path: root/lib/MC/MCAssembler.cpp

//===- lib/MC/MCAssembler.cpp - Assembler Backend Implementation ----------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#define DEBUG_TYPE "assembler"
#include "llvm/MC/MCAssembler.h"
#include "llvm/MC/MCAsmLayout.h"
#include "llvm/MC/MCCodeEmitter.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCObjectWriter.h"
#include "llvm/MC/MCSection.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/MC/MCValue.h"
#include "llvm/MC/MCDwarf.h"
#include "llvm/ADT/OwningPtr.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/Twine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetRegistry.h"
#include "llvm/Target/TargetAsmBackend.h"

using namespace llvm;

namespace {
namespace stats {
STATISTIC(EmittedFragments, "Number of emitted assembler fragments");
STATISTIC(EvaluateFixup, "Number of evaluated fixups");
STATISTIC(FragmentLayouts, "Number of fragment layouts");
STATISTIC(ObjectBytes, "Number of emitted object file bytes");
STATISTIC(RelaxationSteps, "Number of assembler layout and relaxation steps");
STATISTIC(RelaxedInstructions, "Number of relaxed instructions");
}
}

// FIXME FIXME FIXME: There are number of places in this file where we convert
// what is a 64-bit assembler value used for computation into a value in the
// object file, which may truncate it. We should detect that truncation where
// invalid and report errors back.

/* *** */

MCAsmLayout::MCAsmLayout(MCAssembler &Asm)
  : Assembler(Asm), LastValidFragment()
 {
  // Compute the section layout order. Virtual sections must go last.
  for (MCAssembler::iterator it = Asm.begin(), ie = Asm.end(); it != ie; ++it)
    if (!it->getSection().isVirtualSection())
      SectionOrder.push_back(&*it);
  for (MCAssembler::iterator it = Asm.begin(), ie = Asm.end(); it != ie; ++it)
    if (it->getSection().isVirtualSection())
      SectionOrder.push_back(&*it);
}

bool MCAsmLayout::isFragmentUpToDate(const MCFragment *F) const {
  const MCSectionData &SD = *F->getParent();
  const MCFragment *LastValid = LastValidFragment.lookup(&SD);
  if (!LastValid)
    return false;
  assert(LastValid->getParent() == F->getParent());
  return F->getLayoutOrder() <= LastValid->getLayoutOrder();
}

void MCAsmLayout::Invalidate(MCFragment *F) {
  // If this fragment wasn't already up-to-date, we don't need to do anything.
  if (!isFragmentUpToDate(F))
    return;

  // Otherwise, reset the last valid fragment to this fragment.
  const MCSectionData &SD = *F->getParent();
  LastValidFragment[&SD] = F;
}

void MCAsmLayout::EnsureValid(const MCFragment *F) const {
  MCSectionData &SD = *F->getParent();

  MCFragment *Cur = LastValidFragment[&SD];
  if (!Cur)
    Cur = &*SD.begin();
  else
    Cur = Cur->getNextNode();

  // Advance the layout position until the fragment is up-to-date.
  while (!isFragmentUpToDate(F)) {
    const_cast<MCAsmLayout*>(this)->LayoutFragment(Cur);
    Cur = Cur->getNextNode();
  }
}

uint64_t MCAsmLayout::getFragmentOffset(const MCFragment *F) const {
  EnsureValid(F);
  assert(F->Offset != ~UINT64_C(0) && "Address not set!");
  return F->Offset;
}

uint64_t MCAsmLayout::getSymbolOffset(const MCSymbolData *SD) const {
  assert(SD->getFragment() && "Invalid getOffset() on undefined symbol!");
  return getFragmentOffset(SD->getFragment()) + SD->getOffset();
}

uint64_t MCAsmLayout::getSectionAddressSize(const MCSectionData *SD) const {
  // The size is the last fragment's end offset.
  const MCFragment &F = SD->getFragmentList().back();
  return getFragmentOffset(&F) + getAssembler().ComputeFragmentSize(*this, F);
}

uint64_t MCAsmLayout::getSectionFileSize(const MCSectionData *SD) const {
  // Virtual sections have no file size.
  if (SD->getSection().isVirtualSection())
    return 0;

  // Otherwise, the file size is the same as the address space size.
  return getSectionAddressSize(SD);
}

/* *** */

MCFragment::MCFragment() : Kind(FragmentType(~0)) {
}

MCFragment::~MCFragment() {
}

MCFragment::MCFragment(FragmentType _Kind, MCSectionData *_Parent)
  : Kind(_Kind), Parent(_Parent), Atom(0), Offset(~UINT64_C(0))
{
  if (Parent)
    Parent->getFragmentList().push_back(this);
}

/* *** */

MCSectionData::MCSectionData() : Section(0) {}

MCSectionData::MCSectionData(const MCSection &_Section, MCAssembler *A)
  : Section(&_Section),
    Ordinal(~UINT32_C(0)),
    Alignment(1),
    HasInstructions(fals