1 //===- HexagonRDFOpt.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 #include "HexagonInstrInfo.h"
11 #include "HexagonSubtarget.h"
12 #include "MCTargetDesc/HexagonBaseInfo.h"
14 #include "RDFDeadCode.h"
16 #include "RDFLiveness.h"
17 #include "RDFRegisters.h"
18 #include "llvm/ADT/DenseMap.h"
19 #include "llvm/ADT/STLExtras.h"
20 #include "llvm/ADT/SetVector.h"
21 #include "llvm/CodeGen/MachineDominanceFrontier.h"
22 #include "llvm/CodeGen/MachineDominators.h"
23 #include "llvm/CodeGen/MachineFunction.h"
24 #include "llvm/CodeGen/MachineFunctionPass.h"
25 #include "llvm/CodeGen/MachineInstr.h"
26 #include "llvm/CodeGen/MachineOperand.h"
27 #include "llvm/CodeGen/MachineRegisterInfo.h"
28 #include "llvm/Pass.h"
29 #include "llvm/Support/CommandLine.h"
30 #include "llvm/Support/Compiler.h"
31 #include "llvm/Support/Debug.h"
32 #include "llvm/Support/ErrorHandling.h"
33 #include "llvm/Support/raw_ostream.h"
43 void initializeHexagonRDFOptPass(PassRegistry&);
44 FunctionPass *createHexagonRDFOpt();
46 } // end namespace llvm
48 static unsigned RDFCount = 0;
50 static cl::opt<unsigned> RDFLimit("rdf-limit",
51 cl::init(std::numeric_limits<unsigned>::max()));
52 static cl::opt<bool> RDFDump("rdf-dump", cl::init(false));
56 class HexagonRDFOpt : public MachineFunctionPass {
58 HexagonRDFOpt() : MachineFunctionPass(ID) {}
60 void getAnalysisUsage(AnalysisUsage &AU) const override {
61 AU.addRequired<MachineDominatorTree>();
62 AU.addRequired<MachineDominanceFrontier>();
64 MachineFunctionPass::getAnalysisUsage(AU);
67 StringRef getPassName() const override {
68 return "Hexagon RDF optimizations";
71 bool runOnMachineFunction(MachineFunction &MF) override;
73 MachineFunctionProperties getRequiredProperties() const override {
74 return MachineFunctionProperties().set(
75 MachineFunctionProperties::Property::NoVRegs);
81 MachineDominatorTree *MDT;
82 MachineRegisterInfo *MRI;
85 struct HexagonCP : public CopyPropagation {
86 HexagonCP(DataFlowGraph &G) : CopyPropagation(G) {}
88 bool interpretAsCopy(const MachineInstr *MI, EqualityMap &EM) override;
91 struct HexagonDCE : public DeadCodeElimination {
92 HexagonDCE(DataFlowGraph &G, MachineRegisterInfo &MRI)
93 : DeadCodeElimination(G, MRI) {}
95 bool rewrite(NodeAddr<InstrNode*> IA, SetVector<NodeId> &Remove);
96 void removeOperand(NodeAddr<InstrNode*> IA, unsigned OpNum);
101 } // end anonymous namespace
103 char HexagonRDFOpt::ID = 0;
105 INITIALIZE_PASS_BEGIN(HexagonRDFOpt, "hexagon-rdf-opt",
106 "Hexagon RDF optimizations", false, false)
107 INITIALIZE_PASS_DEPENDENCY(MachineDominatorTree)
108 INITIALIZE_PASS_DEPENDENCY(MachineDominanceFrontier)
109 INITIALIZE_PASS_END(HexagonRDFOpt, "hexagon-rdf-opt",
110 "Hexagon RDF optimizations", false, false)
112 bool HexagonCP::interpretAsCopy(const MachineInstr *MI, EqualityMap &EM) {
113 auto mapRegs = [&EM] (RegisterRef DstR, RegisterRef SrcR) -> void {
114 EM.insert(std::make_pair(DstR, SrcR));
117 DataFlowGraph &DFG = getDFG();
118 unsigned Opc = MI->getOpcode();
120 case Hexagon::A2_combinew: {
121 const MachineOperand &DstOp = MI->getOperand(0);
122 const MachineOperand &HiOp = MI->getOperand(1);
123 const MachineOperand &LoOp = MI->getOperand(2);
124 assert(DstOp.getSubReg() == 0 && "Unexpected subregister");
125 mapRegs(DFG.makeRegRef(DstOp.getReg(), Hexagon::isub_hi),
126 DFG.makeRegRef(HiOp.getReg(), HiOp.getSubReg()));
127 mapRegs(DFG.makeRegRef(DstOp.getReg(), Hexagon::isub_lo),
128 DFG.makeRegRef(LoOp.getReg(), LoOp.getSubReg()));
131 case Hexagon::A2_addi: {
132 const MachineOperand &A = MI->getOperand(2);
133 if (!A.isImm() || A.getImm() != 0)
137 case Hexagon::A2_tfr: {
138 const MachineOperand &DstOp = MI->getOperand(0);
139 const MachineOperand &SrcOp = MI->getOperand(1);
140 mapRegs(DFG.makeRegRef(DstOp.getReg(), DstOp.getSubReg()),
141 DFG.makeRegRef(SrcOp.getReg(), SrcOp.getSubReg()));
146 return CopyPropagation::interpretAsCopy(MI, EM);
149 bool HexagonDCE::run() {
150 bool Collected = collect();
154 const SetVector<NodeId> &DeadNodes = getDeadNodes();
155 const SetVector<NodeId> &DeadInstrs = getDeadInstrs();
157 using RefToInstrMap = DenseMap<NodeId, NodeId>;
160 SetVector<NodeId> PartlyDead;
161 DataFlowGraph &DFG = getDFG();
163 for (NodeAddr<BlockNode*> BA : DFG.getFunc().Addr->members(DFG)) {
164 for (auto TA : BA.Addr->members_if(DFG.IsCode<NodeAttrs::Stmt>, DFG)) {
165 NodeAddr<StmtNode*> SA = TA;
166 for (NodeAddr<RefNode*> RA : SA.Addr->members(DFG)) {
167 R2I.insert(std::make_pair(RA.Id, SA.Id));
168 if (DFG.IsDef(RA) && DeadNodes.count(RA.Id))
169 if (!DeadInstrs.count(SA.Id))
170 PartlyDead.insert(SA.Id);
176 SetVector<NodeId> Remove = DeadInstrs;
178 bool Changed = false;
179 for (NodeId N : PartlyDead) {
180 auto SA = DFG.addr<StmtNode*>(N);
182 dbgs() << "Partly dead: " << *SA.Addr->getCode();
183 Changed |= rewrite(SA, Remove);
186 return erase(Remove) || Changed;
189 void HexagonDCE::removeOperand(NodeAddr<InstrNode*> IA, unsigned OpNum) {
190 MachineInstr *MI = NodeAddr<StmtNode*>(IA).Addr->getCode();
192 auto getOpNum = [MI] (MachineOperand &Op) -> unsigned {
193 for (unsigned i = 0, n = MI->getNumOperands(); i != n; ++i)
194 if (&MI->getOperand(i) == &Op)
196 llvm_unreachable("Invalid operand");
198 DenseMap<NodeId,unsigned> OpMap;
199 DataFlowGraph &DFG = getDFG();
200 NodeList Refs = IA.Addr->members(DFG);
201 for (NodeAddr<RefNode*> RA : Refs)
202 OpMap.insert(std::make_pair(RA.Id, getOpNum(RA.Addr->getOp())));
204 MI->RemoveOperand(OpNum);
206 for (NodeAddr<RefNode*> RA : Refs) {
207 unsigned N = OpMap[RA.Id];
209 RA.Addr->setRegRef(&MI->getOperand(N), DFG);
211 RA.Addr->setRegRef(&MI->getOperand(N-1), DFG);
215 bool HexagonDCE::rewrite(NodeAddr<InstrNode*> IA, SetVector<NodeId> &Remove) {
216 if (!getDFG().IsCode<NodeAttrs::Stmt>(IA))
218 DataFlowGraph &DFG = getDFG();
219 MachineInstr &MI = *NodeAddr<StmtNode*>(IA).Addr->getCode();
220 auto &HII = static_cast<const HexagonInstrInfo&>(DFG.getTII());
221 if (HII.getAddrMode(MI) != HexagonII::PostInc)
223 unsigned Opc = MI.getOpcode();
224 unsigned OpNum, NewOpc;
226 case Hexagon::L2_loadri_pi:
227 NewOpc = Hexagon::L2_loadri_io;
230 case Hexagon::L2_loadrd_pi:
231 NewOpc = Hexagon::L2_loadrd_io;
234 case Hexagon::V6_vL32b_pi:
235 NewOpc = Hexagon::V6_vL32b_ai;
238 case Hexagon::S2_storeri_pi:
239 NewOpc = Hexagon::S2_storeri_io;
242 case Hexagon::S2_storerd_pi:
243 NewOpc = Hexagon::S2_storerd_io;
246 case Hexagon::V6_vS32b_pi:
247 NewOpc = Hexagon::V6_vS32b_ai;
253 auto IsDead = [this] (NodeAddr<DefNode*> DA) -> bool {
254 return getDeadNodes().count(DA.Id);
257 MachineOperand &Op = MI.getOperand(OpNum);
258 for (NodeAddr<DefNode*> DA : IA.Addr->members_if(DFG.IsDef, DFG)) {
259 if (&DA.Addr->getOp() != &Op)
261 Defs = DFG.getRelatedRefs(IA, DA);
262 if (!llvm::all_of(Defs, IsDead))
267 // Mark all nodes in Defs for removal.
272 dbgs() << "Rewriting: " << MI;
273 MI.setDesc(HII.get(NewOpc));
274 MI.getOperand(OpNum+2).setImm(0);
275 removeOperand(IA, OpNum);
277 dbgs() << " to: " << MI;
282 bool HexagonRDFOpt::runOnMachineFunction(MachineFunction &MF) {
283 if (skipFunction(MF.getFunction()))
286 if (RDFLimit.getPosition()) {
287 if (RDFCount >= RDFLimit)
292 MDT = &getAnalysis<MachineDominatorTree>();
293 const auto &MDF = getAnalysis<MachineDominanceFrontier>();
294 const auto &HII = *MF.getSubtarget<HexagonSubtarget>().getInstrInfo();
295 const auto &HRI = *MF.getSubtarget<HexagonSubtarget>().getRegisterInfo();
296 MRI = &MF.getRegInfo();
300 MF.print(dbgs() << "Before " << getPassName() << "\n", nullptr);
302 TargetOperandInfo TOI(HII);
303 DataFlowGraph G(MF, HII, HRI, *MDT, MDF, TOI);
304 // Dead phi nodes are necessary for copy propagation: we can add a use
305 // of a register in a block where it would need a phi node, but which
306 // was dead (and removed) during the graph build time.
307 G.build(BuildOptions::KeepDeadPhis);
310 dbgs() << "Starting copy propagation on: " << MF.getName() << '\n'
311 << PrintNode<FuncNode*>(G.getFunc(), G) << '\n';
317 dbgs() << "Starting dead code elimination on: " << MF.getName() << '\n'
318 << PrintNode<FuncNode*>(G.getFunc(), G) << '\n';
319 HexagonDCE DCE(G, *MRI);
321 Changed |= DCE.run();
325 dbgs() << "Starting liveness recomputation on: " << MF.getName() << '\n';
326 Liveness LV(*MRI, G);
334 MF.print(dbgs() << "After " << getPassName() << "\n", nullptr);
339 FunctionPass *llvm::createHexagonRDFOpt() {
340 return new HexagonRDFOpt();