lib/Target/Hexagon/RDFDeadCode.h

   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 {
  34   struct DeadCodeElimination {
  35     DeadCodeElimination(DataFlowGraph &dfg, MachineRegisterInfo &mri)
  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;
  53     MachineRegisterInfo &MRI;
  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