1 //===- SSAUpdaterBulk.h - Unstructured SSA Update Tool ----------*- 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 declares the SSAUpdaterBulk class. 10 // 11 //===----------------------------------------------------------------------===// 12 13 #ifndef LLVM_TRANSFORMS_UTILS_SSAUPDATERBULK_H 14 #define LLVM_TRANSFORMS_UTILS_SSAUPDATERBULK_H 15 16 #include "llvm/ADT/DenseMap.h" 17 #include "llvm/ADT/SmallPtrSet.h" 18 #include "llvm/ADT/StringRef.h" 19 #include "llvm/IR/PredIteratorCache.h" 20 21 namespace llvm { 22 23 class BasicBlock; 24 class PHINode; 25 template <typename T> class SmallVectorImpl; 26 class Type; 27 class Use; 28 class Value; 29 class DominatorTree; 30 31 /// Helper class for SSA formation on a set of values defined in multiple 32 /// blocks. 33 /// 34 /// This is used when code duplication or another unstructured transformation 35 /// wants to rewrite a set of uses of one value with uses of a set of values. 36 /// The update is done only when RewriteAllUses is called, all other methods are 37 /// used for book-keeping. That helps to share some common computations between 38 /// updates of different uses (which is not the case when traditional SSAUpdater 39 /// is used). 40 class SSAUpdaterBulk { 41 struct RewriteInfo { 42 DenseMap<BasicBlock *, Value *> Defines; 43 SmallVector<Use *, 4> Uses; 44 StringRef Name; 45 Type *Ty; RewriteInfoRewriteInfo46 RewriteInfo(){}; RewriteInfoRewriteInfo47 RewriteInfo(StringRef &N, Type *T) : Name(N), Ty(T){}; 48 }; 49 SmallVector<RewriteInfo, 4> Rewrites; 50 51 PredIteratorCache PredCache; 52 53 Value *computeValueAt(BasicBlock *BB, RewriteInfo &R, DominatorTree *DT); 54 55 public: SSAUpdaterBulk()56 explicit SSAUpdaterBulk(){}; 57 SSAUpdaterBulk(const SSAUpdaterBulk &) = delete; 58 SSAUpdaterBulk &operator=(const SSAUpdaterBulk &) = delete; ~SSAUpdaterBulk()59 ~SSAUpdaterBulk(){}; 60 61 /// Add a new variable to the SSA rewriter. This needs to be called before 62 /// AddAvailableValue or AddUse calls. The return value is the variable ID, 63 /// which needs to be passed to AddAvailableValue and AddUse. 64 unsigned AddVariable(StringRef Name, Type *Ty); 65 66 /// Indicate that a rewritten value is available in the specified block with 67 /// the specified value. 68 void AddAvailableValue(unsigned Var, BasicBlock *BB, Value *V); 69 70 /// Record a use of the symbolic value. This use will be updated with a 71 /// rewritten value when RewriteAllUses is called. 72 void AddUse(unsigned Var, Use *U); 73 74 /// Return true if the SSAUpdater already has a value for the specified 75 /// variable in the specified block. 76 bool HasValueForBlock(unsigned Var, BasicBlock *BB); 77 78 /// Perform all the necessary updates, including new PHI-nodes insertion and 79 /// the requested uses update. 80 /// 81 /// The function requires dominator tree DT, which is used for computing 82 /// locations for new phi-nodes insertions. If a nonnull pointer to a vector 83 /// InsertedPHIs is passed, all the new phi-nodes will be added to this 84 /// vector. 85 void RewriteAllUses(DominatorTree *DT, 86 SmallVectorImpl<PHINode *> *InsertedPHIs = nullptr); 87 }; 88 89 } // end namespace llvm 90 91 #endif // LLVM_TRANSFORMS_UTILS_SSAUPDATERBULK_H 92