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      1 //===--- llvm/CodeGen/WasmEHFuncInfo.h --------------------------*- C++ -*-===//
      2 //
      3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
      4 // See https://llvm.org/LICENSE.txt for license information.
      5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
      6 //
      7 //===----------------------------------------------------------------------===//
      8 //
      9 // Data structures for Wasm exception handling schemes.
     10 //
     11 //===----------------------------------------------------------------------===//
     12 
     13 #ifndef LLVM_CODEGEN_WASMEHFUNCINFO_H
     14 #define LLVM_CODEGEN_WASMEHFUNCINFO_H
     15 
     16 #include "llvm/ADT/DenseMap.h"
     17 #include "llvm/ADT/PointerUnion.h"
     18 #include "llvm/ADT/SmallPtrSet.h"
     19 
     20 namespace llvm {
     21 
     22 class BasicBlock;
     23 class Function;
     24 class MachineBasicBlock;
     25 
     26 namespace WebAssembly {
     27 enum EventTag { CPP_EXCEPTION = 0, C_LONGJMP = 1 };
     28 }
     29 
     30 using BBOrMBB = PointerUnion<const BasicBlock *, MachineBasicBlock *>;
     31 
     32 struct WasmEHFuncInfo {
     33   // When there is an entry <A, B>, if an exception is not caught by A, it
     34   // should next unwind to the EH pad B.
     35   DenseMap<BBOrMBB, BBOrMBB> SrcToUnwindDest;
     36   DenseMap<BBOrMBB, SmallPtrSet<BBOrMBB, 4>> UnwindDestToSrcs; // reverse map
     37 
     38   // Helper functions
     39   const BasicBlock *getUnwindDest(const BasicBlock *BB) const {
     40     assert(hasUnwindDest(BB));
     41     return SrcToUnwindDest.lookup(BB).get<const BasicBlock *>();
     42   }
     43   SmallPtrSet<const BasicBlock *, 4> getUnwindSrcs(const BasicBlock *BB) const {
     44     assert(hasUnwindSrcs(BB));
     45     const auto &Set = UnwindDestToSrcs.lookup(BB);
     46     SmallPtrSet<const BasicBlock *, 4> Ret;
     47     for (const auto P : Set)
     48       Ret.insert(P.get<const BasicBlock *>());
     49     return Ret;
     50   }
     51   void setUnwindDest(const BasicBlock *BB, const BasicBlock *Dest) {
     52     SrcToUnwindDest[BB] = Dest;
     53     if (!UnwindDestToSrcs.count(Dest))
     54       UnwindDestToSrcs[Dest] = SmallPtrSet<BBOrMBB, 4>();
     55     UnwindDestToSrcs[Dest].insert(BB);
     56   }
     57   bool hasUnwindDest(const BasicBlock *BB) const {
     58     return SrcToUnwindDest.count(BB);
     59   }
     60   bool hasUnwindSrcs(const BasicBlock *BB) const {
     61     return UnwindDestToSrcs.count(BB);
     62   }
     63 
     64   MachineBasicBlock *getUnwindDest(MachineBasicBlock *MBB) const {
     65     assert(hasUnwindDest(MBB));
     66     return SrcToUnwindDest.lookup(MBB).get<MachineBasicBlock *>();
     67   }
     68   SmallPtrSet<MachineBasicBlock *, 4>
     69   getUnwindSrcs(MachineBasicBlock *MBB) const {
     70     assert(hasUnwindSrcs(MBB));
     71     const auto &Set = UnwindDestToSrcs.lookup(MBB);
     72     SmallPtrSet<MachineBasicBlock *, 4> Ret;
     73     for (const auto P : Set)
     74       Ret.insert(P.get<MachineBasicBlock *>());
     75     return Ret;
     76   }
     77   void setUnwindDest(MachineBasicBlock *MBB, MachineBasicBlock *Dest) {
     78     SrcToUnwindDest[MBB] = Dest;
     79     if (!UnwindDestToSrcs.count(Dest))
     80       UnwindDestToSrcs[Dest] = SmallPtrSet<BBOrMBB, 4>();
     81     UnwindDestToSrcs[Dest].insert(MBB);
     82   }
     83   bool hasUnwindDest(MachineBasicBlock *MBB) const {
     84     return SrcToUnwindDest.count(MBB);
     85   }
     86   bool hasUnwindSrcs(MachineBasicBlock *MBB) const {
     87     return UnwindDestToSrcs.count(MBB);
     88   }
     89 };
     90 
     91 // Analyze the IR in the given function to build WasmEHFuncInfo.
     92 void calculateWasmEHInfo(const Function *F, WasmEHFuncInfo &EHInfo);
     93 
     94 } // namespace llvm
     95 
     96 #endif // LLVM_CODEGEN_WASMEHFUNCINFO_H
     97