DwarfCFIException.cpp revision 60246a96224c8b790177253bf25433b93b335d2b 
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/Module.h"
16#include "llvm/CodeGen/AsmPrinter.h"
17#include "llvm/CodeGen/MachineModuleInfo.h"
18#include "llvm/CodeGen/MachineFrameInfo.h"
19#include "llvm/CodeGen/MachineFunction.h"
20#include "llvm/CodeGen/MachineLocation.h"
21#include "llvm/MC/MCAsmInfo.h"
22#include "llvm/MC/MCContext.h"
23#include "llvm/MC/MCExpr.h"
24#include "llvm/MC/MCSection.h"
25#include "llvm/MC/MCStreamer.h"
26#include "llvm/MC/MCSymbol.h"
27#include "llvm/Target/Mangler.h"
28#include "llvm/Target/TargetData.h"
29#include "llvm/Target/TargetFrameLowering.h"
30#include "llvm/Target/TargetLoweringObjectFile.h"
31#include "llvm/Target/TargetMachine.h"
32#include "llvm/Target/TargetOptions.h"
33#include "llvm/Target/TargetRegisterInfo.h"
34#include "llvm/Support/Dwarf.h"
35#include "llvm/Support/ErrorHandling.h"
36#include "llvm/Support/FormattedStream.h"
37#include "llvm/ADT/SmallString.h"
38#include "llvm/ADT/StringExtras.h"
39#include "llvm/ADT/Twine.h"
40using namespace llvm;
41
42DwarfCFIException::DwarfCFIException(AsmPrinter *A)
43  : DwarfException(A),
44    shouldEmitTable(false), shouldEmitMoves(false), shouldEmitTableModule(false)
45    {}
46
47DwarfCFIException::~DwarfCFIException() {}
48
49/// EndModule - Emit all exception information that should come after the
50/// content.
51void DwarfCFIException::EndModule() {
52  if (!Asm->MAI->isExceptionHandlingDwarf())
53    return;
54
55  if (!shouldEmitTableModule)
56    return;
57
58  const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
59  unsigned PerEncoding = TLOF.getPersonalityEncoding();
60
61  if ((PerEncoding & 0x70) != dwarf::DW_EH_PE_pcrel)
62    return;
63
64  // Emit references to all used personality functions
65  const std::vector<const Function*> &Personalities = MMI->getPersonalities();
66  for (size_t i = 0, e = Personalities.size(); i != e; ++i) {
67    const MCSymbol *Sym = Asm->Mang->getSymbol(Personalities[i]);
68    TLOF.emitPersonalityValue(Asm->OutStreamer, Asm->TM, Sym);
69  }
70}
71
72/// BeginFunction - Gather pre-function exception information. Assumes it's
73/// being emitted immediately after the function entry point.
74void DwarfCFIException::BeginFunction(const MachineFunction *MF) {
75  shouldEmitTable = shouldEmitMoves = false;
76
77  // If any landing pads survive, we need an EH table.
78  shouldEmitTable = !MMI->getLandingPads().empty();
79
80  // See if we need frame move info.
81  shouldEmitMoves = MMI->hasDebugInfo() ||
82    !Asm->MF->getFunction()->doesNotThrow() || UnwindTablesMandatory;
83
84  if (shouldEmitMoves || shouldEmitTable)
85    // Assumes in correct section after the entry point.
86    Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("eh_func_begin",
87                                                  Asm->getFunctionNumber()));
88
89  shouldEmitTableModule |= shouldEmitTable;
90
91  if (shouldEmitMoves || shouldEmitTable)
92    Asm->OutStreamer.EmitCFIStartProc();
93
94  if (!shouldEmitTable)
95    return;
96
97  const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
98
99  // Provide LSDA information.
100  unsigned LSDAEncoding = TLOF.getLSDAEncoding();
101  if (LSDAEncoding != dwarf::DW_EH_PE_omit)
102    Asm->OutStreamer.EmitCFILsda(Asm->GetTempSymbol("exception",
103                                                    Asm->getFunctionNumber()),
104                                 LSDAEncoding);
105
106  // Indicate personality routine, if any.
107  unsigned PerEncoding = TLOF.getPersonalityEncoding();
108  const Function *Per = MMI->getPersonalities()[MMI->getPersonalityIndex()];
109  if (PerEncoding == dwarf::DW_EH_PE_omit || !Per)
110    return;
111
112  const MCSymbol *Sym = TLOF.getCFIPersonalitySymbol(Per, Asm->Mang, MMI);
113  Asm->OutStreamer.EmitCFIPersonality(Sym, PerEncoding);
114}
115
116/// EndFunction - Gather and emit post-function exception information.
117///
118void DwarfCFIException::EndFunction() {
119  if (!shouldEmitMoves && !shouldEmitTable) return;
120
121  Asm->OutStreamer.EmitCFIEndProc();
122
123  Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("eh_func_end",
124                                                Asm->getFunctionNumber()));
125
126  // Map all labels and get rid of any dead landing pads.
127  MMI->TidyLandingPads();
128
129  if (shouldEmitTable)
130    EmitExceptionTable();
131}
132