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
54