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