1 //===--- RDFDeadCode.h ----------------------------------------------------===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // RDF-based generic dead code elimination. 11 // 12 // The main interface of this class are functions "collect" and "erase". 13 // This allows custom processing of the function being optimized by a 14 // particular consumer. The simplest way to use this class would be to 15 // instantiate an object, and then simply call "collect" and "erase", 16 // passing the result of "getDeadInstrs()" to it. 17 // A more complex scenario would be to call "collect" first, then visit 18 // all post-increment instructions to see if the address update is dead 19 // or not, and if it is, convert the instruction to a non-updating form. 20 // After that "erase" can be called with the set of nodes including both, 21 // dead defs from the updating instructions and the nodes corresponding 22 // to the dead instructions. 23 24 #ifndef RDF_DEADCODE_H 25 #define RDF_DEADCODE_H 26 27 #include "RDFGraph.h" 28 #include "RDFLiveness.h" 29 #include "llvm/ADT/SetVector.h" 30 31 namespace llvm { 32 class MachineRegisterInfo; 33 34 namespace rdf { 35 struct DeadCodeElimination { DeadCodeEliminationDeadCodeElimination36 DeadCodeElimination(DataFlowGraph &dfg, MachineRegisterInfo &mri) 37 : Trace(false), DFG(dfg), MRI(mri), LV(mri, dfg) {} 38 39 bool collect(); 40 bool erase(const SetVector<NodeId> &Nodes); traceDeadCodeElimination41 void trace(bool On) { Trace = On; } traceDeadCodeElimination42 bool trace() const { return Trace; } 43 getDeadNodesDeadCodeElimination44 SetVector<NodeId> getDeadNodes() { return DeadNodes; } getDeadInstrsDeadCodeElimination45 SetVector<NodeId> getDeadInstrs() { return DeadInstrs; } getDFGDeadCodeElimination46 DataFlowGraph &getDFG() { return DFG; } 47 48 private: 49 bool Trace; 50 SetVector<NodeId> LiveNodes; 51 SetVector<NodeId> DeadNodes; 52 SetVector<NodeId> DeadInstrs; 53 DataFlowGraph &DFG; 54 MachineRegisterInfo &MRI; 55 Liveness LV; 56 57 template<typename T> struct SetQueue; 58 59 bool isLiveInstr(const MachineInstr *MI) const; 60 void scanInstr(NodeAddr<InstrNode*> IA, SetQueue<NodeId> &WorkQ); 61 void processDef(NodeAddr<DefNode*> DA, SetQueue<NodeId> &WorkQ); 62 void processUse(NodeAddr<UseNode*> UA, SetQueue<NodeId> &WorkQ); 63 }; 64 } // namespace rdf 65 } // namespace llvm 66 67 #endif 68