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      1 //===-- CodeGen/AsmPrinter/Win64Exception.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 Win64 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/Support/Dwarf.h"
     31 #include "llvm/Support/ErrorHandling.h"
     32 #include "llvm/Support/FormattedStream.h"
     33 #include "llvm/Target/Mangler.h"
     34 #include "llvm/Target/TargetFrameLowering.h"
     35 #include "llvm/Target/TargetLoweringObjectFile.h"
     36 #include "llvm/Target/TargetOptions.h"
     37 #include "llvm/Target/TargetRegisterInfo.h"
     38 using namespace llvm;
     39 
     40 Win64Exception::Win64Exception(AsmPrinter *A)
     41   : DwarfException(A),
     42     shouldEmitPersonality(false), shouldEmitLSDA(false), shouldEmitMoves(false)
     43     {}
     44 
     45 Win64Exception::~Win64Exception() {}
     46 
     47 /// EndModule - Emit all exception information that should come after the
     48 /// content.
     49 void Win64Exception::EndModule() {
     50 }
     51 
     52 /// BeginFunction - Gather pre-function exception information. Assumes it's
     53 /// being emitted immediately after the function entry point.
     54 void Win64Exception::BeginFunction(const MachineFunction *MF) {
     55   shouldEmitMoves = shouldEmitPersonality = shouldEmitLSDA = false;
     56 
     57   // If any landing pads survive, we need an EH table.
     58   bool hasLandingPads = !MMI->getLandingPads().empty();
     59 
     60   shouldEmitMoves = Asm->needsSEHMoves();
     61 
     62   const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
     63   unsigned PerEncoding = TLOF.getPersonalityEncoding();
     64   const Function *Per = MMI->getPersonalities()[MMI->getPersonalityIndex()];
     65 
     66   shouldEmitPersonality = hasLandingPads &&
     67     PerEncoding != dwarf::DW_EH_PE_omit && Per;
     68 
     69   unsigned LSDAEncoding = TLOF.getLSDAEncoding();
     70   shouldEmitLSDA = shouldEmitPersonality &&
     71     LSDAEncoding != dwarf::DW_EH_PE_omit;
     72 
     73   if (!shouldEmitPersonality && !shouldEmitMoves)
     74     return;
     75 
     76   Asm->OutStreamer.EmitWin64EHStartProc(Asm->CurrentFnSym);
     77 
     78   if (!shouldEmitPersonality)
     79     return;
     80 
     81   MCSymbol *GCCHandlerSym =
     82     Asm->GetExternalSymbolSymbol("_GCC_specific_handler");
     83   Asm->OutStreamer.EmitWin64EHHandler(GCCHandlerSym, true, true);
     84 
     85   Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("eh_func_begin",
     86                                                 Asm->getFunctionNumber()));
     87 }
     88 
     89 /// EndFunction - Gather and emit post-function exception information.
     90 ///
     91 void Win64Exception::EndFunction() {
     92   if (!shouldEmitPersonality && !shouldEmitMoves)
     93     return;
     94 
     95   Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("eh_func_end",
     96                                                 Asm->getFunctionNumber()));
     97 
     98   // Map all labels and get rid of any dead landing pads.
     99   MMI->TidyLandingPads();
    100 
    101   if (shouldEmitPersonality) {
    102     const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
    103     const Function *Per = MMI->getPersonalities()[MMI->getPersonalityIndex()];
    104     const MCSymbol *Sym = TLOF.getCFIPersonalitySymbol(Per, Asm->Mang, MMI);
    105 
    106     Asm->OutStreamer.PushSection();
    107     Asm->OutStreamer.EmitWin64EHHandlerData();
    108     Asm->OutStreamer.EmitValue(MCSymbolRefExpr::Create(Sym, Asm->OutContext),
    109                                4);
    110     EmitExceptionTable();
    111     Asm->OutStreamer.PopSection();
    112   }
    113   Asm->OutStreamer.EmitWin64EHEndProc();
    114 }
    115