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/Twine.h"
16 #include "llvm/CodeGen/AsmPrinter.h"
17 #include "llvm/CodeGen/MachineFunction.h"
18 #include "llvm/IR/DataLayout.h"
19 #include "llvm/IR/Mangler.h"
20 #include "llvm/IR/Module.h"
21 #include "llvm/MC/MCAsmInfo.h"
22 #include "llvm/MC/MCExpr.h"
23 #include "llvm/MC/MCSection.h"
24 #include "llvm/MC/MCStreamer.h"
25 #include "llvm/MC/MCSymbol.h"
26 #include "llvm/Support/FormattedStream.h"
27 #include "llvm/Target/TargetOptions.h"
28 using namespace llvm;
29 
30 ARMException::ARMException(AsmPrinter *A) : DwarfCFIExceptionBase(A) {}
31 
32 ARMException::~ARMException() {}
33 
34 ARMTargetStreamer &ARMException::getTargetStreamer() {
35   MCTargetStreamer &TS = *Asm->OutStreamer->getTargetStreamer();
36   return static_cast<ARMTargetStreamer &>(TS);
37 }
38 
39 void ARMException::beginFunction(const MachineFunction *MF) {
40   if (Asm->MAI->getExceptionHandlingType() == ExceptionHandling::ARM)
41     getTargetStreamer().emitFnStart();
42   // See if we need call frame info.
43   AsmPrinter::CFIMoveType MoveType = Asm->needsCFIMoves();
44   assert(MoveType != AsmPrinter::CFI_M_EH &&
45          "non-EH CFI not yet supported in prologue with EHABI lowering");
46 
47   if (MoveType == AsmPrinter::CFI_M_Debug) {
48     if (!hasEmittedCFISections) {
49       if (Asm->needsOnlyDebugCFIMoves())
50         Asm->OutStreamer->EmitCFISections(false, true);
51       hasEmittedCFISections = true;
52     }
53 
54     shouldEmitCFI = true;
55     Asm->OutStreamer->EmitCFIStartProc(false);
56   }
57 }
58 
59 /// endFunction - Gather and emit post-function exception information.
60 ///
61 void ARMException::endFunction(const MachineFunction *MF) {
62   ARMTargetStreamer &ATS = getTargetStreamer();
63   const Function &F = MF->getFunction();
64   const Function *Per = nullptr;
65   if (F.hasPersonalityFn())
66     Per = dyn_cast<Function>(F.getPersonalityFn()->stripPointerCasts());
67   bool forceEmitPersonality =
68     F.hasPersonalityFn() && !isNoOpWithoutInvoke(classifyEHPersonality(Per)) &&
69     F.needsUnwindTableEntry();
70   bool shouldEmitPersonality = forceEmitPersonality ||
71     !MF->getLandingPads().empty();
72   if (!Asm->MF->getFunction().needsUnwindTableEntry() &&
73       !shouldEmitPersonality)
74     ATS.emitCantUnwind();
75   else if (shouldEmitPersonality) {
76     // Emit references to personality.
77     if (Per) {
78       MCSymbol *PerSym = Asm->getSymbol(Per);
79       Asm->OutStreamer->EmitSymbolAttribute(PerSym, MCSA_Global);
80       ATS.emitPersonality(PerSym);
81     }
82 
83     // Emit .handlerdata directive.
84     ATS.emitHandlerData();
85 
86     // Emit actual exception table
87     emitExceptionTable();
88   }
89 
90   if (Asm->MAI->getExceptionHandlingType() == ExceptionHandling::ARM)
91     ATS.emitFnEnd();
92 }
93 
94 void ARMException::emitTypeInfos(unsigned TTypeEncoding) {
95   const MachineFunction *MF = Asm->MF;
96   const std::vector<const GlobalValue *> &TypeInfos = MF->getTypeInfos();
97   const std::vector<unsigned> &FilterIds = MF->getFilterIds();
98 
99   bool VerboseAsm = Asm->OutStreamer->isVerboseAsm();
100 
101   int Entry = 0;
102   // Emit the Catch TypeInfos.
103   if (VerboseAsm && !TypeInfos.empty()) {
104     Asm->OutStreamer->AddComment(">> Catch TypeInfos <<");
105     Asm->OutStreamer->AddBlankLine();
106     Entry = TypeInfos.size();
107   }
108 
109   for (const GlobalValue *GV : reverse(TypeInfos)) {
110     if (VerboseAsm)
111       Asm->OutStreamer->AddComment("TypeInfo " + Twine(Entry--));
112     Asm->EmitTTypeReference(GV, TTypeEncoding);
113   }
114 
115   // Emit the Exception Specifications.
116   if (VerboseAsm && !FilterIds.empty()) {
117     Asm->OutStreamer->AddComment(">> Filter TypeInfos <<");
118     Asm->OutStreamer->AddBlankLine();
119     Entry = 0;
120   }
121   for (std::vector<unsigned>::const_iterator
122          I = FilterIds.begin(), E = FilterIds.end(); I < E; ++I) {
123     unsigned TypeID = *I;
124     if (VerboseAsm) {
125       --Entry;
126       if (TypeID != 0)
127         Asm->OutStreamer->AddComment("FilterInfo " + Twine(Entry));
128     }
129 
130     Asm->EmitTTypeReference((TypeID == 0 ? nullptr : TypeInfos[TypeID - 1]),
131                             TTypeEncoding);
132   }
133 }
134