MCStreamer.cpp - Android社区 - https://www.androidos.net.cn/

//===- lib/MC/MCStreamer.cpp - Streaming Machine Code Output --------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCObjectWriter.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/Twine.h"
#include <cstdlib>
using namespace llvm;

MCStreamer::MCStreamer(MCContext &Ctx) : Context(Ctx), EmitEHFrame(true),
                                         EmitDebugFrame(false),
                                         CurrentW64UnwindInfo(0),
                                         LastSymbol(0),
                                         UniqueCodeBeginSuffix(0),
                                         UniqueDataBeginSuffix(0) {
  const MCSection *section = NULL;
  SectionStack.push_back(std::make_pair(section, section));
}

MCStreamer::~MCStreamer() {
  for (unsigned i = 0; i < getNumW64UnwindInfos(); ++i)
    delete W64UnwindInfos[i];
}

const MCExpr *MCStreamer::BuildSymbolDiff(MCContext &Context,
                                          const MCSymbol *A,
                                          const MCSymbol *B) {
  MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
  const MCExpr *ARef =
    MCSymbolRefExpr::Create(A, Variant, Context);
  const MCExpr *BRef =
    MCSymbolRefExpr::Create(B, Variant, Context);
  const MCExpr *AddrDelta =
    MCBinaryExpr::Create(MCBinaryExpr::Sub, ARef, BRef, Context);
  return AddrDelta;
}

const MCExpr *MCStreamer::ForceExpAbs(const MCExpr* Expr) {
  if (Context.getAsmInfo().hasAggressiveSymbolFolding() ||
      isa<MCSymbolRefExpr>(Expr))
    return Expr;

MCSymbol *ABS = Context.CreateTempSymbol();
  EmitAssignment(ABS, Expr);
  return MCSymbolRefExpr::Create(ABS, Context);
}

raw_ostream &MCStreamer::GetCommentOS() {
  // By default, discard comments.
  return nulls();
}

void MCStreamer::EmitDwarfSetLineAddr(int64_t LineDelta,
                                      const MCSymbol *Label, int PointerSize) {
  // emit the sequence to set the address
  EmitIntValue(dwarf::DW_LNS_extended_op, 1);
  EmitULEB128IntValue(PointerSize + 1);
  EmitIntValue(dwarf::DW_LNE_set_address, 1);
  EmitSymbolValue(Label, PointerSize);

// emit the sequence for the LineDelta (from 1) and a zero address delta.
  MCDwarfLineAddr::Emit(this, LineDelta, 0);
}

/// EmitIntValue - Special case of EmitValue that avoids the client having to
/// pass in a MCExpr for constant integers.
void MCStreamer::EmitIntValue(uint64_t Value, unsigned Size,
                              unsigned AddrSpace) {
  assert(Size <= 8 && "Invalid size");
  assert((isUIntN(8 * Size, Value) || isIntN(8 * Size, Value)) &&
         "Invalid size");
  char buf[8];
  const bool isLittleEndian = Context.getAsmInfo().isLittleEndian();
  for (unsigned i = 0; i != Size; ++i) {
    unsigned index = isLittleEndian ? i : (Size - i - 1);
    buf[i] = uint8_t(Value >> (index * 8));
  }
  EmitBytes(StringRef(buf, Size), AddrSpace);
}

/// EmitULEB128Value - Special case of EmitULEB128Value that avoids the
/// client having to pass in a MCExpr for constant integers.
void MCStreamer::EmitULEB128IntValue(uint64_t Value, unsigned AddrSpace) {
  SmallString<32> Tmp;
  raw_svector_ostream OSE(Tmp);
  MCObjectWriter::EncodeULEB128(Value, OSE);
  EmitBytes(OSE.str(), AddrSpace);
}

/// EmitSLEB128Value - Special case of EmitSLEB128Value that avoids the
/// client having to pass in a MCExpr for constant integers.
void MCStreamer::EmitSLEB128IntValue(int64_t Value, unsigned AddrSpace) {
  SmallString<32> Tmp;
  raw_svector_ostream OSE(Tmp);
  MCObjectWriter::EncodeSLEB128(Value, OSE);
  EmitBytes(OSE.str(), AddrSpace);
}

void MCStreamer::EmitAbsValue(const MCExpr *Value, unsigned Size,
                              unsigned AddrSpace) {
  const MCExpr *ABS = ForceExpAbs(Value);
  EmitValue(ABS, Size, AddrSpace);
}

void MCStreamer::EmitValue(const MCExpr *Value, unsigned Size,
                           unsigned AddrSpace) {
  EmitValueImpl(Value, Size, AddrSpace);
}

void MCStreamer::EmitSymbolValue(const MCSymbol *Sym, unsigned Size,
                                  unsigned AddrSpace) {
  EmitValueImpl(MCSymbolRefExpr::Create(Sym, getContext()), Size,
                AddrSpace);
}

void MCStreamer::EmitGPRel32Value(const MCExpr *Value) {
  report_fatal_error("unsupported directive in streamer");
}

/// EmitFill - Emit NumBytes bytes worth of the value specified by
/// FillValue.  This implements directives such as '.space'.
void MCStreamer::EmitFill(uint64_t NumBytes, uint8_t FillValue,
                          unsigned AddrSpace) {
  const MCExpr *E = MCConstantExpr::Create(FillValue, getContext());
  for (uint64_t i = 0, e = NumBytes; i != e; ++i)
    EmitValue(E, 1, AddrSpace);
}

bool MCStreamer::EmitDwarfFileDirective(unsigned FileNo,
                                        StringRef Filename) {
  return getContext().GetDwarfFile(Filename, FileNo) == 0;
}

void MCStreamer::EmitDwarfLocDirective(unsigned FileNo, unsigned Line,
                                       unsigned Column, unsigned Flags,
                                       unsigned Isa,
                                       unsigned Discriminator,
                                       StringRef FileName) {
  getContext().setCurrentDwarfLoc(FileNo, Line, Column, Flags, Isa,
                                  Discriminator);
}

MCDwarfFrameInfo *MCStreamer::getCurrentFrameInfo() {
  if (FrameInfos.empty())
    return NULL;
  return &FrameInfos.back();
}

void MCStreamer::EnsureValidFrame() {
  MCDwarfFrameInfo *CurFrame = getCurrentFrameInfo();
  if (!CurFrame || CurFrame->End)
    report_fatal_error("No open frame");
}

void MCStreamer::EmitEHSymAttributes(const MCSymbol *Symbol,
                                     MCSymbol *EHSymbol) {
}

void MCStreamer::EmitLabel(MCSymbol *Symbol) {
  assert(!Symbol->isVariable() && "Cannot emit a variable symbol!");
  assert(getCurrentSection() && "Cannot emit before setting section!");
  Symbol->setSection(*getCurrentSection());
  LastSymbol = Symbol;
}

void MCStreamer::EmitDataRegion() {
  if (RegionIndicator == Data) return;