1 //===--- RDFCopy.cpp ------------------------------------------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // RDF-based copy propagation.
14 #include "RDFLiveness.h"
15 #include "llvm/CodeGen/MachineBasicBlock.h"
16 #include "llvm/CodeGen/MachineDominators.h"
17 #include "llvm/CodeGen/MachineInstr.h"
18 #include "llvm/CodeGen/MachineRegisterInfo.h"
19 #include "llvm/Support/CommandLine.h"
20 #include "llvm/Target/TargetInstrInfo.h"
21 #include "llvm/Target/TargetRegisterInfo.h"
26 static cl::opt<unsigned> CpLimit("rdf-cp-limit", cl::init(0), cl::Hidden);
27 static unsigned CpCount = 0;
30 bool CopyPropagation::interpretAsCopy(const MachineInstr *MI, EqualityMap &EM) {
31 unsigned Opc = MI->getOpcode();
33 case TargetOpcode::COPY: {
34 const MachineOperand &Dst = MI->getOperand(0);
35 const MachineOperand &Src = MI->getOperand(1);
36 RegisterRef DstR = DFG.makeRegRef(Dst.getReg(), Dst.getSubReg());
37 RegisterRef SrcR = DFG.makeRegRef(Src.getReg(), Src.getSubReg());
38 assert(TargetRegisterInfo::isPhysicalRegister(DstR.Reg));
39 assert(TargetRegisterInfo::isPhysicalRegister(SrcR.Reg));
40 const TargetRegisterInfo &TRI = DFG.getTRI();
41 if (TRI.getMinimalPhysRegClass(DstR.Reg) !=
42 TRI.getMinimalPhysRegClass(SrcR.Reg))
44 EM.insert(std::make_pair(DstR, SrcR));
47 case TargetOpcode::REG_SEQUENCE:
48 llvm_unreachable("Unexpected REG_SEQUENCE");
54 void CopyPropagation::recordCopy(NodeAddr<StmtNode*> SA, EqualityMap &EM) {
55 CopyMap.insert(std::make_pair(SA.Id, EM));
56 Copies.push_back(SA.Id);
60 bool CopyPropagation::scanBlock(MachineBasicBlock *B) {
62 auto BA = DFG.getFunc().Addr->findBlock(B, DFG);
64 for (NodeAddr<InstrNode*> IA : BA.Addr->members(DFG)) {
65 if (DFG.IsCode<NodeAttrs::Stmt>(IA)) {
66 NodeAddr<StmtNode*> SA = IA;
68 if (interpretAsCopy(SA.Addr->getCode(), EM))
73 MachineDomTreeNode *N = MDT.getNode(B);
75 Changed |= scanBlock(I->getBlock());
81 NodeId CopyPropagation::getLocalReachingDef(RegisterRef RefRR,
82 NodeAddr<InstrNode*> IA) {
83 NodeAddr<RefNode*> RA = L.getNearestAliasedRef(RefRR, IA);
85 if (RA.Addr->getKind() == NodeAttrs::Def)
87 assert(RA.Addr->getKind() == NodeAttrs::Use);
88 if (NodeId RD = RA.Addr->getReachingDef())
95 bool CopyPropagation::run() {
96 scanBlock(&DFG.getMF().front());
99 dbgs() << "Copies:\n";
100 for (auto I : Copies) {
101 dbgs() << "Instr: " << *DFG.addr<StmtNode*>(I).Addr->getCode();
103 for (auto J : CopyMap[I])
104 dbgs() << ' ' << Print<RegisterRef>(J.first, DFG) << '='
105 << Print<RegisterRef>(J.second, DFG);
110 bool Changed = false;
112 bool HasLimit = CpLimit.getNumOccurrences() > 0;
115 auto MinPhysReg = [this] (RegisterRef RR) -> unsigned {
116 const TargetRegisterInfo &TRI = DFG.getTRI();
117 const TargetRegisterClass &RC = *TRI.getMinimalPhysRegClass(RR.Reg);
118 if ((RC.LaneMask & RR.Mask) == RC.LaneMask)
120 for (MCSubRegIndexIterator S(RR.Reg, &TRI); S.isValid(); ++S)
121 if (RR.Mask == TRI.getSubRegIndexLaneMask(S.getSubRegIndex()))
122 return S.getSubReg();
123 llvm_unreachable("Should have found a register");
127 for (auto C : Copies) {
129 if (HasLimit && CpCount >= CpLimit)
132 auto SA = DFG.addr<InstrNode*>(C);
133 auto FS = CopyMap.find(SA.Id);
134 if (FS == CopyMap.end())
137 EqualityMap &EM = FS->second;
138 for (NodeAddr<DefNode*> DA : SA.Addr->members_if(DFG.IsDef, DFG)) {
139 RegisterRef DR = DA.Addr->getRegRef(DFG);
140 auto FR = EM.find(DR);
143 RegisterRef SR = FR->second;
147 NodeId AtCopy = getLocalReachingDef(SR, SA);
149 for (NodeId N = DA.Addr->getReachedUse(), NextN; N; N = NextN) {
150 auto UA = DFG.addr<UseNode*>(N);
151 NextN = UA.Addr->getSibling();
152 uint16_t F = UA.Addr->getFlags();
153 if ((F & NodeAttrs::PhiRef) || (F & NodeAttrs::Fixed))
155 if (UA.Addr->getRegRef(DFG) != DR)
158 NodeAddr<InstrNode*> IA = UA.Addr->getOwner(DFG);
159 assert(DFG.IsCode<NodeAttrs::Stmt>(IA));
160 NodeId AtUse = getLocalReachingDef(SR, IA);
164 MachineOperand &Op = UA.Addr->getOp();
168 dbgs() << "Can replace " << Print<RegisterRef>(DR, DFG)
169 << " with " << Print<RegisterRef>(SR, DFG) << " in "
170 << *NodeAddr<StmtNode*>(IA).Addr->getCode();
173 unsigned NewReg = MinPhysReg(SR);
176 DFG.unlinkUse(UA, false);
178 UA.Addr->linkToDef(UA.Id, DFG.addr<DefNode*>(AtCopy));
180 UA.Addr->setReachingDef(0);
181 UA.Addr->setSibling(0);
186 if (HasLimit && CpCount >= CpLimit)
191 auto FC = CopyMap.find(IA.Id);
192 if (FC != CopyMap.end()) {
193 // Update the EM map in the copy's entry.
194 auto &M = FC->second;
202 } // for (N in reached-uses)
203 } // for (DA in defs)
204 } // for (C in Copies)