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 31namespace llvm { 32 class MachineRegisterInfo; 33 34namespace rdf { 35 struct DeadCodeElimination { 36 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); 41 void trace(bool On) { Trace = On; } 42 bool trace() const { return Trace; } 43 44 SetVector<NodeId> getDeadNodes() { return DeadNodes; } 45 SetVector<NodeId> getDeadInstrs() { return DeadInstrs; } 46 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