1 //===- Transform/Utils/CodeMoverUtils.h - CodeMover Utils -------*- 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 family of functions determine movements are safe on basic blocks, and
10 // instructions contained within a function.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #ifndef LLVM_TRANSFORMS_UTILS_CODEMOVERUTILS_H
15 #define LLVM_TRANSFORMS_UTILS_CODEMOVERUTILS_H
16 
17 namespace llvm {
18 
19 class BasicBlock;
20 class DependenceInfo;
21 class DominatorTree;
22 class Instruction;
23 class PostDominatorTree;
24 
25 /// Return true if \p I0 and \p I1 are control flow equivalent.
26 /// Two instructions are control flow equivalent if their basic blocks are
27 /// control flow equivalent.
28 bool isControlFlowEquivalent(const Instruction &I0, const Instruction &I1,
29                              const DominatorTree &DT,
30                              const PostDominatorTree &PDT);
31 
32 /// Return true if \p BB0 and \p BB1 are control flow equivalent.
33 /// Two basic blocks are control flow equivalent if when one executes, the other
34 /// is guaranteed to execute.
35 bool isControlFlowEquivalent(const BasicBlock &BB0, const BasicBlock &BB1,
36                              const DominatorTree &DT,
37                              const PostDominatorTree &PDT);
38 
39 /// Return true if \p I can be safely moved before \p InsertPoint.
40 bool isSafeToMoveBefore(Instruction &I, Instruction &InsertPoint,
41                         DominatorTree &DT,
42                         const PostDominatorTree *PDT = nullptr,
43                         DependenceInfo *DI = nullptr,
44                         bool CheckForEntireBlock = false);
45 
46 /// Return true if all instructions (except the terminator) in \p BB can be
47 /// safely moved before \p InsertPoint.
48 bool isSafeToMoveBefore(BasicBlock &BB, Instruction &InsertPoint,
49                         DominatorTree &DT,
50                         const PostDominatorTree *PDT = nullptr,
51                         DependenceInfo *DI = nullptr);
52 
53 /// Move instructions, in an order-preserving manner, from \p FromBB to the
54 /// beginning of \p ToBB when proven safe.
55 void moveInstructionsToTheBeginning(BasicBlock &FromBB, BasicBlock &ToBB,
56                                     DominatorTree &DT,
57                                     const PostDominatorTree &PDT,
58                                     DependenceInfo &DI);
59 
60 /// Move instructions, in an order-preserving manner, from \p FromBB to the end
61 /// of \p ToBB when proven safe.
62 void moveInstructionsToTheEnd(BasicBlock &FromBB, BasicBlock &ToBB,
63                               DominatorTree &DT, const PostDominatorTree &PDT,
64                               DependenceInfo &DI);
65 
66 /// In case that two BBs \p ThisBlock and \p OtherBlock are control flow
67 /// equivalent but they do not strictly dominate and post-dominate each
68 /// other, we determine if \p ThisBlock is reached after \p OtherBlock
69 /// in the control flow.
70 bool nonStrictlyPostDominate(const BasicBlock *ThisBlock,
71                              const BasicBlock *OtherBlock,
72                              const DominatorTree *DT,
73                              const PostDominatorTree *PDT);
74 
75 // Check if I0 is reached before I1 in the control flow.
76 bool isReachedBefore(const Instruction *I0, const Instruction *I1,
77                      const DominatorTree *DT, const PostDominatorTree *PDT);
78 
79 } // end namespace llvm
80 
81 #endif // LLVM_TRANSFORMS_UTILS_CODEMOVERUTILS_H
82