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