DwarfException.h revision e99c6d49ea0f6f3b562af85580bdf18bd278b933 
1//===-- DwarfException.h - Dwarf Exception Framework -----------*- C++ -*--===//
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#ifndef LLVM_CODEGEN_ASMPRINTER_DWARFEXCEPTION_H
15#define LLVM_CODEGEN_ASMPRINTER_DWARFEXCEPTION_H
16
17#include "DIE.h"
18#include "DwarfPrinter.h"
19#include "llvm/CodeGen/AsmPrinter.h"
20#include "llvm/ADT/DenseMap.h"
21#include <string>
22
23namespace llvm {
24
25struct LandingPadInfo;
26class MachineModuleInfo;
27class MCAsmInfo;
28class Timer;
29class raw_ostream;
30
31//===----------------------------------------------------------------------===//
32/// DwarfException - Emits Dwarf exception handling directives.
33///
34class VISIBILITY_HIDDEN DwarfException : public Dwarf {
35  struct FunctionEHFrameInfo {
36    std::string FnName;
37    unsigned Number;
38    unsigned PersonalityIndex;
39    bool hasCalls;
40    bool hasLandingPads;
41    std::vector<MachineMove> Moves;
42    const Function * function;
43
44    FunctionEHFrameInfo(const std::string &FN, unsigned Num, unsigned P,
45                        bool hC, bool hL,
46                        const std::vector<MachineMove> &M,
47                        const Function *f):
48      FnName(FN), Number(Num), PersonalityIndex(P),
49      hasCalls(hC), hasLandingPads(hL), Moves(M), function (f) { }
50  };
51
52  std::vector<FunctionEHFrameInfo> EHFrames;
53
54  /// UsesLSDA - Indicates whether an FDE that uses the CIE at the given index
55  /// uses an LSDA. If so, then we need to encode that information in the CIE's
56  /// augmentation.
57  DenseMap<unsigned, bool> UsesLSDA;
58
59  /// shouldEmitTable - Per-function flag to indicate if EH tables should
60  /// be emitted.
61  bool shouldEmitTable;
62
63  /// shouldEmitMoves - Per-function flag to indicate if frame moves info
64  /// should be emitted.
65  bool shouldEmitMoves;
66
67  /// shouldEmitTableModule - Per-module flag to indicate if EH tables
68  /// should be emitted.
69  bool shouldEmitTableModule;
70
71  /// shouldEmitFrameModule - Per-module flag to indicate if frame moves
72  /// should be emitted.
73  bool shouldEmitMovesModule;
74
75  /// ExceptionTimer - Timer for the Dwarf exception writer.
76  Timer *ExceptionTimer;
77
78  unsigned SizeOfEncodedValue(unsigned Encoding);
79
80  /// EmitCIE - Emit a Common Information Entry (CIE). This holds information
81  /// that is shared among many Frame Description Entries.  There is at least
82  /// one CIE in every non-empty .debug_frame section.
83  void EmitCIE(const Function *Personality, unsigned Index);
84
85  /// EmitFDE - Emit the Frame Description Entry (FDE) for the function.
86  void EmitFDE(const FunctionEHFrameInfo &EHFrameInfo);
87
88  /// EmitExceptionTable - Emit landing pads and actions.
89  ///
90  /// The general organization of the table is complex, but the basic concepts
91  /// are easy.  First there is a header which describes the location and
92  /// organization of the three components that follow.
93  ///  1. The landing pad site information describes the range of code covered
94  ///     by the try.  In our case it's an accumulation of the ranges covered
95  ///     by the invokes in the try.  There is also a reference to the landing
96  ///     pad that handles the exception once processed.  Finally an index into
97  ///     the actions table.
98  ///  2. The action table, in our case, is composed of pairs of type ids
99  ///     and next action offset.  Starting with the action index from the
100  ///     landing pad site, each type Id is checked for a match to the current
101  ///     exception.  If it matches then the exception and type id are passed
102  ///     on to the landing pad.  Otherwise the next action is looked up.  This
103  ///     chain is terminated with a next action of zero.  If no type id is
104  ///     found the the frame is unwound and handling continues.
105  ///  3. Type id table contains references to all the C++ typeinfo for all
106  ///     catches in the function.  This tables is reversed indexed base 1.
107
108  /// SharedTypeIds - How many leading type ids two landing pads have in common.
109  static unsigned SharedTypeIds(const LandingPadInfo *L,
110                                const LandingPadInfo *R);
111
112  /// PadLT - Order landing pads lexicographically by type id.
113  static bool PadLT(const LandingPadInfo *L, const LandingPadInfo *R);
114
115  struct KeyInfo {
116    static inline unsigned getEmptyKey() { return -1U; }
117    static inline unsigned getTombstoneKey() { return -2U; }
118    static unsigned getHashValue(const unsigned &Key) { return Key; }
119    static bool isEqual(unsigned LHS, unsigned RHS) { return LHS == RHS; }
120    static bool isPod() { return true; }
121  };
122
123  /// PadRange - Structure holding a try-range and the associated landing pad.
124  struct PadRange {
125    // The index of the landing pad.
126    unsigned PadIndex;
127    // The index of the begin and end labels in the landing pad's label lists.
128    unsigned RangeIndex;
129  };
130
131  typedef DenseMap<unsigned, PadRange, KeyInfo> RangeMapType;
132
133  /// ActionEntry - Structure describing an entry in the actions table.
134  struct ActionEntry {
135    int ValueForTypeID; // The value to write - may not be equal to the type id.
136    int NextAction;
137    struct ActionEntry *Previous;
138  };
139
140  /// CallSiteEntry - Structure describing an entry in the call-site table.
141  struct CallSiteEntry {
142    // The 'try-range' is BeginLabel .. EndLabel.
143    unsigned BeginLabel; // zero indicates the start of the function.
144    unsigned EndLabel;   // zero indicates the end of the function.
145
146    // The landing pad starts at PadLabel.
147    unsigned PadLabel;   // zero indicates that there is no landing pad.
148    unsigned Action;
149  };
150
151  /// ComputeActionsTable - Compute the actions table and gather the first
152  /// action index for each landing pad site.
153  unsigned ComputeActionsTable(const SmallVectorImpl<const LandingPadInfo*>&LPs,
154                               SmallVectorImpl<ActionEntry> &Actions,
155                               SmallVectorImpl<unsigned> &FirstActions);
156
157  /// ComputeCallSiteTable - Compute the call-site table.  The entry for an
158  /// invoke has a try-range containing the call, a non-zero landing pad and an
159  /// appropriate action.  The entry for an ordinary call has a try-range
160  /// containing the call and zero for the landing pad and the action.  Calls
161  /// marked 'nounwind' have no entry and must not be contained in the try-range
162  /// of any entry - they form gaps in the table.  Entries must be ordered by
163  /// try-range address.
164  void ComputeCallSiteTable(SmallVectorImpl<CallSiteEntry> &CallSites,
165                            const RangeMapType &PadMap,
166                            const SmallVectorImpl<const LandingPadInfo *> &LPs,
167                            const SmallVectorImpl<unsigned> &FirstActions);
168  void EmitExceptionTable();
169
170public:
171  //===--------------------------------------------------------------------===//
172  // Main entry points.
173  //
174  DwarfException(raw_ostream &OS, AsmPrinter *A, const MCAsmInfo *T);
175  virtual ~DwarfException();
176
177  /// BeginModule - Emit all exception information that should come prior to the
178  /// content.
179  void BeginModule(Module *m, MachineModuleInfo *mmi) {
180    this->M = m;
181    this->MMI = mmi;
182  }
183
184  /// EndModule - Emit all exception information that should come after the
185  /// content.
186  void EndModule();
187
188  /// BeginFunction - Gather pre-function exception information.  Assumes being
189  /// emitted immediately after the function entry point.
190  void BeginFunction(MachineFunction *MF);
191
192  /// EndFunction - Gather and emit post-function exception information.
193  void EndFunction();
194};
195
196} // End of namespace llvm
197
198#endif
199