1 //===-- CodeGen/AsmPrinter/DwarfException.cpp - Dwarf Exception Impl ------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file contains support for writing DWARF exception info into asm files.
12 //===----------------------------------------------------------------------===//
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"
42 DwarfCFIException::DwarfCFIException(AsmPrinter *A)
44 shouldEmitTable(false), shouldEmitMoves(false), shouldEmitTableModule(false)
47 DwarfCFIException::~DwarfCFIException() {}
49 /// EndModule - Emit all exception information that should come after the
51 void DwarfCFIException::EndModule() {
52 if (!Asm->MAI->isExceptionHandlingDwarf())
55 if (!shouldEmitTableModule)
58 const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
59 unsigned PerEncoding = TLOF.getPersonalityEncoding();
61 // Begin eh frame section.
62 Asm->OutStreamer.SwitchSection(TLOF.getEHFrameSection());
64 if ((PerEncoding & 0x70) != dwarf::DW_EH_PE_pcrel)
67 // Emit references to all used personality functions
68 const std::vector<const Function*> &Personalities = MMI->getPersonalities();
69 for (size_t i = 0, e = Personalities.size(); i != e; ++i) {
70 Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("personality", i));
71 const MCSymbol *Sym = Asm->Mang->getSymbol(Personalities[i]);
72 unsigned Size = Asm->TM.getTargetData()->getPointerSize();
73 Asm->OutStreamer.EmitSymbolValue(Sym, Size);
77 /// BeginFunction - Gather pre-function exception information. Assumes it's
78 /// being emitted immediately after the function entry point.
79 void DwarfCFIException::BeginFunction(const MachineFunction *MF) {
80 shouldEmitTable = shouldEmitMoves = false;
82 // If any landing pads survive, we need an EH table.
83 shouldEmitTable = !MMI->getLandingPads().empty();
85 // See if we need frame move info.
86 shouldEmitMoves = MMI->hasDebugInfo() ||
87 !Asm->MF->getFunction()->doesNotThrow() || UnwindTablesMandatory;
89 if (shouldEmitMoves || shouldEmitTable)
90 // Assumes in correct section after the entry point.
91 Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("eh_func_begin",
92 Asm->getFunctionNumber()));
94 shouldEmitTableModule |= shouldEmitTable;
96 if (shouldEmitMoves || shouldEmitTable)
97 Asm->OutStreamer.EmitCFIStartProc();
102 const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
104 // Provide LSDA information.
105 unsigned LSDAEncoding = TLOF.getLSDAEncoding();
106 if (LSDAEncoding != dwarf::DW_EH_PE_omit)
107 Asm->OutStreamer.EmitCFILsda(Asm->GetTempSymbol("exception",
108 Asm->getFunctionNumber()),
111 // Indicate personality routine, if any.
112 unsigned PerEncoding = TLOF.getPersonalityEncoding();
113 const Function *Per = MMI->getPersonalities()[MMI->getPersonalityIndex()];
114 if (PerEncoding == dwarf::DW_EH_PE_omit || !Per)
118 switch (PerEncoding & 0x70) {
120 report_fatal_error("We do not support this DWARF encoding yet!");
121 case dwarf::DW_EH_PE_absptr: {
122 Sym = Asm->Mang->getSymbol(Per);
125 case dwarf::DW_EH_PE_pcrel: {
126 Sym = Asm->GetTempSymbol("personality",
127 MMI->getPersonalityIndex());
131 Asm->OutStreamer.EmitCFIPersonality(Sym, PerEncoding);
134 /// EndFunction - Gather and emit post-function exception information.
136 void DwarfCFIException::EndFunction() {
137 if (!shouldEmitMoves && !shouldEmitTable) return;
140 Asm->OutStreamer.EmitCFIEndProc();
142 Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("eh_func_end",
143 Asm->getFunctionNumber()));
145 // Map all labels and get rid of any dead landing pads.
146 MMI->TidyLandingPads();
149 EmitExceptionTable();