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 "AsmPrinterHandler.h"
18 #include "llvm/ADT/DenseMap.h"
19 #include "llvm/CodeGen/AsmPrinter.h"
20 #include <vector>
21 
22 namespace llvm {
23 
24 template <typename T> class SmallVectorImpl;
25 struct LandingPadInfo;
26 class MachineModuleInfo;
27 class MachineInstr;
28 class MachineFunction;
29 class MCAsmInfo;
30 class MCExpr;
31 class MCSymbol;
32 class Function;
33 class ARMTargetStreamer;
34 class AsmPrinter;
35 
36 //===----------------------------------------------------------------------===//
37 /// DwarfException - Emits Dwarf exception handling directives.
38 ///
39 class DwarfException : public AsmPrinterHandler {
40 protected:
41   /// Asm - Target of Dwarf emission.
42   AsmPrinter *Asm;
43 
44   /// MMI - Collected machine module information.
45   MachineModuleInfo *MMI;
46 
47   /// SharedTypeIds - How many leading type ids two landing pads have in common.
48   static unsigned SharedTypeIds(const LandingPadInfo *L,
49                                 const LandingPadInfo *R);
50 
51   /// PadLT - Order landing pads lexicographically by type id.
52   static bool PadLT(const LandingPadInfo *L, const LandingPadInfo *R);
53 
54   /// PadRange - Structure holding a try-range and the associated landing pad.
55   struct PadRange {
56     // The index of the landing pad.
57     unsigned PadIndex;
58     // The index of the begin and end labels in the landing pad's label lists.
59     unsigned RangeIndex;
60   };
61 
62   typedef DenseMap<MCSymbol *, PadRange> RangeMapType;
63 
64   /// ActionEntry - Structure describing an entry in the actions table.
65   struct ActionEntry {
66     int ValueForTypeID; // The value to write - may not be equal to the type id.
67     int NextAction;
68     unsigned Previous;
69   };
70 
71   /// CallSiteEntry - Structure describing an entry in the call-site table.
72   struct CallSiteEntry {
73     // The 'try-range' is BeginLabel .. EndLabel.
74     MCSymbol *BeginLabel; // zero indicates the start of the function.
75     MCSymbol *EndLabel;   // zero indicates the end of the function.
76 
77     // The landing pad starts at PadLabel.
78     MCSymbol *PadLabel;   // zero indicates that there is no landing pad.
79     unsigned Action;
80   };
81 
82   /// ComputeActionsTable - Compute the actions table and gather the first
83   /// action index for each landing pad site.
84   unsigned ComputeActionsTable(const SmallVectorImpl<const LandingPadInfo*>&LPs,
85                                SmallVectorImpl<ActionEntry> &Actions,
86                                SmallVectorImpl<unsigned> &FirstActions);
87 
88   /// CallToNoUnwindFunction - Return `true' if this is a call to a function
89   /// marked `nounwind'. Return `false' otherwise.
90   bool CallToNoUnwindFunction(const MachineInstr *MI);
91 
92   /// ComputeCallSiteTable - Compute the call-site table.  The entry for an
93   /// invoke has a try-range containing the call, a non-zero landing pad and an
94   /// appropriate action.  The entry for an ordinary call has a try-range
95   /// containing the call and zero for the landing pad and the action.  Calls
96   /// marked 'nounwind' have no entry and must not be contained in the try-range
97   /// of any entry - they form gaps in the table.  Entries must be ordered by
98   /// try-range address.
99   void ComputeCallSiteTable(SmallVectorImpl<CallSiteEntry> &CallSites,
100                             const RangeMapType &PadMap,
101                             const SmallVectorImpl<const LandingPadInfo *> &LPs,
102                             const SmallVectorImpl<unsigned> &FirstActions);
103 
104   /// EmitExceptionTable - Emit landing pads and actions.
105   ///
106   /// The general organization of the table is complex, but the basic concepts
107   /// are easy.  First there is a header which describes the location and
108   /// organization of the three components that follow.
109   ///  1. The landing pad site information describes the range of code covered
110   ///     by the try.  In our case it's an accumulation of the ranges covered
111   ///     by the invokes in the try.  There is also a reference to the landing
112   ///     pad that handles the exception once processed.  Finally an index into
113   ///     the actions table.
114   ///  2. The action table, in our case, is composed of pairs of type ids
115   ///     and next action offset.  Starting with the action index from the
116   ///     landing pad site, each type Id is checked for a match to the current
117   ///     exception.  If it matches then the exception and type id are passed
118   ///     on to the landing pad.  Otherwise the next action is looked up.  This
119   ///     chain is terminated with a next action of zero.  If no type id is
120   ///     found the frame is unwound and handling continues.
121   ///  3. Type id table contains references to all the C++ typeinfo for all
122   ///     catches in the function.  This tables is reversed indexed base 1.
123   void EmitExceptionTable();
124 
125   virtual void EmitTypeInfos(unsigned TTypeEncoding);
126 
127 public:
128   //===--------------------------------------------------------------------===//
129   // Main entry points.
130   //
131   DwarfException(AsmPrinter *A);
132   virtual ~DwarfException();
133 
134   /// endModule - Emit all exception information that should come after the
135   /// content.
136   virtual void endModule();
137 
138   /// beginFunction - Gather pre-function exception information.  Assumes being
139   /// emitted immediately after the function entry point.
140   virtual void beginFunction(const MachineFunction *MF);
141 
142   /// endFunction - Gather and emit post-function exception information.
143   virtual void endFunction(const MachineFunction *);
144 
145   // We don't need these.
146   virtual void setSymbolSize(const MCSymbol *Sym, uint64_t Size) {}
147   virtual void beginInstruction(const MachineInstr *MI) {}
148   virtual void endInstruction() {}
149 };
150 
151 class DwarfCFIException : public DwarfException {
152   /// shouldEmitPersonality - Per-function flag to indicate if .cfi_personality
153   /// should be emitted.
154   bool shouldEmitPersonality;
155 
156   /// shouldEmitLSDA - Per-function flag to indicate if .cfi_lsda
157   /// should be emitted.
158   bool shouldEmitLSDA;
159 
160   /// shouldEmitMoves - Per-function flag to indicate if frame moves info
161   /// should be emitted.
162   bool shouldEmitMoves;
163 
164   AsmPrinter::CFIMoveType moveTypeModule;
165 
166 public:
167   //===--------------------------------------------------------------------===//
168   // Main entry points.
169   //
170   DwarfCFIException(AsmPrinter *A);
171   virtual ~DwarfCFIException();
172 
173   /// endModule - Emit all exception information that should come after the
174   /// content.
175   virtual void endModule();
176 
177   /// beginFunction - Gather pre-function exception information.  Assumes being
178   /// emitted immediately after the function entry point.
179   virtual void beginFunction(const MachineFunction *MF);
180 
181   /// endFunction - Gather and emit post-function exception information.
182   virtual void endFunction(const MachineFunction *);
183 };
184 
185 class ARMException : public DwarfException {
186   void EmitTypeInfos(unsigned TTypeEncoding);
187   ARMTargetStreamer &getTargetStreamer();
188 
189   /// shouldEmitCFI - Per-function flag to indicate if frame CFI info
190   /// should be emitted.
191   bool shouldEmitCFI;
192 
193 public:
194   //===--------------------------------------------------------------------===//
195   // Main entry points.
196   //
197   ARMException(AsmPrinter *A);
198   virtual ~ARMException();
199 
200   /// endModule - Emit all exception information that should come after the
201   /// content.
202   virtual void endModule();
203 
204   /// beginFunction - Gather pre-function exception information.  Assumes being
205   /// emitted immediately after the function entry point.
206   virtual void beginFunction(const MachineFunction *MF);
207 
208   /// endFunction - Gather and emit post-function exception information.
209   virtual void endFunction(const MachineFunction *);
210 };
211 
212 class Win64Exception : public DwarfException {
213   /// shouldEmitPersonality - Per-function flag to indicate if personality
214   /// info should be emitted.
215   bool shouldEmitPersonality;
216 
217   /// shouldEmitLSDA - Per-function flag to indicate if the LSDA
218   /// should be emitted.
219   bool shouldEmitLSDA;
220 
221   /// shouldEmitMoves - Per-function flag to indicate if frame moves info
222   /// should be emitted.
223   bool shouldEmitMoves;
224 
225 public:
226   //===--------------------------------------------------------------------===//
227   // Main entry points.
228   //
229   Win64Exception(AsmPrinter *A);
230   virtual ~Win64Exception();
231 
232   /// endModule - Emit all exception information that should come after the
233   /// content.
234   virtual void endModule();
235 
236   /// beginFunction - Gather pre-function exception information.  Assumes being
237   /// emitted immediately after the function entry point.
238   virtual void beginFunction(const MachineFunction *MF);
239 
240   /// endFunction - Gather and emit post-function exception information.
241   virtual void endFunction(const MachineFunction *);
242 };
243 
244 } // End of namespace llvm
245 
246 #endif
247