6122f3e60d
branch. This brings us very close to the 3.0 release, which is expected in a week or two. MFC after: 1 week
1106 lines
39 KiB
C++
1106 lines
39 KiB
C++
//===-- ELFWriter.cpp - Target-independent ELF Writer code ----------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements the target-independent ELF writer. This file writes out
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// the ELF file in the following order:
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//
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// #1. ELF Header
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// #2. '.text' section
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// #3. '.data' section
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// #4. '.bss' section (conceptual position in file)
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// ...
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// #X. '.shstrtab' section
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// #Y. Section Table
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//
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// The entries in the section table are laid out as:
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// #0. Null entry [required]
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// #1. ".text" entry - the program code
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// #2. ".data" entry - global variables with initializers. [ if needed ]
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// #3. ".bss" entry - global variables without initializers. [ if needed ]
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// ...
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// #N. ".shstrtab" entry - String table for the section names.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "elfwriter"
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#include "ELF.h"
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#include "ELFWriter.h"
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#include "ELFCodeEmitter.h"
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#include "llvm/Constants.h"
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#include "llvm/Module.h"
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#include "llvm/PassManager.h"
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#include "llvm/DerivedTypes.h"
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#include "llvm/CodeGen/BinaryObject.h"
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#include "llvm/CodeGen/MachineCodeEmitter.h"
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#include "llvm/CodeGen/ObjectCodeEmitter.h"
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#include "llvm/CodeGen/MachineCodeEmitter.h"
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#include "llvm/CodeGen/MachineConstantPool.h"
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#include "llvm/MC/MCContext.h"
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#include "llvm/MC/MCSectionELF.h"
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#include "llvm/MC/MCAsmInfo.h"
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#include "llvm/Target/Mangler.h"
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#include "llvm/Target/TargetData.h"
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#include "llvm/Target/TargetELFWriterInfo.h"
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#include "llvm/Target/TargetLowering.h"
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#include "llvm/Target/TargetLoweringObjectFile.h"
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#include "llvm/Target/TargetMachine.h"
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#include "llvm/Target/TargetRegisterInfo.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/ErrorHandling.h"
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#include "llvm/Support/raw_ostream.h"
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#include "llvm/ADT/SmallString.h"
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using namespace llvm;
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char ELFWriter::ID = 0;
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//===----------------------------------------------------------------------===//
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// ELFWriter Implementation
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//===----------------------------------------------------------------------===//
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ELFWriter::ELFWriter(raw_ostream &o, TargetMachine &tm)
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: MachineFunctionPass(ID), O(o), TM(tm),
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OutContext(*new MCContext(*TM.getMCAsmInfo(), *TM.getRegisterInfo(),
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&TM.getTargetLowering()->getObjFileLowering())),
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TLOF(TM.getTargetLowering()->getObjFileLowering()),
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is64Bit(TM.getTargetData()->getPointerSizeInBits() == 64),
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isLittleEndian(TM.getTargetData()->isLittleEndian()),
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ElfHdr(isLittleEndian, is64Bit) {
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MAI = TM.getMCAsmInfo();
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TEW = TM.getELFWriterInfo();
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// Create the object code emitter object for this target.
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ElfCE = new ELFCodeEmitter(*this);
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// Initial number of sections
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NumSections = 0;
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}
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ELFWriter::~ELFWriter() {
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delete ElfCE;
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delete &OutContext;
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while(!SymbolList.empty()) {
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delete SymbolList.back();
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SymbolList.pop_back();
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}
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while(!PrivateSyms.empty()) {
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delete PrivateSyms.back();
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PrivateSyms.pop_back();
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}
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while(!SectionList.empty()) {
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delete SectionList.back();
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SectionList.pop_back();
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}
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// Release the name mangler object.
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delete Mang; Mang = 0;
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}
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// doInitialization - Emit the file header and all of the global variables for
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// the module to the ELF file.
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bool ELFWriter::doInitialization(Module &M) {
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// Initialize TargetLoweringObjectFile.
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const_cast<TargetLoweringObjectFile&>(TLOF).Initialize(OutContext, TM);
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Mang = new Mangler(OutContext, *TM.getTargetData());
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// ELF Header
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// ----------
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// Fields e_shnum e_shstrndx are only known after all section have
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// been emitted. They locations in the ouput buffer are recorded so
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// to be patched up later.
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//
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// Note
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// ----
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// emitWord method behaves differently for ELF32 and ELF64, writing
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// 4 bytes in the former and 8 in the last for *_off and *_addr elf types
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ElfHdr.emitByte(0x7f); // e_ident[EI_MAG0]
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ElfHdr.emitByte('E'); // e_ident[EI_MAG1]
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ElfHdr.emitByte('L'); // e_ident[EI_MAG2]
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ElfHdr.emitByte('F'); // e_ident[EI_MAG3]
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ElfHdr.emitByte(TEW->getEIClass()); // e_ident[EI_CLASS]
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ElfHdr.emitByte(TEW->getEIData()); // e_ident[EI_DATA]
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ElfHdr.emitByte(ELF::EV_CURRENT); // e_ident[EI_VERSION]
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ElfHdr.emitAlignment(16); // e_ident[EI_NIDENT-EI_PAD]
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ElfHdr.emitWord16(ELF::ET_REL); // e_type
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ElfHdr.emitWord16(TEW->getEMachine()); // e_machine = target
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ElfHdr.emitWord32(ELF::EV_CURRENT); // e_version
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ElfHdr.emitWord(0); // e_entry, no entry point in .o file
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ElfHdr.emitWord(0); // e_phoff, no program header for .o
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ELFHdr_e_shoff_Offset = ElfHdr.size();
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ElfHdr.emitWord(0); // e_shoff = sec hdr table off in bytes
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ElfHdr.emitWord32(TEW->getEFlags()); // e_flags = whatever the target wants
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ElfHdr.emitWord16(TEW->getHdrSize()); // e_ehsize = ELF header size
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ElfHdr.emitWord16(0); // e_phentsize = prog header entry size
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ElfHdr.emitWord16(0); // e_phnum = # prog header entries = 0
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// e_shentsize = Section header entry size
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ElfHdr.emitWord16(TEW->getSHdrSize());
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// e_shnum = # of section header ents
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ELFHdr_e_shnum_Offset = ElfHdr.size();
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ElfHdr.emitWord16(0); // Placeholder
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// e_shstrndx = Section # of '.shstrtab'
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ELFHdr_e_shstrndx_Offset = ElfHdr.size();
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ElfHdr.emitWord16(0); // Placeholder
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// Add the null section, which is required to be first in the file.
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getNullSection();
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// The first entry in the symtab is the null symbol and the second
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// is a local symbol containing the module/file name
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SymbolList.push_back(new ELFSym());
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SymbolList.push_back(ELFSym::getFileSym());
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return false;
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}
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// AddPendingGlobalSymbol - Add a global to be processed and to
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// the global symbol lookup, use a zero index because the table
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// index will be determined later.
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void ELFWriter::AddPendingGlobalSymbol(const GlobalValue *GV,
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bool AddToLookup /* = false */) {
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PendingGlobals.insert(GV);
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if (AddToLookup)
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GblSymLookup[GV] = 0;
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}
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// AddPendingExternalSymbol - Add the external to be processed
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// and to the external symbol lookup, use a zero index because
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// the symbol table index will be determined later.
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void ELFWriter::AddPendingExternalSymbol(const char *External) {
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PendingExternals.insert(External);
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ExtSymLookup[External] = 0;
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}
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ELFSection &ELFWriter::getDataSection() {
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const MCSectionELF *Data = (const MCSectionELF *)TLOF.getDataSection();
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return getSection(Data->getSectionName(), Data->getType(),
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Data->getFlags(), 4);
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}
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ELFSection &ELFWriter::getBSSSection() {
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const MCSectionELF *BSS = (const MCSectionELF *)TLOF.getBSSSection();
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return getSection(BSS->getSectionName(), BSS->getType(), BSS->getFlags(), 4);
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}
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// getCtorSection - Get the static constructor section
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ELFSection &ELFWriter::getCtorSection() {
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const MCSectionELF *Ctor = (const MCSectionELF *)TLOF.getStaticCtorSection();
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return getSection(Ctor->getSectionName(), Ctor->getType(), Ctor->getFlags());
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}
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// getDtorSection - Get the static destructor section
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ELFSection &ELFWriter::getDtorSection() {
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const MCSectionELF *Dtor = (const MCSectionELF *)TLOF.getStaticDtorSection();
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return getSection(Dtor->getSectionName(), Dtor->getType(), Dtor->getFlags());
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}
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// getTextSection - Get the text section for the specified function
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ELFSection &ELFWriter::getTextSection(const Function *F) {
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const MCSectionELF *Text =
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(const MCSectionELF *)TLOF.SectionForGlobal(F, Mang, TM);
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return getSection(Text->getSectionName(), Text->getType(), Text->getFlags());
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}
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// getJumpTableSection - Get a read only section for constants when
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// emitting jump tables. TODO: add PIC support
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ELFSection &ELFWriter::getJumpTableSection() {
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const MCSectionELF *JT =
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(const MCSectionELF *)TLOF.getSectionForConstant(SectionKind::getReadOnly());
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return getSection(JT->getSectionName(), JT->getType(), JT->getFlags(),
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TM.getTargetData()->getPointerABIAlignment());
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}
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// getConstantPoolSection - Get a constant pool section based on the machine
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// constant pool entry type and relocation info.
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ELFSection &ELFWriter::getConstantPoolSection(MachineConstantPoolEntry &CPE) {
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SectionKind Kind;
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switch (CPE.getRelocationInfo()) {
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default: llvm_unreachable("Unknown section kind");
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case 2: Kind = SectionKind::getReadOnlyWithRel(); break;
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case 1:
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Kind = SectionKind::getReadOnlyWithRelLocal();
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break;
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case 0:
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switch (TM.getTargetData()->getTypeAllocSize(CPE.getType())) {
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case 4: Kind = SectionKind::getMergeableConst4(); break;
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case 8: Kind = SectionKind::getMergeableConst8(); break;
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case 16: Kind = SectionKind::getMergeableConst16(); break;
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default: Kind = SectionKind::getMergeableConst(); break;
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}
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}
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const MCSectionELF *CPSect =
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(const MCSectionELF *)TLOF.getSectionForConstant(Kind);
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return getSection(CPSect->getSectionName(), CPSect->getType(),
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CPSect->getFlags(), CPE.getAlignment());
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}
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// getRelocSection - Return the relocation section of section 'S'. 'RelA'
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// is true if the relocation section contains entries with addends.
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ELFSection &ELFWriter::getRelocSection(ELFSection &S) {
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unsigned SectionType = TEW->hasRelocationAddend() ?
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ELF::SHT_RELA : ELF::SHT_REL;
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std::string SectionName(".rel");
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if (TEW->hasRelocationAddend())
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SectionName.append("a");
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SectionName.append(S.getName());
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return getSection(SectionName, SectionType, 0, TEW->getPrefELFAlignment());
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}
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// getGlobalELFVisibility - Returns the ELF specific visibility type
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unsigned ELFWriter::getGlobalELFVisibility(const GlobalValue *GV) {
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switch (GV->getVisibility()) {
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default:
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llvm_unreachable("unknown visibility type");
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case GlobalValue::DefaultVisibility:
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return ELF::STV_DEFAULT;
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case GlobalValue::HiddenVisibility:
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return ELF::STV_HIDDEN;
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case GlobalValue::ProtectedVisibility:
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return ELF::STV_PROTECTED;
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}
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return 0;
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}
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// getGlobalELFBinding - Returns the ELF specific binding type
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unsigned ELFWriter::getGlobalELFBinding(const GlobalValue *GV) {
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if (GV->hasInternalLinkage())
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return ELF::STB_LOCAL;
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if (GV->isWeakForLinker() && !GV->hasCommonLinkage())
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return ELF::STB_WEAK;
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return ELF::STB_GLOBAL;
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}
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// getGlobalELFType - Returns the ELF specific type for a global
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unsigned ELFWriter::getGlobalELFType(const GlobalValue *GV) {
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if (GV->isDeclaration())
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return ELF::STT_NOTYPE;
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if (isa<Function>(GV))
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return ELF::STT_FUNC;
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return ELF::STT_OBJECT;
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}
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// IsELFUndefSym - True if the global value must be marked as a symbol
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// which points to a SHN_UNDEF section. This means that the symbol has
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// no definition on the module.
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static bool IsELFUndefSym(const GlobalValue *GV) {
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return GV->isDeclaration() || (isa<Function>(GV));
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}
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// AddToSymbolList - Update the symbol lookup and If the symbol is
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// private add it to PrivateSyms list, otherwise to SymbolList.
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void ELFWriter::AddToSymbolList(ELFSym *GblSym) {
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assert(GblSym->isGlobalValue() && "Symbol must be a global value");
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const GlobalValue *GV = GblSym->getGlobalValue();
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if (GV->hasPrivateLinkage()) {
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// For a private symbols, keep track of the index inside
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// the private list since it will never go to the symbol
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// table and won't be patched up later.
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PrivateSyms.push_back(GblSym);
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GblSymLookup[GV] = PrivateSyms.size()-1;
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} else {
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// Non private symbol are left with zero indices until
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// they are patched up during the symbol table emition
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// (where the indicies are created).
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SymbolList.push_back(GblSym);
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GblSymLookup[GV] = 0;
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}
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}
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/// HasCommonSymbols - True if this section holds common symbols, this is
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/// indicated on the ELF object file by a symbol with SHN_COMMON section
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/// header index.
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static bool HasCommonSymbols(const MCSectionELF &S) {
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// FIXME: this is wrong, a common symbol can be in .data for example.
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if (StringRef(S.getSectionName()).startswith(".gnu.linkonce."))
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return true;
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return false;
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}
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// EmitGlobal - Choose the right section for global and emit it
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void ELFWriter::EmitGlobal(const GlobalValue *GV) {
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// Check if the referenced symbol is already emitted
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if (GblSymLookup.find(GV) != GblSymLookup.end())
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return;
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// Handle ELF Bind, Visibility and Type for the current symbol
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unsigned SymBind = getGlobalELFBinding(GV);
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unsigned SymType = getGlobalELFType(GV);
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bool IsUndefSym = IsELFUndefSym(GV);
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ELFSym *GblSym = IsUndefSym ? ELFSym::getUndefGV(GV, SymBind)
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: ELFSym::getGV(GV, SymBind, SymType, getGlobalELFVisibility(GV));
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if (!IsUndefSym) {
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assert(isa<GlobalVariable>(GV) && "GV not a global variable!");
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const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV);
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// Handle special llvm globals
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if (EmitSpecialLLVMGlobal(GVar))
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return;
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// Get the ELF section where this global belongs from TLOF
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const MCSectionELF *S =
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(const MCSectionELF *)TLOF.SectionForGlobal(GV, Mang, TM);
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ELFSection &ES =
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getSection(S->getSectionName(), S->getType(), S->getFlags());
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SectionKind Kind = S->getKind();
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// The symbol align should update the section alignment if needed
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const TargetData *TD = TM.getTargetData();
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unsigned Align = TD->getPreferredAlignment(GVar);
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unsigned Size = TD->getTypeAllocSize(GVar->getInitializer()->getType());
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GblSym->Size = Size;
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if (HasCommonSymbols(*S)) { // Symbol must go to a common section
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GblSym->SectionIdx = ELF::SHN_COMMON;
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// A new linkonce section is created for each global in the
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// common section, the default alignment is 1 and the symbol
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// value contains its alignment.
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ES.Align = 1;
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GblSym->Value = Align;
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} else if (Kind.isBSS() || Kind.isThreadBSS()) { // Symbol goes to BSS.
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GblSym->SectionIdx = ES.SectionIdx;
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// Update the size with alignment and the next object can
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// start in the right offset in the section
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if (Align) ES.Size = (ES.Size + Align-1) & ~(Align-1);
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ES.Align = std::max(ES.Align, Align);
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// GblSym->Value should contain the virtual offset inside the section.
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// Virtual because the BSS space is not allocated on ELF objects
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GblSym->Value = ES.Size;
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ES.Size += Size;
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} else { // The symbol must go to some kind of data section
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GblSym->SectionIdx = ES.SectionIdx;
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// GblSym->Value should contain the symbol offset inside the section,
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// and all symbols should start on their required alignment boundary
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ES.Align = std::max(ES.Align, Align);
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ES.emitAlignment(Align);
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GblSym->Value = ES.size();
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// Emit the global to the data section 'ES'
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EmitGlobalConstant(GVar->getInitializer(), ES);
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}
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}
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AddToSymbolList(GblSym);
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}
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void ELFWriter::EmitGlobalConstantStruct(const ConstantStruct *CVS,
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ELFSection &GblS) {
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// Print the fields in successive locations. Pad to align if needed!
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const TargetData *TD = TM.getTargetData();
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unsigned Size = TD->getTypeAllocSize(CVS->getType());
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const StructLayout *cvsLayout = TD->getStructLayout(CVS->getType());
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uint64_t sizeSoFar = 0;
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for (unsigned i = 0, e = CVS->getNumOperands(); i != e; ++i) {
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const Constant* field = CVS->getOperand(i);
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// Check if padding is needed and insert one or more 0s.
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uint64_t fieldSize = TD->getTypeAllocSize(field->getType());
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uint64_t padSize = ((i == e-1 ? Size : cvsLayout->getElementOffset(i+1))
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- cvsLayout->getElementOffset(i)) - fieldSize;
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sizeSoFar += fieldSize + padSize;
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// Now print the actual field value.
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EmitGlobalConstant(field, GblS);
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// Insert padding - this may include padding to increase the size of the
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// current field up to the ABI size (if the struct is not packed) as well
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// as padding to ensure that the next field starts at the right offset.
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GblS.emitZeros(padSize);
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}
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assert(sizeSoFar == cvsLayout->getSizeInBytes() &&
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"Layout of constant struct may be incorrect!");
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}
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void ELFWriter::EmitGlobalConstant(const Constant *CV, ELFSection &GblS) {
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const TargetData *TD = TM.getTargetData();
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unsigned Size = TD->getTypeAllocSize(CV->getType());
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if (const ConstantArray *CVA = dyn_cast<ConstantArray>(CV)) {
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for (unsigned i = 0, e = CVA->getNumOperands(); i != e; ++i)
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EmitGlobalConstant(CVA->getOperand(i), GblS);
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return;
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} else if (isa<ConstantAggregateZero>(CV)) {
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GblS.emitZeros(Size);
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return;
|
|
} else if (const ConstantStruct *CVS = dyn_cast<ConstantStruct>(CV)) {
|
|
EmitGlobalConstantStruct(CVS, GblS);
|
|
return;
|
|
} else if (const ConstantFP *CFP = dyn_cast<ConstantFP>(CV)) {
|
|
APInt Val = CFP->getValueAPF().bitcastToAPInt();
|
|
if (CFP->getType()->isDoubleTy())
|
|
GblS.emitWord64(Val.getZExtValue());
|
|
else if (CFP->getType()->isFloatTy())
|
|
GblS.emitWord32(Val.getZExtValue());
|
|
else if (CFP->getType()->isX86_FP80Ty()) {
|
|
unsigned PadSize = TD->getTypeAllocSize(CFP->getType())-
|
|
TD->getTypeStoreSize(CFP->getType());
|
|
GblS.emitWordFP80(Val.getRawData(), PadSize);
|
|
} else if (CFP->getType()->isPPC_FP128Ty())
|
|
llvm_unreachable("PPC_FP128Ty global emission not implemented");
|
|
return;
|
|
} else if (const ConstantInt *CI = dyn_cast<ConstantInt>(CV)) {
|
|
if (Size == 1)
|
|
GblS.emitByte(CI->getZExtValue());
|
|
else if (Size == 2)
|
|
GblS.emitWord16(CI->getZExtValue());
|
|
else if (Size == 4)
|
|
GblS.emitWord32(CI->getZExtValue());
|
|
else
|
|
EmitGlobalConstantLargeInt(CI, GblS);
|
|
return;
|
|
} else if (const ConstantVector *CP = dyn_cast<ConstantVector>(CV)) {
|
|
VectorType *PTy = CP->getType();
|
|
for (unsigned I = 0, E = PTy->getNumElements(); I < E; ++I)
|
|
EmitGlobalConstant(CP->getOperand(I), GblS);
|
|
return;
|
|
} else if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(CV)) {
|
|
// Resolve a constant expression which returns a (Constant, Offset)
|
|
// pair. If 'Res.first' is a GlobalValue, emit a relocation with
|
|
// the offset 'Res.second', otherwise emit a global constant like
|
|
// it is always done for not contant expression types.
|
|
CstExprResTy Res = ResolveConstantExpr(CE);
|
|
const Constant *Op = Res.first;
|
|
|
|
if (isa<GlobalValue>(Op))
|
|
EmitGlobalDataRelocation(cast<const GlobalValue>(Op),
|
|
TD->getTypeAllocSize(Op->getType()),
|
|
GblS, Res.second);
|
|
else
|
|
EmitGlobalConstant(Op, GblS);
|
|
|
|
return;
|
|
} else if (CV->getType()->getTypeID() == Type::PointerTyID) {
|
|
// Fill the data entry with zeros or emit a relocation entry
|
|
if (isa<ConstantPointerNull>(CV))
|
|
GblS.emitZeros(Size);
|
|
else
|
|
EmitGlobalDataRelocation(cast<const GlobalValue>(CV),
|
|
Size, GblS);
|
|
return;
|
|
} else if (const GlobalValue *GV = dyn_cast<GlobalValue>(CV)) {
|
|
// This is a constant address for a global variable or function and
|
|
// therefore must be referenced using a relocation entry.
|
|
EmitGlobalDataRelocation(GV, Size, GblS);
|
|
return;
|
|
}
|
|
|
|
std::string msg;
|
|
raw_string_ostream ErrorMsg(msg);
|
|
ErrorMsg << "Constant unimp for type: " << *CV->getType();
|
|
report_fatal_error(ErrorMsg.str());
|
|
}
|
|
|
|
// ResolveConstantExpr - Resolve the constant expression until it stop
|
|
// yielding other constant expressions.
|
|
CstExprResTy ELFWriter::ResolveConstantExpr(const Constant *CV) {
|
|
const TargetData *TD = TM.getTargetData();
|
|
|
|
// There ins't constant expression inside others anymore
|
|
if (!isa<ConstantExpr>(CV))
|
|
return std::make_pair(CV, 0);
|
|
|
|
const ConstantExpr *CE = dyn_cast<ConstantExpr>(CV);
|
|
switch (CE->getOpcode()) {
|
|
case Instruction::BitCast:
|
|
return ResolveConstantExpr(CE->getOperand(0));
|
|
|
|
case Instruction::GetElementPtr: {
|
|
const Constant *ptrVal = CE->getOperand(0);
|
|
SmallVector<Value*, 8> idxVec(CE->op_begin()+1, CE->op_end());
|
|
int64_t Offset = TD->getIndexedOffset(ptrVal->getType(), idxVec);
|
|
return std::make_pair(ptrVal, Offset);
|
|
}
|
|
case Instruction::IntToPtr: {
|
|
Constant *Op = CE->getOperand(0);
|
|
Op = ConstantExpr::getIntegerCast(Op, TD->getIntPtrType(CV->getContext()),
|
|
false/*ZExt*/);
|
|
return ResolveConstantExpr(Op);
|
|
}
|
|
case Instruction::PtrToInt: {
|
|
Constant *Op = CE->getOperand(0);
|
|
Type *Ty = CE->getType();
|
|
|
|
// We can emit the pointer value into this slot if the slot is an
|
|
// integer slot greater or equal to the size of the pointer.
|
|
if (TD->getTypeAllocSize(Ty) == TD->getTypeAllocSize(Op->getType()))
|
|
return ResolveConstantExpr(Op);
|
|
|
|
llvm_unreachable("Integer size less then pointer size");
|
|
}
|
|
case Instruction::Add:
|
|
case Instruction::Sub: {
|
|
// Only handle cases where there's a constant expression with GlobalValue
|
|
// as first operand and ConstantInt as second, which are the cases we can
|
|
// solve direclty using a relocation entry. GlobalValue=Op0, CstInt=Op1
|
|
// 1) Instruction::Add => (global) + CstInt
|
|
// 2) Instruction::Sub => (global) + -CstInt
|
|
const Constant *Op0 = CE->getOperand(0);
|
|
const Constant *Op1 = CE->getOperand(1);
|
|
assert(isa<ConstantInt>(Op1) && "Op1 must be a ConstantInt");
|
|
|
|
CstExprResTy Res = ResolveConstantExpr(Op0);
|
|
assert(isa<GlobalValue>(Res.first) && "Op0 must be a GlobalValue");
|
|
|
|
const APInt &RHS = cast<ConstantInt>(Op1)->getValue();
|
|
switch (CE->getOpcode()) {
|
|
case Instruction::Add:
|
|
return std::make_pair(Res.first, RHS.getSExtValue());
|
|
case Instruction::Sub:
|
|
return std::make_pair(Res.first, (-RHS).getSExtValue());
|
|
}
|
|
}
|
|
}
|
|
|
|
report_fatal_error(CE->getOpcodeName() +
|
|
StringRef(": Unsupported ConstantExpr type"));
|
|
|
|
return std::make_pair(CV, 0); // silence warning
|
|
}
|
|
|
|
void ELFWriter::EmitGlobalDataRelocation(const GlobalValue *GV, unsigned Size,
|
|
ELFSection &GblS, int64_t Offset) {
|
|
// Create the relocation entry for the global value
|
|
MachineRelocation MR =
|
|
MachineRelocation::getGV(GblS.getCurrentPCOffset(),
|
|
TEW->getAbsoluteLabelMachineRelTy(),
|
|
const_cast<GlobalValue*>(GV),
|
|
Offset);
|
|
|
|
// Fill the data entry with zeros
|
|
GblS.emitZeros(Size);
|
|
|
|
// Add the relocation entry for the current data section
|
|
GblS.addRelocation(MR);
|
|
}
|
|
|
|
void ELFWriter::EmitGlobalConstantLargeInt(const ConstantInt *CI,
|
|
ELFSection &S) {
|
|
const TargetData *TD = TM.getTargetData();
|
|
unsigned BitWidth = CI->getBitWidth();
|
|
assert(isPowerOf2_32(BitWidth) &&
|
|
"Non-power-of-2-sized integers not handled!");
|
|
|
|
const uint64_t *RawData = CI->getValue().getRawData();
|
|
uint64_t Val = 0;
|
|
for (unsigned i = 0, e = BitWidth / 64; i != e; ++i) {
|
|
Val = (TD->isBigEndian()) ? RawData[e - i - 1] : RawData[i];
|
|
S.emitWord64(Val);
|
|
}
|
|
}
|
|
|
|
/// EmitSpecialLLVMGlobal - Check to see if the specified global is a
|
|
/// special global used by LLVM. If so, emit it and return true, otherwise
|
|
/// do nothing and return false.
|
|
bool ELFWriter::EmitSpecialLLVMGlobal(const GlobalVariable *GV) {
|
|
if (GV->getName() == "llvm.used")
|
|
llvm_unreachable("not implemented yet");
|
|
|
|
// Ignore debug and non-emitted data. This handles llvm.compiler.used.
|
|
if (GV->getSection() == "llvm.metadata" ||
|
|
GV->hasAvailableExternallyLinkage())
|
|
return true;
|
|
|
|
if (!GV->hasAppendingLinkage()) return false;
|
|
|
|
assert(GV->hasInitializer() && "Not a special LLVM global!");
|
|
|
|
const TargetData *TD = TM.getTargetData();
|
|
unsigned Align = TD->getPointerPrefAlignment();
|
|
if (GV->getName() == "llvm.global_ctors") {
|
|
ELFSection &Ctor = getCtorSection();
|
|
Ctor.emitAlignment(Align);
|
|
EmitXXStructorList(GV->getInitializer(), Ctor);
|
|
return true;
|
|
}
|
|
|
|
if (GV->getName() == "llvm.global_dtors") {
|
|
ELFSection &Dtor = getDtorSection();
|
|
Dtor.emitAlignment(Align);
|
|
EmitXXStructorList(GV->getInitializer(), Dtor);
|
|
return true;
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
/// EmitXXStructorList - Emit the ctor or dtor list. This just emits out the
|
|
/// function pointers, ignoring the init priority.
|
|
void ELFWriter::EmitXXStructorList(const Constant *List, ELFSection &Xtor) {
|
|
// Should be an array of '{ i32, void ()* }' structs. The first value is the
|
|
// init priority, which we ignore.
|
|
if (List->isNullValue()) return;
|
|
const ConstantArray *InitList = cast<ConstantArray>(List);
|
|
for (unsigned i = 0, e = InitList->getNumOperands(); i != e; ++i) {
|
|
if (InitList->getOperand(i)->isNullValue())
|
|
continue;
|
|
ConstantStruct *CS = cast<ConstantStruct>(InitList->getOperand(i));
|
|
|
|
if (CS->getOperand(1)->isNullValue())
|
|
continue;
|
|
|
|
// Emit the function pointer.
|
|
EmitGlobalConstant(CS->getOperand(1), Xtor);
|
|
}
|
|
}
|
|
|
|
bool ELFWriter::runOnMachineFunction(MachineFunction &MF) {
|
|
// Nothing to do here, this is all done through the ElfCE object above.
|
|
return false;
|
|
}
|
|
|
|
/// doFinalization - Now that the module has been completely processed, emit
|
|
/// the ELF file to 'O'.
|
|
bool ELFWriter::doFinalization(Module &M) {
|
|
// Emit .data section placeholder
|
|
getDataSection();
|
|
|
|
// Emit .bss section placeholder
|
|
getBSSSection();
|
|
|
|
// Build and emit data, bss and "common" sections.
|
|
for (Module::global_iterator I = M.global_begin(), E = M.global_end();
|
|
I != E; ++I)
|
|
EmitGlobal(I);
|
|
|
|
// Emit all pending globals
|
|
for (PendingGblsIter I = PendingGlobals.begin(), E = PendingGlobals.end();
|
|
I != E; ++I)
|
|
EmitGlobal(*I);
|
|
|
|
// Emit all pending externals
|
|
for (PendingExtsIter I = PendingExternals.begin(), E = PendingExternals.end();
|
|
I != E; ++I)
|
|
SymbolList.push_back(ELFSym::getExtSym(*I));
|
|
|
|
// Emit a symbol for each section created until now, skip null section
|
|
for (unsigned i = 1, e = SectionList.size(); i < e; ++i) {
|
|
ELFSection &ES = *SectionList[i];
|
|
ELFSym *SectionSym = ELFSym::getSectionSym();
|
|
SectionSym->SectionIdx = ES.SectionIdx;
|
|
SymbolList.push_back(SectionSym);
|
|
ES.Sym = SymbolList.back();
|
|
}
|
|
|
|
// Emit string table
|
|
EmitStringTable(M.getModuleIdentifier());
|
|
|
|
// Emit the symbol table now, if non-empty.
|
|
EmitSymbolTable();
|
|
|
|
// Emit the relocation sections.
|
|
EmitRelocations();
|
|
|
|
// Emit the sections string table.
|
|
EmitSectionTableStringTable();
|
|
|
|
// Dump the sections and section table to the .o file.
|
|
OutputSectionsAndSectionTable();
|
|
|
|
return false;
|
|
}
|
|
|
|
// RelocateField - Patch relocatable field with 'Offset' in 'BO'
|
|
// using a 'Value' of known 'Size'
|
|
void ELFWriter::RelocateField(BinaryObject &BO, uint32_t Offset,
|
|
int64_t Value, unsigned Size) {
|
|
if (Size == 32)
|
|
BO.fixWord32(Value, Offset);
|
|
else if (Size == 64)
|
|
BO.fixWord64(Value, Offset);
|
|
else
|
|
llvm_unreachable("don't know howto patch relocatable field");
|
|
}
|
|
|
|
/// EmitRelocations - Emit relocations
|
|
void ELFWriter::EmitRelocations() {
|
|
|
|
// True if the target uses the relocation entry to hold the addend,
|
|
// otherwise the addend is written directly to the relocatable field.
|
|
bool HasRelA = TEW->hasRelocationAddend();
|
|
|
|
// Create Relocation sections for each section which needs it.
|
|
for (unsigned i=0, e=SectionList.size(); i != e; ++i) {
|
|
ELFSection &S = *SectionList[i];
|
|
|
|
// This section does not have relocations
|
|
if (!S.hasRelocations()) continue;
|
|
ELFSection &RelSec = getRelocSection(S);
|
|
|
|
// 'Link' - Section hdr idx of the associated symbol table
|
|
// 'Info' - Section hdr idx of the section to which the relocation applies
|
|
ELFSection &SymTab = getSymbolTableSection();
|
|
RelSec.Link = SymTab.SectionIdx;
|
|
RelSec.Info = S.SectionIdx;
|
|
RelSec.EntSize = TEW->getRelocationEntrySize();
|
|
|
|
// Get the relocations from Section
|
|
std::vector<MachineRelocation> Relos = S.getRelocations();
|
|
for (std::vector<MachineRelocation>::iterator MRI = Relos.begin(),
|
|
MRE = Relos.end(); MRI != MRE; ++MRI) {
|
|
MachineRelocation &MR = *MRI;
|
|
|
|
// Relocatable field offset from the section start
|
|
unsigned RelOffset = MR.getMachineCodeOffset();
|
|
|
|
// Symbol index in the symbol table
|
|
unsigned SymIdx = 0;
|
|
|
|
// Target specific relocation field type and size
|
|
unsigned RelType = TEW->getRelocationType(MR.getRelocationType());
|
|
unsigned RelTySize = TEW->getRelocationTySize(RelType);
|
|
int64_t Addend = 0;
|
|
|
|
// There are several machine relocations types, and each one of
|
|
// them needs a different approach to retrieve the symbol table index.
|
|
if (MR.isGlobalValue()) {
|
|
const GlobalValue *G = MR.getGlobalValue();
|
|
int64_t GlobalOffset = MR.getConstantVal();
|
|
SymIdx = GblSymLookup[G];
|
|
if (G->hasPrivateLinkage()) {
|
|
// If the target uses a section offset in the relocation:
|
|
// SymIdx + Addend = section sym for global + section offset
|
|
unsigned SectionIdx = PrivateSyms[SymIdx]->SectionIdx;
|
|
Addend = PrivateSyms[SymIdx]->Value + GlobalOffset;
|
|
SymIdx = SectionList[SectionIdx]->getSymbolTableIndex();
|
|
} else {
|
|
Addend = TEW->getDefaultAddendForRelTy(RelType, GlobalOffset);
|
|
}
|
|
} else if (MR.isExternalSymbol()) {
|
|
const char *ExtSym = MR.getExternalSymbol();
|
|
SymIdx = ExtSymLookup[ExtSym];
|
|
Addend = TEW->getDefaultAddendForRelTy(RelType);
|
|
} else {
|
|
// Get the symbol index for the section symbol
|
|
unsigned SectionIdx = MR.getConstantVal();
|
|
SymIdx = SectionList[SectionIdx]->getSymbolTableIndex();
|
|
|
|
// The symbol offset inside the section
|
|
int64_t SymOffset = (int64_t)MR.getResultPointer();
|
|
|
|
// For pc relative relocations where symbols are defined in the same
|
|
// section they are referenced, ignore the relocation entry and patch
|
|
// the relocatable field with the symbol offset directly.
|
|
if (S.SectionIdx == SectionIdx && TEW->isPCRelativeRel(RelType)) {
|
|
int64_t Value = TEW->computeRelocation(SymOffset, RelOffset, RelType);
|
|
RelocateField(S, RelOffset, Value, RelTySize);
|
|
continue;
|
|
}
|
|
|
|
Addend = TEW->getDefaultAddendForRelTy(RelType, SymOffset);
|
|
}
|
|
|
|
// The target without addend on the relocation symbol must be
|
|
// patched in the relocation place itself to contain the addend
|
|
// otherwise write zeros to make sure there is no garbage there
|
|
RelocateField(S, RelOffset, HasRelA ? 0 : Addend, RelTySize);
|
|
|
|
// Get the relocation entry and emit to the relocation section
|
|
ELFRelocation Rel(RelOffset, SymIdx, RelType, HasRelA, Addend);
|
|
EmitRelocation(RelSec, Rel, HasRelA);
|
|
}
|
|
}
|
|
}
|
|
|
|
/// EmitRelocation - Write relocation 'Rel' to the relocation section 'Rel'
|
|
void ELFWriter::EmitRelocation(BinaryObject &RelSec, ELFRelocation &Rel,
|
|
bool HasRelA) {
|
|
RelSec.emitWord(Rel.getOffset());
|
|
RelSec.emitWord(Rel.getInfo(is64Bit));
|
|
if (HasRelA)
|
|
RelSec.emitWord(Rel.getAddend());
|
|
}
|
|
|
|
/// EmitSymbol - Write symbol 'Sym' to the symbol table 'SymbolTable'
|
|
void ELFWriter::EmitSymbol(BinaryObject &SymbolTable, ELFSym &Sym) {
|
|
if (is64Bit) {
|
|
SymbolTable.emitWord32(Sym.NameIdx);
|
|
SymbolTable.emitByte(Sym.Info);
|
|
SymbolTable.emitByte(Sym.Other);
|
|
SymbolTable.emitWord16(Sym.SectionIdx);
|
|
SymbolTable.emitWord64(Sym.Value);
|
|
SymbolTable.emitWord64(Sym.Size);
|
|
} else {
|
|
SymbolTable.emitWord32(Sym.NameIdx);
|
|
SymbolTable.emitWord32(Sym.Value);
|
|
SymbolTable.emitWord32(Sym.Size);
|
|
SymbolTable.emitByte(Sym.Info);
|
|
SymbolTable.emitByte(Sym.Other);
|
|
SymbolTable.emitWord16(Sym.SectionIdx);
|
|
}
|
|
}
|
|
|
|
/// EmitSectionHeader - Write section 'Section' header in 'SHdrTab'
|
|
/// Section Header Table
|
|
void ELFWriter::EmitSectionHeader(BinaryObject &SHdrTab,
|
|
const ELFSection &SHdr) {
|
|
SHdrTab.emitWord32(SHdr.NameIdx);
|
|
SHdrTab.emitWord32(SHdr.Type);
|
|
if (is64Bit) {
|
|
SHdrTab.emitWord64(SHdr.Flags);
|
|
SHdrTab.emitWord(SHdr.Addr);
|
|
SHdrTab.emitWord(SHdr.Offset);
|
|
SHdrTab.emitWord64(SHdr.Size);
|
|
SHdrTab.emitWord32(SHdr.Link);
|
|
SHdrTab.emitWord32(SHdr.Info);
|
|
SHdrTab.emitWord64(SHdr.Align);
|
|
SHdrTab.emitWord64(SHdr.EntSize);
|
|
} else {
|
|
SHdrTab.emitWord32(SHdr.Flags);
|
|
SHdrTab.emitWord(SHdr.Addr);
|
|
SHdrTab.emitWord(SHdr.Offset);
|
|
SHdrTab.emitWord32(SHdr.Size);
|
|
SHdrTab.emitWord32(SHdr.Link);
|
|
SHdrTab.emitWord32(SHdr.Info);
|
|
SHdrTab.emitWord32(SHdr.Align);
|
|
SHdrTab.emitWord32(SHdr.EntSize);
|
|
}
|
|
}
|
|
|
|
/// EmitStringTable - If the current symbol table is non-empty, emit the string
|
|
/// table for it
|
|
void ELFWriter::EmitStringTable(const std::string &ModuleName) {
|
|
if (!SymbolList.size()) return; // Empty symbol table.
|
|
ELFSection &StrTab = getStringTableSection();
|
|
|
|
// Set the zero'th symbol to a null byte, as required.
|
|
StrTab.emitByte(0);
|
|
|
|
// Walk on the symbol list and write symbol names into the string table.
|
|
unsigned Index = 1;
|
|
for (ELFSymIter I=SymbolList.begin(), E=SymbolList.end(); I != E; ++I) {
|
|
ELFSym &Sym = *(*I);
|
|
|
|
std::string Name;
|
|
if (Sym.isGlobalValue()) {
|
|
SmallString<40> NameStr;
|
|
Mang->getNameWithPrefix(NameStr, Sym.getGlobalValue(), false);
|
|
Name.append(NameStr.begin(), NameStr.end());
|
|
} else if (Sym.isExternalSym())
|
|
Name.append(Sym.getExternalSymbol());
|
|
else if (Sym.isFileType())
|
|
Name.append(ModuleName);
|
|
|
|
if (Name.empty()) {
|
|
Sym.NameIdx = 0;
|
|
} else {
|
|
Sym.NameIdx = Index;
|
|
StrTab.emitString(Name);
|
|
|
|
// Keep track of the number of bytes emitted to this section.
|
|
Index += Name.size()+1;
|
|
}
|
|
}
|
|
assert(Index == StrTab.size());
|
|
StrTab.Size = Index;
|
|
}
|
|
|
|
// SortSymbols - On the symbol table local symbols must come before
|
|
// all other symbols with non-local bindings. The return value is
|
|
// the position of the first non local symbol.
|
|
unsigned ELFWriter::SortSymbols() {
|
|
unsigned FirstNonLocalSymbol;
|
|
std::vector<ELFSym*> LocalSyms, OtherSyms;
|
|
|
|
for (ELFSymIter I=SymbolList.begin(), E=SymbolList.end(); I != E; ++I) {
|
|
if ((*I)->isLocalBind())
|
|
LocalSyms.push_back(*I);
|
|
else
|
|
OtherSyms.push_back(*I);
|
|
}
|
|
SymbolList.clear();
|
|
FirstNonLocalSymbol = LocalSyms.size();
|
|
|
|
for (unsigned i = 0; i < FirstNonLocalSymbol; ++i)
|
|
SymbolList.push_back(LocalSyms[i]);
|
|
|
|
for (ELFSymIter I=OtherSyms.begin(), E=OtherSyms.end(); I != E; ++I)
|
|
SymbolList.push_back(*I);
|
|
|
|
LocalSyms.clear();
|
|
OtherSyms.clear();
|
|
|
|
return FirstNonLocalSymbol;
|
|
}
|
|
|
|
/// EmitSymbolTable - Emit the symbol table itself.
|
|
void ELFWriter::EmitSymbolTable() {
|
|
if (!SymbolList.size()) return; // Empty symbol table.
|
|
|
|
// Now that we have emitted the string table and know the offset into the
|
|
// string table of each symbol, emit the symbol table itself.
|
|
ELFSection &SymTab = getSymbolTableSection();
|
|
SymTab.Align = TEW->getPrefELFAlignment();
|
|
|
|
// Section Index of .strtab.
|
|
SymTab.Link = getStringTableSection().SectionIdx;
|
|
|
|
// Size of each symtab entry.
|
|
SymTab.EntSize = TEW->getSymTabEntrySize();
|
|
|
|
// Reorder the symbol table with local symbols first!
|
|
unsigned FirstNonLocalSymbol = SortSymbols();
|
|
|
|
// Emit all the symbols to the symbol table.
|
|
for (unsigned i = 0, e = SymbolList.size(); i < e; ++i) {
|
|
ELFSym &Sym = *SymbolList[i];
|
|
|
|
// Emit symbol to the symbol table
|
|
EmitSymbol(SymTab, Sym);
|
|
|
|
// Record the symbol table index for each symbol
|
|
if (Sym.isGlobalValue())
|
|
GblSymLookup[Sym.getGlobalValue()] = i;
|
|
else if (Sym.isExternalSym())
|
|
ExtSymLookup[Sym.getExternalSymbol()] = i;
|
|
|
|
// Keep track on the symbol index into the symbol table
|
|
Sym.SymTabIdx = i;
|
|
}
|
|
|
|
// One greater than the symbol table index of the last local symbol
|
|
SymTab.Info = FirstNonLocalSymbol;
|
|
SymTab.Size = SymTab.size();
|
|
}
|
|
|
|
/// EmitSectionTableStringTable - This method adds and emits a section for the
|
|
/// ELF Section Table string table: the string table that holds all of the
|
|
/// section names.
|
|
void ELFWriter::EmitSectionTableStringTable() {
|
|
// First step: add the section for the string table to the list of sections:
|
|
ELFSection &SHStrTab = getSectionHeaderStringTableSection();
|
|
|
|
// Now that we know which section number is the .shstrtab section, update the
|
|
// e_shstrndx entry in the ELF header.
|
|
ElfHdr.fixWord16(SHStrTab.SectionIdx, ELFHdr_e_shstrndx_Offset);
|
|
|
|
// Set the NameIdx of each section in the string table and emit the bytes for
|
|
// the string table.
|
|
unsigned Index = 0;
|
|
|
|
for (ELFSectionIter I=SectionList.begin(), E=SectionList.end(); I != E; ++I) {
|
|
ELFSection &S = *(*I);
|
|
// Set the index into the table. Note if we have lots of entries with
|
|
// common suffixes, we could memoize them here if we cared.
|
|
S.NameIdx = Index;
|
|
SHStrTab.emitString(S.getName());
|
|
|
|
// Keep track of the number of bytes emitted to this section.
|
|
Index += S.getName().size()+1;
|
|
}
|
|
|
|
// Set the size of .shstrtab now that we know what it is.
|
|
assert(Index == SHStrTab.size());
|
|
SHStrTab.Size = Index;
|
|
}
|
|
|
|
/// OutputSectionsAndSectionTable - Now that we have constructed the file header
|
|
/// and all of the sections, emit these to the ostream destination and emit the
|
|
/// SectionTable.
|
|
void ELFWriter::OutputSectionsAndSectionTable() {
|
|
// Pass #1: Compute the file offset for each section.
|
|
size_t FileOff = ElfHdr.size(); // File header first.
|
|
|
|
// Adjust alignment of all section if needed, skip the null section.
|
|
for (unsigned i=1, e=SectionList.size(); i < e; ++i) {
|
|
ELFSection &ES = *SectionList[i];
|
|
if (!ES.size()) {
|
|
ES.Offset = FileOff;
|
|
continue;
|
|
}
|
|
|
|
// Update Section size
|
|
if (!ES.Size)
|
|
ES.Size = ES.size();
|
|
|
|
// Align FileOff to whatever the alignment restrictions of the section are.
|
|
if (ES.Align)
|
|
FileOff = (FileOff+ES.Align-1) & ~(ES.Align-1);
|
|
|
|
ES.Offset = FileOff;
|
|
FileOff += ES.Size;
|
|
}
|
|
|
|
// Align Section Header.
|
|
unsigned TableAlign = TEW->getPrefELFAlignment();
|
|
FileOff = (FileOff+TableAlign-1) & ~(TableAlign-1);
|
|
|
|
// Now that we know where all of the sections will be emitted, set the e_shnum
|
|
// entry in the ELF header.
|
|
ElfHdr.fixWord16(NumSections, ELFHdr_e_shnum_Offset);
|
|
|
|
// Now that we know the offset in the file of the section table, update the
|
|
// e_shoff address in the ELF header.
|
|
ElfHdr.fixWord(FileOff, ELFHdr_e_shoff_Offset);
|
|
|
|
// Now that we know all of the data in the file header, emit it and all of the
|
|
// sections!
|
|
O.write((char *)&ElfHdr.getData()[0], ElfHdr.size());
|
|
FileOff = ElfHdr.size();
|
|
|
|
// Section Header Table blob
|
|
BinaryObject SHdrTable(isLittleEndian, is64Bit);
|
|
|
|
// Emit all of sections to the file and build the section header table.
|
|
for (ELFSectionIter I=SectionList.begin(), E=SectionList.end(); I != E; ++I) {
|
|
ELFSection &S = *(*I);
|
|
DEBUG(dbgs() << "SectionIdx: " << S.SectionIdx << ", Name: " << S.getName()
|
|
<< ", Size: " << S.Size << ", Offset: " << S.Offset
|
|
<< ", SectionData Size: " << S.size() << "\n");
|
|
|
|
// Align FileOff to whatever the alignment restrictions of the section are.
|
|
if (S.size()) {
|
|
if (S.Align) {
|
|
for (size_t NewFileOff = (FileOff+S.Align-1) & ~(S.Align-1);
|
|
FileOff != NewFileOff; ++FileOff)
|
|
O << (char)0xAB;
|
|
}
|
|
O.write((char *)&S.getData()[0], S.Size);
|
|
FileOff += S.Size;
|
|
}
|
|
|
|
EmitSectionHeader(SHdrTable, S);
|
|
}
|
|
|
|
// Align output for the section table.
|
|
for (size_t NewFileOff = (FileOff+TableAlign-1) & ~(TableAlign-1);
|
|
FileOff != NewFileOff; ++FileOff)
|
|
O << (char)0xAB;
|
|
|
|
// Emit the section table itself.
|
|
O.write((char *)&SHdrTable.getData()[0], SHdrTable.size());
|
|
}
|