UnifyFunctionExitNodes.h revision 263508 
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_UNIFYFUNCTIONEXITNODES_H
19#define LLVM_TRANSFORMS_UNIFYFUNCTIONEXITNODES_H
20
21#include "llvm/Pass.h"
22
23namespace llvm {
24
25struct UnifyFunctionExitNodes : public FunctionPass {
26  BasicBlock *ReturnBlock, *UnwindBlock, *UnreachableBlock;
27public:
28  static char ID; // Pass identification, replacement for typeid
29  UnifyFunctionExitNodes() : FunctionPass(ID),
30                             ReturnBlock(0), UnwindBlock(0) {
31    initializeUnifyFunctionExitNodesPass(*PassRegistry::getPassRegistry());
32  }
33
34  // We can preserve non-critical-edgeness when we unify function exit nodes
35  virtual void getAnalysisUsage(AnalysisUsage &AU) const;
36
37  // getReturn|Unwind|UnreachableBlock - Return the new single (or nonexistent)
38  // return, unwind, or unreachable  basic blocks in the CFG.
39  //
40  BasicBlock *getReturnBlock() const { return ReturnBlock; }
41  BasicBlock *getUnwindBlock() const { return UnwindBlock; }
42  BasicBlock *getUnreachableBlock() const { return UnreachableBlock; }
43
44  virtual bool runOnFunction(Function &F);
45};
46
47Pass *createUnifyFunctionExitNodesPass();
48
49} // End llvm namespace
50
51#endif
52