LLVM  10.0.0svn
Localizer.h
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1 //== llvm/CodeGen/GlobalISel/Localizer.h - Localizer -------------*- 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 /// \file This file describes the interface of the Localizer pass.
10 /// This pass moves/duplicates constant-like instructions close to their uses.
11 /// Its primarily goal is to workaround the deficiencies of the fast register
12 /// allocator.
13 /// With GlobalISel constants are all materialized in the entry block of
14 /// a function. However, the fast allocator cannot rematerialize constants and
15 /// has a lot more live-ranges to deal with and will most likely end up
16 /// spilling a lot.
17 /// By pushing the constants close to their use, we only create small
18 /// live-ranges.
19 //===----------------------------------------------------------------------===//
20 
21 #ifndef LLVM_CODEGEN_GLOBALISEL_LOCALIZER_H
22 #define LLVM_CODEGEN_GLOBALISEL_LOCALIZER_H
23 
24 #include "llvm/ADT/SetVector.h"
27 
28 namespace llvm {
29 // Forward declarations.
30 class MachineRegisterInfo;
31 class TargetTransformInfo;
32 
33 /// This pass implements the localization mechanism described at the
34 /// top of this file. One specificity of the implementation is that
35 /// it will materialize one and only one instance of a constant per
36 /// basic block, thus enabling reuse of that constant within that block.
37 /// Moreover, it only materializes constants in blocks where they
38 /// are used. PHI uses are considered happening at the end of the
39 /// related predecessor.
41 public:
42  static char ID;
43 
44 private:
45  /// MRI contains all the register class/bank information that this
46  /// pass uses and updates.
48  /// TTI used for getting remat costs for instructions.
50 
51  /// Check whether or not \p MI needs to be moved close to its uses.
52  bool shouldLocalize(const MachineInstr &MI);
53 
54  /// Check if \p MOUse is used in the same basic block as \p Def.
55  /// If the use is in the same block, we say it is local.
56  /// When the use is not local, \p InsertMBB will contain the basic
57  /// block when to insert \p Def to have a local use.
58  static bool isLocalUse(MachineOperand &MOUse, const MachineInstr &Def,
59  MachineBasicBlock *&InsertMBB);
60 
61  /// Initialize the field members using \p MF.
62  void init(MachineFunction &MF);
63 
65 
66  /// Do inter-block localization from the entry block.
67  bool localizeInterBlock(MachineFunction &MF,
68  LocalizedSetVecT &LocalizedInstrs);
69 
70  /// Do intra-block localization of already localized instructions.
71  bool localizeIntraBlock(LocalizedSetVecT &LocalizedInstrs);
72 
73 public:
74  Localizer();
75 
76  StringRef getPassName() const override { return "Localizer"; }
77 
83  }
84 
85  void getAnalysisUsage(AnalysisUsage &AU) const override;
86 
87  bool runOnMachineFunction(MachineFunction &MF) override;
88 };
89 
90 } // End namespace llvm.
91 
92 #endif
static char ID
Definition: Localizer.h:42
This class represents lattice values for constants.
Definition: AllocatorList.h:23
This pass implements the localization mechanism described at the top of this file.
Definition: Localizer.h:40
MachineFunctionPass - This class adapts the FunctionPass interface to allow convenient creation of pa...
bool runOnMachineFunction(MachineFunction &MF) override
runOnMachineFunction - This method must be overloaded to perform the desired machine code transformat...
Definition: Localizer.cpp:208
StringRef getPassName() const override
getPassName - Return a nice clean name for a pass.
Definition: Localizer.h:76
void getAnalysisUsage(AnalysisUsage &AU) const override
getAnalysisUsage - This function should be overriden by passes that need analysis information to do t...
Definition: Localizer.cpp:92
Represent the analysis usage information of a pass.
MachineFunctionProperties getRequiredProperties() const override
Definition: Localizer.h:78
A SetVector that performs no allocations if smaller than a certain size.
Definition: SetVector.h:297
This pass provides access to the codegen interfaces that are needed for IR-level transformations.
MachineOperand class - Representation of each machine instruction operand.
This file declares the MachineIRBuilder class.
MachineRegisterInfo - Keep track of information for virtual and physical registers, including vreg register classes, use/def chains for registers, etc.
MachineFunctionProperties & set(Property P)
Representation of each machine instruction.
Definition: MachineInstr.h:64
IRTranslator LLVM IR MI
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:48
Properties which a MachineFunction may have at a given point in time.