lib/CodeGen/AsmPrinter/DwarfException.h

   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
  23 namespace llvm {
  24
  25 struct LandingPadInfo;
  26 class MachineModuleInfo;
  27 class MCAsmInfo;
  28 class Timer;
  29 class raw_ostream;
  30
  31 //===----------------------------------------------------------------------===//
  32 /// DwarfException - Emits Dwarf exception handling directives.
  33 ///
  34 class 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   /// SizeOfEncodedValue - Return the size of the encoding in bytes.
  79   unsigned SizeOfEncodedValue(unsigned Encoding);
  80
  81   /// EmitCIE - Emit a Common Information Entry (CIE). This holds information
  82   /// that is shared among many Frame Description Entries.  There is at least
  83   /// one CIE in every non-empty .debug_frame section.
  84   void EmitCIE(const Function *Personality, unsigned Index);
  85
  86   /// EmitFDE - Emit the Frame Description Entry (FDE) for the function.
  87   void EmitFDE(const FunctionEHFrameInfo &EHFrameInfo);
  88
  89   /// EmitExceptionTable - Emit landing pads and actions.
  90   ///
  91   /// The general organization of the table is complex, but the basic concepts
  92   /// are easy.  First there is a header which describes the location and
  93   /// organization of the three components that follow.
  94   ///  1. The landing pad site information describes the range of code covered
  95   ///     by the try.  In our case it's an accumulation of the ranges covered
  96   ///     by the invokes in the try.  There is also a reference to the landing
  97   ///     pad that handles the exception once processed.  Finally an index into
  98   ///     the actions table.
  99   ///  2. The action table, in our case, is composed of pairs of type ids
 100   ///     and next action offset.  Starting with the action index from the
 101   ///     landing pad site, each type Id is checked for a match to the current
 102   ///     exception.  If it matches then the exception and type id are passed
 103   ///     on to the landing pad.  Otherwise the next action is looked up.  This
 104   ///     chain is terminated with a next action of zero.  If no type id is
 105   ///     found the the frame is unwound and handling continues.
 106   ///  3. Type id table contains references to all the C++ typeinfo for all
 107   ///     catches in the function.  This tables is reversed indexed base 1.
 108
 109   /// SharedTypeIds - How many leading type ids two landing pads have in common.
 110   static unsigned SharedTypeIds(const LandingPadInfo *L,
 111                                 const LandingPadInfo *R);
 112
 113   /// PadLT - Order landing pads lexicographically by type id.
 114   static bool PadLT(const LandingPadInfo *L, const LandingPadInfo *R);
 115
 116   struct KeyInfo {
 117     static inline unsigned getEmptyKey() { return -1U; }
 118     static inline unsigned getTombstoneKey() { return -2U; }
 119     static unsigned getHashValue(const unsigned &Key) { return Key; }
 120     static bool isEqual(unsigned LHS, unsigned RHS) { return LHS == RHS; }
 121     static bool isPod() { return true; }
 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   /// ComputeCallSiteTable - Compute the call-site table.  The entry for an
 159   /// invoke has a try-range containing the call, a non-zero landing pad and an
 160   /// appropriate action.  The entry for an ordinary call has a try-range
 161   /// containing the call and zero for the landing pad and the action.  Calls
 162   /// marked 'nounwind' have no entry and must not be contained in the try-range
 163   /// of any entry - they form gaps in the table.  Entries must be ordered by
 164   /// try-range address.
 165   void ComputeCallSiteTable(SmallVectorImpl<CallSiteEntry> &CallSites,
 166                             const RangeMapType &PadMap,
 167                             const SmallVectorImpl<const LandingPadInfo *> &LPs,
 168                             const SmallVectorImpl<unsigned> &FirstActions);
 169   void EmitExceptionTable();
 170
 171 public:
 172   //===--------------------------------------------------------------------===//
 173   // Main entry points.
 174   //
 175   DwarfException(raw_ostream &OS, AsmPrinter *A, const MCAsmInfo *T);
 176   virtual ~DwarfException();
 177
 178   /// BeginModule - Emit all exception information that should come prior to the
 179   /// content.
 180   void BeginModule(Module *m, MachineModuleInfo *mmi) {
 181     this->M = m;
 182     this->MMI = mmi;
 183   }
 184
 185   /// EndModule - Emit all exception information that should come after the
 186   /// content.
 187   void EndModule();
 188
 189   /// BeginFunction - Gather pre-function exception information.  Assumes being
 190   /// emitted immediately after the function entry point.
 191   void BeginFunction(MachineFunction *MF);
 192
 193   /// EndFunction - Gather and emit post-function exception information.
 194   void EndFunction();
 195 };
 196
 197 } // End of namespace llvm
 198
 199 #endif