#define DEBUG_TYPE "lowersubregs"
#include "llvm/CodeGen/Passes.h"
#include "llvm/Function.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
namespace {
struct LowerSubregsInstructionPass : public MachineFunctionPass {
private:
const TargetRegisterInfo *TRI;
const TargetInstrInfo *TII;
public:
static char ID; LowerSubregsInstructionPass() : MachineFunctionPass(&ID) {}
const char *getPassName() const {
return "Subregister lowering instruction pass";
}
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesCFG();
AU.addPreservedID(MachineLoopInfoID);
AU.addPreservedID(MachineDominatorsID);
MachineFunctionPass::getAnalysisUsage(AU);
}
bool runOnMachineFunction(MachineFunction&);
private:
bool LowerExtract(MachineInstr *MI);
bool LowerInsert(MachineInstr *MI);
bool LowerSubregToReg(MachineInstr *MI);
void TransferDeadFlag(MachineInstr *MI, unsigned DstReg,
const TargetRegisterInfo *TRI);
void TransferKillFlag(MachineInstr *MI, unsigned SrcReg,
const TargetRegisterInfo *TRI,
bool AddIfNotFound = false);
};
char LowerSubregsInstructionPass::ID = 0;
}
FunctionPass *llvm::createLowerSubregsPass() {
return new LowerSubregsInstructionPass();
}
void
LowerSubregsInstructionPass::TransferDeadFlag(MachineInstr *MI,
unsigned DstReg,
const TargetRegisterInfo *TRI) {
for (MachineBasicBlock::iterator MII =
prior(MachineBasicBlock::iterator(MI)); ; --MII) {
if (MII->addRegisterDead(DstReg, TRI))
break;
assert(MII != MI->getParent()->begin() &&
"copyRegToReg output doesn't reference destination register!");
}
}
void
LowerSubregsInstructionPass::TransferKillFlag(MachineInstr *MI,
unsigned SrcReg,
const TargetRegisterInfo *TRI,
bool AddIfNotFound) {
for (MachineBasicBlock::iterator MII =
prior(MachineBasicBlock::iterator(MI)); ; --MII) {
if (MII->addRegisterKilled(SrcReg, TRI, AddIfNotFound))
break;
assert(MII != MI->getParent()->begin() &&
"copyRegToReg output doesn't reference source register!");
}
}
bool LowerSubregsInstructionPass::LowerExtract(MachineInstr *MI) {
MachineBasicBlock *MBB = MI->getParent();
assert(MI->getOperand(0).isReg() && MI->getOperand(0).isDef() &&
MI->getOperand(1).isReg() && MI->getOperand(1).isUse() &&
MI->getOperand(2).isImm() && "Malformed extract_subreg");
unsigned DstReg = MI->getOperand(0).getReg();
unsigned SuperReg = MI->getOperand(1).getReg();
unsigned SubIdx = MI->getOperand(2).getImm();
unsigned SrcReg = TRI->getSubReg(SuperReg, SubIdx);
assert(TargetRegisterInfo::isPhysicalRegister(SuperReg) &&
"Extract supperg source must be a physical register");
assert(TargetRegisterInfo::isPhysicalRegister(DstReg) &&
"Extract destination must be in a physical register");
assert(SrcReg && "invalid subregister index for register");
DEBUG(dbgs() << "subreg: CONVERTING: " << *MI);
if (SrcReg == DstReg) {
if (MI->getOperand(1).isKill()) {
MI->setDesc(TII->get(TargetOpcode::KILL));
MI->RemoveOperand(2); DEBUG(dbgs() << "subreg: replace by: " << *MI);
return true;
}
DEBUG(dbgs() << "subreg: eliminated!");
} else {
const TargetRegisterClass *TRCS = TRI->getPhysicalRegisterRegClass(DstReg);
const TargetRegisterClass *TRCD = TRI->getPhysicalRegisterRegClass(SrcReg);
bool Emitted = TII->copyRegToReg(*MBB, MI, DstReg, SrcReg, TRCD, TRCS);
(void)Emitted;
assert(Emitted && "Subreg and Dst must be of compatible register class");
if (MI->getOperand(0).isDead())
TransferDeadFlag(MI, DstReg, TRI);
if (MI->getOperand(1).isKill())
TransferKillFlag(MI, SuperReg, TRI, true);
DEBUG({
MachineBasicBlock::iterator dMI = MI;
dbgs() << "subreg: " << *(--dMI);
});
}
DEBUG(dbgs() << '\n');
MBB->erase(MI);
return true;
}
bool LowerSubregsInstructionPass::LowerSubregToReg(MachineInstr *MI) {
MachineBasicBlock *MBB = MI->getParent();
assert((MI->getOperand(0).isReg() && MI->getOperand(0).isDef()) &&
MI->getOperand(1).isImm() &&
(MI->getOperand(2).isReg() && MI->getOperand(2).isUse()) &&
MI->getOperand(3).isImm() && "Invalid subreg_to_reg");
unsigned DstReg = MI->getOperand(0).getReg();
unsigned InsReg = MI->getOperand(2).getReg();
unsigned InsSIdx = MI->getOperand(2).getSubReg();
unsigned SubIdx = MI->getOperand(3).getImm();
assert(SubIdx != 0 && "Invalid index for insert_subreg");
unsigned DstSubReg = TRI->getSubReg(DstReg, SubIdx);
assert(TargetRegisterInfo::isPhysicalRegister(DstReg) &&
"Insert destination must be in a physical register");
assert(TargetRegisterInfo::isPhysicalRegister(InsReg) &&
"Inserted value must be in a physical register");
DEBUG(dbgs() << "subreg: CONVERTING: " << *MI);
if (DstSubReg == InsReg && InsSIdx == 0) {
DEBUG(dbgs() << "subreg: eliminated!");
} else {
const TargetRegisterClass *TRC0= TRI->getPhysicalRegisterRegClass(DstSubReg);
const TargetRegisterClass *TRC1= TRI->getPhysicalRegisterRegClass(InsReg);
bool Emitted = TII->copyRegToReg(*MBB, MI, DstSubReg, InsReg, TRC0, TRC1);
(void)Emitted;
assert(Emitted && "Subreg and Dst must be of compatible register class");
if (MI->getOperand(0).isDead())
TransferDeadFlag(MI, DstSubReg, TRI);
if (MI->getOperand(2).isKill())
TransferKillFlag(MI, InsReg, TRI);
DEBUG({
MachineBasicBlock::iterator dMI = MI;
dbgs() << "subreg: " << *(--dMI);
});
}
DEBUG(dbgs() << '\n');
MBB->erase(MI);
return true;
}
bool LowerSubregsInstructionPass::LowerInsert(MachineInstr *MI) {
MachineBasicBlock *MBB = MI->getParent();
assert((MI->getOperand(0).isReg() && MI->getOperand(0).isDef()) &&
(MI->getOperand(1).isReg() && MI->getOperand(1).isUse()) &&
(MI->getOperand(2).isReg() && MI->getOperand(2).isUse()) &&
MI->getOperand(3).isImm() && "Invalid insert_subreg");
unsigned DstReg = MI->getOperand(0).getReg();
#ifndef NDEBUG
unsigned SrcReg = MI->getOperand(1).getReg();
#endif
unsigned InsReg = MI->getOperand(2).getReg();
unsigned SubIdx = MI->getOperand(3).getImm();
assert(DstReg == SrcReg && "insert_subreg not a two-address instruction?");
assert(SubIdx != 0 && "Invalid index for insert_subreg");
unsigned DstSubReg = TRI->getSubReg(DstReg, SubIdx);
assert(DstSubReg && "invalid subregister index for register");
assert(TargetRegisterInfo::isPhysicalRegister(SrcReg) &&
"Insert superreg source must be in a physical register");
assert(TargetRegisterInfo::isPhysicalRegister(InsReg) &&
"Inserted value must be in a physical register");
DEBUG(dbgs() << "subreg: CONVERTING: " << *MI);
if (DstSubReg == InsReg) {
if (MI->getOperand(1).isUndef() && !MI->getOperand(0).isDead()) {
MachineInstrBuilder MIB = BuildMI(*MBB, MI, MI->getDebugLoc(),
TII->get(TargetOpcode::KILL), DstReg);
if (MI->getOperand(2).isUndef())
MIB.addReg(InsReg, RegState::Undef);
else
MIB.addReg(InsReg, RegState::Kill);
} else {
DEBUG(dbgs() << "subreg: eliminated!\n");
MBB->erase(MI);
return true;
}
} else {
const TargetRegisterClass *TRC0= TRI->getPhysicalRegisterRegClass(DstSubReg);
const TargetRegisterClass *TRC1= TRI->getPhysicalRegisterRegClass(InsReg);
if (MI->getOperand(2).isUndef())
BuildMI(*MBB, MI, MI->getDebugLoc(),
TII->get(TargetOpcode::KILL), DstSubReg);
else {
bool Emitted = TII->copyRegToReg(*MBB, MI, DstSubReg, InsReg, TRC0, TRC1);
(void)Emitted;
assert(Emitted && "Subreg and Dst must be of compatible register class");
}
MachineBasicBlock::iterator CopyMI = MI;
--CopyMI;
if (!MI->getOperand(1).isUndef())
CopyMI->addOperand(MachineOperand::CreateReg(DstReg, false, true, true));
if (MI->getOperand(0).isDead()) {
TransferDeadFlag(MI, DstSubReg, TRI);
} else {
CopyMI->addOperand(MachineOperand::CreateReg(DstReg, true, true));
}
if (MI->getOperand(2).isKill() && !MI->getOperand(2).isUndef())
TransferKillFlag(MI, InsReg, TRI);
}
DEBUG({
MachineBasicBlock::iterator dMI = MI;
dbgs() << "subreg: " << *(--dMI) << "\n";
});
MBB->erase(MI);
return true;
}
bool LowerSubregsInstructionPass::runOnMachineFunction(MachineFunction &MF) {
DEBUG(dbgs() << "Machine Function\n"
<< "********** LOWERING SUBREG INSTRS **********\n"
<< "********** Function: "
<< MF.getFunction()->getName() << '\n');
TRI = MF.getTarget().getRegisterInfo();
TII = MF.getTarget().getInstrInfo();
bool MadeChange = false;
for (MachineFunction::iterator mbbi = MF.begin(), mbbe = MF.end();
mbbi != mbbe; ++mbbi) {
for (MachineBasicBlock::iterator mi = mbbi->begin(), me = mbbi->end();
mi != me;) {
MachineBasicBlock::iterator nmi = llvm::next(mi);
MachineInstr *MI = mi;
if (MI->isExtractSubreg()) {
MadeChange |= LowerExtract(MI);
} else if (MI->isInsertSubreg()) {
MadeChange |= LowerInsert(MI);
} else if (MI->isSubregToReg()) {
MadeChange |= LowerSubregToReg(MI);
}
mi = nmi;
}
}
return MadeChange;
}