//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "regalloc"
+#include "RegisterClassInfo.h"
#include "llvm/BasicBlock.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstr.h"
public:
static char ID;
RAFast() : MachineFunctionPass(ID), StackSlotForVirtReg(-1),
- isBulkSpilling(false) {
- initializePHIEliminationPass(*PassRegistry::getPassRegistry());
- initializeTwoAddressInstructionPassPass(*PassRegistry::getPassRegistry());
- }
+ isBulkSpilling(false) {}
private:
const TargetMachine *TM;
MachineFunction *MF;
MachineRegisterInfo *MRI;
const TargetRegisterInfo *TRI;
const TargetInstrInfo *TII;
+ RegisterClassInfo RegClassInfo;
// Basic block currently being allocated.
MachineBasicBlock *MBB;
// that is currently available in a physical register.
LiveRegMap LiveVirtRegs;
- DenseMap<unsigned, MachineInstr *> LiveDbgValueMap;
+ DenseMap<unsigned, SmallVector<MachineInstr *, 4> > LiveDbgValueMap;
// RegState - Track the state of a physical register.
enum RegState {
// immediately without checking aliases.
regFree,
- // A reserved register has been assigned expolicitly (e.g., setting up a
+ // A reserved register has been assigned explicitly (e.g., setting up a
// call parameter), and it remains reserved until it is used.
regReserved
// instruction, and so cannot be allocated.
BitVector UsedInInstr;
- // Allocatable - vector of allocatable physical registers.
- BitVector Allocatable;
-
// SkippedInstrs - Descriptors of instructions whose clobber list was
// ignored because all registers were spilled. It is still necessary to
// mark all the clobbered registers as used by the function.
- SmallPtrSet<const TargetInstrDesc*, 4> SkippedInstrs;
+ SmallPtrSet<const MCInstrDesc*, 4> SkippedInstrs;
// isBulkSpilling - This flag is set when LiveRegMap will be cleared
// completely after spilling all live registers. LiveRegMap entries should
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesCFG();
- AU.addRequiredID(PHIEliminationID);
- AU.addRequiredID(TwoAddressInstructionPassID);
MachineFunctionPass::getAnalysisUsage(AU);
}
unsigned VirtReg, unsigned Hint);
void spillAll(MachineInstr *MI);
bool setPhysReg(MachineInstr *MI, unsigned OpNum, unsigned PhysReg);
+ void addRetOperands(MachineBasicBlock *MBB);
};
char RAFast::ID = 0;
}
// If this register is used by DBG_VALUE then insert new DBG_VALUE to
// identify spilled location as the place to find corresponding variable's
// value.
- if (MachineInstr *DBG = LiveDbgValueMap.lookup(LRI->first)) {
+ SmallVector<MachineInstr *, 4> &LRIDbgValues = LiveDbgValueMap[LRI->first];
+ for (unsigned li = 0, le = LRIDbgValues.size(); li != le; ++li) {
+ MachineInstr *DBG = LRIDbgValues[li];
const MDNode *MDPtr =
DBG->getOperand(DBG->getNumOperands()-1).getMetadata();
int64_t Offset = 0;
MachineBasicBlock *MBB = DBG->getParent();
MBB->insert(MI, NewDV);
DEBUG(dbgs() << "Inserting debug info due to spill:" << "\n" << *NewDV);
- LiveDbgValueMap[LRI->first] = NewDV;
}
}
+ // Now this register is spilled there is should not be any DBG_VALUE pointing
+ // to this register because they are all pointing to spilled value now.
+ LRIDbgValues.clear();
if (SpillKill)
LR.LastUse = 0; // Don't kill register again
}
PhysRegState[PhysReg] = NewState;
for (const unsigned *AS = TRI->getAliasSet(PhysReg);
unsigned Alias = *AS; ++AS) {
- UsedInInstr.set(Alias);
switch (unsigned VirtReg = PhysRegState[Alias]) {
case regDisabled:
break;
// can be allocated directly.
// Returns spillImpossible when PhysReg or an alias can't be spilled.
unsigned RAFast::calcSpillCost(unsigned PhysReg) const {
- if (UsedInInstr.test(PhysReg))
+ if (UsedInInstr.test(PhysReg)) {
+ DEBUG(dbgs() << PrintReg(PhysReg, TRI) << " is already used in instr.\n");
return spillImpossible;
+ }
switch (unsigned VirtReg = PhysRegState[PhysReg]) {
case regDisabled:
break;
case regFree:
return 0;
case regReserved:
+ DEBUG(dbgs() << PrintReg(VirtReg, TRI) << " corresponding "
+ << PrintReg(PhysReg, TRI) << " is reserved already.\n");
return spillImpossible;
default:
return LiveVirtRegs.lookup(VirtReg).Dirty ? spillDirty : spillClean;
}
// This is a disabled register, add up cost of aliases.
+ DEBUG(dbgs() << PrintReg(PhysReg, TRI) << " is disabled.\n");
unsigned Cost = 0;
for (const unsigned *AS = TRI->getAliasSet(PhysReg);
unsigned Alias = *AS; ++AS) {
// Ignore invalid hints.
if (Hint && (!TargetRegisterInfo::isPhysicalRegister(Hint) ||
- !RC->contains(Hint) || !Allocatable.test(Hint)))
+ !RC->contains(Hint) || !RegClassInfo.isAllocatable(Hint)))
Hint = 0;
// Take hint when possible.
if (Hint) {
- switch(calcSpillCost(Hint)) {
- default:
- definePhysReg(MI, Hint, regFree);
- // Fall through.
- case 0:
+ // Ignore the hint if we would have to spill a dirty register.
+ unsigned Cost = calcSpillCost(Hint);
+ if (Cost < spillDirty) {
+ if (Cost)
+ definePhysReg(MI, Hint, regFree);
return assignVirtToPhysReg(LRE, Hint);
- case spillImpossible:
- break;
}
}
- TargetRegisterClass::iterator AOB = RC->allocation_order_begin(*MF);
- TargetRegisterClass::iterator AOE = RC->allocation_order_end(*MF);
+ ArrayRef<unsigned> AO = RegClassInfo.getOrder(RC);
// First try to find a completely free register.
- for (TargetRegisterClass::iterator I = AOB; I != AOE; ++I) {
+ for (ArrayRef<unsigned>::iterator I = AO.begin(), E = AO.end(); I != E; ++I) {
unsigned PhysReg = *I;
- if (PhysRegState[PhysReg] == regFree && !UsedInInstr.test(PhysReg) &&
- Allocatable.test(PhysReg))
+ if (PhysRegState[PhysReg] == regFree && !UsedInInstr.test(PhysReg))
return assignVirtToPhysReg(LRE, PhysReg);
}
<< RC->getName() << "\n");
unsigned BestReg = 0, BestCost = spillImpossible;
- for (TargetRegisterClass::iterator I = AOB; I != AOE; ++I) {
- if (!Allocatable.test(*I))
- continue;
+ for (ArrayRef<unsigned>::iterator I = AO.begin(), E = AO.end(); I != E; ++I) {
unsigned Cost = calcSpillCost(*I);
+ DEBUG(dbgs() << "\tRegister: " << PrintReg(*I, TRI) << "\n");
+ DEBUG(dbgs() << "\tCost: " << Cost << "\n");
+ DEBUG(dbgs() << "\tBestCost: " << BestCost << "\n");
// Cost is 0 when all aliases are already disabled.
if (Cost == 0)
return assignVirtToPhysReg(LRE, *I);
return assignVirtToPhysReg(LRE, BestReg);
}
- // Nothing we can do.
- std::string msg;
- raw_string_ostream Msg(msg);
- Msg << "Ran out of registers during register allocation!";
- if (MI->isInlineAsm()) {
- Msg << "\nPlease check your inline asm statement for "
- << "invalid constraints:\n";
- MI->print(Msg, TM);
- }
- report_fatal_error(Msg.str());
+ // Nothing we can do. Report an error and keep going with a bad allocation.
+ MI->emitError("ran out of registers during register allocation");
+ definePhysReg(MI, *AO.begin(), regFree);
+ assignVirtToPhysReg(LRE, *AO.begin());
}
/// defineVirtReg - Allocate a register for VirtReg and mark it as dirty.
}
SmallVector<unsigned, 8> PartialDefs;
- DEBUG(dbgs() << "Allocating tied uses and early clobbers.\n");
+ DEBUG(dbgs() << "Allocating tied uses.\n");
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
MachineOperand &MO = MI->getOperand(i);
if (!MO.isReg()) continue;
// That would confuse the later phys-def processing pass.
LiveRegMap::iterator LRI = reloadVirtReg(MI, i, Reg, 0);
PartialDefs.push_back(LRI->second.PhysReg);
- } else if (MO.isEarlyClobber()) {
- // Note: defineVirtReg may invalidate MO.
- LiveRegMap::iterator LRI = defineVirtReg(MI, i, Reg, 0);
- unsigned PhysReg = LRI->second.PhysReg;
- if (setPhysReg(MI, i, PhysReg))
- VirtDead.push_back(Reg);
}
}
+ DEBUG(dbgs() << "Allocating early clobbers.\n");
+ for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
+ MachineOperand &MO = MI->getOperand(i);
+ if (!MO.isReg()) continue;
+ unsigned Reg = MO.getReg();
+ if (!TargetRegisterInfo::isVirtualRegister(Reg)) continue;
+ if (!MO.isEarlyClobber())
+ continue;
+ // Note: defineVirtReg may invalidate MO.
+ LiveRegMap::iterator LRI = defineVirtReg(MI, i, Reg, 0);
+ unsigned PhysReg = LRI->second.PhysReg;
+ if (setPhysReg(MI, i, PhysReg))
+ VirtDead.push_back(Reg);
+ }
+
// Restore UsedInInstr to a state usable for allocating normal virtual uses.
UsedInInstr.reset();
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
if (!MO.isReg() || (MO.isDef() && !MO.isEarlyClobber())) continue;
unsigned Reg = MO.getReg();
if (!Reg || !TargetRegisterInfo::isPhysicalRegister(Reg)) continue;
+ DEBUG(dbgs() << "\tSetting " << PrintReg(Reg, TRI)
+ << " as used in instr\n");
UsedInInstr.set(Reg);
- for (const unsigned *AS = TRI->getAliasSet(Reg); *AS; ++AS)
- UsedInInstr.set(*AS);
}
// Also mark PartialDefs as used to avoid reallocation.
UsedInInstr.set(PartialDefs[i]);
}
-void RAFast::AllocateBasicBlock() {
- DEBUG(dbgs() << "\nAllocating " << *MBB);
+/// addRetOperand - ensure that a return instruction has an operand for each
+/// value live out of the function.
+///
+/// Things marked both call and return are tail calls; do not do this for them.
+/// The tail callee need not take the same registers as input that it produces
+/// as output, and there are dependencies for its input registers elsewhere.
+///
+/// FIXME: This should be done as part of instruction selection, and this helper
+/// should be deleted. Until then, we use custom logic here to create the proper
+/// operand under all circumstances. We can't use addRegisterKilled because that
+/// doesn't make sense for undefined values. We can't simply avoid calling it
+/// for undefined values, because we must ensure that the operand always exists.
+void RAFast::addRetOperands(MachineBasicBlock *MBB) {
+ if (MBB->empty() || !MBB->back().isReturn() || MBB->back().isCall())
+ return;
+
+ MachineInstr *MI = &MBB->back();
+
+ for (MachineRegisterInfo::liveout_iterator
+ I = MBB->getParent()->getRegInfo().liveout_begin(),
+ E = MBB->getParent()->getRegInfo().liveout_end(); I != E; ++I) {
+ unsigned Reg = *I;
+ assert(TargetRegisterInfo::isPhysicalRegister(Reg) &&
+ "Cannot have a live-out virtual register.");
+
+ bool hasDef = PhysRegState[Reg] == regReserved;
+
+ // Check if this register already has an operand.
+ bool Found = false;
+ for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
+ MachineOperand &MO = MI->getOperand(i);
+ if (!MO.isReg() || !MO.isUse())
+ continue;
- // FIXME: This should probably be added by instruction selection instead?
- // If the last instruction in the block is a return, make sure to mark it as
- // using all of the live-out values in the function. Things marked both call
- // and return are tail calls; do not do this for them. The tail callee need
- // not take the same registers as input that it produces as output, and there
- // are dependencies for its input registers elsewhere.
- if (!MBB->empty() && MBB->back().getDesc().isReturn() &&
- !MBB->back().getDesc().isCall()) {
- MachineInstr *Ret = &MBB->back();
-
- for (MachineRegisterInfo::liveout_iterator
- I = MF->getRegInfo().liveout_begin(),
- E = MF->getRegInfo().liveout_end(); I != E; ++I) {
- assert(TargetRegisterInfo::isPhysicalRegister(*I) &&
- "Cannot have a live-out virtual register.");
-
- // Add live-out registers as implicit uses.
- Ret->addRegisterKilled(*I, TRI, true);
+ unsigned OperReg = MO.getReg();
+ if (!TargetRegisterInfo::isPhysicalRegister(OperReg))
+ continue;
+
+ if (OperReg == Reg || TRI->isSuperRegister(OperReg, Reg)) {
+ // If the ret already has an operand for this physreg or a superset,
+ // don't duplicate it. Set the kill flag if the value is defined.
+ if (hasDef && !MO.isKill())
+ MO.setIsKill();
+ Found = true;
+ break;
+ }
}
+ if (!Found)
+ MI->addOperand(MachineOperand::CreateReg(Reg,
+ false /*IsDef*/,
+ true /*IsImp*/,
+ hasDef/*IsKill*/));
}
+}
+
+void RAFast::AllocateBasicBlock() {
+ DEBUG(dbgs() << "\nAllocating " << *MBB);
PhysRegState.assign(TRI->getNumRegs(), regDisabled);
assert(LiveVirtRegs.empty() && "Mapping not cleared form last block?");
// Add live-in registers as live.
for (MachineBasicBlock::livein_iterator I = MBB->livein_begin(),
E = MBB->livein_end(); I != E; ++I)
- if (Allocatable.test(*I))
+ if (RegClassInfo.isAllocatable(*I))
definePhysReg(MII, *I, regReserved);
SmallVector<unsigned, 8> VirtDead;
// Otherwise, sequentially allocate each instruction in the MBB.
while (MII != MBB->end()) {
MachineInstr *MI = MII++;
- const TargetInstrDesc &TID = MI->getDesc();
+ const MCInstrDesc &MCID = MI->getDesc();
DEBUG({
dbgs() << "\n>> " << *MI << "Regs:";
for (unsigned Reg = 1, E = TRI->getNumRegs(); Reg != E; ++Reg) {
if (!MO.isReg()) continue;
unsigned Reg = MO.getReg();
if (!TargetRegisterInfo::isVirtualRegister(Reg)) continue;
- LiveDbgValueMap[Reg] = MI;
LiveRegMap::iterator LRI = LiveVirtRegs.find(Reg);
if (LRI != LiveVirtRegs.end())
setPhysReg(MI, i, LRI->second.PhysReg);
}
}
}
+ LiveDbgValueMap[Reg].push_back(MI);
}
}
// Next instruction.
VirtOpEnd = i+1;
if (MO.isUse()) {
hasTiedOps = hasTiedOps ||
- TID.getOperandConstraint(i, TOI::TIED_TO) != -1;
+ MCID.getOperandConstraint(i, MCOI::TIED_TO) != -1;
} else {
if (MO.isEarlyClobber())
hasEarlyClobbers = true;
}
continue;
}
- if (!Allocatable.test(Reg)) continue;
+ if (!RegClassInfo.isAllocatable(Reg)) continue;
if (MO.isUse()) {
usePhysReg(MO);
} else if (MO.isEarlyClobber()) {
// We didn't detect inline asm tied operands above, so just make this extra
// pass for all inline asm.
if (MI->isInlineAsm() || hasEarlyClobbers || hasPartialRedefs ||
- (hasTiedOps && (hasPhysDefs || TID.getNumDefs() > 1))) {
+ (hasTiedOps && (hasPhysDefs || MCID.getNumDefs() > 1))) {
handleThroughOperands(MI, VirtDead);
// Don't attempt coalescing when we have funny stuff going on.
CopyDst = 0;
}
unsigned DefOpEnd = MI->getNumOperands();
- if (TID.isCall()) {
+ if (MI->isCall()) {
// Spill all virtregs before a call. This serves two purposes: 1. If an
// exception is thrown, the landing pad is going to expect to find
// registers in their spill slots, and 2. we don't have to wade through
// The imp-defs are skipped below, but we still need to mark those
// registers as used by the function.
- SkippedInstrs.insert(&TID);
+ SkippedInstrs.insert(&MCID);
}
// Third scan.
unsigned Reg = MO.getReg();
if (TargetRegisterInfo::isPhysicalRegister(Reg)) {
- if (!Allocatable.test(Reg)) continue;
+ if (!RegClassInfo.isAllocatable(Reg)) continue;
definePhysReg(MI, Reg, (MO.isImplicit() || MO.isDead()) ?
regFree : regReserved);
continue;
MBB->erase(Coalesced[i]);
NumCopies += Coalesced.size();
+ // addRetOperands must run after we've seen all defs in this block.
+ addRetOperands(MBB);
+
DEBUG(MBB->dump());
}
TM = &Fn.getTarget();
TRI = TM->getRegisterInfo();
TII = TM->getInstrInfo();
-
+ MRI->freezeReservedRegs(Fn);
+ RegClassInfo.runOnMachineFunction(Fn);
UsedInInstr.resize(TRI->getNumRegs());
- Allocatable = TRI->getAllocatableSet(*MF);
+
+ assert(!MRI->isSSA() && "regalloc requires leaving SSA");
// initialize the virtual->physical register map to have a 'null'
// mapping for all virtual registers
MRI->closePhysRegsUsed(*TRI);
// Add the clobber lists for all the instructions we skipped earlier.
- for (SmallPtrSet<const TargetInstrDesc*, 4>::const_iterator
+ for (SmallPtrSet<const MCInstrDesc*, 4>::const_iterator
I = SkippedInstrs.begin(), E = SkippedInstrs.end(); I != E; ++I)
if (const unsigned *Defs = (*I)->getImplicitDefs())
while (*Defs)
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