src/llvm/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp

   1 //===-- CodeGen/AsmPrinter/DwarfException.cpp - Dwarf Exception Impl ------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file contains support for writing DWARF exception info into asm files.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "DwarfException.h"
  15 #include "llvm/ADT/SmallString.h"
  16 #include "llvm/ADT/StringExtras.h"
  17 #include "llvm/ADT/Twine.h"
  18 #include "llvm/CodeGen/AsmPrinter.h"
  19 #include "llvm/CodeGen/MachineFrameInfo.h"
  20 #include "llvm/CodeGen/MachineFunction.h"
  21 #include "llvm/CodeGen/MachineModuleInfo.h"
  22 #include "llvm/IR/DataLayout.h"
  23 #include "llvm/IR/Module.h"
  24 #include "llvm/MC/MCAsmInfo.h"
  25 #include "llvm/MC/MCContext.h"
  26 #include "llvm/MC/MCExpr.h"
  27 #include "llvm/MC/MCSection.h"
  28 #include "llvm/MC/MCStreamer.h"
  29 #include "llvm/MC/MCSymbol.h"
  30 #include "llvm/MC/MachineLocation.h"
  31 #include "llvm/Support/Dwarf.h"
  32 #include "llvm/Support/ErrorHandling.h"
  33 #include "llvm/Support/FormattedStream.h"
  34 #include "llvm/Target/Mangler.h"
  35 #include "llvm/Target/TargetFrameLowering.h"
  36 #include "llvm/Target/TargetLoweringObjectFile.h"
  37 #include "llvm/Target/TargetMachine.h"
  38 #include "llvm/Target/TargetOptions.h"
  39 #include "llvm/Target/TargetRegisterInfo.h"
  40 using namespace llvm;
  41
  42 DwarfCFIException::DwarfCFIException(AsmPrinter *A)
  43   : DwarfException(A),
  44     shouldEmitPersonality(false), shouldEmitLSDA(false), shouldEmitMoves(false),
  45     moveTypeModule(AsmPrinter::CFI_M_None) {}
  46
  47 DwarfCFIException::~DwarfCFIException() {}
  48
  49 /// EndModule - Emit all exception information that should come after the
  50 /// content.
  51 void DwarfCFIException::EndModule() {
  52   if (moveTypeModule == AsmPrinter::CFI_M_Debug)
  53     Asm->OutStreamer.EmitCFISections(false, true);
  54
  55   if (!Asm->MAI->isExceptionHandlingDwarf())
  56     return;
  57
  58   const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
  59
  60   unsigned PerEncoding = TLOF.getPersonalityEncoding();
  61
  62   if ((PerEncoding & 0x70) != dwarf::DW_EH_PE_pcrel)
  63     return;
  64
  65   // Emit references to all used personality functions
  66   bool AtLeastOne = false;
  67   const std::vector<const Function*> &Personalities = MMI->getPersonalities();
  68   for (size_t i = 0, e = Personalities.size(); i != e; ++i) {
  69     if (!Personalities[i])
  70       continue;
  71     MCSymbol *Sym = Asm->Mang->getSymbol(Personalities[i]);
  72     TLOF.emitPersonalityValue(Asm->OutStreamer, Asm->TM, Sym);
  73     AtLeastOne = true;
  74   }
  75
  76   if (AtLeastOne && !TLOF.isFunctionEHFrameSymbolPrivate()) {
  77     // This is a temporary hack to keep sections in the same order they
  78     // were before. This lets us produce bit identical outputs while
  79     // transitioning to CFI.
  80     Asm->OutStreamer.SwitchSection(
  81                const_cast<TargetLoweringObjectFile&>(TLOF).getEHFrameSection());
  82   }
  83 }
  84
  85 /// BeginFunction - Gather pre-function exception information. Assumes it's
  86 /// being emitted immediately after the function entry point.
  87 void DwarfCFIException::BeginFunction(const MachineFunction *MF) {
  88   shouldEmitMoves = shouldEmitPersonality = shouldEmitLSDA = false;
  89
  90   // If any landing pads survive, we need an EH table.
  91   bool hasLandingPads = !MMI->getLandingPads().empty();
  92
  93   // See if we need frame move info.
  94   AsmPrinter::CFIMoveType MoveType = Asm->needsCFIMoves();
  95   if (MoveType == AsmPrinter::CFI_M_EH ||
  96       (MoveType == AsmPrinter::CFI_M_Debug &&
  97        moveTypeModule == AsmPrinter::CFI_M_None))
  98     moveTypeModule = MoveType;
  99
 100   shouldEmitMoves = MoveType != AsmPrinter::CFI_M_None;
 101
 102   const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
 103   unsigned PerEncoding = TLOF.getPersonalityEncoding();
 104   const Function *Per = MMI->getPersonalities()[MMI->getPersonalityIndex()];
 105
 106   shouldEmitPersonality = hasLandingPads &&
 107     PerEncoding != dwarf::DW_EH_PE_omit && Per;
 108
 109   unsigned LSDAEncoding = TLOF.getLSDAEncoding();
 110   shouldEmitLSDA = shouldEmitPersonality &&
 111     LSDAEncoding != dwarf::DW_EH_PE_omit;
 112
 113   if (!shouldEmitPersonality && !shouldEmitMoves)
 114     return;
 115
 116   Asm->OutStreamer.EmitCFIStartProc();
 117
 118   // Indicate personality routine, if any.
 119   if (!shouldEmitPersonality)
 120     return;
 121
 122   const MCSymbol *Sym = TLOF.getCFIPersonalitySymbol(Per, Asm->Mang, MMI);
 123   Asm->OutStreamer.EmitCFIPersonality(Sym, PerEncoding);
 124
 125   Asm->OutStreamer.EmitDebugLabel
 126     (Asm->GetTempSymbol("eh_func_begin",
 127                         Asm->getFunctionNumber()));
 128
 129   // Provide LSDA information.
 130   if (!shouldEmitLSDA)
 131     return;
 132
 133   Asm->OutStreamer.EmitCFILsda(Asm->GetTempSymbol("exception",
 134                                                   Asm->getFunctionNumber()),
 135                                LSDAEncoding);
 136 }
 137
 138 /// EndFunction - Gather and emit post-function exception information.
 139 ///
 140 void DwarfCFIException::EndFunction() {
 141   if (!shouldEmitPersonality && !shouldEmitMoves)
 142     return;
 143
 144   Asm->OutStreamer.EmitCFIEndProc();
 145
 146   if (!shouldEmitPersonality)
 147     return;
 148
 149   Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("eh_func_end",
 150                                                 Asm->getFunctionNumber()));
 151
 152   // Map all labels and get rid of any dead landing pads.
 153   MMI->TidyLandingPads();
 154
 155   EmitExceptionTable();
 156 }