Change allowsUnalignedMemoryAccesses to take type argument since some targets
[llvm/avr.git] / lib / CodeGen / ELFWriter.cpp
blobffbaf6ba9252e059c3df6c9029833dbf7f65396b
1 //===-- ELFWriter.cpp - Target-independent ELF Writer code ----------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file implements the target-independent ELF writer. This file writes out
11 // the ELF file in the following order:
13 // #1. ELF Header
14 // #2. '.text' section
15 // #3. '.data' section
16 // #4. '.bss' section (conceptual position in file)
17 // ...
18 // #X. '.shstrtab' section
19 // #Y. Section Table
21 // The entries in the section table are laid out as:
22 // #0. Null entry [required]
23 // #1. ".text" entry - the program code
24 // #2. ".data" entry - global variables with initializers. [ if needed ]
25 // #3. ".bss" entry - global variables without initializers. [ if needed ]
26 // ...
27 // #N. ".shstrtab" entry - String table for the section names.
29 //===----------------------------------------------------------------------===//
31 #define DEBUG_TYPE "elfwriter"
32 #include "ELF.h"
33 #include "ELFWriter.h"
34 #include "ELFCodeEmitter.h"
35 #include "llvm/Constants.h"
36 #include "llvm/Module.h"
37 #include "llvm/PassManager.h"
38 #include "llvm/DerivedTypes.h"
39 #include "llvm/CodeGen/BinaryObject.h"
40 #include "llvm/CodeGen/FileWriters.h"
41 #include "llvm/CodeGen/MachineCodeEmitter.h"
42 #include "llvm/CodeGen/ObjectCodeEmitter.h"
43 #include "llvm/CodeGen/MachineCodeEmitter.h"
44 #include "llvm/CodeGen/MachineConstantPool.h"
45 #include "llvm/MC/MCContext.h"
46 #include "llvm/MC/MCSectionELF.h"
47 #include "llvm/Target/TargetAsmInfo.h"
48 #include "llvm/Target/TargetData.h"
49 #include "llvm/Target/TargetELFWriterInfo.h"
50 #include "llvm/Target/TargetLowering.h"
51 #include "llvm/Target/TargetLoweringObjectFile.h"
52 #include "llvm/Target/TargetMachine.h"
53 #include "llvm/Support/Mangler.h"
54 #include "llvm/Support/Streams.h"
55 #include "llvm/Support/raw_ostream.h"
56 #include "llvm/Support/Debug.h"
57 #include "llvm/Support/ErrorHandling.h"
59 using namespace llvm;
61 char ELFWriter::ID = 0;
63 /// AddELFWriter - Add the ELF writer to the function pass manager
64 ObjectCodeEmitter *llvm::AddELFWriter(PassManagerBase &PM,
65 raw_ostream &O,
66 TargetMachine &TM) {
67 ELFWriter *EW = new ELFWriter(O, TM);
68 PM.add(EW);
69 return EW->getObjectCodeEmitter();
72 //===----------------------------------------------------------------------===//
73 // ELFWriter Implementation
74 //===----------------------------------------------------------------------===//
76 ELFWriter::ELFWriter(raw_ostream &o, TargetMachine &tm)
77 : MachineFunctionPass(&ID), O(o), TM(tm),
78 OutContext(*new MCContext()),
79 TLOF(TM.getTargetLowering()->getObjFileLowering()),
80 is64Bit(TM.getTargetData()->getPointerSizeInBits() == 64),
81 isLittleEndian(TM.getTargetData()->isLittleEndian()),
82 ElfHdr(isLittleEndian, is64Bit) {
84 TAI = TM.getTargetAsmInfo();
85 TEW = TM.getELFWriterInfo();
87 // Create the object code emitter object for this target.
88 ElfCE = new ELFCodeEmitter(*this);
90 // Inital number of sections
91 NumSections = 0;
94 ELFWriter::~ELFWriter() {
95 delete ElfCE;
96 delete &OutContext;
99 // doInitialization - Emit the file header and all of the global variables for
100 // the module to the ELF file.
101 bool ELFWriter::doInitialization(Module &M) {
102 // Initialize TargetLoweringObjectFile.
103 const_cast<TargetLoweringObjectFile&>(TLOF).Initialize(OutContext, TM);
105 Mang = new Mangler(M);
107 // ELF Header
108 // ----------
109 // Fields e_shnum e_shstrndx are only known after all section have
110 // been emitted. They locations in the ouput buffer are recorded so
111 // to be patched up later.
113 // Note
114 // ----
115 // emitWord method behaves differently for ELF32 and ELF64, writing
116 // 4 bytes in the former and 8 in the last for *_off and *_addr elf types
118 ElfHdr.emitByte(0x7f); // e_ident[EI_MAG0]
119 ElfHdr.emitByte('E'); // e_ident[EI_MAG1]
120 ElfHdr.emitByte('L'); // e_ident[EI_MAG2]
121 ElfHdr.emitByte('F'); // e_ident[EI_MAG3]
123 ElfHdr.emitByte(TEW->getEIClass()); // e_ident[EI_CLASS]
124 ElfHdr.emitByte(TEW->getEIData()); // e_ident[EI_DATA]
125 ElfHdr.emitByte(EV_CURRENT); // e_ident[EI_VERSION]
126 ElfHdr.emitAlignment(16); // e_ident[EI_NIDENT-EI_PAD]
128 ElfHdr.emitWord16(ET_REL); // e_type
129 ElfHdr.emitWord16(TEW->getEMachine()); // e_machine = target
130 ElfHdr.emitWord32(EV_CURRENT); // e_version
131 ElfHdr.emitWord(0); // e_entry, no entry point in .o file
132 ElfHdr.emitWord(0); // e_phoff, no program header for .o
133 ELFHdr_e_shoff_Offset = ElfHdr.size();
134 ElfHdr.emitWord(0); // e_shoff = sec hdr table off in bytes
135 ElfHdr.emitWord32(TEW->getEFlags()); // e_flags = whatever the target wants
136 ElfHdr.emitWord16(TEW->getHdrSize()); // e_ehsize = ELF header size
137 ElfHdr.emitWord16(0); // e_phentsize = prog header entry size
138 ElfHdr.emitWord16(0); // e_phnum = # prog header entries = 0
140 // e_shentsize = Section header entry size
141 ElfHdr.emitWord16(TEW->getSHdrSize());
143 // e_shnum = # of section header ents
144 ELFHdr_e_shnum_Offset = ElfHdr.size();
145 ElfHdr.emitWord16(0); // Placeholder
147 // e_shstrndx = Section # of '.shstrtab'
148 ELFHdr_e_shstrndx_Offset = ElfHdr.size();
149 ElfHdr.emitWord16(0); // Placeholder
151 // Add the null section, which is required to be first in the file.
152 getNullSection();
154 // The first entry in the symtab is the null symbol and the second
155 // is a local symbol containing the module/file name
156 SymbolList.push_back(new ELFSym());
157 SymbolList.push_back(ELFSym::getFileSym());
159 return false;
162 // AddPendingGlobalSymbol - Add a global to be processed and to
163 // the global symbol lookup, use a zero index because the table
164 // index will be determined later.
165 void ELFWriter::AddPendingGlobalSymbol(const GlobalValue *GV,
166 bool AddToLookup /* = false */) {
167 PendingGlobals.insert(GV);
168 if (AddToLookup)
169 GblSymLookup[GV] = 0;
172 // AddPendingExternalSymbol - Add the external to be processed
173 // and to the external symbol lookup, use a zero index because
174 // the symbol table index will be determined later.
175 void ELFWriter::AddPendingExternalSymbol(const char *External) {
176 PendingExternals.insert(External);
177 ExtSymLookup[External] = 0;
180 ELFSection &ELFWriter::getDataSection() {
181 const MCSectionELF *Data = (const MCSectionELF *)TLOF.getDataSection();
182 return getSection(Data->getSectionName(), Data->getType(),
183 Data->getFlags(), 4);
186 ELFSection &ELFWriter::getBSSSection() {
187 const MCSectionELF *BSS = (const MCSectionELF *)TLOF.getBSSSection();
188 return getSection(BSS->getSectionName(), BSS->getType(), BSS->getFlags(), 4);
191 // getCtorSection - Get the static constructor section
192 ELFSection &ELFWriter::getCtorSection() {
193 const MCSectionELF *Ctor = (const MCSectionELF *)TLOF.getStaticCtorSection();
194 return getSection(Ctor->getSectionName(), Ctor->getType(), Ctor->getFlags());
197 // getDtorSection - Get the static destructor section
198 ELFSection &ELFWriter::getDtorSection() {
199 const MCSectionELF *Dtor = (const MCSectionELF *)TLOF.getStaticDtorSection();
200 return getSection(Dtor->getSectionName(), Dtor->getType(), Dtor->getFlags());
203 // getTextSection - Get the text section for the specified function
204 ELFSection &ELFWriter::getTextSection(Function *F) {
205 const MCSectionELF *Text =
206 (const MCSectionELF *)TLOF.SectionForGlobal(F, Mang, TM);
207 return getSection(Text->getSectionName(), Text->getType(), Text->getFlags());
210 // getJumpTableSection - Get a read only section for constants when
211 // emitting jump tables. TODO: add PIC support
212 ELFSection &ELFWriter::getJumpTableSection() {
213 const MCSectionELF *JT =
214 (const MCSectionELF *)TLOF.getSectionForConstant(SectionKind::getReadOnly());
215 return getSection(JT->getSectionName(), JT->getType(), JT->getFlags(),
216 TM.getTargetData()->getPointerABIAlignment());
219 // getConstantPoolSection - Get a constant pool section based on the machine
220 // constant pool entry type and relocation info.
221 ELFSection &ELFWriter::getConstantPoolSection(MachineConstantPoolEntry &CPE) {
222 SectionKind Kind;
223 switch (CPE.getRelocationInfo()) {
224 default: llvm_unreachable("Unknown section kind");
225 case 2: Kind = SectionKind::getReadOnlyWithRel(); break;
226 case 1:
227 Kind = SectionKind::getReadOnlyWithRelLocal();
228 break;
229 case 0:
230 switch (TM.getTargetData()->getTypeAllocSize(CPE.getType())) {
231 case 4: Kind = SectionKind::getMergeableConst4(); break;
232 case 8: Kind = SectionKind::getMergeableConst8(); break;
233 case 16: Kind = SectionKind::getMergeableConst16(); break;
234 default: Kind = SectionKind::getMergeableConst(); break;
238 const MCSectionELF *CPSect =
239 (const MCSectionELF *)TLOF.getSectionForConstant(Kind);
240 return getSection(CPSect->getSectionName(), CPSect->getType(),
241 CPSect->getFlags(), CPE.getAlignment());
244 // getRelocSection - Return the relocation section of section 'S'. 'RelA'
245 // is true if the relocation section contains entries with addends.
246 ELFSection &ELFWriter::getRelocSection(ELFSection &S) {
247 unsigned SectionType = TEW->hasRelocationAddend() ?
248 ELFSection::SHT_RELA : ELFSection::SHT_REL;
250 std::string SectionName(".rel");
251 if (TEW->hasRelocationAddend())
252 SectionName.append("a");
253 SectionName.append(S.getName());
255 return getSection(SectionName, SectionType, 0, TEW->getPrefELFAlignment());
258 // getGlobalELFVisibility - Returns the ELF specific visibility type
259 unsigned ELFWriter::getGlobalELFVisibility(const GlobalValue *GV) {
260 switch (GV->getVisibility()) {
261 default:
262 llvm_unreachable("unknown visibility type");
263 case GlobalValue::DefaultVisibility:
264 return ELFSym::STV_DEFAULT;
265 case GlobalValue::HiddenVisibility:
266 return ELFSym::STV_HIDDEN;
267 case GlobalValue::ProtectedVisibility:
268 return ELFSym::STV_PROTECTED;
270 return 0;
273 // getGlobalELFBinding - Returns the ELF specific binding type
274 unsigned ELFWriter::getGlobalELFBinding(const GlobalValue *GV) {
275 if (GV->hasInternalLinkage())
276 return ELFSym::STB_LOCAL;
278 if (GV->isWeakForLinker() && !GV->hasCommonLinkage())
279 return ELFSym::STB_WEAK;
281 return ELFSym::STB_GLOBAL;
284 // getGlobalELFType - Returns the ELF specific type for a global
285 unsigned ELFWriter::getGlobalELFType(const GlobalValue *GV) {
286 if (GV->isDeclaration())
287 return ELFSym::STT_NOTYPE;
289 if (isa<Function>(GV))
290 return ELFSym::STT_FUNC;
292 return ELFSym::STT_OBJECT;
295 // IsELFUndefSym - True if the global value must be marked as a symbol
296 // which points to a SHN_UNDEF section. This means that the symbol has
297 // no definition on the module.
298 static bool IsELFUndefSym(const GlobalValue *GV) {
299 return GV->isDeclaration() || (isa<Function>(GV));
302 // AddToSymbolList - Update the symbol lookup and If the symbol is
303 // private add it to PrivateSyms list, otherwise to SymbolList.
304 void ELFWriter::AddToSymbolList(ELFSym *GblSym) {
305 assert(GblSym->isGlobalValue() && "Symbol must be a global value");
307 const GlobalValue *GV = GblSym->getGlobalValue();
308 if (GV->hasPrivateLinkage()) {
309 // For a private symbols, keep track of the index inside
310 // the private list since it will never go to the symbol
311 // table and won't be patched up later.
312 PrivateSyms.push_back(GblSym);
313 GblSymLookup[GV] = PrivateSyms.size()-1;
314 } else {
315 // Non private symbol are left with zero indices until
316 // they are patched up during the symbol table emition
317 // (where the indicies are created).
318 SymbolList.push_back(GblSym);
319 GblSymLookup[GV] = 0;
323 // EmitGlobal - Choose the right section for global and emit it
324 void ELFWriter::EmitGlobal(const GlobalValue *GV) {
326 // Check if the referenced symbol is already emitted
327 if (GblSymLookup.find(GV) != GblSymLookup.end())
328 return;
330 // Handle ELF Bind, Visibility and Type for the current symbol
331 unsigned SymBind = getGlobalELFBinding(GV);
332 unsigned SymType = getGlobalELFType(GV);
333 bool IsUndefSym = IsELFUndefSym(GV);
335 ELFSym *GblSym = IsUndefSym ? ELFSym::getUndefGV(GV, SymBind)
336 : ELFSym::getGV(GV, SymBind, SymType, getGlobalELFVisibility(GV));
338 if (!IsUndefSym) {
339 assert(isa<GlobalVariable>(GV) && "GV not a global variable!");
340 const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV);
342 // Handle special llvm globals
343 if (EmitSpecialLLVMGlobal(GVar))
344 return;
346 // Get the ELF section where this global belongs from TLOF
347 const MCSectionELF *S =
348 (const MCSectionELF *)TLOF.SectionForGlobal(GV, Mang, TM);
349 ELFSection &ES =
350 getSection(S->getSectionName(), S->getType(), S->getFlags());
351 SectionKind Kind = S->getKind();
353 // The symbol align should update the section alignment if needed
354 const TargetData *TD = TM.getTargetData();
355 unsigned Align = TD->getPreferredAlignment(GVar);
356 unsigned Size = TD->getTypeAllocSize(GVar->getInitializer()->getType());
357 GblSym->Size = Size;
359 if (S->HasCommonSymbols()) { // Symbol must go to a common section
360 GblSym->SectionIdx = ELFSection::SHN_COMMON;
362 // A new linkonce section is created for each global in the
363 // common section, the default alignment is 1 and the symbol
364 // value contains its alignment.
365 ES.Align = 1;
366 GblSym->Value = Align;
368 } else if (Kind.isBSS() || Kind.isThreadBSS()) { // Symbol goes to BSS.
369 GblSym->SectionIdx = ES.SectionIdx;
371 // Update the size with alignment and the next object can
372 // start in the right offset in the section
373 if (Align) ES.Size = (ES.Size + Align-1) & ~(Align-1);
374 ES.Align = std::max(ES.Align, Align);
376 // GblSym->Value should contain the virtual offset inside the section.
377 // Virtual because the BSS space is not allocated on ELF objects
378 GblSym->Value = ES.Size;
379 ES.Size += Size;
381 } else { // The symbol must go to some kind of data section
382 GblSym->SectionIdx = ES.SectionIdx;
384 // GblSym->Value should contain the symbol offset inside the section,
385 // and all symbols should start on their required alignment boundary
386 ES.Align = std::max(ES.Align, Align);
387 ES.emitAlignment(Align);
388 GblSym->Value = ES.size();
390 // Emit the global to the data section 'ES'
391 EmitGlobalConstant(GVar->getInitializer(), ES);
395 AddToSymbolList(GblSym);
398 void ELFWriter::EmitGlobalConstantStruct(const ConstantStruct *CVS,
399 ELFSection &GblS) {
401 // Print the fields in successive locations. Pad to align if needed!
402 const TargetData *TD = TM.getTargetData();
403 unsigned Size = TD->getTypeAllocSize(CVS->getType());
404 const StructLayout *cvsLayout = TD->getStructLayout(CVS->getType());
405 uint64_t sizeSoFar = 0;
406 for (unsigned i = 0, e = CVS->getNumOperands(); i != e; ++i) {
407 const Constant* field = CVS->getOperand(i);
409 // Check if padding is needed and insert one or more 0s.
410 uint64_t fieldSize = TD->getTypeAllocSize(field->getType());
411 uint64_t padSize = ((i == e-1 ? Size : cvsLayout->getElementOffset(i+1))
412 - cvsLayout->getElementOffset(i)) - fieldSize;
413 sizeSoFar += fieldSize + padSize;
415 // Now print the actual field value.
416 EmitGlobalConstant(field, GblS);
418 // Insert padding - this may include padding to increase the size of the
419 // current field up to the ABI size (if the struct is not packed) as well
420 // as padding to ensure that the next field starts at the right offset.
421 GblS.emitZeros(padSize);
423 assert(sizeSoFar == cvsLayout->getSizeInBytes() &&
424 "Layout of constant struct may be incorrect!");
427 void ELFWriter::EmitGlobalConstant(const Constant *CV, ELFSection &GblS) {
428 const TargetData *TD = TM.getTargetData();
429 unsigned Size = TD->getTypeAllocSize(CV->getType());
431 if (const ConstantArray *CVA = dyn_cast<ConstantArray>(CV)) {
432 for (unsigned i = 0, e = CVA->getNumOperands(); i != e; ++i)
433 EmitGlobalConstant(CVA->getOperand(i), GblS);
434 return;
435 } else if (isa<ConstantAggregateZero>(CV)) {
436 GblS.emitZeros(Size);
437 return;
438 } else if (const ConstantStruct *CVS = dyn_cast<ConstantStruct>(CV)) {
439 EmitGlobalConstantStruct(CVS, GblS);
440 return;
441 } else if (const ConstantFP *CFP = dyn_cast<ConstantFP>(CV)) {
442 APInt Val = CFP->getValueAPF().bitcastToAPInt();
443 if (CFP->getType() == Type::getDoubleTy(CV->getContext()))
444 GblS.emitWord64(Val.getZExtValue());
445 else if (CFP->getType() == Type::getFloatTy(CV->getContext()))
446 GblS.emitWord32(Val.getZExtValue());
447 else if (CFP->getType() == Type::getX86_FP80Ty(CV->getContext())) {
448 unsigned PadSize =
449 TD->getTypeAllocSize(Type::getX86_FP80Ty(CV->getContext()))-
450 TD->getTypeStoreSize(Type::getX86_FP80Ty(CV->getContext()));
451 GblS.emitWordFP80(Val.getRawData(), PadSize);
452 } else if (CFP->getType() == Type::getPPC_FP128Ty(CV->getContext()))
453 llvm_unreachable("PPC_FP128Ty global emission not implemented");
454 return;
455 } else if (const ConstantInt *CI = dyn_cast<ConstantInt>(CV)) {
456 if (Size == 1)
457 GblS.emitByte(CI->getZExtValue());
458 else if (Size == 2)
459 GblS.emitWord16(CI->getZExtValue());
460 else if (Size == 4)
461 GblS.emitWord32(CI->getZExtValue());
462 else
463 EmitGlobalConstantLargeInt(CI, GblS);
464 return;
465 } else if (const ConstantVector *CP = dyn_cast<ConstantVector>(CV)) {
466 const VectorType *PTy = CP->getType();
467 for (unsigned I = 0, E = PTy->getNumElements(); I < E; ++I)
468 EmitGlobalConstant(CP->getOperand(I), GblS);
469 return;
470 } else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(CV)) {
471 // Resolve a constant expression which returns a (Constant, Offset)
472 // pair. If 'Res.first' is a GlobalValue, emit a relocation with
473 // the offset 'Res.second', otherwise emit a global constant like
474 // it is always done for not contant expression types.
475 CstExprResTy Res = ResolveConstantExpr(CE);
476 const Constant *Op = Res.first;
478 if (isa<GlobalValue>(Op))
479 EmitGlobalDataRelocation(cast<const GlobalValue>(Op),
480 TD->getTypeAllocSize(Op->getType()),
481 GblS, Res.second);
482 else
483 EmitGlobalConstant(Op, GblS);
485 return;
486 } else if (CV->getType()->getTypeID() == Type::PointerTyID) {
487 // Fill the data entry with zeros or emit a relocation entry
488 if (isa<ConstantPointerNull>(CV))
489 GblS.emitZeros(Size);
490 else
491 EmitGlobalDataRelocation(cast<const GlobalValue>(CV),
492 Size, GblS);
493 return;
494 } else if (const GlobalValue *GV = dyn_cast<GlobalValue>(CV)) {
495 // This is a constant address for a global variable or function and
496 // therefore must be referenced using a relocation entry.
497 EmitGlobalDataRelocation(GV, Size, GblS);
498 return;
501 std::string msg;
502 raw_string_ostream ErrorMsg(msg);
503 ErrorMsg << "Constant unimp for type: " << *CV->getType();
504 llvm_report_error(ErrorMsg.str());
507 // ResolveConstantExpr - Resolve the constant expression until it stop
508 // yielding other constant expressions.
509 CstExprResTy ELFWriter::ResolveConstantExpr(const Constant *CV) {
510 const TargetData *TD = TM.getTargetData();
512 // There ins't constant expression inside others anymore
513 if (!isa<ConstantExpr>(CV))
514 return std::make_pair(CV, 0);
516 const ConstantExpr *CE = dyn_cast<ConstantExpr>(CV);
517 switch (CE->getOpcode()) {
518 case Instruction::BitCast:
519 return ResolveConstantExpr(CE->getOperand(0));
521 case Instruction::GetElementPtr: {
522 const Constant *ptrVal = CE->getOperand(0);
523 SmallVector<Value*, 8> idxVec(CE->op_begin()+1, CE->op_end());
524 int64_t Offset = TD->getIndexedOffset(ptrVal->getType(), &idxVec[0],
525 idxVec.size());
526 return std::make_pair(ptrVal, Offset);
528 case Instruction::IntToPtr: {
529 Constant *Op = CE->getOperand(0);
530 Op = ConstantExpr::getIntegerCast(Op, TD->getIntPtrType(CV->getContext()),
531 false/*ZExt*/);
532 return ResolveConstantExpr(Op);
534 case Instruction::PtrToInt: {
535 Constant *Op = CE->getOperand(0);
536 const Type *Ty = CE->getType();
538 // We can emit the pointer value into this slot if the slot is an
539 // integer slot greater or equal to the size of the pointer.
540 if (TD->getTypeAllocSize(Ty) == TD->getTypeAllocSize(Op->getType()))
541 return ResolveConstantExpr(Op);
543 llvm_unreachable("Integer size less then pointer size");
545 case Instruction::Add:
546 case Instruction::Sub: {
547 // Only handle cases where there's a constant expression with GlobalValue
548 // as first operand and ConstantInt as second, which are the cases we can
549 // solve direclty using a relocation entry. GlobalValue=Op0, CstInt=Op1
550 // 1) Instruction::Add => (global) + CstInt
551 // 2) Instruction::Sub => (global) + -CstInt
552 const Constant *Op0 = CE->getOperand(0);
553 const Constant *Op1 = CE->getOperand(1);
554 assert(isa<ConstantInt>(Op1) && "Op1 must be a ConstantInt");
556 CstExprResTy Res = ResolveConstantExpr(Op0);
557 assert(isa<GlobalValue>(Res.first) && "Op0 must be a GlobalValue");
559 const APInt &RHS = cast<ConstantInt>(Op1)->getValue();
560 switch (CE->getOpcode()) {
561 case Instruction::Add:
562 return std::make_pair(Res.first, RHS.getSExtValue());
563 case Instruction::Sub:
564 return std::make_pair(Res.first, (-RHS).getSExtValue());
569 std::string msg(CE->getOpcodeName());
570 raw_string_ostream ErrorMsg(msg);
571 ErrorMsg << ": Unsupported ConstantExpr type";
572 llvm_report_error(ErrorMsg.str());
574 return std::make_pair(CV, 0); // silence warning
577 void ELFWriter::EmitGlobalDataRelocation(const GlobalValue *GV, unsigned Size,
578 ELFSection &GblS, int64_t Offset) {
579 // Create the relocation entry for the global value
580 MachineRelocation MR =
581 MachineRelocation::getGV(GblS.getCurrentPCOffset(),
582 TEW->getAbsoluteLabelMachineRelTy(),
583 const_cast<GlobalValue*>(GV),
584 Offset);
586 // Fill the data entry with zeros
587 GblS.emitZeros(Size);
589 // Add the relocation entry for the current data section
590 GblS.addRelocation(MR);
593 void ELFWriter::EmitGlobalConstantLargeInt(const ConstantInt *CI,
594 ELFSection &S) {
595 const TargetData *TD = TM.getTargetData();
596 unsigned BitWidth = CI->getBitWidth();
597 assert(isPowerOf2_32(BitWidth) &&
598 "Non-power-of-2-sized integers not handled!");
600 const uint64_t *RawData = CI->getValue().getRawData();
601 uint64_t Val = 0;
602 for (unsigned i = 0, e = BitWidth / 64; i != e; ++i) {
603 Val = (TD->isBigEndian()) ? RawData[e - i - 1] : RawData[i];
604 S.emitWord64(Val);
608 /// EmitSpecialLLVMGlobal - Check to see if the specified global is a
609 /// special global used by LLVM. If so, emit it and return true, otherwise
610 /// do nothing and return false.
611 bool ELFWriter::EmitSpecialLLVMGlobal(const GlobalVariable *GV) {
612 if (GV->getName() == "llvm.used")
613 llvm_unreachable("not implemented yet");
615 // Ignore debug and non-emitted data. This handles llvm.compiler.used.
616 if (GV->getSection() == "llvm.metadata" ||
617 GV->hasAvailableExternallyLinkage())
618 return true;
620 if (!GV->hasAppendingLinkage()) return false;
622 assert(GV->hasInitializer() && "Not a special LLVM global!");
624 const TargetData *TD = TM.getTargetData();
625 unsigned Align = TD->getPointerPrefAlignment();
626 if (GV->getName() == "llvm.global_ctors") {
627 ELFSection &Ctor = getCtorSection();
628 Ctor.emitAlignment(Align);
629 EmitXXStructorList(GV->getInitializer(), Ctor);
630 return true;
633 if (GV->getName() == "llvm.global_dtors") {
634 ELFSection &Dtor = getDtorSection();
635 Dtor.emitAlignment(Align);
636 EmitXXStructorList(GV->getInitializer(), Dtor);
637 return true;
640 return false;
643 /// EmitXXStructorList - Emit the ctor or dtor list. This just emits out the
644 /// function pointers, ignoring the init priority.
645 void ELFWriter::EmitXXStructorList(Constant *List, ELFSection &Xtor) {
646 // Should be an array of '{ int, void ()* }' structs. The first value is the
647 // init priority, which we ignore.
648 if (!isa<ConstantArray>(List)) return;
649 ConstantArray *InitList = cast<ConstantArray>(List);
650 for (unsigned i = 0, e = InitList->getNumOperands(); i != e; ++i)
651 if (ConstantStruct *CS = dyn_cast<ConstantStruct>(InitList->getOperand(i))){
652 if (CS->getNumOperands() != 2) return; // Not array of 2-element structs.
654 if (CS->getOperand(1)->isNullValue())
655 return; // Found a null terminator, exit printing.
656 // Emit the function pointer.
657 EmitGlobalConstant(CS->getOperand(1), Xtor);
661 bool ELFWriter::runOnMachineFunction(MachineFunction &MF) {
662 // Nothing to do here, this is all done through the ElfCE object above.
663 return false;
666 /// doFinalization - Now that the module has been completely processed, emit
667 /// the ELF file to 'O'.
668 bool ELFWriter::doFinalization(Module &M) {
669 // Emit .data section placeholder
670 getDataSection();
672 // Emit .bss section placeholder
673 getBSSSection();
675 // Build and emit data, bss and "common" sections.
676 for (Module::global_iterator I = M.global_begin(), E = M.global_end();
677 I != E; ++I)
678 EmitGlobal(I);
680 // Emit all pending globals
681 for (PendingGblsIter I = PendingGlobals.begin(), E = PendingGlobals.end();
682 I != E; ++I)
683 EmitGlobal(*I);
685 // Emit all pending externals
686 for (PendingExtsIter I = PendingExternals.begin(), E = PendingExternals.end();
687 I != E; ++I)
688 SymbolList.push_back(ELFSym::getExtSym(*I));
690 // Emit non-executable stack note
691 if (TAI->getNonexecutableStackDirective())
692 getNonExecStackSection();
694 // Emit a symbol for each section created until now, skip null section
695 for (unsigned i = 1, e = SectionList.size(); i < e; ++i) {
696 ELFSection &ES = *SectionList[i];
697 ELFSym *SectionSym = ELFSym::getSectionSym();
698 SectionSym->SectionIdx = ES.SectionIdx;
699 SymbolList.push_back(SectionSym);
700 ES.Sym = SymbolList.back();
703 // Emit string table
704 EmitStringTable(M.getModuleIdentifier());
706 // Emit the symbol table now, if non-empty.
707 EmitSymbolTable();
709 // Emit the relocation sections.
710 EmitRelocations();
712 // Emit the sections string table.
713 EmitSectionTableStringTable();
715 // Dump the sections and section table to the .o file.
716 OutputSectionsAndSectionTable();
718 // We are done with the abstract symbols.
719 SymbolList.clear();
720 SectionList.clear();
721 NumSections = 0;
723 // Release the name mangler object.
724 delete Mang; Mang = 0;
725 return false;
728 // RelocateField - Patch relocatable field with 'Offset' in 'BO'
729 // using a 'Value' of known 'Size'
730 void ELFWriter::RelocateField(BinaryObject &BO, uint32_t Offset,
731 int64_t Value, unsigned Size) {
732 if (Size == 32)
733 BO.fixWord32(Value, Offset);
734 else if (Size == 64)
735 BO.fixWord64(Value, Offset);
736 else
737 llvm_unreachable("don't know howto patch relocatable field");
740 /// EmitRelocations - Emit relocations
741 void ELFWriter::EmitRelocations() {
743 // True if the target uses the relocation entry to hold the addend,
744 // otherwise the addend is written directly to the relocatable field.
745 bool HasRelA = TEW->hasRelocationAddend();
747 // Create Relocation sections for each section which needs it.
748 for (unsigned i=0, e=SectionList.size(); i != e; ++i) {
749 ELFSection &S = *SectionList[i];
751 // This section does not have relocations
752 if (!S.hasRelocations()) continue;
753 ELFSection &RelSec = getRelocSection(S);
755 // 'Link' - Section hdr idx of the associated symbol table
756 // 'Info' - Section hdr idx of the section to which the relocation applies
757 ELFSection &SymTab = getSymbolTableSection();
758 RelSec.Link = SymTab.SectionIdx;
759 RelSec.Info = S.SectionIdx;
760 RelSec.EntSize = TEW->getRelocationEntrySize();
762 // Get the relocations from Section
763 std::vector<MachineRelocation> Relos = S.getRelocations();
764 for (std::vector<MachineRelocation>::iterator MRI = Relos.begin(),
765 MRE = Relos.end(); MRI != MRE; ++MRI) {
766 MachineRelocation &MR = *MRI;
768 // Relocatable field offset from the section start
769 unsigned RelOffset = MR.getMachineCodeOffset();
771 // Symbol index in the symbol table
772 unsigned SymIdx = 0;
774 // Target specific relocation field type and size
775 unsigned RelType = TEW->getRelocationType(MR.getRelocationType());
776 unsigned RelTySize = TEW->getRelocationTySize(RelType);
777 int64_t Addend = 0;
779 // There are several machine relocations types, and each one of
780 // them needs a different approach to retrieve the symbol table index.
781 if (MR.isGlobalValue()) {
782 const GlobalValue *G = MR.getGlobalValue();
783 int64_t GlobalOffset = MR.getConstantVal();
784 SymIdx = GblSymLookup[G];
785 if (G->hasPrivateLinkage()) {
786 // If the target uses a section offset in the relocation:
787 // SymIdx + Addend = section sym for global + section offset
788 unsigned SectionIdx = PrivateSyms[SymIdx]->SectionIdx;
789 Addend = PrivateSyms[SymIdx]->Value + GlobalOffset;
790 SymIdx = SectionList[SectionIdx]->getSymbolTableIndex();
791 } else {
792 Addend = TEW->getDefaultAddendForRelTy(RelType, GlobalOffset);
794 } else if (MR.isExternalSymbol()) {
795 const char *ExtSym = MR.getExternalSymbol();
796 SymIdx = ExtSymLookup[ExtSym];
797 Addend = TEW->getDefaultAddendForRelTy(RelType);
798 } else {
799 // Get the symbol index for the section symbol
800 unsigned SectionIdx = MR.getConstantVal();
801 SymIdx = SectionList[SectionIdx]->getSymbolTableIndex();
803 // The symbol offset inside the section
804 int64_t SymOffset = (int64_t)MR.getResultPointer();
806 // For pc relative relocations where symbols are defined in the same
807 // section they are referenced, ignore the relocation entry and patch
808 // the relocatable field with the symbol offset directly.
809 if (S.SectionIdx == SectionIdx && TEW->isPCRelativeRel(RelType)) {
810 int64_t Value = TEW->computeRelocation(SymOffset, RelOffset, RelType);
811 RelocateField(S, RelOffset, Value, RelTySize);
812 continue;
815 Addend = TEW->getDefaultAddendForRelTy(RelType, SymOffset);
818 // The target without addend on the relocation symbol must be
819 // patched in the relocation place itself to contain the addend
820 // otherwise write zeros to make sure there is no garbage there
821 RelocateField(S, RelOffset, HasRelA ? 0 : Addend, RelTySize);
823 // Get the relocation entry and emit to the relocation section
824 ELFRelocation Rel(RelOffset, SymIdx, RelType, HasRelA, Addend);
825 EmitRelocation(RelSec, Rel, HasRelA);
830 /// EmitRelocation - Write relocation 'Rel' to the relocation section 'Rel'
831 void ELFWriter::EmitRelocation(BinaryObject &RelSec, ELFRelocation &Rel,
832 bool HasRelA) {
833 RelSec.emitWord(Rel.getOffset());
834 RelSec.emitWord(Rel.getInfo(is64Bit));
835 if (HasRelA)
836 RelSec.emitWord(Rel.getAddend());
839 /// EmitSymbol - Write symbol 'Sym' to the symbol table 'SymbolTable'
840 void ELFWriter::EmitSymbol(BinaryObject &SymbolTable, ELFSym &Sym) {
841 if (is64Bit) {
842 SymbolTable.emitWord32(Sym.NameIdx);
843 SymbolTable.emitByte(Sym.Info);
844 SymbolTable.emitByte(Sym.Other);
845 SymbolTable.emitWord16(Sym.SectionIdx);
846 SymbolTable.emitWord64(Sym.Value);
847 SymbolTable.emitWord64(Sym.Size);
848 } else {
849 SymbolTable.emitWord32(Sym.NameIdx);
850 SymbolTable.emitWord32(Sym.Value);
851 SymbolTable.emitWord32(Sym.Size);
852 SymbolTable.emitByte(Sym.Info);
853 SymbolTable.emitByte(Sym.Other);
854 SymbolTable.emitWord16(Sym.SectionIdx);
858 /// EmitSectionHeader - Write section 'Section' header in 'SHdrTab'
859 /// Section Header Table
860 void ELFWriter::EmitSectionHeader(BinaryObject &SHdrTab,
861 const ELFSection &SHdr) {
862 SHdrTab.emitWord32(SHdr.NameIdx);
863 SHdrTab.emitWord32(SHdr.Type);
864 if (is64Bit) {
865 SHdrTab.emitWord64(SHdr.Flags);
866 SHdrTab.emitWord(SHdr.Addr);
867 SHdrTab.emitWord(SHdr.Offset);
868 SHdrTab.emitWord64(SHdr.Size);
869 SHdrTab.emitWord32(SHdr.Link);
870 SHdrTab.emitWord32(SHdr.Info);
871 SHdrTab.emitWord64(SHdr.Align);
872 SHdrTab.emitWord64(SHdr.EntSize);
873 } else {
874 SHdrTab.emitWord32(SHdr.Flags);
875 SHdrTab.emitWord(SHdr.Addr);
876 SHdrTab.emitWord(SHdr.Offset);
877 SHdrTab.emitWord32(SHdr.Size);
878 SHdrTab.emitWord32(SHdr.Link);
879 SHdrTab.emitWord32(SHdr.Info);
880 SHdrTab.emitWord32(SHdr.Align);
881 SHdrTab.emitWord32(SHdr.EntSize);
885 /// EmitStringTable - If the current symbol table is non-empty, emit the string
886 /// table for it
887 void ELFWriter::EmitStringTable(const std::string &ModuleName) {
888 if (!SymbolList.size()) return; // Empty symbol table.
889 ELFSection &StrTab = getStringTableSection();
891 // Set the zero'th symbol to a null byte, as required.
892 StrTab.emitByte(0);
894 // Walk on the symbol list and write symbol names into the string table.
895 unsigned Index = 1;
896 for (ELFSymIter I=SymbolList.begin(), E=SymbolList.end(); I != E; ++I) {
897 ELFSym &Sym = *(*I);
899 std::string Name;
900 if (Sym.isGlobalValue())
901 Name.append(Mang->getMangledName(Sym.getGlobalValue()));
902 else if (Sym.isExternalSym())
903 Name.append(Sym.getExternalSymbol());
904 else if (Sym.isFileType())
905 Name.append(ModuleName);
907 if (Name.empty()) {
908 Sym.NameIdx = 0;
909 } else {
910 Sym.NameIdx = Index;
911 StrTab.emitString(Name);
913 // Keep track of the number of bytes emitted to this section.
914 Index += Name.size()+1;
917 assert(Index == StrTab.size());
918 StrTab.Size = Index;
921 // SortSymbols - On the symbol table local symbols must come before
922 // all other symbols with non-local bindings. The return value is
923 // the position of the first non local symbol.
924 unsigned ELFWriter::SortSymbols() {
925 unsigned FirstNonLocalSymbol;
926 std::vector<ELFSym*> LocalSyms, OtherSyms;
928 for (ELFSymIter I=SymbolList.begin(), E=SymbolList.end(); I != E; ++I) {
929 if ((*I)->isLocalBind())
930 LocalSyms.push_back(*I);
931 else
932 OtherSyms.push_back(*I);
934 SymbolList.clear();
935 FirstNonLocalSymbol = LocalSyms.size();
937 for (unsigned i = 0; i < FirstNonLocalSymbol; ++i)
938 SymbolList.push_back(LocalSyms[i]);
940 for (ELFSymIter I=OtherSyms.begin(), E=OtherSyms.end(); I != E; ++I)
941 SymbolList.push_back(*I);
943 LocalSyms.clear();
944 OtherSyms.clear();
946 return FirstNonLocalSymbol;
949 /// EmitSymbolTable - Emit the symbol table itself.
950 void ELFWriter::EmitSymbolTable() {
951 if (!SymbolList.size()) return; // Empty symbol table.
953 // Now that we have emitted the string table and know the offset into the
954 // string table of each symbol, emit the symbol table itself.
955 ELFSection &SymTab = getSymbolTableSection();
956 SymTab.Align = TEW->getPrefELFAlignment();
958 // Section Index of .strtab.
959 SymTab.Link = getStringTableSection().SectionIdx;
961 // Size of each symtab entry.
962 SymTab.EntSize = TEW->getSymTabEntrySize();
964 // Reorder the symbol table with local symbols first!
965 unsigned FirstNonLocalSymbol = SortSymbols();
967 // Emit all the symbols to the symbol table.
968 for (unsigned i = 0, e = SymbolList.size(); i < e; ++i) {
969 ELFSym &Sym = *SymbolList[i];
971 // Emit symbol to the symbol table
972 EmitSymbol(SymTab, Sym);
974 // Record the symbol table index for each symbol
975 if (Sym.isGlobalValue())
976 GblSymLookup[Sym.getGlobalValue()] = i;
977 else if (Sym.isExternalSym())
978 ExtSymLookup[Sym.getExternalSymbol()] = i;
980 // Keep track on the symbol index into the symbol table
981 Sym.SymTabIdx = i;
984 // One greater than the symbol table index of the last local symbol
985 SymTab.Info = FirstNonLocalSymbol;
986 SymTab.Size = SymTab.size();
989 /// EmitSectionTableStringTable - This method adds and emits a section for the
990 /// ELF Section Table string table: the string table that holds all of the
991 /// section names.
992 void ELFWriter::EmitSectionTableStringTable() {
993 // First step: add the section for the string table to the list of sections:
994 ELFSection &SHStrTab = getSectionHeaderStringTableSection();
996 // Now that we know which section number is the .shstrtab section, update the
997 // e_shstrndx entry in the ELF header.
998 ElfHdr.fixWord16(SHStrTab.SectionIdx, ELFHdr_e_shstrndx_Offset);
1000 // Set the NameIdx of each section in the string table and emit the bytes for
1001 // the string table.
1002 unsigned Index = 0;
1004 for (ELFSectionIter I=SectionList.begin(), E=SectionList.end(); I != E; ++I) {
1005 ELFSection &S = *(*I);
1006 // Set the index into the table. Note if we have lots of entries with
1007 // common suffixes, we could memoize them here if we cared.
1008 S.NameIdx = Index;
1009 SHStrTab.emitString(S.getName());
1011 // Keep track of the number of bytes emitted to this section.
1012 Index += S.getName().size()+1;
1015 // Set the size of .shstrtab now that we know what it is.
1016 assert(Index == SHStrTab.size());
1017 SHStrTab.Size = Index;
1020 /// OutputSectionsAndSectionTable - Now that we have constructed the file header
1021 /// and all of the sections, emit these to the ostream destination and emit the
1022 /// SectionTable.
1023 void ELFWriter::OutputSectionsAndSectionTable() {
1024 // Pass #1: Compute the file offset for each section.
1025 size_t FileOff = ElfHdr.size(); // File header first.
1027 // Adjust alignment of all section if needed, skip the null section.
1028 for (unsigned i=1, e=SectionList.size(); i < e; ++i) {
1029 ELFSection &ES = *SectionList[i];
1030 if (!ES.size()) {
1031 ES.Offset = FileOff;
1032 continue;
1035 // Update Section size
1036 if (!ES.Size)
1037 ES.Size = ES.size();
1039 // Align FileOff to whatever the alignment restrictions of the section are.
1040 if (ES.Align)
1041 FileOff = (FileOff+ES.Align-1) & ~(ES.Align-1);
1043 ES.Offset = FileOff;
1044 FileOff += ES.Size;
1047 // Align Section Header.
1048 unsigned TableAlign = TEW->getPrefELFAlignment();
1049 FileOff = (FileOff+TableAlign-1) & ~(TableAlign-1);
1051 // Now that we know where all of the sections will be emitted, set the e_shnum
1052 // entry in the ELF header.
1053 ElfHdr.fixWord16(NumSections, ELFHdr_e_shnum_Offset);
1055 // Now that we know the offset in the file of the section table, update the
1056 // e_shoff address in the ELF header.
1057 ElfHdr.fixWord(FileOff, ELFHdr_e_shoff_Offset);
1059 // Now that we know all of the data in the file header, emit it and all of the
1060 // sections!
1061 O.write((char *)&ElfHdr.getData()[0], ElfHdr.size());
1062 FileOff = ElfHdr.size();
1064 // Section Header Table blob
1065 BinaryObject SHdrTable(isLittleEndian, is64Bit);
1067 // Emit all of sections to the file and build the section header table.
1068 for (ELFSectionIter I=SectionList.begin(), E=SectionList.end(); I != E; ++I) {
1069 ELFSection &S = *(*I);
1070 DOUT << "SectionIdx: " << S.SectionIdx << ", Name: " << S.getName()
1071 << ", Size: " << S.Size << ", Offset: " << S.Offset
1072 << ", SectionData Size: " << S.size() << "\n";
1074 // Align FileOff to whatever the alignment restrictions of the section are.
1075 if (S.size()) {
1076 if (S.Align) {
1077 for (size_t NewFileOff = (FileOff+S.Align-1) & ~(S.Align-1);
1078 FileOff != NewFileOff; ++FileOff)
1079 O << (char)0xAB;
1081 O.write((char *)&S.getData()[0], S.Size);
1082 FileOff += S.Size;
1085 EmitSectionHeader(SHdrTable, S);
1088 // Align output for the section table.
1089 for (size_t NewFileOff = (FileOff+TableAlign-1) & ~(TableAlign-1);
1090 FileOff != NewFileOff; ++FileOff)
1091 O << (char)0xAB;
1093 // Emit the section table itself.
1094 O.write((char *)&SHdrTable.getData()[0], SHdrTable.size());