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llvm-project/llvm/lib/Target/Hexagon/HexagonRDFOpt.cpp

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//===- HexagonRDFOpt.cpp --------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "HexagonInstrInfo.h"
#include "HexagonSubtarget.h"
#include "MCTargetDesc/HexagonBaseInfo.h"
#include "RDFCopy.h"
#include "RDFDeadCode.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/CodeGen/MachineDominanceFrontier.h"
#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineOperand.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/RDFGraph.h"
#include "llvm/CodeGen/RDFLiveness.h"
#include "llvm/CodeGen/RDFRegisters.h"
#include "llvm/InitializePasses.h"
#include "llvm/Pass.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
#include <cassert>
#include <limits>
#include <utility>
using namespace llvm;
using namespace rdf;
namespace llvm {
void initializeHexagonRDFOptPass(PassRegistry&);
FunctionPass *createHexagonRDFOpt();
} // end namespace llvm
static unsigned RDFCount = 0;
static cl::opt<unsigned> RDFLimit("rdf-limit",
cl::init(std::numeric_limits<unsigned>::max()));
static cl::opt<bool> RDFDump("rdf-dump", cl::init(false));
namespace {
class HexagonRDFOpt : public MachineFunctionPass {
public:
HexagonRDFOpt() : MachineFunctionPass(ID) {}
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.addRequired<MachineDominatorTree>();
AU.addRequired<MachineDominanceFrontier>();
AU.setPreservesAll();
MachineFunctionPass::getAnalysisUsage(AU);
}
StringRef getPassName() const override {
return "Hexagon RDF optimizations";
}
bool runOnMachineFunction(MachineFunction &MF) override;
MachineFunctionProperties getRequiredProperties() const override {
return MachineFunctionProperties().set(
MachineFunctionProperties::Property::NoVRegs);
}
static char ID;
private:
MachineDominatorTree *MDT;
MachineRegisterInfo *MRI;
};
struct HexagonCP : public CopyPropagation {
HexagonCP(DataFlowGraph &G) : CopyPropagation(G) {}
bool interpretAsCopy(const MachineInstr *MI, EqualityMap &EM) override;
};
struct HexagonDCE : public DeadCodeElimination {
HexagonDCE(DataFlowGraph &G, MachineRegisterInfo &MRI)
: DeadCodeElimination(G, MRI) {}
bool rewrite(NodeAddr<InstrNode*> IA, SetVector<NodeId> &Remove);
void removeOperand(NodeAddr<InstrNode*> IA, unsigned OpNum);
bool run();
};
} // end anonymous namespace
char HexagonRDFOpt::ID = 0;
INITIALIZE_PASS_BEGIN(HexagonRDFOpt, "hexagon-rdf-opt",
"Hexagon RDF optimizations", false, false)
INITIALIZE_PASS_DEPENDENCY(MachineDominatorTree)
INITIALIZE_PASS_DEPENDENCY(MachineDominanceFrontier)
INITIALIZE_PASS_END(HexagonRDFOpt, "hexagon-rdf-opt",
"Hexagon RDF optimizations", false, false)
bool HexagonCP::interpretAsCopy(const MachineInstr *MI, EqualityMap &EM) {
auto mapRegs = [&EM] (RegisterRef DstR, RegisterRef SrcR) -> void {
EM.insert(std::make_pair(DstR, SrcR));
};
DataFlowGraph &DFG = getDFG();
unsigned Opc = MI->getOpcode();
switch (Opc) {
case Hexagon::A2_combinew: {
const MachineOperand &DstOp = MI->getOperand(0);
const MachineOperand &HiOp = MI->getOperand(1);
const MachineOperand &LoOp = MI->getOperand(2);
assert(DstOp.getSubReg() == 0 && "Unexpected subregister");
mapRegs(DFG.makeRegRef(DstOp.getReg(), Hexagon::isub_hi),
DFG.makeRegRef(HiOp.getReg(), HiOp.getSubReg()));
mapRegs(DFG.makeRegRef(DstOp.getReg(), Hexagon::isub_lo),
DFG.makeRegRef(LoOp.getReg(), LoOp.getSubReg()));
return true;
}
case Hexagon::A2_addi: {
const MachineOperand &A = MI->getOperand(2);
if (!A.isImm() || A.getImm() != 0)
return false;
LLVM_FALLTHROUGH;
}
case Hexagon::A2_tfr: {
const MachineOperand &DstOp = MI->getOperand(0);
const MachineOperand &SrcOp = MI->getOperand(1);
mapRegs(DFG.makeRegRef(DstOp.getReg(), DstOp.getSubReg()),
DFG.makeRegRef(SrcOp.getReg(), SrcOp.getSubReg()));
return true;
}
}
return CopyPropagation::interpretAsCopy(MI, EM);
}
bool HexagonDCE::run() {
bool Collected = collect();
if (!Collected)
return false;
const SetVector<NodeId> &DeadNodes = getDeadNodes();
const SetVector<NodeId> &DeadInstrs = getDeadInstrs();
using RefToInstrMap = DenseMap<NodeId, NodeId>;
RefToInstrMap R2I;
SetVector<NodeId> PartlyDead;
DataFlowGraph &DFG = getDFG();
for (NodeAddr<BlockNode*> BA : DFG.getFunc().Addr->members(DFG)) {
for (auto TA : BA.Addr->members_if(DFG.IsCode<NodeAttrs::Stmt>, DFG)) {
NodeAddr<StmtNode*> SA = TA;
for (NodeAddr<RefNode*> RA : SA.Addr->members(DFG)) {
R2I.insert(std::make_pair(RA.Id, SA.Id));
if (DFG.IsDef(RA) && DeadNodes.count(RA.Id))
if (!DeadInstrs.count(SA.Id))
PartlyDead.insert(SA.Id);
}
}
}
// Nodes to remove.
SetVector<NodeId> Remove = DeadInstrs;
bool Changed = false;
for (NodeId N : PartlyDead) {
auto SA = DFG.addr<StmtNode*>(N);
if (trace())
dbgs() << "Partly dead: " << *SA.Addr->getCode();
Changed |= rewrite(SA, Remove);
}
return erase(Remove) || Changed;
}
void HexagonDCE::removeOperand(NodeAddr<InstrNode*> IA, unsigned OpNum) {
MachineInstr *MI = NodeAddr<StmtNode*>(IA).Addr->getCode();
auto getOpNum = [MI] (MachineOperand &Op) -> unsigned {
for (unsigned i = 0, n = MI->getNumOperands(); i != n; ++i)
if (&MI->getOperand(i) == &Op)
return i;
llvm_unreachable("Invalid operand");
};
DenseMap<NodeId,unsigned> OpMap;
DataFlowGraph &DFG = getDFG();
NodeList Refs = IA.Addr->members(DFG);
for (NodeAddr<RefNode*> RA : Refs)
OpMap.insert(std::make_pair(RA.Id, getOpNum(RA.Addr->getOp())));
MI->RemoveOperand(OpNum);
for (NodeAddr<RefNode*> RA : Refs) {
unsigned N = OpMap[RA.Id];
if (N < OpNum)
RA.Addr->setRegRef(&MI->getOperand(N), DFG);
else if (N > OpNum)
RA.Addr->setRegRef(&MI->getOperand(N-1), DFG);
}
}
bool HexagonDCE::rewrite(NodeAddr<InstrNode*> IA, SetVector<NodeId> &Remove) {
if (!getDFG().IsCode<NodeAttrs::Stmt>(IA))
return false;
DataFlowGraph &DFG = getDFG();
MachineInstr &MI = *NodeAddr<StmtNode*>(IA).Addr->getCode();
auto &HII = static_cast<const HexagonInstrInfo&>(DFG.getTII());
if (HII.getAddrMode(MI) != HexagonII::PostInc)
return false;
unsigned Opc = MI.getOpcode();
unsigned OpNum, NewOpc;
switch (Opc) {
case Hexagon::L2_loadri_pi:
NewOpc = Hexagon::L2_loadri_io;
OpNum = 1;
break;
case Hexagon::L2_loadrd_pi:
NewOpc = Hexagon::L2_loadrd_io;
OpNum = 1;
break;
case Hexagon::V6_vL32b_pi:
NewOpc = Hexagon::V6_vL32b_ai;
OpNum = 1;
break;
case Hexagon::S2_storeri_pi:
NewOpc = Hexagon::S2_storeri_io;
OpNum = 0;
break;
case Hexagon::S2_storerd_pi:
NewOpc = Hexagon::S2_storerd_io;
OpNum = 0;
break;
case Hexagon::V6_vS32b_pi:
NewOpc = Hexagon::V6_vS32b_ai;
OpNum = 0;
break;
default:
return false;
}
auto IsDead = [this] (NodeAddr<DefNode*> DA) -> bool {
return getDeadNodes().count(DA.Id);
};
NodeList Defs;
MachineOperand &Op = MI.getOperand(OpNum);
for (NodeAddr<DefNode*> DA : IA.Addr->members_if(DFG.IsDef, DFG)) {
if (&DA.Addr->getOp() != &Op)
continue;
Defs = DFG.getRelatedRefs(IA, DA);
if (!llvm::all_of(Defs, IsDead))
return false;
break;
}
// Mark all nodes in Defs for removal.
for (auto D : Defs)
Remove.insert(D.Id);
if (trace())
dbgs() << "Rewriting: " << MI;
MI.setDesc(HII.get(NewOpc));
MI.getOperand(OpNum+2).setImm(0);
removeOperand(IA, OpNum);
if (trace())
dbgs() << " to: " << MI;
return true;
}
bool HexagonRDFOpt::runOnMachineFunction(MachineFunction &MF) {
if (skipFunction(MF.getFunction()))
return false;
if (RDFLimit.getPosition()) {
if (RDFCount >= RDFLimit)
return false;
RDFCount++;
}
MDT = &getAnalysis<MachineDominatorTree>();
const auto &MDF = getAnalysis<MachineDominanceFrontier>();
const auto &HII = *MF.getSubtarget<HexagonSubtarget>().getInstrInfo();
const auto &HRI = *MF.getSubtarget<HexagonSubtarget>().getRegisterInfo();
MRI = &MF.getRegInfo();
bool Changed;
if (RDFDump)
MF.print(dbgs() << "Before " << getPassName() << "\n", nullptr);
TargetOperandInfo TOI(HII);
DataFlowGraph G(MF, HII, HRI, *MDT, MDF, TOI);
// Dead phi nodes are necessary for copy propagation: we can add a use
// of a register in a block where it would need a phi node, but which
// was dead (and removed) during the graph build time.
G.build(BuildOptions::KeepDeadPhis);
if (RDFDump)
dbgs() << "Starting copy propagation on: " << MF.getName() << '\n'
<< PrintNode<FuncNode*>(G.getFunc(), G) << '\n';
HexagonCP CP(G);
CP.trace(RDFDump);
Changed = CP.run();
if (RDFDump)
dbgs() << "Starting dead code elimination on: " << MF.getName() << '\n'
<< PrintNode<FuncNode*>(G.getFunc(), G) << '\n';
HexagonDCE DCE(G, *MRI);
DCE.trace(RDFDump);
Changed |= DCE.run();
if (Changed) {
if (RDFDump)
dbgs() << "Starting liveness recomputation on: " << MF.getName() << '\n';
Liveness LV(*MRI, G);
LV.trace(RDFDump);
LV.computeLiveIns();
LV.resetLiveIns();
LV.resetKills();
}
if (RDFDump)
MF.print(dbgs() << "After " << getPassName() << "\n", nullptr);
return false;
}
FunctionPass *llvm::createHexagonRDFOpt() {
return new HexagonRDFOpt();
}
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