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       1             : //===-- UnifyFunctionExitNodes.h - Ensure fn's have one return --*- 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 pass is used to ensure that functions have at most one return and one
      11             : // unwind instruction in them.  Additionally, it keeps track of which node is
      12             : // the new exit node of the CFG.  If there are no return or unwind instructions
      13             : // in the function, the getReturnBlock/getUnwindBlock methods will return a null
      14             : // pointer.
      15             : //
      16             : //===----------------------------------------------------------------------===//
      17             : 
      18             : #ifndef LLVM_TRANSFORMS_UTILS_UNIFYFUNCTIONEXITNODES_H
      19             : #define LLVM_TRANSFORMS_UTILS_UNIFYFUNCTIONEXITNODES_H
      20             : 
      21             : #include "llvm/Pass.h"
      22             : #include "llvm/PassRegistry.h"
      23             : 
      24             : namespace llvm {
      25             : 
      26             : struct UnifyFunctionExitNodes : public FunctionPass {
      27             :   BasicBlock *ReturnBlock = nullptr;
      28             :   BasicBlock *UnwindBlock = nullptr;
      29             :   BasicBlock *UnreachableBlock;
      30             : 
      31             : public:
      32             :   static char ID; // Pass identification, replacement for typeid
      33           0 :   UnifyFunctionExitNodes() : FunctionPass(ID) {
      34           0 :     initializeUnifyFunctionExitNodesPass(*PassRegistry::getPassRegistry());
      35           0 :   }
      36             : 
      37             :   // We can preserve non-critical-edgeness when we unify function exit nodes
      38             :   void getAnalysisUsage(AnalysisUsage &AU) const override;
      39             : 
      40             :   // getReturn|Unwind|UnreachableBlock - Return the new single (or nonexistent)
      41             :   // return, unwind, or unreachable  basic blocks in the CFG.
      42             :   //
      43             :   BasicBlock *getReturnBlock() const { return ReturnBlock; }
      44             :   BasicBlock *getUnwindBlock() const { return UnwindBlock; }
      45             :   BasicBlock *getUnreachableBlock() const { return UnreachableBlock; }
      46             : 
      47             :   bool runOnFunction(Function &F) override;
      48             : };
      49             : 
      50             : Pass *createUnifyFunctionExitNodesPass();
      51             : 
      52             : } // end namespace llvm
      53             : 
      54             : #endif // LLVM_TRANSFORMS_UTILS_UNIFYFUNCTIONEXITNODES_H