1 //===-- CodeGen/AsmPrinter/ARMException.cpp - ARM EHABI 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/Support/CommandLine.h"
32 #include "llvm/Support/Dwarf.h"
33 #include "llvm/Support/FormattedStream.h"
34 #include "llvm/Target/TargetFrameLowering.h"
35 #include "llvm/Target/TargetOptions.h"
36 #include "llvm/Target/TargetRegisterInfo.h"
37 using namespace llvm;
38 
39 static cl::opt<bool>
40 EnableARMEHABIDescriptors("arm-enable-ehabi-descriptors", cl::Hidden,
41   cl::desc("Generate ARM EHABI tables with unwinding descriptors"),
42   cl::init(false));
43 
44 
45 ARMException::ARMException(AsmPrinter *A)
46   : DwarfException(A) {}
47 
48 ARMException::~ARMException() {}
49 
50 ARMTargetStreamer &ARMException::getTargetStreamer() {
51   MCTargetStreamer &TS = *Asm->OutStreamer.getTargetStreamer();
52   return static_cast<ARMTargetStreamer &>(TS);
53 }
54 
55 void ARMException::endModule() {
56 }
57 
58 /// beginFunction - Gather pre-function exception information. Assumes it's
59 /// being emitted immediately after the function entry point.
60 void ARMException::beginFunction(const MachineFunction *MF) {
61   getTargetStreamer().emitFnStart();
62   if (Asm->MF->getFunction()->needsUnwindTableEntry())
63     Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("eh_func_begin",
64                                                   Asm->getFunctionNumber()));
65 }
66 
67 /// endFunction - Gather and emit post-function exception information.
68 ///
69 void ARMException::endFunction(const MachineFunction *) {
70   ARMTargetStreamer &ATS = getTargetStreamer();
71   if (!Asm->MF->getFunction()->needsUnwindTableEntry())
72     ATS.emitCantUnwind();
73   else {
74     Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("eh_func_end",
75                                                   Asm->getFunctionNumber()));
76 
77     if (EnableARMEHABIDescriptors) {
78       // Map all labels and get rid of any dead landing pads.
79       MMI->TidyLandingPads();
80 
81       if (!MMI->getLandingPads().empty()) {
82         // Emit references to personality.
83         if (const Function * Personality =
84             MMI->getPersonalities()[MMI->getPersonalityIndex()]) {
85           MCSymbol *PerSym = Asm->getSymbol(Personality);
86           Asm->OutStreamer.EmitSymbolAttribute(PerSym, MCSA_Global);
87           ATS.emitPersonality(PerSym);
88         }
89 
90         // Emit .handlerdata directive.
91         ATS.emitHandlerData();
92 
93         // Emit actual exception table
94         EmitExceptionTable();
95       }
96     }
97   }
98 
99   ATS.emitFnEnd();
100 }
101 
102 void ARMException::EmitTypeInfos(unsigned TTypeEncoding) {
103   const std::vector<const GlobalVariable *> &TypeInfos = MMI->getTypeInfos();
104   const std::vector<unsigned> &FilterIds = MMI->getFilterIds();
105 
106   bool VerboseAsm = Asm->OutStreamer.isVerboseAsm();
107 
108   int Entry = 0;
109   // Emit the Catch TypeInfos.
110   if (VerboseAsm && !TypeInfos.empty()) {
111     Asm->OutStreamer.AddComment(">> Catch TypeInfos <<");
112     Asm->OutStreamer.AddBlankLine();
113     Entry = TypeInfos.size();
114   }
115 
116   for (std::vector<const GlobalVariable *>::const_reverse_iterator
117          I = TypeInfos.rbegin(), E = TypeInfos.rend(); I != E; ++I) {
118     const GlobalVariable *GV = *I;
119     if (VerboseAsm)
120       Asm->OutStreamer.AddComment("TypeInfo " + Twine(Entry--));
121     Asm->EmitTTypeReference(GV, TTypeEncoding);
122   }
123 
124   // Emit the Exception Specifications.
125   if (VerboseAsm && !FilterIds.empty()) {
126     Asm->OutStreamer.AddComment(">> Filter TypeInfos <<");
127     Asm->OutStreamer.AddBlankLine();
128     Entry = 0;
129   }
130   for (std::vector<unsigned>::const_iterator
131          I = FilterIds.begin(), E = FilterIds.end(); I < E; ++I) {
132     unsigned TypeID = *I;
133     if (VerboseAsm) {
134       --Entry;
135       if (TypeID != 0)
136         Asm->OutStreamer.AddComment("FilterInfo " + Twine(Entry));
137     }
138 
139     Asm->EmitTTypeReference((TypeID == 0 ? 0 : TypeInfos[TypeID - 1]),
140                             TTypeEncoding);
141   }
142 }
143