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
UnifyFunctionExitNodesUnifyFunctionExitNodes33   UnifyFunctionExitNodes() : FunctionPass(ID) {
34     initializeUnifyFunctionExitNodesPass(*PassRegistry::getPassRegistry());
35   }
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   //
getReturnBlockUnifyFunctionExitNodes43   BasicBlock *getReturnBlock() const { return ReturnBlock; }
getUnwindBlockUnifyFunctionExitNodes44   BasicBlock *getUnwindBlock() const { return UnwindBlock; }
getUnreachableBlockUnifyFunctionExitNodes45   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
55