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 
23 namespace llvm {
24 
25 struct UnifyFunctionExitNodes : public FunctionPass {
26   BasicBlock *ReturnBlock, *UnwindBlock, *UnreachableBlock;
27 
28 public:
29   static char ID; // Pass identification, replacement for typeid
UnifyFunctionExitNodesUnifyFunctionExitNodes30   UnifyFunctionExitNodes() : FunctionPass(ID),
31                              ReturnBlock(nullptr), UnwindBlock(nullptr) {
32     initializeUnifyFunctionExitNodesPass(*PassRegistry::getPassRegistry());
33   }
34 
35   // We can preserve non-critical-edgeness when we unify function exit nodes
36   void getAnalysisUsage(AnalysisUsage &AU) const override;
37 
38   // getReturn|Unwind|UnreachableBlock - Return the new single (or nonexistent)
39   // return, unwind, or unreachable  basic blocks in the CFG.
40   //
getReturnBlockUnifyFunctionExitNodes41   BasicBlock *getReturnBlock() const { return ReturnBlock; }
getUnwindBlockUnifyFunctionExitNodes42   BasicBlock *getUnwindBlock() const { return UnwindBlock; }
getUnreachableBlockUnifyFunctionExitNodes43   BasicBlock *getUnreachableBlock() const { return UnreachableBlock; }
44 
45   bool runOnFunction(Function &F) override;
46 };
47 
48 Pass *createUnifyFunctionExitNodesPass();
49 
50 } // End llvm namespace
51 
52 #endif
53