include/llvm/Transforms/Utils/UnifyFunctionExitNodes.h

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