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llvm-mirror/lib/Target/Hexagon/HexagonOptAddrMode.cpp
Simon Pilgrim 539b0b67e9 HexagonOptAddrMode::changeStore - fix null dereference warning (PR43463) 
As detailed on PR43463, this fixes a static analyzer null dereference warning by sinking Changed = true into the if() blocks where the MIB is actually created.

I did a quick check that suggested that one of those if() blocks is always guaranteed to be hit (so we could change it to if-else), but this seems like a safer approach

Differential Revision: https://reviews.llvm.org/D73883
2020-02-03 16:50:04 +00:00

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//===- HexagonOptAddrMode.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
//
//===----------------------------------------------------------------------===//
// This implements a Hexagon-specific pass to optimize addressing mode for
// load/store instructions.
//===----------------------------------------------------------------------===//
#include "HexagonInstrInfo.h"
#include "HexagonSubtarget.h"
#include "MCTargetDesc/HexagonBaseInfo.h"
#include "RDFGraph.h"
#include "RDFLiveness.h"
#include "RDFRegisters.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/CodeGen/MachineBasicBlock.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/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineOperand.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/TargetSubtargetInfo.h"
#include "llvm/InitializePasses.h"
#include "llvm/MC/MCInstrDesc.h"
#include "llvm/Pass.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
#include <cassert>
#include <cstdint>
#define DEBUG_TYPE "opt-addr-mode"
using namespace llvm;
using namespace rdf;
static cl::opt<int> CodeGrowthLimit("hexagon-amode-growth-limit",
cl::Hidden, cl::init(0), cl::desc("Code growth limit for address mode "
"optimization"));
namespace llvm {
FunctionPass *createHexagonOptAddrMode();
void initializeHexagonOptAddrModePass(PassRegistry&);
} // end namespace llvm
namespace {
class HexagonOptAddrMode : public MachineFunctionPass {
public:
static char ID;
HexagonOptAddrMode() : MachineFunctionPass(ID) {}
StringRef getPassName() const override {
return "Optimize addressing mode of load/store";
}
void getAnalysisUsage(AnalysisUsage &AU) const override {
MachineFunctionPass::getAnalysisUsage(AU);
AU.addRequired<MachineDominatorTree>();
AU.addRequired<MachineDominanceFrontier>();
AU.setPreservesAll();
}
bool runOnMachineFunction(MachineFunction &MF) override;
private:
using MISetType = DenseSet<MachineInstr *>;
using InstrEvalMap = DenseMap<MachineInstr *, bool>;
MachineRegisterInfo *MRI = nullptr;
const HexagonInstrInfo *HII = nullptr;
const HexagonRegisterInfo *HRI = nullptr;
MachineDominatorTree *MDT = nullptr;
DataFlowGraph *DFG = nullptr;
DataFlowGraph::DefStackMap DefM;
Liveness *LV = nullptr;
MISetType Deleted;
bool processBlock(NodeAddr<BlockNode *> BA);
bool xformUseMI(MachineInstr *TfrMI, MachineInstr *UseMI,
NodeAddr<UseNode *> UseN, unsigned UseMOnum);
bool processAddUses(NodeAddr<StmtNode *> AddSN, MachineInstr *AddMI,
const NodeList &UNodeList);
bool updateAddUses(MachineInstr *AddMI, MachineInstr *UseMI);
bool analyzeUses(unsigned DefR, const NodeList &UNodeList,
InstrEvalMap &InstrEvalResult, short &SizeInc);
bool hasRepForm(MachineInstr &MI, unsigned TfrDefR);
bool canRemoveAddasl(NodeAddr<StmtNode *> AddAslSN, MachineInstr &MI,
const NodeList &UNodeList);
bool isSafeToExtLR(NodeAddr<StmtNode *> SN, MachineInstr *MI,
unsigned LRExtReg, const NodeList &UNodeList);
void getAllRealUses(NodeAddr<StmtNode *> SN, NodeList &UNodeList);
bool allValidCandidates(NodeAddr<StmtNode *> SA, NodeList &UNodeList);
short getBaseWithLongOffset(const MachineInstr &MI) const;
bool changeStore(MachineInstr *OldMI, MachineOperand ImmOp,
unsigned ImmOpNum);
bool changeLoad(MachineInstr *OldMI, MachineOperand ImmOp, unsigned ImmOpNum);
bool changeAddAsl(NodeAddr<UseNode *> AddAslUN, MachineInstr *AddAslMI,
const MachineOperand &ImmOp, unsigned ImmOpNum);
bool isValidOffset(MachineInstr *MI, int Offset);
};
} // end anonymous namespace
char HexagonOptAddrMode::ID = 0;
INITIALIZE_PASS_BEGIN(HexagonOptAddrMode, "amode-opt",
"Optimize addressing mode", false, false)
INITIALIZE_PASS_DEPENDENCY(MachineDominatorTree)
INITIALIZE_PASS_DEPENDENCY(MachineDominanceFrontier)
INITIALIZE_PASS_END(HexagonOptAddrMode, "amode-opt", "Optimize addressing mode",
false, false)
bool HexagonOptAddrMode::hasRepForm(MachineInstr &MI, unsigned TfrDefR) {
const MCInstrDesc &MID = MI.getDesc();
if ((!MID.mayStore() && !MID.mayLoad()) || HII->isPredicated(MI))
return false;
if (MID.mayStore()) {
MachineOperand StOp = MI.getOperand(MI.getNumOperands() - 1);
if (StOp.isReg() && StOp.getReg() == TfrDefR)
return false;
}
if (HII->getAddrMode(MI) == HexagonII::BaseRegOffset)
// Tranform to Absolute plus register offset.
return (HII->changeAddrMode_rr_ur(MI) >= 0);
else if (HII->getAddrMode(MI) == HexagonII::BaseImmOffset)
// Tranform to absolute addressing mode.
return (HII->changeAddrMode_io_abs(MI) >= 0);
return false;
}
// Check if addasl instruction can be removed. This is possible only
// if it's feeding to only load/store instructions with base + register
// offset as these instruction can be tranformed to use 'absolute plus
// shifted register offset'.
// ex:
// Rs = ##foo
// Rx = addasl(Rs, Rt, #2)
// Rd = memw(Rx + #28)
// Above three instructions can be replaced with Rd = memw(Rt<<#2 + ##foo+28)
bool HexagonOptAddrMode::canRemoveAddasl(NodeAddr<StmtNode *> AddAslSN,
MachineInstr &MI,
const NodeList &UNodeList) {
// check offset size in addasl. if 'offset > 3' return false
const MachineOperand &OffsetOp = MI.getOperand(3);
if (!OffsetOp.isImm() || OffsetOp.getImm() > 3)
return false;
Register OffsetReg = MI.getOperand(2).getReg();
RegisterRef OffsetRR;
NodeId OffsetRegRD = 0;
for (NodeAddr<UseNode *> UA : AddAslSN.Addr->members_if(DFG->IsUse, *DFG)) {
RegisterRef RR = UA.Addr->getRegRef(*DFG);
if (OffsetReg == RR.Reg) {
OffsetRR = RR;
OffsetRegRD = UA.Addr->getReachingDef();
}
}
for (auto I = UNodeList.rbegin(), E = UNodeList.rend(); I != E; ++I) {
NodeAddr<UseNode *> UA = *I;
NodeAddr<InstrNode *> IA = UA.Addr->getOwner(*DFG);
if (UA.Addr->getFlags() & NodeAttrs::PhiRef)
return false;
NodeAddr<RefNode*> AA = LV->getNearestAliasedRef(OffsetRR, IA);
if ((DFG->IsDef(AA) && AA.Id != OffsetRegRD) ||
AA.Addr->getReachingDef() != OffsetRegRD)
return false;
MachineInstr &UseMI = *NodeAddr<StmtNode *>(IA).Addr->getCode();
NodeAddr<DefNode *> OffsetRegDN = DFG->addr<DefNode *>(OffsetRegRD);
// Reaching Def to an offset register can't be a phi.
if ((OffsetRegDN.Addr->getFlags() & NodeAttrs::PhiRef) &&
MI.getParent() != UseMI.getParent())
return false;
const MCInstrDesc &UseMID = UseMI.getDesc();
if ((!UseMID.mayLoad() && !UseMID.mayStore()) ||
HII->getAddrMode(UseMI) != HexagonII::BaseImmOffset ||
getBaseWithLongOffset(UseMI) < 0)
return false;
// Addasl output can't be a store value.
if (UseMID.mayStore() && UseMI.getOperand(2).isReg() &&
UseMI.getOperand(2).getReg() == MI.getOperand(0).getReg())
return false;
for (auto &Mo : UseMI.operands())
if (Mo.isFI())
return false;
}
return true;
}
bool HexagonOptAddrMode::allValidCandidates(NodeAddr<StmtNode *> SA,
NodeList &UNodeList) {
for (auto I = UNodeList.rbegin(), E = UNodeList.rend(); I != E; ++I) {
NodeAddr<UseNode *> UN = *I;
RegisterRef UR = UN.Addr->getRegRef(*DFG);
NodeSet Visited, Defs;
const auto &P = LV->getAllReachingDefsRec(UR, UN, Visited, Defs);
if (!P.second) {
LLVM_DEBUG({
dbgs() << "*** Unable to collect all reaching defs for use ***\n"
<< PrintNode<UseNode*>(UN, *DFG) << '\n'
<< "The program's complexity may exceed the limits.\n";
});
return false;
}
const auto &ReachingDefs = P.first;
if (ReachingDefs.size() > 1) {
LLVM_DEBUG({
dbgs() << "*** Multiple Reaching Defs found!!! ***\n";
for (auto DI : ReachingDefs) {
NodeAddr<UseNode *> DA = DFG->addr<UseNode *>(DI);
NodeAddr<StmtNode *> TempIA = DA.Addr->getOwner(*DFG);
dbgs() << "\t\t[Reaching Def]: "
<< Print<NodeAddr<InstrNode *>>(TempIA, *DFG) << "\n";
}
});
return false;
}
}
return true;
}
void HexagonOptAddrMode::getAllRealUses(NodeAddr<StmtNode *> SA,
NodeList &UNodeList) {
for (NodeAddr<DefNode *> DA : SA.Addr->members_if(DFG->IsDef, *DFG)) {
LLVM_DEBUG(dbgs() << "\t\t[DefNode]: "
<< Print<NodeAddr<DefNode *>>(DA, *DFG) << "\n");
RegisterRef DR = DFG->getPRI().normalize(DA.Addr->getRegRef(*DFG));
auto UseSet = LV->getAllReachedUses(DR, DA);
for (auto UI : UseSet) {
NodeAddr<UseNode *> UA = DFG->addr<UseNode *>(UI);
LLVM_DEBUG({
NodeAddr<StmtNode *> TempIA = UA.Addr->getOwner(*DFG);
dbgs() << "\t\t\t[Reached Use]: "
<< Print<NodeAddr<InstrNode *>>(TempIA, *DFG) << "\n";
});
if (UA.Addr->getFlags() & NodeAttrs::PhiRef) {
NodeAddr<PhiNode *> PA = UA.Addr->getOwner(*DFG);
NodeId id = PA.Id;
const Liveness::RefMap &phiUse = LV->getRealUses(id);
LLVM_DEBUG(dbgs() << "\t\t\t\tphi real Uses"
<< Print<Liveness::RefMap>(phiUse, *DFG) << "\n");
if (!phiUse.empty()) {
for (auto I : phiUse) {
if (!DFG->getPRI().alias(RegisterRef(I.first), DR))
continue;
auto phiUseSet = I.second;
for (auto phiUI : phiUseSet) {
NodeAddr<UseNode *> phiUA = DFG->addr<UseNode *>(phiUI.first);
UNodeList.push_back(phiUA);
}
}
}
} else
UNodeList.push_back(UA);
}
}
}
bool HexagonOptAddrMode::isSafeToExtLR(NodeAddr<StmtNode *> SN,
MachineInstr *MI, unsigned LRExtReg,
const NodeList &UNodeList) {
RegisterRef LRExtRR;
NodeId LRExtRegRD = 0;
// Iterate through all the UseNodes in SN and find the reaching def
// for the LRExtReg.
for (NodeAddr<UseNode *> UA : SN.Addr->members_if(DFG->IsUse, *DFG)) {
RegisterRef RR = UA.Addr->getRegRef(*DFG);
if (LRExtReg == RR.Reg) {
LRExtRR = RR;
LRExtRegRD = UA.Addr->getReachingDef();
}
}
for (auto I = UNodeList.rbegin(), E = UNodeList.rend(); I != E; ++I) {
NodeAddr<UseNode *> UA = *I;
NodeAddr<InstrNode *> IA = UA.Addr->getOwner(*DFG);
// The reaching def of LRExtRR at load/store node should be same as the
// one reaching at the SN.
if (UA.Addr->getFlags() & NodeAttrs::PhiRef)
return false;
NodeAddr<RefNode*> AA = LV->getNearestAliasedRef(LRExtRR, IA);
if ((DFG->IsDef(AA) && AA.Id != LRExtRegRD) ||
AA.Addr->getReachingDef() != LRExtRegRD) {
LLVM_DEBUG(
dbgs() << "isSafeToExtLR: Returning false; another reaching def\n");
return false;
}
MachineInstr *UseMI = NodeAddr<StmtNode *>(IA).Addr->getCode();
NodeAddr<DefNode *> LRExtRegDN = DFG->addr<DefNode *>(LRExtRegRD);
// Reaching Def to LRExtReg can't be a phi.
if ((LRExtRegDN.Addr->getFlags() & NodeAttrs::PhiRef) &&
MI->getParent() != UseMI->getParent())
return false;
}
return true;
}
bool HexagonOptAddrMode::isValidOffset(MachineInstr *MI, int Offset) {
unsigned AlignMask = 0;
switch (HII->getMemAccessSize(*MI)) {
case HexagonII::MemAccessSize::DoubleWordAccess:
AlignMask = 0x7;
break;
case HexagonII::MemAccessSize::WordAccess:
AlignMask = 0x3;
break;
case HexagonII::MemAccessSize::HalfWordAccess:
AlignMask = 0x1;
break;
case HexagonII::MemAccessSize::ByteAccess:
AlignMask = 0x0;
break;
default:
return false;
}
if ((AlignMask & Offset) != 0)
return false;
return HII->isValidOffset(MI->getOpcode(), Offset, HRI, false);
}
bool HexagonOptAddrMode::processAddUses(NodeAddr<StmtNode *> AddSN,
MachineInstr *AddMI,
const NodeList &UNodeList) {
Register AddDefR = AddMI->getOperand(0).getReg();
for (auto I = UNodeList.rbegin(), E = UNodeList.rend(); I != E; ++I) {
NodeAddr<UseNode *> UN = *I;
NodeAddr<StmtNode *> SN = UN.Addr->getOwner(*DFG);
MachineInstr *MI = SN.Addr->getCode();
const MCInstrDesc &MID = MI->getDesc();
if ((!MID.mayLoad() && !MID.mayStore()) ||
HII->getAddrMode(*MI) != HexagonII::BaseImmOffset ||
HII->isHVXVec(*MI))
return false;
MachineOperand BaseOp = MID.mayLoad() ? MI->getOperand(1)
: MI->getOperand(0);
if (!BaseOp.isReg() || BaseOp.getReg() != AddDefR)
return false;
MachineOperand OffsetOp = MID.mayLoad() ? MI->getOperand(2)
: MI->getOperand(1);
if (!OffsetOp.isImm())
return false;
int64_t newOffset = OffsetOp.getImm() + AddMI->getOperand(2).getImm();
if (!isValidOffset(MI, newOffset))
return false;
// Since we'll be extending the live range of Rt in the following example,
// make sure that is safe. another definition of Rt doesn't exist between 'add'
// and load/store instruction.
//
// Ex: Rx= add(Rt,#10)
// memw(Rx+#0) = Rs
// will be replaced with => memw(Rt+#10) = Rs
Register BaseReg = AddMI->getOperand(1).getReg();
if (!isSafeToExtLR(AddSN, AddMI, BaseReg, UNodeList))
return false;
}
// Update all the uses of 'add' with the appropriate base and offset
// values.
bool Changed = false;
for (auto I = UNodeList.rbegin(), E = UNodeList.rend(); I != E; ++I) {
NodeAddr<UseNode *> UseN = *I;
assert(!(UseN.Addr->getFlags() & NodeAttrs::PhiRef) &&
"Found a PhiRef node as a real reached use!!");
NodeAddr<StmtNode *> OwnerN = UseN.Addr->getOwner(*DFG);
MachineInstr *UseMI = OwnerN.Addr->getCode();
LLVM_DEBUG(dbgs() << "\t\t[MI <BB#" << UseMI->getParent()->getNumber()
<< ">]: " << *UseMI << "\n");
Changed |= updateAddUses(AddMI, UseMI);
}
if (Changed)
Deleted.insert(AddMI);
return Changed;
}
bool HexagonOptAddrMode::updateAddUses(MachineInstr *AddMI,
MachineInstr *UseMI) {
const MachineOperand ImmOp = AddMI->getOperand(2);
const MachineOperand AddRegOp = AddMI->getOperand(1);
Register newReg = AddRegOp.getReg();
const MCInstrDesc &MID = UseMI->getDesc();
MachineOperand &BaseOp = MID.mayLoad() ? UseMI->getOperand(1)
: UseMI->getOperand(0);
MachineOperand &OffsetOp = MID.mayLoad() ? UseMI->getOperand(2)
: UseMI->getOperand(1);
BaseOp.setReg(newReg);
BaseOp.setIsUndef(AddRegOp.isUndef());
BaseOp.setImplicit(AddRegOp.isImplicit());
OffsetOp.setImm(ImmOp.getImm() + OffsetOp.getImm());
MRI->clearKillFlags(newReg);
return true;
}
bool HexagonOptAddrMode::analyzeUses(unsigned tfrDefR,
const NodeList &UNodeList,
InstrEvalMap &InstrEvalResult,
short &SizeInc) {
bool KeepTfr = false;
bool HasRepInstr = false;
InstrEvalResult.clear();
for (auto I = UNodeList.rbegin(), E = UNodeList.rend(); I != E; ++I) {
bool CanBeReplaced = false;
NodeAddr<UseNode *> UN = *I;
NodeAddr<StmtNode *> SN = UN.Addr->getOwner(*DFG);
MachineInstr &MI = *SN.Addr->getCode();
const MCInstrDesc &MID = MI.getDesc();
if ((MID.mayLoad() || MID.mayStore())) {
if (!hasRepForm(MI, tfrDefR)) {
KeepTfr = true;
continue;
}
SizeInc++;
CanBeReplaced = true;
} else if (MI.getOpcode() == Hexagon::S2_addasl_rrri) {
NodeList AddaslUseList;
LLVM_DEBUG(dbgs() << "\nGetting ReachedUses for === " << MI << "\n");
getAllRealUses(SN, AddaslUseList);
// Process phi nodes.
if (allValidCandidates(SN, AddaslUseList) &&
canRemoveAddasl(SN, MI, AddaslUseList)) {
SizeInc += AddaslUseList.size();
SizeInc -= 1; // Reduce size by 1 as addasl itself can be removed.
CanBeReplaced = true;
} else
SizeInc++;
} else
// Currently, only load/store and addasl are handled.
// Some other instructions to consider -
// A2_add -> A2_addi
// M4_mpyrr_addr -> M4_mpyrr_addi
KeepTfr = true;
InstrEvalResult[&MI] = CanBeReplaced;
HasRepInstr |= CanBeReplaced;
}
// Reduce total size by 2 if original tfr can be deleted.
if (!KeepTfr)
SizeInc -= 2;
return HasRepInstr;
}
bool HexagonOptAddrMode::changeLoad(MachineInstr *OldMI, MachineOperand ImmOp,
unsigned ImmOpNum) {
bool Changed = false;
MachineBasicBlock *BB = OldMI->getParent();
auto UsePos = MachineBasicBlock::iterator(OldMI);
MachineBasicBlock::instr_iterator InsertPt = UsePos.getInstrIterator();
++InsertPt;
unsigned OpStart;
unsigned OpEnd = OldMI->getNumOperands();
MachineInstrBuilder MIB;
if (ImmOpNum == 1) {
if (HII->getAddrMode(*OldMI) == HexagonII::BaseRegOffset) {
short NewOpCode = HII->changeAddrMode_rr_ur(*OldMI);
assert(NewOpCode >= 0 && "Invalid New opcode\n");
MIB = BuildMI(*BB, InsertPt, OldMI->getDebugLoc(), HII->get(NewOpCode));
MIB.add(OldMI->getOperand(0));
MIB.add(OldMI->getOperand(2));
MIB.add(OldMI->getOperand(3));
MIB.add(ImmOp);
OpStart = 4;
Changed = true;
} else if (HII->getAddrMode(*OldMI) == HexagonII::BaseImmOffset &&
OldMI->getOperand(2).isImm()) {
short NewOpCode = HII->changeAddrMode_io_abs(*OldMI);
assert(NewOpCode >= 0 && "Invalid New opcode\n");
MIB = BuildMI(*BB, InsertPt, OldMI->getDebugLoc(), HII->get(NewOpCode))
.add(OldMI->getOperand(0));
const GlobalValue *GV = ImmOp.getGlobal();
int64_t Offset = ImmOp.getOffset() + OldMI->getOperand(2).getImm();
MIB.addGlobalAddress(GV, Offset, ImmOp.getTargetFlags());
OpStart = 3;
Changed = true;
} else
Changed = false;
LLVM_DEBUG(dbgs() << "[Changing]: " << *OldMI << "\n");
LLVM_DEBUG(dbgs() << "[TO]: " << *MIB << "\n");
} else if (ImmOpNum == 2) {
if (OldMI->getOperand(3).isImm() && OldMI->getOperand(3).getImm() == 0) {
short NewOpCode = HII->changeAddrMode_rr_io(*OldMI);
assert(NewOpCode >= 0 && "Invalid New opcode\n");
MIB = BuildMI(*BB, InsertPt, OldMI->getDebugLoc(), HII->get(NewOpCode));
MIB.add(OldMI->getOperand(0));
MIB.add(OldMI->getOperand(1));
MIB.add(ImmOp);
OpStart = 4;
Changed = true;
LLVM_DEBUG(dbgs() << "[Changing]: " << *OldMI << "\n");
LLVM_DEBUG(dbgs() << "[TO]: " << *MIB << "\n");
}
}
if (Changed)
for (unsigned i = OpStart; i < OpEnd; ++i)
MIB.add(OldMI->getOperand(i));
return Changed;
}
bool HexagonOptAddrMode::changeStore(MachineInstr *OldMI, MachineOperand ImmOp,
unsigned ImmOpNum) {
bool Changed = false;
unsigned OpStart = 0;
unsigned OpEnd = OldMI->getNumOperands();
MachineBasicBlock *BB = OldMI->getParent();
auto UsePos = MachineBasicBlock::iterator(OldMI);
MachineBasicBlock::instr_iterator InsertPt = UsePos.getInstrIterator();
++InsertPt;
MachineInstrBuilder MIB;
if (ImmOpNum == 0) {
if (HII->getAddrMode(*OldMI) == HexagonII::BaseRegOffset) {
short NewOpCode = HII->changeAddrMode_rr_ur(*OldMI);
assert(NewOpCode >= 0 && "Invalid New opcode\n");
MIB = BuildMI(*BB, InsertPt, OldMI->getDebugLoc(), HII->get(NewOpCode));
MIB.add(OldMI->getOperand(1));
MIB.add(OldMI->getOperand(2));
MIB.add(ImmOp);
MIB.add(OldMI->getOperand(3));
OpStart = 4;
Changed = true;
} else if (HII->getAddrMode(*OldMI) == HexagonII::BaseImmOffset) {
short NewOpCode = HII->changeAddrMode_io_abs(*OldMI);
assert(NewOpCode >= 0 && "Invalid New opcode\n");
MIB = BuildMI(*BB, InsertPt, OldMI->getDebugLoc(), HII->get(NewOpCode));
const GlobalValue *GV = ImmOp.getGlobal();
int64_t Offset = ImmOp.getOffset() + OldMI->getOperand(1).getImm();
MIB.addGlobalAddress(GV, Offset, ImmOp.getTargetFlags());
MIB.add(OldMI->getOperand(2));
OpStart = 3;
Changed = true;
}
} else if (ImmOpNum == 1 && OldMI->getOperand(2).getImm() == 0) {
short NewOpCode = HII->changeAddrMode_rr_io(*OldMI);
assert(NewOpCode >= 0 && "Invalid New opcode\n");
MIB = BuildMI(*BB, InsertPt, OldMI->getDebugLoc(), HII->get(NewOpCode));
MIB.add(OldMI->getOperand(0));
MIB.add(ImmOp);
OpStart = 3;
Changed = true;
}
if (Changed) {
LLVM_DEBUG(dbgs() << "[Changing]: " << *OldMI << "\n");
LLVM_DEBUG(dbgs() << "[TO]: " << *MIB << "\n");
for (unsigned i = OpStart; i < OpEnd; ++i)
MIB.add(OldMI->getOperand(i));
}
return Changed;
}
short HexagonOptAddrMode::getBaseWithLongOffset(const MachineInstr &MI) const {
if (HII->getAddrMode(MI) == HexagonII::BaseImmOffset) {
short TempOpCode = HII->changeAddrMode_io_rr(MI);
return HII->changeAddrMode_rr_ur(TempOpCode);
}
return HII->changeAddrMode_rr_ur(MI);
}
bool HexagonOptAddrMode::changeAddAsl(NodeAddr<UseNode *> AddAslUN,
MachineInstr *AddAslMI,
const MachineOperand &ImmOp,
unsigned ImmOpNum) {
NodeAddr<StmtNode *> SA = AddAslUN.Addr->getOwner(*DFG);
LLVM_DEBUG(dbgs() << "Processing addasl :" << *AddAslMI << "\n");
NodeList UNodeList;
getAllRealUses(SA, UNodeList);
for (auto I = UNodeList.rbegin(), E = UNodeList.rend(); I != E; ++I) {
NodeAddr<UseNode *> UseUN = *I;
assert(!(UseUN.Addr->getFlags() & NodeAttrs::PhiRef) &&
"Can't transform this 'AddAsl' instruction!");
NodeAddr<StmtNode *> UseIA = UseUN.Addr->getOwner(*DFG);
LLVM_DEBUG(dbgs() << "[InstrNode]: "
<< Print<NodeAddr<InstrNode *>>(UseIA, *DFG) << "\n");
MachineInstr *UseMI = UseIA.Addr->getCode();
LLVM_DEBUG(dbgs() << "[MI <" << printMBBReference(*UseMI->getParent())
<< ">]: " << *UseMI << "\n");
const MCInstrDesc &UseMID = UseMI->getDesc();
assert(HII->getAddrMode(*UseMI) == HexagonII::BaseImmOffset);
auto UsePos = MachineBasicBlock::iterator(UseMI);
MachineBasicBlock::instr_iterator InsertPt = UsePos.getInstrIterator();
short NewOpCode = getBaseWithLongOffset(*UseMI);
assert(NewOpCode >= 0 && "Invalid New opcode\n");
unsigned OpStart;
unsigned OpEnd = UseMI->getNumOperands();
MachineBasicBlock *BB = UseMI->getParent();
MachineInstrBuilder MIB =
BuildMI(*BB, InsertPt, UseMI->getDebugLoc(), HII->get(NewOpCode));
// change mem(Rs + # ) -> mem(Rt << # + ##)
if (UseMID.mayLoad()) {
MIB.add(UseMI->getOperand(0));
MIB.add(AddAslMI->getOperand(2));
MIB.add(AddAslMI->getOperand(3));
const GlobalValue *GV = ImmOp.getGlobal();
MIB.addGlobalAddress(GV, UseMI->getOperand(2).getImm()+ImmOp.getOffset(),
ImmOp.getTargetFlags());
OpStart = 3;
} else if (UseMID.mayStore()) {
MIB.add(AddAslMI->getOperand(2));
MIB.add(AddAslMI->getOperand(3));
const GlobalValue *GV = ImmOp.getGlobal();
MIB.addGlobalAddress(GV, UseMI->getOperand(1).getImm()+ImmOp.getOffset(),
ImmOp.getTargetFlags());
MIB.add(UseMI->getOperand(2));
OpStart = 3;
} else
llvm_unreachable("Unhandled instruction");
for (unsigned i = OpStart; i < OpEnd; ++i)
MIB.add(UseMI->getOperand(i));
Deleted.insert(UseMI);
}
return true;
}
bool HexagonOptAddrMode::xformUseMI(MachineInstr *TfrMI, MachineInstr *UseMI,
NodeAddr<UseNode *> UseN,
unsigned UseMOnum) {
const MachineOperand ImmOp = TfrMI->getOperand(1);
const MCInstrDesc &MID = UseMI->getDesc();
unsigned Changed = false;
if (MID.mayLoad())
Changed = changeLoad(UseMI, ImmOp, UseMOnum);
else if (MID.mayStore())
Changed = changeStore(UseMI, ImmOp, UseMOnum);
else if (UseMI->getOpcode() == Hexagon::S2_addasl_rrri)
Changed = changeAddAsl(UseN, UseMI, ImmOp, UseMOnum);
if (Changed)
Deleted.insert(UseMI);
return Changed;
}
bool HexagonOptAddrMode::processBlock(NodeAddr<BlockNode *> BA) {
bool Changed = false;
for (auto IA : BA.Addr->members(*DFG)) {
if (!DFG->IsCode<NodeAttrs::Stmt>(IA))
continue;
NodeAddr<StmtNode *> SA = IA;
MachineInstr *MI = SA.Addr->getCode();
if ((MI->getOpcode() != Hexagon::A2_tfrsi ||
!MI->getOperand(1).isGlobal()) &&
(MI->getOpcode() != Hexagon::A2_addi ||
!MI->getOperand(2).isImm() || HII->isConstExtended(*MI)))
continue;
LLVM_DEBUG(dbgs() << "[Analyzing " << HII->getName(MI->getOpcode())
<< "]: " << *MI << "\n\t[InstrNode]: "
<< Print<NodeAddr<InstrNode *>>(IA, *DFG) << '\n');
NodeList UNodeList;
getAllRealUses(SA, UNodeList);
if (!allValidCandidates(SA, UNodeList))
continue;
// Analyze all uses of 'add'. If the output of 'add' is used as an address
// in the base+immediate addressing mode load/store instructions, see if
// they can be updated to use the immediate value as an offet. Thus,
// providing us the opportunity to eliminate 'add'.
// Ex: Rx= add(Rt,#12)
// memw(Rx+#0) = Rs
// This can be replaced with memw(Rt+#12) = Rs
//
// This transformation is only performed if all uses can be updated and
// the offset isn't required to be constant extended.
if (MI->getOpcode() == Hexagon::A2_addi) {
Changed |= processAddUses(SA, MI, UNodeList);
continue;
}
short SizeInc = 0;
Register DefR = MI->getOperand(0).getReg();
InstrEvalMap InstrEvalResult;
// Analyze all uses and calculate increase in size. Perform the optimization
// only if there is no increase in size.
if (!analyzeUses(DefR, UNodeList, InstrEvalResult, SizeInc))
continue;
if (SizeInc > CodeGrowthLimit)
continue;
bool KeepTfr = false;
LLVM_DEBUG(dbgs() << "\t[Total reached uses] : " << UNodeList.size()
<< "\n");
LLVM_DEBUG(dbgs() << "\t[Processing Reached Uses] ===\n");
for (auto I = UNodeList.rbegin(), E = UNodeList.rend(); I != E; ++I) {
NodeAddr<UseNode *> UseN = *I;
assert(!(UseN.Addr->getFlags() & NodeAttrs::PhiRef) &&
"Found a PhiRef node as a real reached use!!");
NodeAddr<StmtNode *> OwnerN = UseN.Addr->getOwner(*DFG);
MachineInstr *UseMI = OwnerN.Addr->getCode();
LLVM_DEBUG(dbgs() << "\t\t[MI <" << printMBBReference(*UseMI->getParent())
<< ">]: " << *UseMI << "\n");
int UseMOnum = -1;
unsigned NumOperands = UseMI->getNumOperands();
for (unsigned j = 0; j < NumOperands - 1; ++j) {
const MachineOperand &op = UseMI->getOperand(j);
if (op.isReg() && op.isUse() && DefR == op.getReg())
UseMOnum = j;
}
// It is possible that the register will not be found in any operand.
// This could happen, for example, when DefR = R4, but the used
// register is D2.
// Change UseMI if replacement is possible. If any replacement failed,
// or wasn't attempted, make sure to keep the TFR.
bool Xformed = false;
if (UseMOnum >= 0 && InstrEvalResult[UseMI])
Xformed = xformUseMI(MI, UseMI, UseN, UseMOnum);
Changed |= Xformed;
KeepTfr |= !Xformed;
}
if (!KeepTfr)
Deleted.insert(MI);
}
return Changed;
}
bool HexagonOptAddrMode::runOnMachineFunction(MachineFunction &MF) {
if (skipFunction(MF.getFunction()))
return false;
bool Changed = false;
auto &HST = MF.getSubtarget<HexagonSubtarget>();
MRI = &MF.getRegInfo();
HII = HST.getInstrInfo();
HRI = HST.getRegisterInfo();
const auto &MDF = getAnalysis<MachineDominanceFrontier>();
MDT = &getAnalysis<MachineDominatorTree>();
const TargetOperandInfo TOI(*HII);
DataFlowGraph G(MF, *HII, *HRI, *MDT, MDF, TOI);
// Need to keep dead phis because we can propagate uses of registers into
// nodes dominated by those would-be phis.
G.build(BuildOptions::KeepDeadPhis);
DFG = &G;
Liveness L(*MRI, *DFG);
L.computePhiInfo();
LV = &L;
Deleted.clear();
NodeAddr<FuncNode *> FA = DFG->getFunc();
LLVM_DEBUG(dbgs() << "==== [RefMap#]=====:\n "
<< Print<NodeAddr<FuncNode *>>(FA, *DFG) << "\n");
for (NodeAddr<BlockNode *> BA : FA.Addr->members(*DFG))
Changed |= processBlock(BA);
for (auto MI : Deleted)
MI->eraseFromParent();
if (Changed) {
G.build();
L.computeLiveIns();
L.resetLiveIns();
L.resetKills();
}
return Changed;
}
//===----------------------------------------------------------------------===//
// Public Constructor Functions
//===----------------------------------------------------------------------===//
FunctionPass *llvm::createHexagonOptAddrMode() {
return new HexagonOptAddrMode();
}
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