1 //===- PredIteratorCache.h - pred_iterator Cache ----------------*- 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 file defines the PredIteratorCache class. 10 // 11 //===----------------------------------------------------------------------===// 12 13 #ifndef LLVM_IR_PREDITERATORCACHE_H 14 #define LLVM_IR_PREDITERATORCACHE_H 15 16 #include "llvm/ADT/ArrayRef.h" 17 #include "llvm/ADT/DenseMap.h" 18 #include "llvm/ADT/SmallVector.h" 19 #include "llvm/IR/CFG.h" 20 #include "llvm/Support/Allocator.h" 21 22 namespace llvm { 23 24 /// PredIteratorCache - This class is an extremely trivial cache for 25 /// predecessor iterator queries. This is useful for code that repeatedly 26 /// wants the predecessor list for the same blocks. 27 class PredIteratorCache { 28 /// Cached list of predecessors, allocated in Memory. 29 DenseMap<BasicBlock *, ArrayRef<BasicBlock *>> BlockToPredsMap; 30 31 /// Memory - This is the space that holds cached preds. 32 BumpPtrAllocator Memory; 33 34 public: 35 size_t size(BasicBlock *BB) { return get(BB).size(); } 36 ArrayRef<BasicBlock *> get(BasicBlock *BB) { 37 ArrayRef<BasicBlock *> &Entry = BlockToPredsMap[BB]; 38 if (Entry.data()) 39 return Entry; 40 41 SmallVector<BasicBlock *, 32> PredCache(predecessors(BB)); 42 BasicBlock **Data = Memory.Allocate<BasicBlock *>(PredCache.size()); 43 std::copy(PredCache.begin(), PredCache.end(), Data); 44 Entry = ArrayRef(Data, PredCache.size()); 45 return Entry; 46 } 47 48 /// clear - Remove all information. 49 void clear() { 50 BlockToPredsMap.clear(); 51 Memory.Reset(); 52 } 53 }; 54 55 } // end namespace llvm 56 57 #endif 58