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
21namespace llvm {
22
23class BasicBlock;
24class PHINode;
25template <typename T> class SmallVectorImpl;
26class Type;
27class Use;
28class Value;
29class 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).
40class SSAUpdaterBulk {
41  struct RewriteInfo {
42    DenseMap<BasicBlock *, Value *> Defines;
43    SmallVector<Use *, 4> Uses;
44    StringRef Name;
45    Type *Ty;
46    RewriteInfo(){};
47    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
55public:
56  explicit SSAUpdaterBulk(){};
57  SSAUpdaterBulk(const SSAUpdaterBulk &) = delete;
58  SSAUpdaterBulk &operator=(const SSAUpdaterBulk &) = delete;
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