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 ARMException::ARMException(AsmPrinter *A)
40   : DwarfException(A),
41     shouldEmitCFI(false) {}
42 
43 ARMException::~ARMException() {}
44 
45 ARMTargetStreamer &ARMException::getTargetStreamer() {
46   MCTargetStreamer &TS = *Asm->OutStreamer.getTargetStreamer();
47   return static_cast<ARMTargetStreamer &>(TS);
48 }
49 
50 /// endModule - Emit all exception information that should come after the
51 /// content.
52 void ARMException::endModule() {
53   if (shouldEmitCFI)
54     Asm->OutStreamer.EmitCFISections(false, true);
55 }
56 
57 /// beginFunction - Gather pre-function exception information. Assumes it's
58 /// being emitted immediately after the function entry point.
59 void ARMException::beginFunction(const MachineFunction *MF) {
60   if (Asm->MAI->getExceptionHandlingType() == ExceptionHandling::ARM)
61     getTargetStreamer().emitFnStart();
62   if (Asm->MF->getFunction()->needsUnwindTableEntry())
63     Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("eh_func_begin",
64                                                   Asm->getFunctionNumber()));
65   // See if we need call frame info.
66   AsmPrinter::CFIMoveType MoveType = Asm->needsCFIMoves();
67   assert(MoveType != AsmPrinter::CFI_M_EH &&
68          "non-EH CFI not yet supported in prologue with EHABI lowering");
69   if (MoveType == AsmPrinter::CFI_M_Debug) {
70     shouldEmitCFI = true;
71     Asm->OutStreamer.EmitCFIStartProc(false);
72   }
73 }
74 
75 /// endFunction - Gather and emit post-function exception information.
76 ///
77 void ARMException::endFunction(const MachineFunction *) {
78   if (shouldEmitCFI)
79     Asm->OutStreamer.EmitCFIEndProc();
80 
81   ARMTargetStreamer &ATS = getTargetStreamer();
82   if (!Asm->MF->getFunction()->needsUnwindTableEntry())
83     ATS.emitCantUnwind();
84   else {
85     Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("eh_func_end",
86                                                   Asm->getFunctionNumber()));
87 
88     // Map all labels and get rid of any dead landing pads.
89     MMI->TidyLandingPads();
90 
91     if (!MMI->getLandingPads().empty()) {
92       // Emit references to personality.
93       if (const Function * Personality =
94           MMI->getPersonalities()[MMI->getPersonalityIndex()]) {
95         MCSymbol *PerSym = Asm->getSymbol(Personality);
96         Asm->OutStreamer.EmitSymbolAttribute(PerSym, MCSA_Global);
97         ATS.emitPersonality(PerSym);
98       }
99 
100       // Emit .handlerdata directive.
101       ATS.emitHandlerData();
102 
103       // Emit actual exception table
104       EmitExceptionTable();
105     }
106   }
107 
108   if (Asm->MAI->getExceptionHandlingType() == ExceptionHandling::ARM)
109     ATS.emitFnEnd();
110 }
111 
112 void ARMException::EmitTypeInfos(unsigned TTypeEncoding) {
113   const std::vector<const GlobalVariable *> &TypeInfos = MMI->getTypeInfos();
114   const std::vector<unsigned> &FilterIds = MMI->getFilterIds();
115 
116   bool VerboseAsm = Asm->OutStreamer.isVerboseAsm();
117 
118   int Entry = 0;
119   // Emit the Catch TypeInfos.
120   if (VerboseAsm && !TypeInfos.empty()) {
121     Asm->OutStreamer.AddComment(">> Catch TypeInfos <<");
122     Asm->OutStreamer.AddBlankLine();
123     Entry = TypeInfos.size();
124   }
125 
126   for (std::vector<const GlobalVariable *>::const_reverse_iterator
127          I = TypeInfos.rbegin(), E = TypeInfos.rend(); I != E; ++I) {
128     const GlobalVariable *GV = *I;
129     if (VerboseAsm)
130       Asm->OutStreamer.AddComment("TypeInfo " + Twine(Entry--));
131     Asm->EmitTTypeReference(GV, TTypeEncoding);
132   }
133 
134   // Emit the Exception Specifications.
135   if (VerboseAsm && !FilterIds.empty()) {
136     Asm->OutStreamer.AddComment(">> Filter TypeInfos <<");
137     Asm->OutStreamer.AddBlankLine();
138     Entry = 0;
139   }
140   for (std::vector<unsigned>::const_iterator
141          I = FilterIds.begin(), E = FilterIds.end(); I < E; ++I) {
142     unsigned TypeID = *I;
143     if (VerboseAsm) {
144       --Entry;
145       if (TypeID != 0)
146         Asm->OutStreamer.AddComment("FilterInfo " + Twine(Entry));
147     }
148 
149     Asm->EmitTTypeReference((TypeID == 0 ? nullptr : TypeInfos[TypeID - 1]),
150                             TTypeEncoding);
151   }
152 }
153