This is an archive of the discontinued LLVM Phabricator instance.

Show First 20 Lines • Show All 154 Lines • ▼ Show 20 Lines	public:

/// Get an array of scavenging frame indices.		/// Get an array of scavenging frame indices.
void getScavengingFrameIndices(SmallVectorImpl<int> &A) const {		void getScavengingFrameIndices(SmallVectorImpl<int> &A) const {
for (const ScavengedInfo &I : Scavenged)		for (const ScavengedInfo &I : Scavenged)
if (I.FrameIndex >= 0)		if (I.FrameIndex >= 0)
A.push_back(I.FrameIndex);		A.push_back(I.FrameIndex);
}		}

/// Make a register of the specific register class
/// available and do the appropriate bookkeeping. SPAdj is the stack
/// adjustment due to call frame, it's passed along to eliminateFrameIndex().
/// Returns the scavenged register.
/// This is deprecated as it depends on the quality of the kill flags being
/// present; Use scavengeRegisterBackwards() instead!
///
/// If \p AllowSpill is false, fail if a spill is required to make the
/// register available, and return NoRegister.
Register scavengeRegister(const TargetRegisterClass *RC,
MachineBasicBlock::iterator I, int SPAdj,
bool AllowSpill = true);
Register scavengeRegister(const TargetRegisterClass *RegClass, int SPAdj,
bool AllowSpill = true) {
return scavengeRegister(RegClass, MBBI, SPAdj, AllowSpill);
}

/// Make a register of the specific register class available from the current		/// Make a register of the specific register class available from the current
/// position backwards to the place before \p To. If \p RestoreAfter is true		/// position backwards to the place before \p To. If \p RestoreAfter is true
/// this includes the instruction following the current position.		/// this includes the instruction following the current position.
/// SPAdj is the stack adjustment due to call frame, it's passed along to		/// SPAdj is the stack adjustment due to call frame, it's passed along to
/// eliminateFrameIndex().		/// eliminateFrameIndex().
/// Returns the scavenged register.		/// Returns the scavenged register.
///		///
/// If \p AllowSpill is false, fail if a spill is required to make the		/// If \p AllowSpill is false, fail if a spill is required to make the
Show All 24 Lines	private:
void determineKillsAndDefs();		void determineKillsAndDefs();

/// Add all Reg Units that Reg contains to BV.		/// Add all Reg Units that Reg contains to BV.
void addRegUnits(BitVector &BV, MCRegister Reg);		void addRegUnits(BitVector &BV, MCRegister Reg);

/// Remove all Reg Units that \p Reg contains from \p BV.		/// Remove all Reg Units that \p Reg contains from \p BV.
void removeRegUnits(BitVector &BV, MCRegister Reg);		void removeRegUnits(BitVector &BV, MCRegister Reg);

/// Return the candidate register that is unused for the longest after
/// StartMI. UseMI is set to the instruction where the search stopped.
///
/// No more than InstrLimit instructions are inspected.
Register findSurvivorReg(MachineBasicBlock::iterator StartMI,
BitVector &Candidates,
ArrayRef<MCPhysReg> AllocationOrder,
unsigned InstrLimit,
MachineBasicBlock::iterator &UseMI);

/// Initialize RegisterScavenger.		/// Initialize RegisterScavenger.
void init(MachineBasicBlock &MBB);		void init(MachineBasicBlock &MBB);

/// Spill a register after position \p After and reload it before position		/// Spill a register after position \p After and reload it before position
/// \p UseMI.		/// \p UseMI.
ScavengedInfo &spill(Register Reg, const TargetRegisterClass &RC, int SPAdj,		ScavengedInfo &spill(Register Reg, const TargetRegisterClass &RC, int SPAdj,
MachineBasicBlock::iterator Before,		MachineBasicBlock::iterator Before,
MachineBasicBlock::iterator &UseMI);		MachineBasicBlock::iterator &UseMI);
Show All 9 Lines

llvm/lib/CodeGen/RegisterScavenging.cpp

Show First 20 Lines • Show All 264 Lines • ▼ Show 20 Lines
BitVector RegScavenger::getRegsAvailable(const TargetRegisterClass *RC) {		BitVector RegScavenger::getRegsAvailable(const TargetRegisterClass *RC) {
BitVector Mask(TRI->getNumRegs());		BitVector Mask(TRI->getNumRegs());
for (Register Reg : *RC)		for (Register Reg : *RC)
if (!isRegUsed(Reg))		if (!isRegUsed(Reg))
Mask.set(Reg);		Mask.set(Reg);
return Mask;		return Mask;
}		}

Register RegScavenger::findSurvivorReg(MachineBasicBlock::iterator StartMI,
BitVector &Candidates,
ArrayRef<MCPhysReg> AllocationOrder,
unsigned InstrLimit,
MachineBasicBlock::iterator &UseMI) {
auto FindFirstCandidate = [&]() -> int {
for (MCPhysReg Reg : AllocationOrder) {
if (Candidates.test(Reg))
return Reg;
}
return -1;
};

int Survivor = FindFirstCandidate();
assert(Survivor > 0 && "No candidates for scavenging");

MachineBasicBlock::iterator ME = MBB->getFirstTerminator();
assert(StartMI != ME && "MI already at terminator");
MachineBasicBlock::iterator RestorePointMI = StartMI;
MachineBasicBlock::iterator MI = StartMI;

bool inVirtLiveRange = false;
for (++MI; InstrLimit > 0 && MI != ME; ++MI, --InstrLimit) {
if (MI->isDebugOrPseudoInstr()) {
++InstrLimit; // Don't count debug instructions
continue;
}
bool isVirtKillInsn = false;
bool isVirtDefInsn = false;
// Remove any candidates touched by instruction.
for (const MachineOperand &MO : MI->operands()) {
if (MO.isRegMask())
Candidates.clearBitsNotInMask(MO.getRegMask());
if (!MO.isReg() \|\| MO.isUndef() \|\| !MO.getReg())
continue;
if (MO.getReg().isVirtual()) {
if (MO.isDef())
isVirtDefInsn = true;
else if (MO.isKill())
isVirtKillInsn = true;
continue;
}
for (MCRegAliasIterator AI(MO.getReg(), TRI, true); AI.isValid(); ++AI)
Candidates.reset(*AI);
}
// If we're not in a virtual reg's live range, this is a valid
// restore point.
if (!inVirtLiveRange) RestorePointMI = MI;

// Update whether we're in the live range of a virtual register
if (isVirtKillInsn) inVirtLiveRange = false;
if (isVirtDefInsn) inVirtLiveRange = true;

// Was our survivor untouched by this instruction?
if (Candidates.test(Survivor))
continue;

// All candidates gone?
if (Candidates.none())
break;

Survivor = FindFirstCandidate();
}
// If we ran off the end, that's where we want to restore.
if (MI == ME) RestorePointMI = ME;
assert(RestorePointMI != StartMI &&
"No available scavenger restore location!");

// We ran out of candidates, so stop the search.
UseMI = RestorePointMI;
return Survivor;
}

/// Given the bitvector \p Available of free register units at position		/// Given the bitvector \p Available of free register units at position
/// \p From. Search backwards to find a register that is part of \p		/// \p From. Search backwards to find a register that is part of \p
/// Candidates and not used/clobbered until the point \p To. If there is		/// Candidates and not used/clobbered until the point \p To. If there is
/// multiple candidates continue searching and pick the one that is not used/		/// multiple candidates continue searching and pick the one that is not used/
/// clobbered for the longest time.		/// clobbered for the longest time.
/// Returns the register and the earliest position we know it to be free or		/// Returns the register and the earliest position we know it to be free or
/// the position MBB.end() if no register is available.		/// the position MBB.end() if no register is available.
static std::pair<MCPhysReg, MachineBasicBlock::iterator>		static std::pair<MCPhysReg, MachineBasicBlock::iterator>
▲ Show 20 Lines • Show All 160 Lines • ▼ Show 20 Lines	if (!TRI->saveScavengerRegister(*MBB, Before, UseMI, &RC, Reg)) {
II = std::prev(UseMI);		II = std::prev(UseMI);

FIOperandNum = getFrameIndexOperandNum(*II);		FIOperandNum = getFrameIndexOperandNum(*II);
TRI->eliminateFrameIndex(II, SPAdj, FIOperandNum, this);		TRI->eliminateFrameIndex(II, SPAdj, FIOperandNum, this);
}		}
return Scavenged[SI];		return Scavenged[SI];
}		}

Register RegScavenger::scavengeRegister(const TargetRegisterClass *RC,
MachineBasicBlock::iterator I,
int SPAdj, bool AllowSpill) {
MachineInstr &MI = *I;
const MachineFunction &MF = *MI.getMF();
// Consider all allocatable registers in the register class initially
BitVector Candidates = TRI->getAllocatableSet(MF, RC);

// Exclude all the registers being used by the instruction.
for (const MachineOperand &MO : MI.operands()) {
if (MO.isReg() && MO.getReg() != 0 && !(MO.isUse() && MO.isUndef()) &&
!MO.getReg().isVirtual())
for (MCRegAliasIterator AI(MO.getReg(), TRI, true); AI.isValid(); ++AI)
Candidates.reset(*AI);
}

// If we have already scavenged some registers, remove them from the
// candidates. If we end up recursively calling eliminateFrameIndex, we don't
// want to be clobbering previously scavenged registers or their associated
// stack slots.
for (ScavengedInfo &SI : Scavenged) {
if (SI.Reg) {
if (isRegUsed(SI.Reg)) {
LLVM_DEBUG(
dbgs() << "Removing " << printReg(SI.Reg, TRI) <<
" from scavenging candidates since it was already scavenged\n");
for (MCRegAliasIterator AI(SI.Reg, TRI, true); AI.isValid(); ++AI)
Candidates.reset(*AI);
}
}
}

// Try to find a register that's unused if there is one, as then we won't
// have to spill.
BitVector Available = getRegsAvailable(RC);
Available &= Candidates;
if (Available.any())
Candidates = Available;

// Find the register whose use is furthest away.
MachineBasicBlock::iterator UseMI;
Register SReg =
findSurvivorReg(I, Candidates, RC->getRawAllocationOrder(MF), 25, UseMI);

// If we found an unused register there is no reason to spill it.
if (!isRegUsed(SReg)) {
LLVM_DEBUG(dbgs() << "Scavenged register: " << printReg(SReg, TRI) << "\n");
return SReg;
}

if (!AllowSpill)
return 0;

#ifndef NDEBUG
for (ScavengedInfo &SI : Scavenged) {
assert(SI.Reg != SReg && "scavenged a previously scavenged register");
}
#endif

ScavengedInfo &Scavenged = spill(SReg, *RC, SPAdj, I, UseMI);
Scavenged.Restore = &*std::prev(UseMI);

LLVM_DEBUG(dbgs() << "Scavenged register (with spill): "
<< printReg(SReg, TRI) << "\n");

return SReg;
}

Register RegScavenger::scavengeRegisterBackwards(const TargetRegisterClass &RC,		Register RegScavenger::scavengeRegisterBackwards(const TargetRegisterClass &RC,
MachineBasicBlock::iterator To,		MachineBasicBlock::iterator To,
bool RestoreAfter, int SPAdj,		bool RestoreAfter, int SPAdj,
bool AllowSpill) {		bool AllowSpill) {
const MachineBasicBlock &MBB = *To->getParent();		const MachineBasicBlock &MBB = *To->getParent();
const MachineFunction &MF = *MBB.getParent();		const MachineFunction &MF = *MBB.getParent();

// Find the register whose use is furthest away.		// Find the register whose use is furthest away.
▲ Show 20 Lines • Show All 230 Lines • Show Last 20 Lines

This is an archive of the discontinued LLVM Phabricator instance.

[RegScavenger] Remove scavengeRegisterClosedPublic

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Diff 529545

llvm/include/llvm/CodeGen/RegisterScavenging.h

llvm/lib/CodeGen/RegisterScavenging.cpp

[RegScavenger] Remove scavengeRegister
ClosedPublic