Transforms/Utils/SSAUpdaterBulk.h

0001 //===- SSAUpdaterBulk.h - Unstructured SSA Update Tool ----------*- C++ -*-===//
0002 //
0003 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
0004 // See https://llvm.org/LICENSE.txt for license information.
0005 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
0006 //
0007 //===----------------------------------------------------------------------===//
0008 //
0009 // This file declares the SSAUpdaterBulk class.
0010 //
0011 //===----------------------------------------------------------------------===//
0012
0013 #ifndef LLVM_TRANSFORMS_UTILS_SSAUPDATERBULK_H
0014 #define LLVM_TRANSFORMS_UTILS_SSAUPDATERBULK_H
0015
0016 #include "llvm/ADT/DenseMap.h"
0017 #include "llvm/ADT/StringRef.h"
0018 #include "llvm/IR/PredIteratorCache.h"
0019
0020 namespace llvm {
0021
0022 class BasicBlock;
0023 class PHINode;
0024 template <typename T> class SmallVectorImpl;
0025 class Type;
0026 class Use;
0027 class Value;
0028 class DominatorTree;
0029
0030 /// Helper class for SSA formation on a set of values defined in multiple
0031 /// blocks.
0032 ///
0033 /// This is used when code duplication or another unstructured transformation
0034 /// wants to rewrite a set of uses of one value with uses of a set of values.
0035 /// The update is done only when RewriteAllUses is called, all other methods are
0036 /// used for book-keeping. That helps to share some common computations between
0037 /// updates of different uses (which is not the case when traditional SSAUpdater
0038 /// is used).
0039 class SSAUpdaterBulk {
0040   struct RewriteInfo {
0041     DenseMap<BasicBlock *, Value *> Defines;
0042     SmallVector<Use *, 4> Uses;
0043     StringRef Name;
0044     Type *Ty;
0045     RewriteInfo() = default;
0046     RewriteInfo(StringRef &N, Type *T) : Name(N), Ty(T){};
0047   };
0048   SmallVector<RewriteInfo, 4> Rewrites;
0049
0050   PredIteratorCache PredCache;
0051
0052   Value *computeValueAt(BasicBlock *BB, RewriteInfo &R, DominatorTree *DT);
0053
0054 public:
0055   explicit SSAUpdaterBulk() = default;
0056   SSAUpdaterBulk(const SSAUpdaterBulk &) = delete;
0057   SSAUpdaterBulk &operator=(const SSAUpdaterBulk &) = delete;
0058   ~SSAUpdaterBulk() = default;
0059
0060   /// Add a new variable to the SSA rewriter. This needs to be called before
0061   /// AddAvailableValue or AddUse calls. The return value is the variable ID,
0062   /// which needs to be passed to AddAvailableValue and AddUse.
0063   unsigned AddVariable(StringRef Name, Type *Ty);
0064
0065   /// Indicate that a rewritten value is available in the specified block with
0066   /// the specified value.
0067   void AddAvailableValue(unsigned Var, BasicBlock *BB, Value *V);
0068
0069   /// Record a use of the symbolic value. This use will be updated with a
0070   /// rewritten value when RewriteAllUses is called.
0071   void AddUse(unsigned Var, Use *U);
0072
0073   /// Perform all the necessary updates, including new PHI-nodes insertion and
0074   /// the requested uses update.
0075   ///
0076   /// The function requires dominator tree DT, which is used for computing
0077   /// locations for new phi-nodes insertions. If a nonnull pointer to a vector
0078   /// InsertedPHIs is passed, all the new phi-nodes will be added to this
0079   /// vector.
0080   void RewriteAllUses(DominatorTree *DT,
0081                       SmallVectorImpl<PHINode *> *InsertedPHIs = nullptr);
0082 };
0083
0084 } // end namespace llvm
0085
0086 #endif // LLVM_TRANSFORMS_UTILS_SSAUPDATERBULK_H