DwarfCFIException.cpp revision cd81d94322a39503e4a3e87b6ee03d4fcb3465fb 
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/Mangler.h"
24#include "llvm/IR/Module.h"
25#include "llvm/MC/MCAsmInfo.h"
26#include "llvm/MC/MCContext.h"
27#include "llvm/MC/MCExpr.h"
28#include "llvm/MC/MCSection.h"
29#include "llvm/MC/MCStreamer.h"
30#include "llvm/MC/MCSymbol.h"
31#include "llvm/MC/MachineLocation.h"
32#include "llvm/Support/Dwarf.h"
33#include "llvm/Support/ErrorHandling.h"
34#include "llvm/Support/FormattedStream.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"
40using namespace llvm;
41
42DwarfCFIException::DwarfCFIException(AsmPrinter *A)
43  : EHStreamer(A), shouldEmitPersonality(false), shouldEmitLSDA(false),
44    shouldEmitMoves(false), moveTypeModule(AsmPrinter::CFI_M_None) {}
45
46DwarfCFIException::~DwarfCFIException() {}
47
48/// endModule - Emit all exception information that should come after the
49/// content.
50void DwarfCFIException::endModule() {
51  if (moveTypeModule == AsmPrinter::CFI_M_Debug)
52    Asm->OutStreamer.EmitCFISections(false, true);
53
54  if (!Asm->MAI->isExceptionHandlingDwarf())
55    return;
56
57  const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
58
59  unsigned PerEncoding = TLOF.getPersonalityEncoding();
60
61  if ((PerEncoding & 0x80) != dwarf::DW_EH_PE_indirect)
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    if (!Personalities[i])
68      continue;
69    MCSymbol *Sym = Asm->getSymbol(Personalities[i]);
70    TLOF.emitPersonalityValue(Asm->OutStreamer, Asm->TM, Sym);
71  }
72}
73
74/// beginFunction - Gather pre-function exception information. Assumes it's
75/// being emitted immediately after the function entry point.
76void DwarfCFIException::beginFunction(const MachineFunction *MF) {
77  shouldEmitMoves = shouldEmitPersonality = shouldEmitLSDA = false;
78
79  // If any landing pads survive, we need an EH table.
80  bool hasLandingPads = !MMI->getLandingPads().empty();
81
82  // See if we need frame move info.
83  AsmPrinter::CFIMoveType MoveType = Asm->needsCFIMoves();
84  if (MoveType == AsmPrinter::CFI_M_EH ||
85      (MoveType == AsmPrinter::CFI_M_Debug &&
86       moveTypeModule == AsmPrinter::CFI_M_None))
87    moveTypeModule = MoveType;
88
89  shouldEmitMoves = MoveType != AsmPrinter::CFI_M_None;
90
91  const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
92  unsigned PerEncoding = TLOF.getPersonalityEncoding();
93  const Function *Per = MMI->getPersonalities()[MMI->getPersonalityIndex()];
94
95  shouldEmitPersonality = hasLandingPads &&
96    PerEncoding != dwarf::DW_EH_PE_omit && Per;
97
98  unsigned LSDAEncoding = TLOF.getLSDAEncoding();
99  shouldEmitLSDA = shouldEmitPersonality &&
100    LSDAEncoding != dwarf::DW_EH_PE_omit;
101
102  if (!shouldEmitPersonality && !shouldEmitMoves)
103    return;
104
105  Asm->OutStreamer.EmitCFIStartProc(/*IsSimple=*/false);
106
107  // Indicate personality routine, if any.
108  if (!shouldEmitPersonality)
109    return;
110
111  const MCSymbol *Sym =
112      TLOF.getCFIPersonalitySymbol(Per, *Asm->Mang, Asm->TM, MMI);
113  Asm->OutStreamer.EmitCFIPersonality(Sym, PerEncoding);
114
115  MCSymbol *EHBegin =
116      Asm->GetTempSymbol("eh_func_begin", Asm->getFunctionNumber());
117  if (Asm->MAI->useAssignmentForEHBegin()) {
118    MCContext &Ctx = Asm->OutContext;
119    MCSymbol *CurPos = Ctx.CreateTempSymbol();
120    Asm->OutStreamer.EmitLabel(CurPos);
121    Asm->OutStreamer.EmitAssignment(EHBegin,
122                                    MCSymbolRefExpr::Create(CurPos, Ctx));
123  } else {
124    Asm->OutStreamer.EmitLabel(EHBegin);
125  }
126
127  // Provide LSDA information.
128  if (!shouldEmitLSDA)
129    return;
130
131  Asm->OutStreamer.EmitCFILsda(Asm->GetTempSymbol("exception",
132                                                  Asm->getFunctionNumber()),
133                               LSDAEncoding);
134}
135
136/// endFunction - Gather and emit post-function exception information.
137///
138void DwarfCFIException::endFunction(const MachineFunction *) {
139  if (!shouldEmitPersonality && !shouldEmitMoves)
140    return;
141
142  Asm->OutStreamer.EmitCFIEndProc();
143
144  if (!shouldEmitPersonality)
145    return;
146
147  Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("eh_func_end",
148                                                Asm->getFunctionNumber()));
149
150  // Map all labels and get rid of any dead landing pads.
151  MMI->TidyLandingPads();
152
153  emitExceptionTable();
154}
155