LLVM  9.0.0svn
RDFDeadCode.h
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1 //===--- RDFDeadCode.h ----------------------------------------------------===//
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 // RDF-based generic dead code elimination.
10 //
11 // The main interface of this class are functions "collect" and "erase".
12 // This allows custom processing of the function being optimized by a
13 // particular consumer. The simplest way to use this class would be to
14 // instantiate an object, and then simply call "collect" and "erase",
15 // passing the result of "getDeadInstrs()" to it.
16 // A more complex scenario would be to call "collect" first, then visit
17 // all post-increment instructions to see if the address update is dead
18 // or not, and if it is, convert the instruction to a non-updating form.
19 // After that "erase" can be called with the set of nodes including both,
20 // dead defs from the updating instructions and the nodes corresponding
21 // to the dead instructions.
22 
23 #ifndef RDF_DEADCODE_H
24 #define RDF_DEADCODE_H
25 
26 #include "RDFGraph.h"
27 #include "RDFLiveness.h"
28 #include "llvm/ADT/SetVector.h"
29 
30 namespace llvm {
31  class MachineRegisterInfo;
32 
33 namespace rdf {
36  : Trace(false), DFG(dfg), MRI(mri), LV(mri, dfg) {}
37 
38  bool collect();
39  bool erase(const SetVector<NodeId> &Nodes);
40  void trace(bool On) { Trace = On; }
41  bool trace() const { return Trace; }
42 
43  SetVector<NodeId> getDeadNodes() { return DeadNodes; }
44  SetVector<NodeId> getDeadInstrs() { return DeadInstrs; }
45  DataFlowGraph &getDFG() { return DFG; }
46 
47  private:
48  bool Trace;
49  SetVector<NodeId> LiveNodes;
50  SetVector<NodeId> DeadNodes;
51  SetVector<NodeId> DeadInstrs;
52  DataFlowGraph &DFG;
54  Liveness LV;
55 
56  template<typename T> struct SetQueue;
57 
58  bool isLiveInstr(const MachineInstr *MI) const;
59  void scanInstr(NodeAddr<InstrNode*> IA, SetQueue<NodeId> &WorkQ);
60  void processDef(NodeAddr<DefNode*> DA, SetQueue<NodeId> &WorkQ);
61  void processUse(NodeAddr<UseNode*> UA, SetQueue<NodeId> &WorkQ);
62  };
63 } // namespace rdf
64 } // namespace llvm
65 
66 #endif
This class represents lattice values for constants.
Definition: AllocatorList.h:23
SetVector< NodeId > getDeadInstrs()
Definition: RDFDeadCode.h:44
DataFlowGraph & getDFG()
Definition: RDFDeadCode.h:45
SetVector< NodeId > getDeadNodes()
Definition: RDFDeadCode.h:43
DeadCodeElimination(DataFlowGraph &dfg, MachineRegisterInfo &mri)
Definition: RDFDeadCode.h:35
MachineRegisterInfo - Keep track of information for virtual and physical registers, including vreg register classes, use/def chains for registers, etc.
Representation of each machine instruction.
Definition: MachineInstr.h:64
bool erase(const SetVector< NodeId > &Nodes)
A vector that has set insertion semantics.
Definition: SetVector.h:40
IRTranslator LLVM IR MI