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   /// 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   /// EmitCIE - Emit a Common Information Entry (CIE). This holds information
  74   /// that is shared among many Frame Description Entries.  There is at least
  75   /// one CIE in every non-empty .debug_frame section.
  76   void EmitCIE(const Function *Personality, unsigned Index);
  77
  78   /// EmitFDE - Emit the Frame Description Entry (FDE) for the function.
  79   void EmitFDE(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
 163 public:
 164   //===--------------------------------------------------------------------===//
 165   // Main entry points.
 166   //
 167   DwarfException(raw_ostream &OS, AsmPrinter *A, const MCAsmInfo *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