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      1 //===-- llvm/CodeGen/WinEHFuncInfo.h ----------------------------*- 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 // Data structures and associated state for Windows exception handling schemes.
     11 //
     12 //===----------------------------------------------------------------------===//
     13 
     14 #ifndef LLVM_CODEGEN_WINEHFUNCINFO_H
     15 #define LLVM_CODEGEN_WINEHFUNCINFO_H
     16 
     17 #include "llvm/ADT/SmallVector.h"
     18 #include "llvm/ADT/TinyPtrVector.h"
     19 #include "llvm/ADT/DenseMap.h"
     20 
     21 namespace llvm {
     22 class BasicBlock;
     23 class Constant;
     24 class Function;
     25 class GlobalValue;
     26 class IntrinsicInst;
     27 class LandingPadInst;
     28 class MCSymbol;
     29 class Value;
     30 
     31 enum ActionType { Catch, Cleanup };
     32 
     33 class ActionHandler {
     34 public:
     35   ActionHandler(BasicBlock *BB, ActionType Type)
     36       : StartBB(BB), Type(Type), EHState(-1), HandlerBlockOrFunc(nullptr) {}
     37 
     38   ActionType getType() const { return Type; }
     39   BasicBlock *getStartBlock() const { return StartBB; }
     40 
     41   bool hasBeenProcessed() { return HandlerBlockOrFunc != nullptr; }
     42 
     43   void setHandlerBlockOrFunc(Constant *F) { HandlerBlockOrFunc = F; }
     44   Constant *getHandlerBlockOrFunc() { return HandlerBlockOrFunc; }
     45 
     46   void setEHState(int State) { EHState = State; }
     47   int getEHState() const { return EHState; }
     48 
     49 private:
     50   BasicBlock *StartBB;
     51   ActionType Type;
     52   int EHState;
     53 
     54   // Can be either a BlockAddress or a Function depending on the EH personality.
     55   Constant *HandlerBlockOrFunc;
     56 };
     57 
     58 class CatchHandler : public ActionHandler {
     59 public:
     60   CatchHandler(BasicBlock *BB, Constant *Selector, BasicBlock *NextBB)
     61       : ActionHandler(BB, ActionType::Catch), Selector(Selector),
     62       NextBB(NextBB), ExceptionObjectVar(nullptr),
     63       ExceptionObjectIndex(-1) {}
     64 
     65   // Method for support type inquiry through isa, cast, and dyn_cast:
     66   static inline bool classof(const ActionHandler *H) {
     67     return H->getType() == ActionType::Catch;
     68   }
     69 
     70   Constant *getSelector() const { return Selector; }
     71   BasicBlock *getNextBB() const { return NextBB; }
     72 
     73   const Value *getExceptionVar() { return ExceptionObjectVar; }
     74   TinyPtrVector<BasicBlock *> &getReturnTargets() { return ReturnTargets; }
     75 
     76   void setExceptionVar(const Value *Val) { ExceptionObjectVar = Val; }
     77   void setExceptionVarIndex(int Index) { ExceptionObjectIndex = Index;  }
     78   int getExceptionVarIndex() const { return ExceptionObjectIndex; }
     79   void setReturnTargets(TinyPtrVector<BasicBlock *> &Targets) {
     80     ReturnTargets = Targets;
     81   }
     82 
     83 private:
     84   Constant *Selector;
     85   BasicBlock *NextBB;
     86   // While catch handlers are being outlined the ExceptionObjectVar field will
     87   // be populated with the instruction in the parent frame that corresponds
     88   // to the exception object (or nullptr if the catch does not use an
     89   // exception object) and the ExceptionObjectIndex field will be -1.
     90   // When the parseEHActions function is called to populate a vector of
     91   // instances of this class, the ExceptionObjectVar field will be nullptr
     92   // and the ExceptionObjectIndex will be the index of the exception object in
     93   // the parent function's frameescape block.
     94   const Value *ExceptionObjectVar;
     95   int ExceptionObjectIndex;
     96   TinyPtrVector<BasicBlock *> ReturnTargets;
     97 };
     98 
     99 class CleanupHandler : public ActionHandler {
    100 public:
    101   CleanupHandler(BasicBlock *BB) : ActionHandler(BB, ActionType::Cleanup) {}
    102 
    103   // Method for support type inquiry through isa, cast, and dyn_cast:
    104   static inline bool classof(const ActionHandler *H) {
    105     return H->getType() == ActionType::Cleanup;
    106   }
    107 };
    108 
    109 void parseEHActions(const IntrinsicInst *II,
    110   SmallVectorImpl<ActionHandler *> &Actions);
    111 
    112 
    113 // The following structs respresent the .xdata for functions using C++
    114 // exceptions on Windows.
    115 
    116 struct WinEHUnwindMapEntry {
    117   int ToState;
    118   Function *Cleanup;
    119 };
    120 
    121 struct WinEHHandlerType {
    122   int Adjectives;
    123   GlobalVariable *TypeDescriptor;
    124   int CatchObjRecoverIdx;
    125   Function *Handler;
    126 };
    127 
    128 struct WinEHTryBlockMapEntry {
    129   int TryLow;
    130   int TryHigh;
    131   SmallVector<WinEHHandlerType, 1> HandlerArray;
    132 };
    133 
    134 struct WinEHFuncInfo {
    135   DenseMap<const LandingPadInst *, int> LandingPadStateMap;
    136   DenseMap<const Function *, int> CatchHandlerParentFrameObjIdx;
    137   DenseMap<const Function *, int> CatchHandlerParentFrameObjOffset;
    138   DenseMap<const Function *, int> CatchHandlerMaxState;
    139   SmallVector<WinEHUnwindMapEntry, 4> UnwindMap;
    140   SmallVector<WinEHTryBlockMapEntry, 4> TryBlockMap;
    141   SmallVector<std::pair<MCSymbol *, int>, 4> IPToStateList;
    142   int UnwindHelpFrameIdx;
    143   int UnwindHelpFrameOffset;
    144 
    145   unsigned NumIPToStateFuncsVisited;
    146 
    147   WinEHFuncInfo()
    148       : UnwindHelpFrameIdx(INT_MAX), UnwindHelpFrameOffset(-1),
    149         NumIPToStateFuncsVisited(0) {}
    150 };
    151 
    152 }
    153 #endif // LLVM_CODEGEN_WINEHFUNCINFO_H
    154