 return SectionKind::getDataRelLocal();
239 case Constant::GlobalRelocations:
240 return SectionKind::getDataRel();
244 /// SectionForGlobal - This method computes the appropriate section to emit
245 /// the specified global variable or function definition. This should not
246 /// be passed external (or available externally) globals.
247 const MCSection *TargetLoweringObjectFile::
248 SectionForGlobal(const GlobalValue *GV, SectionKind Kind, Mangler *Mang,
249 const TargetMachine &TM) const {
250 // Select section name.
251 if (GV->hasSection())
252 return getExplicitSectionGlobal(GV, Kind, Mang, TM);
255 // Use default section depending on the 'type' of global
256 return SelectSectionForGlobal(GV, Kind, Mang, TM);
260 // Lame default implementation. Calculate the section name for global.
262 TargetLoweringObjectFile::SelectSectionForGlobal(const GlobalValue *GV,
265 const TargetMachine &TM) const{
266 assert(!Kind.isThreadLocal() && "Doesn't support TLS");
269 return getTextSection();
271 if (Kind.isBSS() && BSSSection != 0)
274 if (Kind.isReadOnly() && ReadOnlySection != 0)
275 return ReadOnlySection;
277 return getDataSection();
280 /// getSectionForConstant - Given a mergable constant with the
281 /// specified size and relocation information, return a section that it
282 /// should be placed in.
284 TargetLoweringObjectFile::getSectionForConstant(SectionKind Kind) const {
285 if (Kind.isReadOnly() && ReadOnlySection != 0)
286 return ReadOnlySection;
291 /// getSymbolForDwarfGlobalReference - Return an MCExpr to use for a
292 /// pc-relative reference to the specified global variable from exception
293 /// handling information. In addition to the symbol, this returns
296 /// IsIndirect - True if the returned symbol is actually a stub that contains
297 /// the address of the symbol, false if the symbol is the global itself.
299 /// IsPCRel - True if the symbol reference is already pc-relative, false if
300 /// the caller needs to subtract off the address of the reference from the
303 const MCExpr *TargetLoweringObjectFile::
304 getSymbolForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang,
305 MachineModuleInfo *MMI,
306 bool &IsIndirect, bool &IsPCRel) const {
307 // The generic implementation of this just returns a direct reference to the
312 // FIXME: Use GetGlobalValueSymbol.
313 SmallString<128> Name;
314 Mang->getNameWithPrefix(Name, GV, false);
315 return MCSymbolRefExpr::Create(Name.str(), getContext());
319 //===----------------------------------------------------------------------===//
321 //===----------------------------------------------------------------------===//
322 typedef StringMap<const MCSectionELF*> ELFUniqueMapTy;
324 TargetLoweringObjectFileELF::~TargetLoweringObjectFileELF() {
325 // If we have the section uniquing map, free it.
326 delete (ELFUniqueMapTy*)UniquingMap;
329 const MCSection *TargetLoweringObjectFileELF::
330 getELFSection(StringRef Section, unsigned Type, unsigned Flags,
331 SectionKind Kind, bool IsExplicit) const {
332 if (UniquingMap == 0)
333 UniquingMap = new ELFUniqueMapTy();
334 ELFUniqueMapTy &Map = *(ELFUniqueMapTy*)UniquingMap;
336 // Do the lookup, if we have a hit, return it.
337 const MCSectionELF *&Entry = Map[Section];
338 if (Entry) return Entry;
340 return Entry = MCSectionELF::Create(Section, Type, Flags, Kind, IsExplicit,
344 void TargetLoweringObjectFileELF::Initialize(MCContext &Ctx,
345 const TargetMachine &TM) {
346 if (UniquingMap != 0)
347 ((ELFUniqueMapTy*)UniquingMap)->clear();
348 TargetLoweringObjectFile::Initialize(Ctx, TM);
351 getELFSection(".bss", MCSectionELF::SHT_NOBITS,
352 MCSectionELF::SHF_WRITE | MCSectionELF::SHF_ALLOC,
353 SectionKind::getBSS());
356 getELFSection(".text", MCSectionELF::SHT_PROGBITS,
357 MCSectionELF::SHF_EXECINSTR | MCSectionELF::SHF_ALLOC,
358 SectionKind::getText());
361 getELFSection(".data", MCSectionELF::SHT_PROGBITS,
362 MCSectionELF::SHF_WRITE | MCSectionELF::SHF_ALLOC,
363 SectionKind::getDataRel());
366 getELFSection(".rodata", MCSectionELF::SHT_PROGBITS,
367 MCSectionELF::SHF_ALLOC,
368 SectionKind::getReadOnly());
371 getELFSection(".tdata", MCSectionELF::SHT_PROGBITS,
372 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_TLS |
373 MCSectionELF::SHF_WRITE, SectionKind::getThreadData());
376 getELFSection(".tbss", MCSectionELF::SHT_NOBITS,
377 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_TLS |
378 MCSectionELF::SHF_WRITE, SectionKind::getThreadBSS());
381 getELFSection(".data.rel", MCSectionELF::SHT_PROGBITS,
382 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
383 SectionKind::getDataRel());
385 DataRelLocalSection =
386 getELFSection(".data.rel.local", MCSectionELF::SHT_PROGBITS,
387 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
388 SectionKind::getDataRelLocal());
391 getELFSection(".data.rel.ro", MCSectionELF::SHT_PROGBITS,
392 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
393 SectionKind::getReadOnlyWithRel());
395 DataRelROLocalSection =
396 getELFSection(".data.rel.ro.local", MCSectionELF::SHT_PROGBITS,
397 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
398 SectionKind::getReadOnlyWithRelLocal());
400 MergeableConst4Section =
401 getELFSection(".rodata.cst4", MCSectionELF::SHT_PROGBITS,
402 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_MERGE,
403 SectionKind::getMergeableConst4());
405 MergeableConst8Section =
406 getELFSection(".rodata.cst8", MCSectionELF::SHT_PROGBITS,
407 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_MERGE,
408 SectionKind::getMergeableConst8());
410 MergeableConst16Section =
411 getELFSection(".rodata.cst16", MCSectionELF::SHT_PROGBITS,
412 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_MERGE,
413 SectionKind::getMergeableConst16());
416 getELFSection(".ctors", MCSectionELF::SHT_PROGBITS,
417 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
418 SectionKind::getDataRel());
421 getELFSection(".dtors", MCSectionELF::SHT_PROGBITS,
422 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
423 SectionKind::getDataRel());
425 // Exception Handling Sections.
427 // FIXME: We're emitting LSDA info into a readonly section on ELF, even though
428 // it contains relocatable pointers. In PIC mode, this is probably a big
429 // runtime hit for C++ apps. Either the contents of the LSDA need to be
430 // adjusted or this should be a data section.
432 getELFSection(".gcc_except_table", MCSectionELF::SHT_PROGBITS,
433 MCSectionELF::SHF_ALLOC, SectionKind::getReadOnly());
435 getELFSection(".eh_frame", MCSectionELF::SHT_PROGBITS,
436 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
437 SectionKind::getDataRel());
439 // Debug Info Sections.
441 getELFSection(".debug_abbrev", MCSectionELF::SHT_PROGBITS, 0,
442 SectionKind::getMetadata());
444 getELFSection(".debug_info", MCSectionELF::SHT_PROGBITS, 0,
445 SectionKind::getMetadata());
447 getELFSection(".debug_line", MCSectionELF::SHT_PROGBITS, 0,
448 SectionKind::getMetadata());
450 getELFSection(".debug_frame", MCSectionELF::SHT_PROGBITS, 0,
451 SectionKind::getMetadata());
452 DwarfPubNamesSection =
453 getELFSection(".debug_pubnames", MCSectionELF::SHT_PROGBITS, 0,
454 SectionKind::getMetadata());
455 DwarfPubTypesSection =
456 getELFSection(".debug_pubtypes", MCSectionELF::SHT_PROGBITS, 0,
457 SectionKind::getMetadata());
459 getELFSection(".debug_str", MCSectionELF::SHT_PROGBITS, 0,
460 SectionKind::getMetadata());
462 getELFSection(".debug_loc", MCSectionELF::SHT_PROGBITS, 0,
463 SectionKind::getMetadata());
464 DwarfARangesSection =
465 getELFSection(".debug_aranges", MCSectionELF::SHT_PROGBITS, 0,
466 SectionKind::getMetadata());
468 getELFSection(".debug_ranges", MCSectionELF::SHT_PROGBITS, 0,
469 SectionKind::getMetadata());
470 DwarfMacroInfoSection =
471 getELFSection(".debug_macinfo", MCSectionELF::SHT_PROGBITS, 0,
472 SectionKind::getMetadata());
477 getELFKindForNamedSection(const char *Name, SectionKind K) {
478 if (Name[0] != '.') return K;
480 // Some lame default implementation based on some magic section names.
481 if (strcmp(Name, ".bss") == 0 ||
482 strncmp(Name, ".bss.", 5) == 0 ||
483 strncmp(Name, ".gnu.linkonce.b.", 16) == 0 ||
484 strncmp(Name, ".llvm.linkonce.b.", 17) == 0 ||
485 strcmp(Name, ".sbss") == 0 ||
486 strncmp(Name, ".sbss.", 6) == 0 ||
487 strncmp(Name, ".gnu.linkonce.sb.", 17) == 0 ||
488 strncmp(Name, ".llvm.linkonce.sb.", 18) == 0)
489 return SectionKind::getBSS();
491 if (strcmp(Name, ".tdata") == 0 ||
492 strncmp(Name, ".tdata.", 7) == 0 ||
493 strncmp(Name, ".gnu.linkonce.td.", 17) == 0 ||
494 strncmp(Name, ".llvm.linkonce.td.", 18) == 0)
495 return SectionKind::getThreadData();
497 if (strcmp(Name, ".tbss") == 0 ||
498 strncmp(Name, ".tbss.", 6) == 0 ||
499 strncmp(Name, ".gnu.linkonce.tb.", 17) == 0 ||
500 strncmp(Name, ".llvm.linkonce.tb.", 18) == 0)
501 return SectionKind::getThreadBSS();
507 static unsigned getELFSectionType(StringRef Name, SectionKind K) {
509 if (Name == ".init_array")
510 return MCSectionELF::SHT_INIT_ARRAY;
512 if (Name == ".fini_array")
513 return MCSectionELF::SHT_FINI_ARRAY;
515 if (Name == ".preinit_array")
516 return MCSectionELF::SHT_PREINIT_ARRAY;
518 if (K.isBSS() || K.isThreadBSS())
519 return MCSectionELF::SHT_NOBITS;
521 return MCSectionELF::SHT_PROGBITS;
526 getELFSectionFlags(SectionKind K) {
530 Flags |= MCSectionELF::SHF_ALLOC;
533 Flags |= MCSectionELF::SHF_EXECINSTR;
536 Flags |= MCSectionELF::SHF_WRITE;
538 if (K.isThreadLocal())
539 Flags |= MCSectionELF::SHF_TLS;
541 // K.isMergeableConst() is left out to honour PR4650
542 if (K.isMergeableCString() || K.isMergeableConst4() ||
543 K.isMergeableConst8() || K.isMergeableConst16())
544 Flags |= MCSectionELF::SHF_MERGE;
546 if (K.isMergeableCString())
547 Flags |= MCSectionELF::SHF_STRINGS;
553 const MCSection *TargetLoweringObjectFileELF::
554 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
555 Mangler *Mang, const TargetMachine &TM) const {
556 const char *SectionName = GV->getSection().c_str();
558 // Infer section flags from the section name if we can.
559 Kind = getELFKindForNamedSection(SectionName, Kind);
561 return getELFSection(SectionName,
562 getELFSectionType(SectionName, Kind),
563 getELFSectionFlags(Kind), Kind, true);
566 static const char *getSectionPrefixForUniqueGlobal(SectionKind Kind) {
567 if (Kind.isText()) return ".gnu.linkonce.t.";
568 if (Kind.isReadOnly()) return ".gnu.linkonce.r.";
570 if (Kind.isThreadData()) return ".gnu.linkonce.td.";
571 if (Kind.isThreadBSS()) return ".gnu.linkonce.tb.";
573 if (Kind.isDataNoRel()) return ".gnu.linkonce.d.";
574 if (Kind.isDataRelLocal()) return ".gnu.linkonce.d.rel.local.";
575 if (Kind.isDataRel()) return ".gnu.linkonce.d.rel.";
576 if (Kind.isReadOnlyWithRelLocal()) return ".gnu.linkonce.d.rel.ro.local.";
578 assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
579 return ".gnu.linkonce.d.rel.ro.";
582 const MCSection *TargetLoweringObjectFileELF::
583 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
584 Mangler *Mang, const TargetMachine &TM) const {
586 // If this global is linkonce/weak and the target handles this by emitting it
587 // into a 'uniqued' section name, create and return the section now.
588 if (GV->isWeakForLinker() && !Kind.isCommon() && !Kind.isBSS()) {
589 const char *Prefix = getSectionPrefixForUniqueGlobal(Kind);
590 SmallString<128> Name;
591 Name.append(Prefix, Prefix+strlen(Prefix));
592 Mang->getNameWithPrefix(Name, GV, false);
593 return getELFSection(Name.str(), getELFSectionType(Name.str(), Kind),
594 getELFSectionFlags(Kind), Kind);
597 if (Kind.isText()) return TextSection;
599 if (Kind.isMergeable1ByteCString() ||
600 Kind.isMergeable2ByteCString() ||
601 Kind.isMergeable4ByteCString()) {
603 // We also need alignment here.
604 // FIXME: this is getting the alignment of the character, not the
605 // alignment of the global!
607 TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV));
609 const char *SizeSpec = ".rodata.str1.";
610 if (Kind.isMergeable2ByteCString())
611 SizeSpec = ".rodata.str2.";
612 else if (Kind.isMergeable4ByteCString())
613 SizeSpec = ".rodata.str4.";
615 assert(Kind.isMergeable1ByteCString() && "unknown string width");
618 std::string Name = SizeSpec + utostr(Align);
619 return getELFSection(Name.c_str(), MCSectionELF::SHT_PROGBITS,
620 MCSectionELF::SHF_ALLOC |
621 MCSectionELF::SHF_MERGE |
622 MCSectionELF::SHF_STRINGS,
626 if (Kind.isMergeableConst()) {
627 if (Kind.isMergeableConst4() && MergeableConst4Section)
628 return MergeableConst4Section;
629 if (Kind.isMergeableConst8() && MergeableConst8Section)
630 return MergeableConst8Section;
631 if (Kind.isMergeableConst16() && MergeableConst16Section)
632 return MergeableConst16Section;
633 return ReadOnlySection; // .const
636 if (Kind.isReadOnly()) return ReadOnlySection;
638 if (Kind.isThreadData()) return TLSDataSection;
639 if (Kind.isThreadBSS()) return TLSBSSSection;
641 // Note: we claim that common symbols are put in BSSSection, but they are
642 // really emitted with the magic .comm directive, which creates a symbol table
643 // entry but not a section.
644 if (Kind.isBSS() || Kind.isCommon()) return BSSSection;
646 if (Kind.isDataNoRel()) return DataSection;
647 if (Kind.isDataRelLocal()) return DataRelLocalSection;
648 if (Kind.isDataRel()) return DataRelSection;
649 if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection;
651 assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
652 return DataRelROSection;
655 /// getSectionForConstant - Given a mergeable constant with the
656 /// specified size and relocation information, return a section that it
657 /// should be placed in.
658 const MCSection *TargetLoweringObjectFileELF::
659 getSectionForConstant(SectionKind Kind) const {
660 if (Kind.isMergeableConst4() && MergeableConst4Section)
661 return MergeableConst4Section;
662 if (Kind.isMergeableConst8() && MergeableConst8Section)
663 return MergeableConst8Section;
664 if (Kind.isMergeableConst16() && MergeableConst16Section)
665 return MergeableConst16Section;
666 if (Kind.isReadOnly())
667 return ReadOnlySection;
669 if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection;
670 assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
671 return DataRelROSection;
674 //===----------------------------------------------------------------------===//
676 //===----------------------------------------------------------------------===//
678 typedef StringMap<const MCSectionMachO*> MachOUniqueMapTy;
680 TargetLoweringObjectFileMachO::~TargetLoweringObjectFileMachO() {
681 // If we have the MachO uniquing map, free it.
682 delete (MachOUniqueMapTy*)UniquingMap;
686 const MCSectionMachO *TargetLoweringObjectFileMachO::
687 getMachOSection(StringRef Segment, StringRef Section,
688 unsigned TypeAndAttributes,
689 unsigned Reserved2, SectionKind Kind) const {
690 // We unique sections by their segment/section pair. The returned section
691 // may not have the same flags as the requested section, if so this should be
692 // diagnosed by the client as an error.
694 // Create the map if it doesn't already exist.
695 if (UniquingMap == 0)
696 UniquingMap = new MachOUniqueMapTy();
697 MachOUniqueMapTy &Map = *(MachOUniqueMapTy*)UniquingMap;
699 // Form the name to look up.
700 SmallString<64> Name;
705 // Do the lookup, if we have a hit, return it.
706 const MCSectionMachO *&Entry = Map[Name.str()];
707 if (Entry) return Entry;
709 // Otherwise, return a new section.
710 return Entry = MCSectionMachO::Create(Segment, Section, TypeAndAttributes,
711 Reserved2, Kind, getContext());
715 void TargetLoweringObjectFileMachO::Initialize(MCContext &Ctx,
716 const TargetMachine &TM) {
717 if (UniquingMap != 0)
718 ((MachOUniqueMapTy*)UniquingMap)->clear();
719 TargetLoweringObjectFile::Initialize(Ctx, TM);
722 = getMachOSection("__TEXT", "__text",
723 MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
724 SectionKind::getText());
726 = getMachOSection("__DATA", "__data", 0, SectionKind::getDataRel());
728 CStringSection // .cstring
729 = getMachOSection("__TEXT", "__cstring", MCSectionMachO::S_CSTRING_LITERALS,
730 SectionKind::getMergeable1ByteCString());
732 = getMachOSection("__TEXT","__ustring", 0,
733 SectionKind::getMergeable2ByteCString());
734 FourByteConstantSection // .literal4
735 = getMachOSection("__TEXT", "__literal4", MCSectionMachO::S_4BYTE_LITERALS,
736 SectionKind::getMergeableConst4());
737 EightByteConstantSection // .literal8
738 = getMachOSection("__TEXT", "__literal8", MCSectionMachO::S_8BYTE_LITERALS,
739 SectionKind::getMergeableConst8());
741 // ld_classic doesn't support .literal16 in 32-bit mode, and ld64 falls back
742 // to using it in -static mode.
743 SixteenByteConstantSection = 0;
744 if (TM.getRelocationModel() != Reloc::Static &&
745 TM.getTargetData()->getPointerSize() == 32)
746 SixteenByteConstantSection = // .literal16
747 getMachOSection("__TEXT", "__literal16",MCSectionMachO::S_16BYTE_LITERALS,
748 SectionKind::getMergeableConst16());
750 ReadOnlySection // .const
751 = getMachOSection("__TEXT", "__const", 0, SectionKind::getReadOnly());
754 = getMachOSection("__TEXT", "__textcoal_nt",
755 MCSectionMachO::S_COALESCED |
756 MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
757 SectionKind::getText());
759 = getMachOSection("__TEXT", "__const_coal", MCSectionMachO::S_COALESCED,
760 SectionKind::getText());
762 = getMachOSection("__DATA","__const_coal", MCSectionMachO::S_COALESCED,
763 SectionKind::getText());
765 = getMachOSection("__DATA","__common", MCSectionMachO::S_ZEROFILL,
766 SectionKind::getBSS());
767 ConstDataSection // .const_data
768 = getMachOSection("__DATA", "__const", 0,
769 SectionKind::getReadOnlyWithRel());
771 = getMachOSection("__DATA","__datacoal_nt", MCSectionMachO::S_COALESCED,
772 SectionKind::getDataRel());
775 LazySymbolPointerSection
776 = getMachOSection("__DATA", "__la_symbol_ptr",
777 MCSectionMachO::S_LAZY_SYMBOL_POINTERS,
778 SectionKind::getMetadata());
779 NonLazySymbolPointerSection
780 = getMachOSection("__DATA", "__nl_symbol_ptr",
781 MCSectionMachO::S_NON_LAZY_SYMBOL_POINTERS,
782 SectionKind::getMetadata());
784 if (TM.getRelocationModel() == Reloc::Static) {
786 = getMachOSection("__TEXT", "__constructor", 0,SectionKind::getDataRel());
788 = getMachOSection("__TEXT", "__destructor", 0, SectionKind::getDataRel());
791 = getMachOSection("__DATA", "__mod_init_func",
792 MCSectionMachO::S_MOD_INIT_FUNC_POINTERS,
793 SectionKind::getDataRel());
795 = getMachOSection("__DATA", "__mod_term_func",
796 MCSectionMachO::S_MOD_TERM_FUNC_POINTERS,
797 SectionKind::getDataRel());
800 // Exception Handling.
801 LSDASection = getMachOSection("__DATA", "__gcc_except_tab", 0,
802 SectionKind::getDataRel());
804 getMachOSection("__TEXT", "__eh_frame",
805 MCSectionMachO::S_COALESCED |
806 MCSectionMachO::S_ATTR_NO_TOC |
807 MCSectionMachO::S_ATTR_STRIP_STATIC_SYMS |
808 MCSectionMachO::S_ATTR_LIVE_SUPPORT,
809 SectionKind::getReadOnly());
811 // Debug Information.
813 getMachOSection("__DWARF", "__debug_abbrev", MCSectionMachO::S_ATTR_DEBUG,
814 SectionKind::getMetadata());
816 getMachOSection("__DWARF", "__debug_info", MCSectionMachO::S_ATTR_DEBUG,
817 SectionKind::getMetadata());
819 getMachOSection("__DWARF", "__debug_line", MCSectionMachO::S_ATTR_DEBUG,
820 SectionKind::getMetadata());
822 getMachOSection("__DWARF", "__debug_frame", MCSectionMachO::S_ATTR_DEBUG,
823 SectionKind::getMetadata());
824 DwarfPubNamesSection =
825 getMachOSection("__DWARF", "__debug_pubnames", MCSectionMachO::S_ATTR_DEBUG,
826 SectionKind::getMetadata());
827 DwarfPubTypesSection =
828 getMachOSection("__DWARF", "__debug_pubtypes", MCSectionMachO::S_ATTR_DEBUG,
829 SectionKind::getMetadata());
831 getMachOSection("__DWARF", "__debug_str", MCSectionMachO::S_ATTR_DEBUG,
832 SectionKind::getMetadata());
834 getMachOSection("__DWARF", "__debug_loc", MCSectionMachO::S_ATTR_DEBUG,
835 SectionKind::getMetadata());
836 DwarfARangesSection =
837 getMachOSection("__DWARF", "__debug_aranges", MCSectionMachO::S_ATTR_DEBUG,
838 SectionKind::getMetadata());
840 getMachOSection("__DWARF", "__debug_ranges", MCSectionMachO::S_ATTR_DEBUG,
841 SectionKind::getMetadata());
842 DwarfMacroInfoSection =
843 getMachOSection("__DWARF", "__debug_macinfo", MCSectionMachO::S_ATTR_DEBUG,
844 SectionKind::getMetadata());
845 DwarfDebugInlineSection =
846 getMachOSection("__DWARF", "__debug_inlined", MCSectionMachO::S_ATTR_DEBUG,
847 SectionKind::getMetadata());
850 const MCSection *TargetLoweringObjectFileMachO::
851 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
852 Mangler *Mang, const TargetMachine &TM) const {
853 // Parse the section specifier and create it if valid.
854 StringRef Segment, Section;
855 unsigned TAA, StubSize;
856 std::string ErrorCode =
857 MCSectionMachO::ParseSectionSpecifier(GV->getSection(), Segment, Section,
859 if (!ErrorCode.empty()) {
860 // If invalid, report the error with llvm_report_error.
861 llvm_report_error("Global variable '" + GV->getNameStr() +
862 "' has an invalid section specifier '" + GV->getSection()+
863 "': " + ErrorCode + ".");
864 // Fall back to dropping it into the data section.
869 const MCSectionMachO *S =
870 getMachOSection(Segment, Section, TAA, StubSize, Kind);
872 // Okay, now that we got the section, verify that the TAA & StubSize agree.
873 // If the user declared multiple globals with different section flags, we need
874 // to reject it here.
875 if (S->getTypeAndAttributes() != TAA || S->getStubSize() != StubSize) {
876 // If invalid, report the error with llvm_report_error.
877 llvm_report_error("Global variable '" + GV->getNameStr() +
878 "' section type or attributes does not match previous"
879 " section specifier");
885 const MCSection *TargetLoweringObjectFileMachO::
886 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
887 Mangler *Mang, const TargetMachine &TM) const {
888 assert(!Kind.isThreadLocal() && "Darwin doesn't support TLS");
891 return GV->isWeakForLinker() ? TextCoalSection : TextSection;
893 // If this is weak/linkonce, put this in a coalescable section, either in text
894 // or data depending on if it is writable.
895 if (GV->isWeakForLinker()) {
896 if (Kind.isReadOnly())
897 return ConstTextCoalSection;
898 return DataCoalSection;
901 // FIXME: Alignment check should be handled by section classifier.
902 if (Kind.isMergeable1ByteCString() ||
903 Kind.isMergeable2ByteCString()) {
904 if (TM.getTargetData()->getPreferredAlignment(
905 cast<GlobalVariable>(GV)) < 32) {
906 if (Kind.isMergeable1ByteCString())
907 return CStringSection;
908 assert(Kind.isMergeable2ByteCString());
909 return UStringSection;
913 if (Kind.isMergeableConst()) {
914 if (Kind.isMergeableConst4())
915 return FourByteConstantSection;
916 if (Kind.isMergeableConst8())
917 return EightByteConstantSection;
918 if (Kind.isMergeableConst16() && SixteenByteConstantSection)
919 return SixteenByteConstantSection;
922 // Otherwise, if it is readonly, but not something we can specially optimize,
923 // just drop it in .const.
924 if (Kind.isReadOnly())
925 return ReadOnlySection;
927 // If this is marked const, put it into a const section. But if the dynamic
928 // linker needs to write to it, put it in the data segment.
929 if (Kind.isReadOnlyWithRel())
930 return ConstDataSection;
932 // Put zero initialized globals with strong external linkage in the
933 // DATA, __common section with the .zerofill directive.
934 if (Kind.isBSSExtern())
935 return DataCommonSection;
937 // Otherwise, just drop the variable in the normal data section.
942 TargetLoweringObjectFileMachO::getSectionForConstant(SectionKind Kind) const {
943 // If this constant requires a relocation, we have to put it in the data
944 // segment, not in the text segment.
945 if (Kind.isDataRel() || Kind.isReadOnlyWithRel())
946 return ConstDataSection;
948 if (Kind.isMergeableConst4())
949 return FourByteConstantSection;
950 if (Kind.isMergeableConst8())
951 return EightByteConstantSection;
952 if (Kind.isMergeableConst16() && SixteenByteConstantSection)
953 return SixteenByteConstantSection;
954 return ReadOnlySection; // .const
957 /// shouldEmitUsedDirectiveFor - This hook allows targets to selectively decide
958 /// not to emit the UsedDirective for some symbols in llvm.used.
959 // FIXME: REMOVE this (rdar://7071300)
960 bool TargetLoweringObjectFileMachO::
961 shouldEmitUsedDirectiveFor(const GlobalValue *GV, Mangler *Mang) const {
962 /// On Darwin, internally linked data beginning with "L" or "l" does not have
963 /// the directive emitted (this occurs in ObjC metadata).
964 if (!GV) return false;
966 // Check whether the mangled name has the "Private" or "LinkerPrivate" prefix.
967 if (GV->hasLocalLinkage() && !isa<Function>(GV)) {
968 // FIXME: ObjC metadata is currently emitted as internal symbols that have
969 // \1L and \0l prefixes on them. Fix them to be Private/LinkerPrivate and
970 // this horrible hack can go away.
971 SmallString<64> Name;
972 Mang->getNameWithPrefix(Name, GV, false);
973 if (Name[0] == 'L' || Name[0] == 'l')
980 const MCExpr *TargetLoweringObjectFileMachO::
981 getSymbolForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang,
982 MachineModuleInfo *MMI,
983 bool &IsIndirect, bool &IsPCRel) const {
984 // The mach-o version of this method defaults to returning a stub reference.
988 SmallString<128> Name;
989 Mang->getNameWithPrefix(Name, GV, true);
990 Name += "$non_lazy_ptr";
991 return MCSymbolRefExpr::Create(Name.str(), getContext());
995 //===----------------------------------------------------------------------===//
997 //===----------------------------------------------------------------------===//
999 typedef StringMap<const MCSectionCOFF*> COFFUniqueMapTy;
1001 TargetLoweringObjectFileCOFF::~TargetLoweringObjectFileCOFF() {
1002 delete (COFFUniqueMapTy*)UniquingMap;
1006 const MCSection *TargetLoweringObjectFileCOFF::
1007 getCOFFSection(StringRef Name, bool isDirective, SectionKind Kind) const {
1008 // Create the map if it doesn't already exist.
1009 if (UniquingMap == 0)
1010 UniquingMap = new MachOUniqueMapTy();
1011 COFFUniqueMapTy &Map = *(COFFUniqueMapTy*)UniquingMap;
1013 // Do the lookup, if we have a hit, return it.
1014 const MCSectionCOFF *&Entry = Map[Name];
1015 if (Entry) return Entry;
1017 return Entry = MCSectionCOFF::Create(Name, isDirective, Kind, getContext());
1020 void TargetLoweringObjectFileCOFF::Initialize(MCContext &Ctx,
1021 const TargetMachine &TM) {
1022 if (UniquingMap != 0)
1023 ((COFFUniqueMapTy*)UniquingMap)->clear();
1024 TargetLoweringObjectFile::Initialize(Ctx, TM);
1025 TextSection = getCOFFSection("\t.text", true, SectionKind::getText());
1026 DataSection = getCOFFSection("\t.data", true, SectionKind::getDataRel());
1028 getCOFFSection(".ctors", false, SectionKind::getDataRel());
1030 getCOFFSection(".dtors", false, SectionKind::getDataRel());
1032 // FIXME: We're emitting LSDA info into a readonly section on COFF, even
1033 // though it contains relocatable pointers. In PIC mode, this is probably a
1034 // big runtime hit for C++ apps. Either the contents of the LSDA need to be
1035 // adjusted or this should be a data section.
1037 getCOFFSection(".gcc_except_table", false, SectionKind::getReadOnly());
1039 getCOFFSection(".eh_frame", false, SectionKind::getDataRel());
1042 // FIXME: Don't use 'directive' mode here.
1043 DwarfAbbrevSection =
1044 getCOFFSection("\t.section\t.debug_abbrev,\"dr\"",
1045 true, SectionKind::getMetadata());
1047 getCOFFSection("\t.section\t.debug_info,\"dr\"",
1048 true, SectionKind::getMetadata());
1050 getCOFFSection("\t.section\t.debug_line,\"dr\"",
1051 true, SectionKind::getMetadata());
1053 getCOFFSection("\t.section\t.debug_frame,\"dr\"",
1054 true, SectionKind::getMetadata());
1055 DwarfPubNamesSection =
1056 getCOFFSection("\t.section\t.debug_pubnames,\"dr\"",
1057 true, SectionKind::getMetadata());
1058 DwarfPubTypesSection =
1059 getCOFFSection("\t.section\t.debug_pubtypes,\"dr\"",
1060 true, SectionKind::getMetadata());
1062 getCOFFSection("\t.section\t.debug_str,\"dr\"",
1063 true, SectionKind::getMetadata());
1065 getCOFFSection("\t.section\t.debug_loc,\"dr\"",
1066 true, SectionKind::getMetadata());
1067 DwarfARangesSection =
1068 getCOFFSection("\t.section\t.debug_aranges,\"dr\"",
1069 true, SectionKind::getMetadata());
1070 DwarfRangesSection =
1071 getCOFFSection("\t.section\t.debug_ranges,\"dr\"",
1072 true, SectionKind::getMetadata());
1073 DwarfMacroInfoSection =
1074 getCOFFSection("\t.section\t.debug_macinfo,\"dr\"",
1075 true, SectionKind::getMetadata());
1078 const MCSection *TargetLoweringObjectFileCOFF::
1079 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
1080 Mangler *Mang, const TargetMachine &TM) const {
1081 return getCOFFSection(GV->getSection().c_str(), false, Kind);
1084 static const char *getCOFFSectionPrefixForUniqueGlobal(SectionKind Kind) {
1086 return ".text$linkonce";
1087 if (Kind.isWriteable())
1088 return ".data$linkonce";
1089 return ".rdata$linkonce";
1093 const MCSection *TargetLoweringObjectFileCOFF::
1094 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
1095 Mangler *Mang, const TargetMachine &TM) const {
1096 assert(!Kind.isThreadLocal() && "Doesn't support TLS");
1098 // If this global is linkonce/weak and the target handles this by emitting it
1099 // into a 'uniqued' section name, create and return the section now.
1100 if (GV->isWeakForLinker()) {
1101 const char *Prefix = getCOFFSectionPrefixForUniqueGlobal(Kind);
1102 SmallString<128> Name(Prefix, Prefix+strlen(Prefix));
1103 Mang->getNameWithPrefix(Name, GV, false);
1104 return getCOFFSection(Name.str(), false, Kind);
1108 return getTextSection();
1110 return getDataSection();