1 //===-- DwarfException.h - Dwarf Exception Framework -----------*- C++ -*--===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file contains support for writing dwarf exception info into asm files.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_CODEGEN_ASMPRINTER_DWARFEXCEPTION_H
15 #define LLVM_CODEGEN_ASMPRINTER_DWARFEXCEPTION_H
17 #include "llvm/ADT/DenseMap.h"
22 template <typename T> class SmallVectorImpl;
23 struct LandingPadInfo;
24 class MachineModuleInfo;
27 class MachineFunction;
35 //===----------------------------------------------------------------------===//
36 /// DwarfException - Emits Dwarf exception handling directives.
38 class DwarfException {
39 /// Asm - Target of Dwarf emission.
42 /// MMI - Collected machine module information.
43 MachineModuleInfo *MMI;
45 struct FunctionEHFrameInfo {
46 MCSymbol *FunctionEHSym; // L_foo.eh
48 unsigned PersonalityIndex;
51 std::vector<MachineMove> Moves;
52 const Function *function;
54 FunctionEHFrameInfo(MCSymbol *EHSym, unsigned Num, unsigned P,
56 const std::vector<MachineMove> &M,
58 FunctionEHSym(EHSym), Number(Num), PersonalityIndex(P),
59 hasCalls(hC), hasLandingPads(hL), Moves(M), function (f) { }
62 std::vector<FunctionEHFrameInfo> EHFrames;
64 /// UsesLSDA - Indicates whether an FDE that uses the CIE at the given index
65 /// uses an LSDA. If so, then we need to encode that information in the CIE's
67 DenseMap<unsigned, bool> UsesLSDA;
69 /// shouldEmitTable - Per-function flag to indicate if EH tables should
73 /// shouldEmitMoves - Per-function flag to indicate if frame moves info
74 /// should be emitted.
77 /// shouldEmitTableModule - Per-module flag to indicate if EH tables
78 /// should be emitted.
79 bool shouldEmitTableModule;
81 /// shouldEmitFrameModule - Per-module flag to indicate if frame moves
82 /// should be emitted.
83 bool shouldEmitMovesModule;
85 /// ExceptionTimer - Timer for the Dwarf exception writer.
86 Timer *ExceptionTimer;
88 /// EmitCIE - Emit a Common Information Entry (CIE). This holds information
89 /// that is shared among many Frame Description Entries. There is at least
90 /// one CIE in every non-empty .debug_frame section.
91 void EmitCIE(const Function *Personality, unsigned Index);
93 /// EmitFDE - Emit the Frame Description Entry (FDE) for the function.
94 void EmitFDE(const FunctionEHFrameInfo &EHFrameInfo);
96 /// EmitExceptionTable - Emit landing pads and actions.
98 /// The general organization of the table is complex, but the basic concepts
99 /// are easy. First there is a header which describes the location and
100 /// organization of the three components that follow.
101 /// 1. The landing pad site information describes the range of code covered
102 /// by the try. In our case it's an accumulation of the ranges covered
103 /// by the invokes in the try. There is also a reference to the landing
104 /// pad that handles the exception once processed. Finally an index into
105 /// the actions table.
106 /// 2. The action table, in our case, is composed of pairs of type ids
107 /// and next action offset. Starting with the action index from the
108 /// landing pad site, each type Id is checked for a match to the current
109 /// exception. If it matches then the exception and type id are passed
110 /// on to the landing pad. Otherwise the next action is looked up. This
111 /// chain is terminated with a next action of zero. If no type id is
112 /// found the frame is unwound and handling continues.
113 /// 3. Type id table contains references to all the C++ typeinfo for all
114 /// catches in the function. This tables is reversed indexed base 1.
116 /// SharedTypeIds - How many leading type ids two landing pads have in common.
117 static unsigned SharedTypeIds(const LandingPadInfo *L,
118 const LandingPadInfo *R);
120 /// PadLT - Order landing pads lexicographically by type id.
121 static bool PadLT(const LandingPadInfo *L, const LandingPadInfo *R);
123 /// PadRange - Structure holding a try-range and the associated landing pad.
125 // The index of the landing pad.
127 // The index of the begin and end labels in the landing pad's label lists.
131 typedef DenseMap<MCSymbol *, PadRange> RangeMapType;
133 /// ActionEntry - Structure describing an entry in the actions table.
135 int ValueForTypeID; // The value to write - may not be equal to the type id.
140 /// CallSiteEntry - Structure describing an entry in the call-site table.
141 struct CallSiteEntry {
142 // The 'try-range' is BeginLabel .. EndLabel.
143 MCSymbol *BeginLabel; // zero indicates the start of the function.
144 MCSymbol *EndLabel; // zero indicates the end of the function.
146 // The landing pad starts at PadLabel.
147 MCSymbol *PadLabel; // zero indicates that there is no landing pad.
151 /// ComputeActionsTable - Compute the actions table and gather the first
152 /// action index for each landing pad site.
153 unsigned ComputeActionsTable(const SmallVectorImpl<const LandingPadInfo*>&LPs,
154 SmallVectorImpl<ActionEntry> &Actions,
155 SmallVectorImpl<unsigned> &FirstActions);
157 /// CallToNoUnwindFunction - Return `true' if this is a call to a function
158 /// marked `nounwind'. Return `false' otherwise.
159 bool CallToNoUnwindFunction(const MachineInstr *MI);
161 /// ComputeCallSiteTable - Compute the call-site table. The entry for an
162 /// invoke has a try-range containing the call, a non-zero landing pad and an
163 /// appropriate action. The entry for an ordinary call has a try-range
164 /// containing the call and zero for the landing pad and the action. Calls
165 /// marked 'nounwind' have no entry and must not be contained in the try-range
166 /// of any entry - they form gaps in the table. Entries must be ordered by
167 /// try-range address.
168 void ComputeCallSiteTable(SmallVectorImpl<CallSiteEntry> &CallSites,
169 const RangeMapType &PadMap,
170 const SmallVectorImpl<const LandingPadInfo *> &LPs,
171 const SmallVectorImpl<unsigned> &FirstActions);
172 void EmitExceptionTable();
175 //===--------------------------------------------------------------------===//
176 // Main entry points.
178 DwarfException(AsmPrinter *A);
181 /// EndModule - Emit all exception information that should come after the
185 /// BeginFunction - Gather pre-function exception information. Assumes being
186 /// emitted immediately after the function entry point.
187 void BeginFunction(const MachineFunction *MF);
189 /// EndFunction - Gather and emit post-function exception information.
193 } // End of namespace llvm