AsmPrinter.cpp

//===-- AsmPrinter.cpp - Common AsmPrinter code ---------------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the AsmPrinter class.
//
//===----------------------------------------------------------------------===//

#define DEBUG_TYPE "asm-printer"
#include "llvm/CodeGen/AsmPrinter.h"
#include "llvm/Assembly/Writer.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Constants.h"
#include "llvm/Module.h"
#include "llvm/CodeGen/DwarfWriter.h"
#include "llvm/CodeGen/GCMetadataPrinter.h"
#include "llvm/CodeGen/MachineConstantPool.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineJumpTableInfo.h"
#include "llvm/CodeGen/MachineLoopInfo.h"
#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/Analysis/DebugInfo.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCInst.h"
#include "llvm/MC/MCSection.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/Target/Mangler.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetLowering.h"
#include "llvm/Target/TargetLoweringObjectFile.h"
#include "llvm/Target/TargetOptions.h"
#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/Format.h"
#include "llvm/Support/FormattedStream.h"
#include <cerrno>
using namespace llvm;

STATISTIC(EmittedInsts, "Number of machine instrs printed");

static cl::opt<cl::boolOrDefault>
AsmVerbose("asm-verbose", cl::desc("Add comments to directives."),
           cl::init(cl::BOU_UNSET));

static bool getVerboseAsm(bool VDef) {
  switch (AsmVerbose) {
  default:
  case cl::BOU_UNSET: return VDef;
  case cl::BOU_TRUE:  return true;
  case cl::BOU_FALSE: return false;
  }      
}

char AsmPrinter::ID = 0;
AsmPrinter::AsmPrinter(formatted_raw_ostream &o, TargetMachine &tm,
                       const MCAsmInfo *T, bool VDef)
  : MachineFunctionPass(&ID), O(o),
    TM(tm), MAI(T), TRI(tm.getRegisterInfo()),

    OutContext(*new MCContext()),
    // FIXME: Pass instprinter to streamer.
    OutStreamer(*createAsmStreamer(OutContext, O, *T,
                                   TM.getTargetData()->isLittleEndian(),
                                   getVerboseAsm(VDef), 0)),

    LastMI(0), LastFn(0), Counter(~0U), PrevDLT(NULL) {
  DW = 0; MMI = 0;
  VerboseAsm = getVerboseAsm(VDef);
}

AsmPrinter::~AsmPrinter() {
  for (gcp_iterator I = GCMetadataPrinters.begin(),
                    E = GCMetadataPrinters.end(); I != E; ++I)
    delete I->second;
  
  delete &OutStreamer;
  delete &OutContext;
}

/// getFunctionNumber - Return a unique ID for the current function.
///
unsigned AsmPrinter::getFunctionNumber() const {
  return MF->getFunctionNumber();
}

TargetLoweringObjectFile &AsmPrinter::getObjFileLowering() const {
  return TM.getTargetLowering()->getObjFileLowering();
}

/// getCurrentSection() - Return the current section we are emitting to.
const MCSection *AsmPrinter::getCurrentSection() const {
  return OutStreamer.getCurrentSection();
}


void AsmPrinter::getAnalysisUsage(AnalysisUsage &AU) const {
  AU.setPreservesAll();
  MachineFunctionPass::getAnalysisUsage(AU);
  AU.addRequired<GCModuleInfo>();
  if (VerboseAsm)
    AU.addRequired<MachineLoopInfo>();
}

bool AsmPrinter::doInitialization(Module &M) {
  // Initialize TargetLoweringObjectFile.
  const_cast<TargetLoweringObjectFile&>(getObjFileLowering())
    .Initialize(OutContext, TM);
  
  Mang = new Mangler(*MAI);
  
  // Allow the target to emit any magic that it wants at the start of the file.
  EmitStartOfAsmFile(M);

  // Very minimal debug info. It is ignored if we emit actual debug info. If we
  // don't, this at least helps the user find where a global came from.
  if (MAI->hasSingleParameterDotFile()) {
    // .file "foo.c"
    OutStreamer.EmitFileDirective(M.getModuleIdentifier());
  }

  GCModuleInfo *MI = getAnalysisIfAvailable<GCModuleInfo>();
  assert(MI && "AsmPrinter didn't require GCModuleInfo?");
  for (GCModuleInfo::iterator I = MI->begin(), E = MI->end(); I != E; ++I)
    if (GCMetadataPrinter *MP = GetOrCreateGCPrinter(*I))
      MP->beginAssembly(O, *this, *MAI);
  
  if (!M.getModuleInlineAsm().empty())
    O << MAI->getCommentString() << " Start of file scope inline assembly\n"
      << M.getModuleInlineAsm()
      << '\n' << MAI->getCommentString()
      << " End of file scope inline assembly\n";

  MMI = getAnalysisIfAvailable<MachineModuleInfo>();
  if (MMI)
    MMI->AnalyzeModule(M);
  DW = getAnalysisIfAvailable<DwarfWriter>();
  if (DW)
    DW->BeginModule(&M, MMI, O, this, MAI);

  return false;
}

void AsmPrinter::EmitLinkage(unsigned Linkage, MCSymbol *GVSym) const {
  switch ((GlobalValue::LinkageTypes)Linkage) {
  case GlobalValue::CommonLinkage:
  case GlobalValue::LinkOnceAnyLinkage:
  case GlobalValue::LinkOnceODRLinkage:
  case GlobalValue::WeakAnyLinkage:
  case GlobalValue::WeakODRLinkage:
  case GlobalValue::LinkerPrivateLinkage:
    if (MAI->getWeakDefDirective() != 0) {
      // .globl _foo
      OutStreamer.EmitSymbolAttribute(GVSym, MCSA_Global);
      // .weak_definition _foo
      OutStreamer.EmitSymbolAttribute(GVSym, MCSA_WeakDefinition);
    } else if (const char *LinkOnce = MAI->getLinkOnceDirective()) {
      // .globl _foo
      OutStreamer.EmitSymbolAttribute(GVSym, MCSA_Global);
      // FIXME: linkonce should be a section attribute, handled by COFF Section
      // assignment.
      // http://sourceware.org/binutils/docs-2.20/as/Linkonce.html#Linkonce
      // .linkonce discard
      // FIXME: It would be nice to use .linkonce samesize for non-common
      // globals.
      O << LinkOnce;
    } else {
      // .weak _foo
      OutStreamer.EmitSymbolAttribute(GVSym, MCSA_Weak);
    }
    break;
  case GlobalValue::DLLExportLinkage:
  case GlobalValue::AppendingLinkage:
    // FIXME: appending linkage variables should go into a section of
    // their name or something.  For now, just emit them as external.
  case GlobalValue::ExternalLinkage:
    // If external or appending, declare as a global symbol.
    // .globl _foo
    OutStreamer.EmitSymbolAttribute(GVSym, MCSA_Global);
    break;
  case GlobalValue::PrivateLinkage:
  case GlobalValue::InternalLinkage:
    break;
  default:
    llvm_unreachable("Unknown linkage type!");
  }