DwarfException.h revision 8b818d7e98309125c6058c4ea72a7dc73b031db2 
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 TargetAsmInfo;
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  /// shouldEmitTable - Per-function flag to indicate if EH tables should
55  /// be emitted.
56  bool shouldEmitTable;
57
58  /// shouldEmitMoves - Per-function flag to indicate if frame moves info
59  /// should be emitted.
60  bool shouldEmitMoves;
61
62  /// shouldEmitTableModule - Per-module flag to indicate if EH tables
63  /// should be emitted.
64  bool shouldEmitTableModule;
65
66  /// shouldEmitFrameModule - Per-module flag to indicate if frame moves
67  /// should be emitted.
68  bool shouldEmitMovesModule;
69
70  /// ExceptionTimer - Timer for the Dwarf exception writer.
71  Timer *ExceptionTimer;
72
73  /// EmitCommonEHFrame - Emit the common eh unwind frame.
74  ///
75  void EmitCommonEHFrame(const Function *Personality, unsigned Index);
76
77  /// EmitEHFrame - Emit function exception frame information.
78  ///
79  void EmitEHFrame(const FunctionEHFrameInfo &EHFrameInfo);
80
81  /// EmitExceptionTable - Emit landing pads and actions.
82  ///
83  /// The general organization of the table is complex, but the basic concepts
84  /// are easy.  First there is a header which describes the location and
85  /// organization of the three components that follow.
86  ///  1. The landing pad site information describes the range of code covered
87  ///     by the try.  In our case it's an accumulation of the ranges covered
88  ///     by the invokes in the try.  There is also a reference to the landing
89  ///     pad that handles the exception once processed.  Finally an index into
90  ///     the actions table.
91  ///  2. The action table, in our case, is composed of pairs of type ids
92  ///     and next action offset.  Starting with the action index from the
93  ///     landing pad site, each type Id is checked for a match to the current
94  ///     exception.  If it matches then the exception and type id are passed
95  ///     on to the landing pad.  Otherwise the next action is looked up.  This
96  ///     chain is terminated with a next action of zero.  If no type id is
97  ///     found the the frame is unwound and handling continues.
98  ///  3. Type id table contains references to all the C++ typeinfo for all
99  ///     catches in the function.  This tables is reversed indexed base 1.
100
101  /// SharedTypeIds - How many leading type ids two landing pads have in common.
102  static unsigned SharedTypeIds(const LandingPadInfo *L,
103                                const LandingPadInfo *R);
104
105  /// PadLT - Order landing pads lexicographically by type id.
106  static bool PadLT(const LandingPadInfo *L, const LandingPadInfo *R);
107
108  struct KeyInfo {
109    static inline unsigned getEmptyKey() { return -1U; }
110    static inline unsigned getTombstoneKey() { return -2U; }
111    static unsigned getHashValue(const unsigned &Key) { return Key; }
112    static bool isEqual(unsigned LHS, unsigned RHS) { return LHS == RHS; }
113    static bool isPod() { return true; }
114  };
115
116  /// PadRange - Structure holding a try-range and the associated landing pad.
117  struct PadRange {
118    // The index of the landing pad.
119    unsigned PadIndex;
120    // The index of the begin and end labels in the landing pad's label lists.
121    unsigned RangeIndex;
122  };
123
124  typedef DenseMap<unsigned, PadRange, KeyInfo> RangeMapType;
125
126  /// ActionEntry - Structure describing an entry in the actions table.
127  struct ActionEntry {
128    int ValueForTypeID; // The value to write - may not be equal to the type id.
129    int NextAction;
130    struct ActionEntry *Previous;
131  };
132
133  /// CallSiteEntry - Structure describing an entry in the call-site table.
134  struct CallSiteEntry {
135    // The 'try-range' is BeginLabel .. EndLabel.
136    unsigned BeginLabel; // zero indicates the start of the function.
137    unsigned EndLabel;   // zero indicates the end of the function.
138
139    // The landing pad starts at PadLabel.
140    unsigned PadLabel;   // zero indicates that there is no landing pad.
141    unsigned Action;
142  };
143
144  /// ComputeActionsTable - Compute the actions table and gather the first
145  /// action index for each landing pad site.
146  unsigned ComputeActionsTable(const SmallVectorImpl<const LandingPadInfo*>&LPs,
147                               SmallVectorImpl<ActionEntry> &Actions,
148                               SmallVectorImpl<unsigned> &FirstActions);
149
150  /// ComputeCallSiteTable - Compute the call-site table.  The entry for an
151  /// invoke has a try-range containing the call, a non-zero landing pad and an
152  /// appropriate action.  The entry for an ordinary call has a try-range
153  /// containing the call and zero for the landing pad and the action.  Calls
154  /// marked 'nounwind' have no entry and must not be contained in the try-range
155  /// of any entry - they form gaps in the table.  Entries must be ordered by
156  /// try-range address.
157  void ComputeCallSiteTable(SmallVectorImpl<CallSiteEntry> &CallSites,
158                            const RangeMapType &PadMap,
159                            const SmallVectorImpl<const LandingPadInfo *> &LPs,
160                            const SmallVectorImpl<unsigned> &FirstActions);
161  void EmitExceptionTable();
162
163public:
164  //===--------------------------------------------------------------------===//
165  // Main entry points.
166  //
167  DwarfException(raw_ostream &OS, AsmPrinter *A, const TargetAsmInfo *T);
168  virtual ~DwarfException();
169
170  /// BeginModule - Emit all exception information that should come prior to the
171  /// content.
172  void BeginModule(Module *m, MachineModuleInfo *mmi) {
173    this->M = m;
174    this->MMI = mmi;
175  }
176
177  /// EndModule - Emit all exception information that should come after the
178  /// content.
179  void EndModule();
180
181  /// BeginFunction - Gather pre-function exception information.  Assumes being
182  /// emitted immediately after the function entry point.
183  void BeginFunction(MachineFunction *MF);
184
185  /// EndFunction - Gather and emit post-function exception information.
186  void EndFunction();
187};
188
189} // End of namespace llvm
190
191#endif
192