DwarfException.h revision d779bcb96ab72939243f1fdd85a2daae863a82c4 
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 DwarfPrinter {
36  struct FunctionEHFrameInfo {
37    MCSymbol *FunctionEHSym;  // L_foo.eh
38    unsigned Number;
39    unsigned PersonalityIndex;
40    bool hasCalls;
41    bool hasLandingPads;
42    std::vector<MachineMove> Moves;
43    const Function *function;
44
45    FunctionEHFrameInfo(MCSymbol *EHSym, unsigned Num, unsigned P,
46                        bool hC, bool hL,
47                        const std::vector<MachineMove> &M,
48                        const Function *f):
49      FunctionEHSym(EHSym), 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  /// EmitCIE - Emit a Common Information Entry (CIE). This holds information
80  /// that is shared among many Frame Description Entries.  There is at least
81  /// one CIE in every non-empty .debug_frame section.
82  void EmitCIE(const Function *Personality, unsigned Index);
83
84  /// EmitFDE - Emit the Frame Description Entry (FDE) for the function.
85  void EmitFDE(const FunctionEHFrameInfo &EHFrameInfo);
86
87  /// EmitExceptionTable - Emit landing pads and actions.
88  ///
89  /// The general organization of the table is complex, but the basic concepts
90  /// are easy.  First there is a header which describes the location and
91  /// organization of the three components that follow.
92  ///  1. The landing pad site information describes the range of code covered
93  ///     by the try.  In our case it's an accumulation of the ranges covered
94  ///     by the invokes in the try.  There is also a reference to the landing
95  ///     pad that handles the exception once processed.  Finally an index into
96  ///     the actions table.
97  ///  2. The action table, in our case, is composed of pairs of type ids
98  ///     and next action offset.  Starting with the action index from the
99  ///     landing pad site, each type Id is checked for a match to the current
100  ///     exception.  If it matches then the exception and type id are passed
101  ///     on to the landing pad.  Otherwise the next action is looked up.  This
102  ///     chain is terminated with a next action of zero.  If no type id is
103  ///     found the frame is unwound and handling continues.
104  ///  3. Type id table contains references to all the C++ typeinfo for all
105  ///     catches in the function.  This tables is reversed indexed base 1.
106
107  /// SharedTypeIds - How many leading type ids two landing pads have in common.
108  static unsigned SharedTypeIds(const LandingPadInfo *L,
109                                const LandingPadInfo *R);
110
111  /// PadLT - Order landing pads lexicographically by type id.
112  static bool PadLT(const LandingPadInfo *L, const LandingPadInfo *R);
113
114  struct KeyInfo {
115    static inline unsigned getEmptyKey() { return -1U; }
116    static inline unsigned getTombstoneKey() { return -2U; }
117    static unsigned getHashValue(const unsigned &Key) { return Key; }
118    static bool isEqual(unsigned LHS, unsigned RHS) { return LHS == RHS; }
119  };
120
121  /// PadRange - Structure holding a try-range and the associated landing pad.
122  struct PadRange {
123    // The index of the landing pad.
124    unsigned PadIndex;
125    // The index of the begin and end labels in the landing pad's label lists.
126    unsigned RangeIndex;
127  };
128
129  typedef DenseMap<unsigned, PadRange, KeyInfo> RangeMapType;
130
131  /// ActionEntry - Structure describing an entry in the actions table.
132  struct ActionEntry {
133    int ValueForTypeID; // The value to write - may not be equal to the type id.
134    int NextAction;
135    unsigned Previous;
136  };
137
138  /// CallSiteEntry - Structure describing an entry in the call-site table.
139  struct CallSiteEntry {
140    // The 'try-range' is BeginLabel .. EndLabel.
141    unsigned BeginLabel; // zero indicates the start of the function.
142    unsigned EndLabel;   // zero indicates the end of the function.
143
144    // The landing pad starts at PadLabel.
145    unsigned PadLabel;   // zero indicates that there is no landing pad.
146    unsigned Action;
147  };
148
149  /// ComputeActionsTable - Compute the actions table and gather the first
150  /// action index for each landing pad site.
151  unsigned ComputeActionsTable(const SmallVectorImpl<const LandingPadInfo*>&LPs,
152                               SmallVectorImpl<ActionEntry> &Actions,
153                               SmallVectorImpl<unsigned> &FirstActions);
154
155  /// CallToNoUnwindFunction - Return `true' if this is a call to a function
156  /// marked `nounwind'. Return `false' otherwise.
157  bool CallToNoUnwindFunction(const MachineInstr *MI);
158
159  /// ComputeCallSiteTable - Compute the call-site table.  The entry for an
160  /// invoke has a try-range containing the call, a non-zero landing pad and an
161  /// appropriate action.  The entry for an ordinary call has a try-range
162  /// containing the call and zero for the landing pad and the action.  Calls
163  /// marked 'nounwind' have no entry and must not be contained in the try-range
164  /// of any entry - they form gaps in the table.  Entries must be ordered by
165  /// try-range address.
166  void ComputeCallSiteTable(SmallVectorImpl<CallSiteEntry> &CallSites,
167                            const RangeMapType &PadMap,
168                            const SmallVectorImpl<const LandingPadInfo *> &LPs,
169                            const SmallVectorImpl<unsigned> &FirstActions);
170  void EmitExceptionTable();
171
172  /// CreateLabelDiff - Emit a label and subtract it from the expression we
173  /// already have.  This is equivalent to emitting "foo - .", but we have to
174  /// emit the label for "." directly.
175  const MCExpr *CreateLabelDiff(const MCExpr *ExprRef, const char *LabelName,
176                                unsigned Index);
177public:
178  //===--------------------------------------------------------------------===//
179  // Main entry points.
180  //
181  DwarfException(raw_ostream &OS, AsmPrinter *A, const MCAsmInfo *T);
182  virtual ~DwarfException();
183
184  /// BeginModule - Emit all exception information that should come prior to the
185  /// content.
186  void BeginModule(Module *m, MachineModuleInfo *mmi) {
187    this->M = m;
188    this->MMI = mmi;
189  }
190
191  /// EndModule - Emit all exception information that should come after the
192  /// content.
193  void EndModule();
194
195  /// BeginFunction - Gather pre-function exception information.  Assumes being
196  /// emitted immediately after the function entry point.
197  void BeginFunction(const MachineFunction *MF);
198
199  /// EndFunction - Gather and emit post-function exception information.
200  void EndFunction();
201};
202
203} // End of namespace llvm
204
205#endif
206