DwarfException.h revision 169f3a233e90dcdd01e42829b396c823d016fe30 
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 MCExpr;
29class Timer;
30class raw_ostream;
31
32//===----------------------------------------------------------------------===//
33/// DwarfException - Emits Dwarf exception handling directives.
34///
35class DwarfException : public Dwarf {
36  struct FunctionEHFrameInfo {
37    std::string FnName;
38    unsigned Number;
39    unsigned PersonalityIndex;
40    bool hasCalls;
41    bool hasLandingPads;
42    std::vector<MachineMove> Moves;
43    const Function * function;
44
45    FunctionEHFrameInfo(const std::string &FN, unsigned Num, unsigned P,
46                        bool hC, bool hL,
47                        const std::vector<MachineMove> &M,
48                        const Function *f):
49      FnName(FN), Number(Num), PersonalityIndex(P),
50      hasCalls(hC), hasLandingPads(hL), Moves(M), function (f) { }
51  };
52
53  std::vector<FunctionEHFrameInfo> EHFrames;
54
55  /// UsesLSDA - Indicates whether an FDE that uses the CIE at the given index
56  /// uses an LSDA. If so, then we need to encode that information in the CIE's
57  /// augmentation.
58  DenseMap<unsigned, bool> UsesLSDA;
59
60  /// shouldEmitTable - Per-function flag to indicate if EH tables should
61  /// be emitted.
62  bool shouldEmitTable;
63
64  /// shouldEmitMoves - Per-function flag to indicate if frame moves info
65  /// should be emitted.
66  bool shouldEmitMoves;
67
68  /// shouldEmitTableModule - Per-module flag to indicate if EH tables
69  /// should be emitted.
70  bool shouldEmitTableModule;
71
72  /// shouldEmitFrameModule - Per-module flag to indicate if frame moves
73  /// should be emitted.
74  bool shouldEmitMovesModule;
75
76  /// ExceptionTimer - Timer for the Dwarf exception writer.
77  Timer *ExceptionTimer;
78
79  /// SizeOfEncodedValue - Return the size of the encoding in bytes.
80  unsigned SizeOfEncodedValue(unsigned Encoding);
81
82  /// EmitCIE - Emit a Common Information Entry (CIE). This holds information
83  /// that is shared among many Frame Description Entries.  There is at least
84  /// one CIE in every non-empty .debug_frame section.
85  void EmitCIE(const Function *Personality, unsigned Index);
86
87  /// EmitFDE - Emit the Frame Description Entry (FDE) for the function.
88  void EmitFDE(const FunctionEHFrameInfo &EHFrameInfo);
89
90  /// EmitExceptionTable - Emit landing pads and actions.
91  ///
92  /// The general organization of the table is complex, but the basic concepts
93  /// are easy.  First there is a header which describes the location and
94  /// organization of the three components that follow.
95  ///  1. The landing pad site information describes the range of code covered
96  ///     by the try.  In our case it's an accumulation of the ranges covered
97  ///     by the invokes in the try.  There is also a reference to the landing
98  ///     pad that handles the exception once processed.  Finally an index into
99  ///     the actions table.
100  ///  2. The action table, in our case, is composed of pairs of type ids
101  ///     and next action offset.  Starting with the action index from the
102  ///     landing pad site, each type Id is checked for a match to the current
103  ///     exception.  If it matches then the exception and type id are passed
104  ///     on to the landing pad.  Otherwise the next action is looked up.  This
105  ///     chain is terminated with a next action of zero.  If no type id is
106  ///     found the the frame is unwound and handling continues.
107  ///  3. Type id table contains references to all the C++ typeinfo for all
108  ///     catches in the function.  This tables is reversed indexed base 1.
109
110  /// SharedTypeIds - How many leading type ids two landing pads have in common.
111  static unsigned SharedTypeIds(const LandingPadInfo *L,
112                                const LandingPadInfo *R);
113
114  /// PadLT - Order landing pads lexicographically by type id.
115  static bool PadLT(const LandingPadInfo *L, const LandingPadInfo *R);
116
117  struct KeyInfo {
118    static inline unsigned getEmptyKey() { return -1U; }
119    static inline unsigned getTombstoneKey() { return -2U; }
120    static unsigned getHashValue(const unsigned &Key) { return Key; }
121    static bool isEqual(unsigned LHS, unsigned RHS) { return LHS == RHS; }
122  };
123
124  /// PadRange - Structure holding a try-range and the associated landing pad.
125  struct PadRange {
126    // The index of the landing pad.
127    unsigned PadIndex;
128    // The index of the begin and end labels in the landing pad's label lists.
129    unsigned RangeIndex;
130  };
131
132  typedef DenseMap<unsigned, PadRange, KeyInfo> RangeMapType;
133
134  /// ActionEntry - Structure describing an entry in the actions table.
135  struct ActionEntry {
136    int ValueForTypeID; // The value to write - may not be equal to the type id.
137    int NextAction;
138    struct ActionEntry *Previous;
139  };
140
141  /// CallSiteEntry - Structure describing an entry in the call-site table.
142  struct CallSiteEntry {
143    // The 'try-range' is BeginLabel .. EndLabel.
144    unsigned BeginLabel; // zero indicates the start of the function.
145    unsigned EndLabel;   // zero indicates the end of the function.
146
147    // The landing pad starts at PadLabel.
148    unsigned PadLabel;   // zero indicates that there is no landing pad.
149    unsigned Action;
150  };
151
152  /// ComputeActionsTable - Compute the actions table and gather the first
153  /// action index for each landing pad site.
154  unsigned ComputeActionsTable(const SmallVectorImpl<const LandingPadInfo*>&LPs,
155                               SmallVectorImpl<ActionEntry> &Actions,
156                               SmallVectorImpl<unsigned> &FirstActions);
157
158  /// CallToNoUnwindFunction - Return `true' if this is a call to a function
159  /// marked `nounwind'. Return `false' otherwise.
160  bool CallToNoUnwindFunction(const MachineInstr *MI);
161
162  /// ComputeCallSiteTable - Compute the call-site table.  The entry for an
163  /// invoke has a try-range containing the call, a non-zero landing pad and an
164  /// appropriate action.  The entry for an ordinary call has a try-range
165  /// containing the call and zero for the landing pad and the action.  Calls
166  /// marked 'nounwind' have no entry and must not be contained in the try-range
167  /// of any entry - they form gaps in the table.  Entries must be ordered by
168  /// try-range address.
169  void ComputeCallSiteTable(SmallVectorImpl<CallSiteEntry> &CallSites,
170                            const RangeMapType &PadMap,
171                            const SmallVectorImpl<const LandingPadInfo *> &LPs,
172                            const SmallVectorImpl<unsigned> &FirstActions);
173  void EmitExceptionTable();
174
175  /// CreateLabelDiff - Emit a label and subtract it from the expression we
176  /// already have.  This is equivalent to emitting "foo - .", but we have to
177  /// emit the label for "." directly.
178  const MCExpr *CreateLabelDiff(const MCExpr *ExprRef, const char *LabelName,
179                                unsigned Index);
180public:
181  //===--------------------------------------------------------------------===//
182  // Main entry points.
183  //
184  DwarfException(raw_ostream &OS, AsmPrinter *A, const MCAsmInfo *T);
185  virtual ~DwarfException();
186
187  /// BeginModule - Emit all exception information that should come prior to the
188  /// content.
189  void BeginModule(Module *m, MachineModuleInfo *mmi) {
190    this->M = m;
191    this->MMI = mmi;
192  }
193
194  /// EndModule - Emit all exception information that should come after the
195  /// content.
196  void EndModule();
197
198  /// BeginFunction - Gather pre-function exception information.  Assumes being
199  /// emitted immediately after the function entry point.
200  void BeginFunction(MachineFunction *MF);
201
202  /// EndFunction - Gather and emit post-function exception information.
203  void EndFunction();
204};
205
206} // End of namespace llvm
207
208#endif
209