UnifyFunctionExitNodes.h revision 360784 
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
23namespace llvm {
24
25struct UnifyFunctionExitNodes : public FunctionPass {
26  BasicBlock *ReturnBlock = nullptr;
27  BasicBlock *UnwindBlock = nullptr;
28  BasicBlock *UnreachableBlock;
29
30public:
31  static char ID; // Pass identification, replacement for typeid
32  UnifyFunctionExitNodes();
33
34  // We can preserve non-critical-edgeness when we unify function exit nodes
35  void getAnalysisUsage(AnalysisUsage &AU) const override;
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  bool runOnFunction(Function &F) override;
45};
46
47Pass *createUnifyFunctionExitNodesPass();
48
49} // end namespace llvm
50
51#endif // LLVM_TRANSFORMS_UTILS_UNIFYFUNCTIONEXITNODES_H
52