llvm-6502/lib/MC/MCELFStreamer.cpp

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//===- lib/MC/MCELFStreamer.cpp - ELF Object Output -----------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file assembles .s files and emits ELF .o object files.
//
//===----------------------------------------------------------------------===//
#include "llvm/MC/MCELFStreamer.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/MC/MCAssembler.h"
#include "llvm/MC/MCCodeEmitter.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCELF.h"
#include "llvm/MC/MCELFSymbolFlags.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCInst.h"
#include "llvm/MC/MCObjectStreamer.h"
#include "llvm/MC/MCSection.h"
#include "llvm/MC/MCSectionELF.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/MC/MCValue.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ELF.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
inline void MCELFStreamer::SetSection(StringRef Section, unsigned Type,
unsigned Flags, SectionKind Kind) {
SwitchSection(getContext().getELFSection(Section, Type, Flags, Kind));
}
inline void MCELFStreamer::SetSectionData() {
SetSection(".data",
ELF::SHT_PROGBITS,
ELF::SHF_WRITE | ELF::SHF_ALLOC,
SectionKind::getDataRel());
EmitCodeAlignment(4, 0);
}
inline void MCELFStreamer::SetSectionText() {
SetSection(".text",
ELF::SHT_PROGBITS,
ELF::SHF_EXECINSTR | ELF::SHF_ALLOC,
SectionKind::getText());
EmitCodeAlignment(4, 0);
}
inline void MCELFStreamer::SetSectionBss() {
SetSection(".bss",
ELF::SHT_NOBITS,
ELF::SHF_WRITE | ELF::SHF_ALLOC,
SectionKind::getBSS());
EmitCodeAlignment(4, 0);
}
MCELFStreamer::~MCELFStreamer() {
}
void MCELFStreamer::InitToTextSection() {
SetSectionText();
}
void MCELFStreamer::InitSections() {
// This emulates the same behavior of GNU as. This makes it easier
// to compare the output as the major sections are in the same order.
SetSectionText();
SetSectionData();
SetSectionBss();
SetSectionText();
}
void MCELFStreamer::EmitLabel(MCSymbol *Symbol) {
assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
MCObjectStreamer::EmitLabel(Symbol);
const MCSectionELF &Section =
static_cast<const MCSectionELF&>(Symbol->getSection());
MCSymbolData &SD = getAssembler().getSymbolData(*Symbol);
if (Section.getFlags() & ELF::SHF_TLS)
MCELF::SetType(SD, ELF::STT_TLS);
}
This patch is needed to make c++ exceptions work for mips16. Mips16 is really a processor decoding mode (ala thumb 1) and in the same program, mips16 and mips32 functions can exist and can call each other. If a jal type instruction encounters an address with the lower bit set, then the processor switches to mips16 mode (if it is not already in it). If the lower bit is not set, then it switches to mips32 mode. The linker knows which functions are mips16 and which are mips32. When relocation is performed on code labels, this lower order bit is set if the code label is a mips16 code label. In general this works just fine, however when creating exception handling tables and dwarf, there are cases where you don't want this lower order bit added in. This has been traditionally distinguished in gas assembly source by using a different syntax for the label. lab1: ; this will cause the lower order bit to be added lab2=. ; this will not cause the lower order bit to be added In some cases, it does not matter because in dwarf and debug tables the difference of two labels is used and in that case the lower order bits subtract each other out. To fix this, I have added to mcstreamer the notion of a debuglabel. The default is for label and debug label to be the same. So calling EmitLabel and EmitDebugLabel produce the same result. For various reasons, there is only one set of labels that needs to be modified for the mips exceptions to work. These are the "$eh_func_beginXXX" labels. Mips overrides the debug label suffix from ":" to "=." . This initial patch fixes exceptions. More changes most likely will be needed to DwarfCFException to make all of this work for actual debugging. These changes will be to emit debug labels in some places where a simple label is emitted now. Some historical discussion on this from gcc can be found at: http://gcc.gnu.org/ml/gcc-patches/2008-08/msg00623.html http://gcc.gnu.org/ml/gcc-patches/2008-11/msg01273.html git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@170279 91177308-0d34-0410-b5e6-96231b3b80d8
2012-12-16 04:00:45 +00:00
void MCELFStreamer::EmitDebugLabel(MCSymbol *Symbol) {
EmitLabel(Symbol);
}
void MCELFStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
switch (Flag) {
case MCAF_SyntaxUnified: return; // no-op here.
case MCAF_Code16: return; // Change parsing mode; no-op here.
case MCAF_Code32: return; // Change parsing mode; no-op here.
case MCAF_Code64: return; // Change parsing mode; no-op here.
case MCAF_SubsectionsViaSymbols:
getAssembler().setSubsectionsViaSymbols(true);
return;
}
llvm_unreachable("invalid assembler flag!");
}
void MCELFStreamer::ChangeSection(const MCSection *Section) {
MCSectionData *CurSection = getCurrentSectionData();
if (CurSection && CurSection->isBundleLocked())
report_fatal_error("Unterminated .bundle_lock when changing a section");
const MCSymbol *Grp = static_cast<const MCSectionELF *>(Section)->getGroup();
if (Grp)
getAssembler().getOrCreateSymbolData(*Grp);
this->MCObjectStreamer::ChangeSection(Section);
}
void MCELFStreamer::EmitWeakReference(MCSymbol *Alias, const MCSymbol *Symbol) {
getAssembler().getOrCreateSymbolData(*Symbol);
MCSymbolData &AliasSD = getAssembler().getOrCreateSymbolData(*Alias);
AliasSD.setFlags(AliasSD.getFlags() | ELF_Other_Weakref);
const MCExpr *Value = MCSymbolRefExpr::Create(Symbol, getContext());
Alias->setVariableValue(Value);
}
// When GNU as encounters more than one .type declaration for an object it seems
// to use a mechanism similar to the one below to decide which type is actually
// used in the object file. The greater of T1 and T2 is selected based on the
// following ordering:
// STT_NOTYPE < STT_OBJECT < STT_FUNC < STT_GNU_IFUNC < STT_TLS < anything else
// If neither T1 < T2 nor T2 < T1 according to this ordering, use T2 (the user
// provided type).
static unsigned CombineSymbolTypes(unsigned T1, unsigned T2) {
unsigned TypeOrdering[] = {ELF::STT_NOTYPE, ELF::STT_OBJECT, ELF::STT_FUNC,
ELF::STT_GNU_IFUNC, ELF::STT_TLS};
for (unsigned i = 0; i != array_lengthof(TypeOrdering); ++i) {
if (T1 == TypeOrdering[i])
return T2;
if (T2 == TypeOrdering[i])
return T1;
}
return T2;
}
void MCELFStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
MCSymbolAttr Attribute) {
// Indirect symbols are handled differently, to match how 'as' handles
// them. This makes writing matching .o files easier.
if (Attribute == MCSA_IndirectSymbol) {
// Note that we intentionally cannot use the symbol data here; this is
// important for matching the string table that 'as' generates.
IndirectSymbolData ISD;
ISD.Symbol = Symbol;
ISD.SectionData = getCurrentSectionData();
getAssembler().getIndirectSymbols().push_back(ISD);
return;
}
// Adding a symbol attribute always introduces the symbol, note that an
// important side effect of calling getOrCreateSymbolData here is to register
// the symbol with the assembler.
MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
// The implementation of symbol attributes is designed to match 'as', but it
// leaves much to desired. It doesn't really make sense to arbitrarily add and
// remove flags, but 'as' allows this (in particular, see .desc).
//
// In the future it might be worth trying to make these operations more well
// defined.
switch (Attribute) {
case MCSA_LazyReference:
case MCSA_Reference:
case MCSA_SymbolResolver:
case MCSA_PrivateExtern:
case MCSA_WeakDefinition:
case MCSA_WeakDefAutoPrivate:
case MCSA_Invalid:
case MCSA_IndirectSymbol:
llvm_unreachable("Invalid symbol attribute for ELF!");
case MCSA_NoDeadStrip:
case MCSA_ELF_TypeGnuUniqueObject:
// Ignore for now.
break;
case MCSA_Global:
MCELF::SetBinding(SD, ELF::STB_GLOBAL);
SD.setExternal(true);
BindingExplicitlySet.insert(Symbol);
break;
case MCSA_WeakReference:
case MCSA_Weak:
MCELF::SetBinding(SD, ELF::STB_WEAK);
SD.setExternal(true);
BindingExplicitlySet.insert(Symbol);
break;
case MCSA_Local:
MCELF::SetBinding(SD, ELF::STB_LOCAL);
SD.setExternal(false);
BindingExplicitlySet.insert(Symbol);
break;
case MCSA_ELF_TypeFunction:
MCELF::SetType(SD, CombineSymbolTypes(MCELF::GetType(SD),
ELF::STT_FUNC));
break;
case MCSA_ELF_TypeIndFunction:
MCELF::SetType(SD, CombineSymbolTypes(MCELF::GetType(SD),
ELF::STT_GNU_IFUNC));
break;
case MCSA_ELF_TypeObject:
MCELF::SetType(SD, CombineSymbolTypes(MCELF::GetType(SD),
ELF::STT_OBJECT));
break;
case MCSA_ELF_TypeTLS:
MCELF::SetType(SD, CombineSymbolTypes(MCELF::GetType(SD),
ELF::STT_TLS));
break;
case MCSA_ELF_TypeCommon:
// TODO: Emit these as a common symbol.
MCELF::SetType(SD, CombineSymbolTypes(MCELF::GetType(SD),
ELF::STT_OBJECT));
break;
case MCSA_ELF_TypeNoType:
MCELF::SetType(SD, CombineSymbolTypes(MCELF::GetType(SD),
ELF::STT_NOTYPE));
break;
case MCSA_Protected:
MCELF::SetVisibility(SD, ELF::STV_PROTECTED);
break;
case MCSA_Hidden:
MCELF::SetVisibility(SD, ELF::STV_HIDDEN);
break;
case MCSA_Internal:
MCELF::SetVisibility(SD, ELF::STV_INTERNAL);
break;
}
}
void MCELFStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
unsigned ByteAlignment) {
MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
if (!BindingExplicitlySet.count(Symbol)) {
MCELF::SetBinding(SD, ELF::STB_GLOBAL);
SD.setExternal(true);
}
MCELF::SetType(SD, ELF::STT_OBJECT);
if (MCELF::GetBinding(SD) == ELF_STB_Local) {
const MCSection *Section = getAssembler().getContext().getELFSection(".bss",
ELF::SHT_NOBITS,
ELF::SHF_WRITE |
ELF::SHF_ALLOC,
SectionKind::getBSS());
Symbol->setSection(*Section);
struct LocalCommon L = {&SD, Size, ByteAlignment};
LocalCommons.push_back(L);
} else {
SD.setCommon(Size, ByteAlignment);
}
SD.setSize(MCConstantExpr::Create(Size, getContext()));
}
void MCELFStreamer::EmitELFSize(MCSymbol *Symbol, const MCExpr *Value) {
MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
SD.setSize(Value);
}
void MCELFStreamer::EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
unsigned ByteAlignment) {
// FIXME: Should this be caught and done earlier?
MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
MCELF::SetBinding(SD, ELF::STB_LOCAL);
SD.setExternal(false);
BindingExplicitlySet.insert(Symbol);
EmitCommonSymbol(Symbol, Size, ByteAlignment);
}
void MCELFStreamer::EmitValueImpl(const MCExpr *Value, unsigned Size,
unsigned AddrSpace) {
if (getCurrentSectionData()->isBundleLocked())
report_fatal_error("Emitting values inside a locked bundle is forbidden");
fixSymbolsInTLSFixups(Value);
MCObjectStreamer::EmitValueImpl(Value, Size, AddrSpace);
}
void MCELFStreamer::EmitValueToAlignment(unsigned ByteAlignment,
int64_t Value,
unsigned ValueSize,
unsigned MaxBytesToEmit) {
if (getCurrentSectionData()->isBundleLocked())
report_fatal_error("Emitting values inside a locked bundle is forbidden");
MCObjectStreamer::EmitValueToAlignment(ByteAlignment, Value,
ValueSize, MaxBytesToEmit);
}
// Add a symbol for the file name of this module. This is the second
// entry in the module's symbol table (the first being the null symbol).
void MCELFStreamer::EmitFileDirective(StringRef Filename) {
MCSymbol *Symbol = getAssembler().getContext().GetOrCreateSymbol(Filename);
Symbol->setSection(*getCurrentSection());
Symbol->setAbsolute();
MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
SD.setFlags(ELF_STT_File | ELF_STB_Local | ELF_STV_Default);
}
void MCELFStreamer::fixSymbolsInTLSFixups(const MCExpr *expr) {
switch (expr->getKind()) {
case MCExpr::Target:
cast<MCTargetExpr>(expr)->fixELFSymbolsInTLSFixups(getAssembler());
break;
case MCExpr::Constant:
break;
case MCExpr::Binary: {
const MCBinaryExpr *be = cast<MCBinaryExpr>(expr);
fixSymbolsInTLSFixups(be->getLHS());
fixSymbolsInTLSFixups(be->getRHS());
break;
}
case MCExpr::SymbolRef: {
const MCSymbolRefExpr &symRef = *cast<MCSymbolRefExpr>(expr);
switch (symRef.getKind()) {
default:
return;
case MCSymbolRefExpr::VK_GOTTPOFF:
case MCSymbolRefExpr::VK_INDNTPOFF:
case MCSymbolRefExpr::VK_NTPOFF:
case MCSymbolRefExpr::VK_GOTNTPOFF:
case MCSymbolRefExpr::VK_TLSGD:
case MCSymbolRefExpr::VK_TLSLD:
case MCSymbolRefExpr::VK_TLSLDM:
case MCSymbolRefExpr::VK_TPOFF:
case MCSymbolRefExpr::VK_DTPOFF:
case MCSymbolRefExpr::VK_ARM_TLSGD:
case MCSymbolRefExpr::VK_ARM_TPOFF:
case MCSymbolRefExpr::VK_ARM_GOTTPOFF:
case MCSymbolRefExpr::VK_Mips_TLSGD:
case MCSymbolRefExpr::VK_Mips_GOTTPREL:
case MCSymbolRefExpr::VK_Mips_TPREL_HI:
case MCSymbolRefExpr::VK_Mips_TPREL_LO:
case MCSymbolRefExpr::VK_PPC_TPREL16_HA:
case MCSymbolRefExpr::VK_PPC_TPREL16_LO:
case MCSymbolRefExpr::VK_PPC_DTPREL16_HA:
case MCSymbolRefExpr::VK_PPC_DTPREL16_LO:
case MCSymbolRefExpr::VK_PPC_GOT_TPREL16_HA:
case MCSymbolRefExpr::VK_PPC_GOT_TPREL16_LO:
case MCSymbolRefExpr::VK_PPC_TLS:
case MCSymbolRefExpr::VK_PPC_GOT_TLSGD16_HA:
case MCSymbolRefExpr::VK_PPC_GOT_TLSGD16_LO:
case MCSymbolRefExpr::VK_PPC_TLSGD:
case MCSymbolRefExpr::VK_PPC_GOT_TLSLD16_HA:
case MCSymbolRefExpr::VK_PPC_GOT_TLSLD16_LO:
case MCSymbolRefExpr::VK_PPC_TLSLD:
break;
}
MCSymbolData &SD = getAssembler().getOrCreateSymbolData(symRef.getSymbol());
MCELF::SetType(SD, ELF::STT_TLS);
break;
}
case MCExpr::Unary:
fixSymbolsInTLSFixups(cast<MCUnaryExpr>(expr)->getSubExpr());
break;
}
}
void MCELFStreamer::EmitInstToFragment(const MCInst &Inst) {
this->MCObjectStreamer::EmitInstToFragment(Inst);
MCRelaxableFragment &F = *cast<MCRelaxableFragment>(getCurrentFragment());
for (unsigned i = 0, e = F.getFixups().size(); i != e; ++i)
fixSymbolsInTLSFixups(F.getFixups()[i].getValue());
}
void MCELFStreamer::EmitInstToData(const MCInst &Inst) {
MCAssembler &Assembler = getAssembler();
SmallVector<MCFixup, 4> Fixups;
SmallString<256> Code;
raw_svector_ostream VecOS(Code);
Assembler.getEmitter().EncodeInstruction(Inst, VecOS, Fixups);
VecOS.flush();
for (unsigned i = 0, e = Fixups.size(); i != e; ++i)
fixSymbolsInTLSFixups(Fixups[i].getValue());
// There are several possibilities here:
//
// If bundling is disabled, append the encoded instruction to the current data
// fragment (or create a new such fragment if the current fragment is not a
// data fragment).
//
// If bundling is enabled:
// - If we're not in a bundle-locked group, emit the instruction into a
// fragment of its own. If there are no fixups registered for the
// instruction, emit a MCCompactEncodedInstFragment. Otherwise, emit a
// MCDataFragment.
// - If we're in a bundle-locked group, append the instruction to the current
// data fragment because we want all the instructions in a group to get into
// the same fragment. Be careful not to do that for the first instruction in
// the group, though.
MCDataFragment *DF;
if (Assembler.isBundlingEnabled()) {
MCSectionData *SD = getCurrentSectionData();
if (SD->isBundleLocked() && !SD->isBundleGroupBeforeFirstInst())
// If we are bundle-locked, we re-use the current fragment.
// The bundle-locking directive ensures this is a new data fragment.
DF = cast<MCDataFragment>(getCurrentFragment());
else if (!SD->isBundleLocked() && Fixups.size() == 0) {
// Optimize memory usage by emitting the instruction to a
// MCCompactEncodedInstFragment when not in a bundle-locked group and
// there are no fixups registered.
MCCompactEncodedInstFragment *CEIF = new MCCompactEncodedInstFragment(SD);
CEIF->getContents().append(Code.begin(), Code.end());
return;
} else {
DF = new MCDataFragment(SD);
if (SD->getBundleLockState() == MCSectionData::BundleLockedAlignToEnd) {
// If this is a new fragment created for a bundle-locked group, and the
// group was marked as "align_to_end", set a flag in the fragment.
DF->setAlignToBundleEnd(true);
}
}
// We're now emitting an instruction in a bundle group, so this flag has
// to be turned off.
SD->setBundleGroupBeforeFirstInst(false);
} else {
DF = getOrCreateDataFragment();
}
// Add the fixups and data.
for (unsigned i = 0, e = Fixups.size(); i != e; ++i) {
Fixups[i].setOffset(Fixups[i].getOffset() + DF->getContents().size());
DF->getFixups().push_back(Fixups[i]);
}
DF->setHasInstructions(true);
DF->getContents().append(Code.begin(), Code.end());
}
void MCELFStreamer::EmitBundleAlignMode(unsigned AlignPow2) {
assert(AlignPow2 <= 30 && "Invalid bundle alignment");
MCAssembler &Assembler = getAssembler();
if (Assembler.getBundleAlignSize() == 0 && AlignPow2 > 0)
Assembler.setBundleAlignSize(1 << AlignPow2);
else
report_fatal_error(".bundle_align_mode should be only set once per file");
}
void MCELFStreamer::EmitBundleLock(bool AlignToEnd) {
MCSectionData *SD = getCurrentSectionData();
// Sanity checks
//
if (!getAssembler().isBundlingEnabled())
report_fatal_error(".bundle_lock forbidden when bundling is disabled");
else if (SD->isBundleLocked())
report_fatal_error("Nesting of .bundle_lock is forbidden");
SD->setBundleLockState(AlignToEnd ? MCSectionData::BundleLockedAlignToEnd :
MCSectionData::BundleLocked);
SD->setBundleGroupBeforeFirstInst(true);
}
void MCELFStreamer::EmitBundleUnlock() {
MCSectionData *SD = getCurrentSectionData();
// Sanity checks
if (!getAssembler().isBundlingEnabled())
report_fatal_error(".bundle_unlock forbidden when bundling is disabled");
else if (!SD->isBundleLocked())
report_fatal_error(".bundle_unlock without matching lock");
else if (SD->isBundleGroupBeforeFirstInst())
report_fatal_error("Empty bundle-locked group is forbidden");
SD->setBundleLockState(MCSectionData::NotBundleLocked);
}
void MCELFStreamer::FinishImpl() {
EmitFrames(true);
for (std::vector<LocalCommon>::const_iterator i = LocalCommons.begin(),
e = LocalCommons.end();
i != e; ++i) {
MCSymbolData *SD = i->SD;
uint64_t Size = i->Size;
unsigned ByteAlignment = i->ByteAlignment;
const MCSymbol &Symbol = SD->getSymbol();
const MCSection &Section = Symbol.getSection();
MCSectionData &SectData = getAssembler().getOrCreateSectionData(Section);
new MCAlignFragment(ByteAlignment, 0, 1, ByteAlignment, &SectData);
MCFragment *F = new MCFillFragment(0, 0, Size, &SectData);
SD->setFragment(F);
// Update the maximum alignment of the section if necessary.
if (ByteAlignment > SectData.getAlignment())
SectData.setAlignment(ByteAlignment);
}
this->MCObjectStreamer::FinishImpl();
}
void MCELFStreamer::EmitTCEntry(const MCSymbol &S) {
// Creates a R_PPC64_TOC relocation
MCObjectStreamer::EmitSymbolValue(&S, 8);
}
MCStreamer *llvm::createELFStreamer(MCContext &Context, MCAsmBackend &MAB,
raw_ostream &OS, MCCodeEmitter *CE,
bool RelaxAll, bool NoExecStack) {
MCELFStreamer *S = new MCELFStreamer(Context, MAB, OS, CE);
if (RelaxAll)
S->getAssembler().setRelaxAll(true);
if (NoExecStack)
S->getAssembler().setNoExecStack(true);
return S;
}
void MCELFStreamer::EmitThumbFunc(MCSymbol *Func) {
llvm_unreachable("Generic ELF doesn't support this directive");
}
MCSymbolData &MCELFStreamer::getOrCreateSymbolData(MCSymbol *Symbol) {
return getAssembler().getOrCreateSymbolData(*Symbol);
}
void MCELFStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
llvm_unreachable("ELF doesn't support this directive");
}
void MCELFStreamer::BeginCOFFSymbolDef(const MCSymbol *Symbol) {
llvm_unreachable("ELF doesn't support this directive");
}
void MCELFStreamer::EmitCOFFSymbolStorageClass(int StorageClass) {
llvm_unreachable("ELF doesn't support this directive");
}
void MCELFStreamer::EmitCOFFSymbolType(int Type) {
llvm_unreachable("ELF doesn't support this directive");
}
void MCELFStreamer::EndCOFFSymbolDef() {
llvm_unreachable("ELF doesn't support this directive");
}
void MCELFStreamer::EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
uint64_t Size, unsigned ByteAlignment) {
llvm_unreachable("ELF doesn't support this directive");
}
void MCELFStreamer::EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
uint64_t Size, unsigned ByteAlignment) {
llvm_unreachable("ELF doesn't support this directive");
}