1 //===- SSAUpdaterBulk.h - Unstructured SSA Update Tool ----------*- 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 file declares the SSAUpdaterBulk class. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #ifndef LLVM_TRANSFORMS_UTILS_SSAUPDATERBULK_H 15 #define LLVM_TRANSFORMS_UTILS_SSAUPDATERBULK_H 16 17 #include "llvm/ADT/DenseMap.h" 18 #include "llvm/ADT/SmallPtrSet.h" 19 #include "llvm/ADT/StringRef.h" 20 #include "llvm/IR/PredIteratorCache.h" 21 22 namespace llvm { 23 24 class BasicBlock; 25 class PHINode; 26 template <typename T> class SmallVectorImpl; 27 class Type; 28 class Use; 29 class Value; 30 class DominatorTree; 31 32 /// Helper class for SSA formation on a set of values defined in multiple 33 /// blocks. 34 /// 35 /// This is used when code duplication or another unstructured transformation 36 /// wants to rewrite a set of uses of one value with uses of a set of values. 37 /// The update is done only when RewriteAllUses is called, all other methods are 38 /// used for book-keeping. That helps to share some common computations between 39 /// updates of different uses (which is not the case when traditional SSAUpdater 40 /// is used). 41 class SSAUpdaterBulk { 42 struct RewriteInfo { 43 DenseMap<BasicBlock *, Value *> Defines; 44 SmallVector<Use *, 4> Uses; 45 StringRef Name; 46 Type *Ty; 47 RewriteInfo(){}; 48 RewriteInfo(StringRef &N, Type *T) : Name(N), Ty(T){}; 49 }; 50 SmallVector<RewriteInfo, 4> Rewrites; 51 52 PredIteratorCache PredCache; 53 54 Value *computeValueAt(BasicBlock *BB, RewriteInfo &R, DominatorTree *DT); 55 56 public: 57 explicit SSAUpdaterBulk(){}; 58 SSAUpdaterBulk(const SSAUpdaterBulk &) = delete; 59 SSAUpdaterBulk &operator=(const SSAUpdaterBulk &) = delete; 60 ~SSAUpdaterBulk(){}; 61 62 /// Add a new variable to the SSA rewriter. This needs to be called before 63 /// AddAvailableValue or AddUse calls. The return value is the variable ID, 64 /// which needs to be passed to AddAvailableValue and AddUse. 65 unsigned AddVariable(StringRef Name, Type *Ty); 66 67 /// Indicate that a rewritten value is available in the specified block with 68 /// the specified value. 69 void AddAvailableValue(unsigned Var, BasicBlock *BB, Value *V); 70 71 /// Record a use of the symbolic value. This use will be updated with a 72 /// rewritten value when RewriteAllUses is called. 73 void AddUse(unsigned Var, Use *U); 74 75 /// Return true if the SSAUpdater already has a value for the specified 76 /// variable in the specified block. 77 bool HasValueForBlock(unsigned Var, BasicBlock *BB); 78 79 /// Perform all the necessary updates, including new PHI-nodes insertion and 80 /// the requested uses update. 81 /// 82 /// The function requires dominator tree DT, which is used for computing 83 /// locations for new phi-nodes insertions. If a nonnull pointer to a vector 84 /// InsertedPHIs is passed, all the new phi-nodes will be added to this 85 /// vector. 86 void RewriteAllUses(DominatorTree *DT, 87 SmallVectorImpl<PHINode *> *InsertedPHIs = nullptr); 88 }; 89 90 } // end namespace llvm 91 92 #endif // LLVM_TRANSFORMS_UTILS_SSAUPDATERBULK_H 93