ARMException.cpp

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//===-- CodeGen/AsmPrinter/ARMException.cpp - ARM EHABI Exception Impl ----===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains support for writing DWARF exception info into asm files.
//
//===----------------------------------------------------------------------===//

#include "DwarfException.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/Twine.h"
#include "llvm/CodeGen/AsmPrinter.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/Mangler.h"
#include "llvm/IR/Module.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCSection.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Dwarf.h"
#include "llvm/Support/FormattedStream.h"
#include "llvm/Target/TargetFrameLowering.h"
#include "llvm/Target/TargetOptions.h"
#include "llvm/Target/TargetRegisterInfo.h"
using namespace llvm;

ARMException::ARMException(AsmPrinter *A)
  : EHStreamer(A), shouldEmitCFI(false) {}

ARMException::~ARMException() {}

ARMTargetStreamer &ARMException::getTargetStreamer() {
  MCTargetStreamer &TS = *Asm->OutStreamer.getTargetStreamer();
  return static_cast<ARMTargetStreamer &>(TS);
}

/// endModule - Emit all exception information that should come after the
/// content.
void ARMException::endModule() {
  if (shouldEmitCFI)
    Asm->OutStreamer.EmitCFISections(false, true);
}

/// beginFunction - Gather pre-function exception information. Assumes it's
/// being emitted immediately after the function entry point.
void ARMException::beginFunction(const MachineFunction *MF) {
  if (Asm->MAI->getExceptionHandlingType() == ExceptionHandling::ARM)
    getTargetStreamer().emitFnStart();
  Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("eh_func_begin",
                                                Asm->getFunctionNumber()));
  // See if we need call frame info.
  AsmPrinter::CFIMoveType MoveType = Asm->needsCFIMoves();
  assert(MoveType != AsmPrinter::CFI_M_EH &&
         "non-EH CFI not yet supported in prologue with EHABI lowering");
  if (MoveType == AsmPrinter::CFI_M_Debug) {
    shouldEmitCFI = true;
    Asm->OutStreamer.EmitCFIStartProc(false);
  }
}

/// endFunction - Gather and emit post-function exception information.
///
void ARMException::endFunction(const MachineFunction *) {
  if (shouldEmitCFI)
    Asm->OutStreamer.EmitCFIEndProc();

  // Map all labels and get rid of any dead landing pads.
  MMI->TidyLandingPads();

  ARMTargetStreamer &ATS = getTargetStreamer();
  if (!Asm->MF->getFunction()->needsUnwindTableEntry() &&
      MMI->getLandingPads().empty())
    ATS.emitCantUnwind();
  else {
    Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("eh_func_end",
                                                  Asm->getFunctionNumber()));
    if (!MMI->getLandingPads().empty()) {
      // Emit references to personality.
      if (const Function * Personality =
          MMI->getPersonalities()[MMI->getPersonalityIndex()]) {
        MCSymbol *PerSym = Asm->getSymbol(Personality);
        Asm->OutStreamer.EmitSymbolAttribute(PerSym, MCSA_Global);
        ATS.emitPersonality(PerSym);
      }

      // Emit .handlerdata directive.
      ATS.emitHandlerData();

      // Emit actual exception table
      emitExceptionTable();
    }
  }

  if (Asm->MAI->getExceptionHandlingType() == ExceptionHandling::ARM)
    ATS.emitFnEnd();
}

void ARMException::emitTypeInfos(unsigned TTypeEncoding) {
  const std::vector<const GlobalVariable *> &TypeInfos = MMI->getTypeInfos();
  const std::vector<unsigned> &FilterIds = MMI->getFilterIds();

  bool VerboseAsm = Asm->OutStreamer.isVerboseAsm();

  int Entry = 0;
  // Emit the Catch TypeInfos.
  if (VerboseAsm && !TypeInfos.empty()) {
    Asm->OutStreamer.AddComment(">> Catch TypeInfos <<");
    Asm->OutStreamer.AddBlankLine();
    Entry = TypeInfos.size();
  }

  for (std::vector<const GlobalVariable *>::const_reverse_iterator
         I = TypeInfos.rbegin(), E = TypeInfos.rend(); I != E; ++I) {
    const GlobalVariable *GV = *I;
    if (VerboseAsm)
      Asm->OutStreamer.AddComment("TypeInfo " + Twine(Entry--));
    Asm->EmitTTypeReference(GV, TTypeEncoding);
  }

  // Emit the Exception Specifications.
  if (VerboseAsm && !FilterIds.empty()) {
    Asm->OutStreamer.AddComment(">> Filter TypeInfos <<");
    Asm->OutStreamer.AddBlankLine();
    Entry = 0;
  }
  for (std::vector<unsigned>::const_iterator
         I = FilterIds.begin(), E = FilterIds.end(); I < E; ++I) {
    unsigned TypeID = *I;
    if (VerboseAsm) {
      --Entry;
      if (TypeID != 0)
        Asm->OutStreamer.AddComment("FilterInfo " + Twine(Entry));
    }

    Asm->EmitTTypeReference((TypeID == 0 ? nullptr : TypeInfos[TypeID - 1]),
                            TTypeEncoding);
  }
}