ELFCodeEmitter.cpp [plain text]
#define DEBUG_TYPE "elfce"
#include "ELF.h"
#include "ELFWriter.h"
#include "ELFCodeEmitter.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Function.h"
#include "llvm/CodeGen/BinaryObject.h"
#include "llvm/CodeGen/MachineConstantPool.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineJumpTableInfo.h"
#include "llvm/CodeGen/MachineRelocation.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Target/TargetELFWriterInfo.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
namespace llvm {
void ELFCodeEmitter::startFunction(MachineFunction &MF) {
DEBUG(dbgs() << "processing function: "
<< MF.getFunction()->getName() << "\n");
ES = &EW.getTextSection(MF.getFunction());
setBinaryObject(ES);
unsigned Align = (1 << MF.getAlignment());
ES->emitAlignment(Align);
ES->Align = std::max(ES->Align, Align);
FnStartOff = ES->getCurrentPCOffset();
emitConstantPool(MF.getConstantPool());
if (MF.getJumpTableInfo())
emitJumpTables(MF.getJumpTableInfo());
}
bool ELFCodeEmitter::finishFunction(MachineFunction &MF) {
const Function *F = MF.getFunction();
ELFSym *FnSym = ELFSym::getGV(F, EW.getGlobalELFBinding(F), ELFSym::STT_FUNC,
EW.getGlobalELFVisibility(F));
FnSym->SectionIdx = ES->SectionIdx;
FnSym->Size = ES->getCurrentPCOffset()-FnStartOff;
EW.AddPendingGlobalSymbol(F, true);
FnSym->Value = FnStartOff;
if (!F->hasPrivateLinkage())
EW.SymbolList.push_back(FnSym);
if (MF.getJumpTableInfo()) {
ELFSection &JTSection = EW.getJumpTableSection();
for (std::vector<MachineRelocation>::iterator MRI = JTRelocations.begin(),
MRE = JTRelocations.end(); MRI != MRE; ++MRI) {
MachineRelocation &MR = *MRI;
unsigned MBBOffset = getMachineBasicBlockAddress(MR.getBasicBlock());
MR.setResultPointer((void*)MBBOffset);
MR.setConstantVal(ES->SectionIdx);
JTSection.addRelocation(MR);
}
}
for (unsigned i = 0, e = Relocations.size(); i != e; ++i) {
MachineRelocation &MR = Relocations[i];
intptr_t Addr;
if (MR.isGlobalValue()) {
EW.AddPendingGlobalSymbol(MR.getGlobalValue());
} else if (MR.isExternalSymbol()) {
EW.AddPendingExternalSymbol(MR.getExternalSymbol());
} else if (MR.isBasicBlock()) {
Addr = getMachineBasicBlockAddress(MR.getBasicBlock());
MR.setConstantVal(ES->SectionIdx);
MR.setResultPointer((void*)Addr);
} else if (MR.isConstantPoolIndex()) {
Addr = getConstantPoolEntryAddress(MR.getConstantPoolIndex());
MR.setConstantVal(CPSections[MR.getConstantPoolIndex()]);
MR.setResultPointer((void*)Addr);
} else if (MR.isJumpTableIndex()) {
ELFSection &JTSection = EW.getJumpTableSection();
Addr = getJumpTableEntryAddress(MR.getJumpTableIndex());
MR.setConstantVal(JTSection.SectionIdx);
MR.setResultPointer((void*)Addr);
} else {
llvm_unreachable("Unhandled relocation type");
}
ES->addRelocation(MR);
}
JTRelocations.clear();
Relocations.clear();
CPLocations.clear();
CPSections.clear();
JTLocations.clear();
MBBLocations.clear();
return false;
}
void ELFCodeEmitter::emitConstantPool(MachineConstantPool *MCP) {
const std::vector<MachineConstantPoolEntry> &CP = MCP->getConstants();
if (CP.empty()) return;
assert(TM.getRelocationModel() != Reloc::PIC_ &&
"PIC codegen not yet handled for elf constant pools!");
for (unsigned i = 0, e = CP.size(); i != e; ++i) {
MachineConstantPoolEntry CPE = CP[i];
ELFSection &CstPool = EW.getConstantPoolSection(CPE);
CPLocations.push_back(CstPool.size());
CPSections.push_back(CstPool.SectionIdx);
if (CPE.isMachineConstantPoolEntry())
assert("CPE.isMachineConstantPoolEntry not supported yet");
EW.EmitGlobalConstant(CPE.Val.ConstVal, CstPool);
}
}
void ELFCodeEmitter::emitJumpTables(MachineJumpTableInfo *MJTI) {
const std::vector<MachineJumpTableEntry> &JT = MJTI->getJumpTables();
if (JT.empty()) return;
assert(TM.getRelocationModel() != Reloc::PIC_ &&
"PIC codegen not yet handled for elf jump tables!");
const TargetELFWriterInfo *TEW = TM.getELFWriterInfo();
unsigned EntrySize = 4;
ELFSection &JTSection = EW.getJumpTableSection();
for (unsigned i = 0, e = JT.size(); i != e; ++i) {
const std::vector<MachineBasicBlock*> &MBBs = JT[i].MBBs;
JTLocations.push_back(JTSection.size());
for (unsigned mi = 0, me = MBBs.size(); mi != me; ++mi) {
unsigned MachineRelTy = TEW->getAbsoluteLabelMachineRelTy();
MachineRelocation MR =
MachineRelocation::getBB(JTSection.size(), MachineRelTy, MBBs[mi]);
JTRelocations.push_back(MR);
for (unsigned s=0; s < EntrySize; ++s)
JTSection.emitByte(0);
}
}
}
}