#include "CriticalAntiDepBreaker.h"
#include "llvm/CodeGen/MachineBasicBlock.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
-#include "llvm/Target/TargetMachine.h"
-#include "llvm/Target/TargetInstrInfo.h"
-#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
+#include "llvm/Target/TargetInstrInfo.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetRegisterInfo.h"
using namespace llvm;
CriticalAntiDepBreaker::
-CriticalAntiDepBreaker(MachineFunction& MFi) :
+CriticalAntiDepBreaker(MachineFunction& MFi, const RegisterClassInfo &RCI) :
AntiDepBreaker(), MF(MFi),
MRI(MF.getRegInfo()),
TII(MF.getTarget().getInstrInfo()),
TRI(MF.getTarget().getRegisterInfo()),
- AllocatableSet(TRI->getAllocatableSet(MF)),
+ RegClassInfo(RCI),
Classes(TRI->getNumRegs(), static_cast<const TargetRegisterClass *>(0)),
KillIndices(TRI->getNumRegs(), 0),
- DefIndices(TRI->getNumRegs(), 0) {}
+ DefIndices(TRI->getNumRegs(), 0),
+ KeepRegs(TRI->getNumRegs(), false) {}
CriticalAntiDepBreaker::~CriticalAntiDepBreaker() {
}
}
// Clear "do not change" set.
- KeepRegs.clear();
+ KeepRegs.reset();
- bool IsReturnBlock = (!BB->empty() && BB->back().getDesc().isReturn());
-
- // Determine the live-out physregs for this block.
- if (IsReturnBlock) {
- // In a return block, examine the function live-out regs.
- for (MachineRegisterInfo::liveout_iterator I = MRI.liveout_begin(),
- E = MRI.liveout_end(); I != E; ++I) {
- unsigned Reg = *I;
- Classes[Reg] = reinterpret_cast<TargetRegisterClass *>(-1);
- KillIndices[Reg] = BB->size();
- DefIndices[Reg] = ~0u;
-
- // Repeat, for all aliases.
- for (const unsigned *Alias = TRI->getAliasSet(Reg); *Alias; ++Alias) {
- unsigned AliasReg = *Alias;
- Classes[AliasReg] = reinterpret_cast<TargetRegisterClass *>(-1);
- KillIndices[AliasReg] = BB->size();
- DefIndices[AliasReg] = ~0u;
- }
- }
- }
+ bool IsReturnBlock = (BBSize != 0 && BB->back().isReturn());
- // In a non-return block, examine the live-in regs of all successors.
- // Note a return block can have successors if the return instruction is
- // predicated.
+ // Examine the live-in regs of all successors.
for (MachineBasicBlock::succ_iterator SI = BB->succ_begin(),
SE = BB->succ_end(); SI != SE; ++SI)
for (MachineBasicBlock::livein_iterator I = (*SI)->livein_begin(),
E = (*SI)->livein_end(); I != E; ++I) {
- unsigned Reg = *I;
- Classes[Reg] = reinterpret_cast<TargetRegisterClass *>(-1);
- KillIndices[Reg] = BB->size();
- DefIndices[Reg] = ~0u;
-
- // Repeat, for all aliases.
- for (const unsigned *Alias = TRI->getAliasSet(Reg); *Alias; ++Alias) {
- unsigned AliasReg = *Alias;
- Classes[AliasReg] = reinterpret_cast<TargetRegisterClass *>(-1);
- KillIndices[AliasReg] = BB->size();
- DefIndices[AliasReg] = ~0u;
+ for (MCRegAliasIterator AI(*I, TRI, true); AI.isValid(); ++AI) {
+ unsigned Reg = *AI;
+ Classes[Reg] = reinterpret_cast<TargetRegisterClass *>(-1);
+ KillIndices[Reg] = BBSize;
+ DefIndices[Reg] = ~0u;
}
}
// callee-saved register that is not saved in the prolog.
const MachineFrameInfo *MFI = MF.getFrameInfo();
BitVector Pristine = MFI->getPristineRegs(BB);
- for (const unsigned *I = TRI->getCalleeSavedRegs(); *I; ++I) {
- unsigned Reg = *I;
- if (!IsReturnBlock && !Pristine.test(Reg)) continue;
- Classes[Reg] = reinterpret_cast<TargetRegisterClass *>(-1);
- KillIndices[Reg] = BB->size();
- DefIndices[Reg] = ~0u;
-
- // Repeat, for all aliases.
- for (const unsigned *Alias = TRI->getAliasSet(Reg); *Alias; ++Alias) {
- unsigned AliasReg = *Alias;
- Classes[AliasReg] = reinterpret_cast<TargetRegisterClass *>(-1);
- KillIndices[AliasReg] = BB->size();
- DefIndices[AliasReg] = ~0u;
+ for (const uint16_t *I = TRI->getCalleeSavedRegs(&MF); *I; ++I) {
+ if (!IsReturnBlock && !Pristine.test(*I)) continue;
+ for (MCRegAliasIterator AI(*I, TRI, true); AI.isValid(); ++AI) {
+ unsigned Reg = *AI;
+ Classes[Reg] = reinterpret_cast<TargetRegisterClass *>(-1);
+ KillIndices[Reg] = BBSize;
+ DefIndices[Reg] = ~0u;
}
}
}
void CriticalAntiDepBreaker::FinishBlock() {
RegRefs.clear();
- KeepRegs.clear();
+ KeepRegs.reset();
}
void CriticalAntiDepBreaker::Observe(MachineInstr *MI, unsigned Count,
// instruction which may not be executed. The second R6 def may or may not
// re-define R6 so it's not safe to change it since the last R6 use cannot be
// changed.
- bool Special = MI->getDesc().isCall() ||
- MI->getDesc().hasExtraSrcRegAllocReq() ||
+ bool Special = MI->isCall() ||
+ MI->hasExtraSrcRegAllocReq() ||
TII->isPredicated(MI);
// Scan the register operands for this instruction and update
const TargetRegisterClass *NewRC = 0;
if (i < MI->getDesc().getNumOperands())
- NewRC = MI->getDesc().OpInfo[i].getRegClass(TRI);
+ NewRC = TII->getRegClass(MI->getDesc(), i, TRI, MF);
// For now, only allow the register to be changed if its register
// class is consistent across all uses.
Classes[Reg] = reinterpret_cast<TargetRegisterClass *>(-1);
// Now check for aliases.
- for (const unsigned *Alias = TRI->getAliasSet(Reg); *Alias; ++Alias) {
+ for (MCRegAliasIterator AI(Reg, TRI, false); AI.isValid(); ++AI) {
// If an alias of the reg is used during the live range, give up.
// Note that this allows us to skip checking if AntiDepReg
// overlaps with any of the aliases, among other things.
- unsigned AliasReg = *Alias;
+ unsigned AliasReg = *AI;
if (Classes[AliasReg]) {
Classes[AliasReg] = reinterpret_cast<TargetRegisterClass *>(-1);
Classes[Reg] = reinterpret_cast<TargetRegisterClass *>(-1);
RegRefs.insert(std::make_pair(Reg, &MO));
if (MO.isUse() && Special) {
- if (KeepRegs.insert(Reg)) {
- for (const unsigned *Subreg = TRI->getSubRegisters(Reg);
- *Subreg; ++Subreg)
- KeepRegs.insert(*Subreg);
+ if (!KeepRegs.test(Reg)) {
+ for (MCSubRegIterator SubRegs(Reg, TRI, /*IncludeSelf=*/true);
+ SubRegs.isValid(); ++SubRegs)
+ KeepRegs.set(*SubRegs);
}
}
}
void CriticalAntiDepBreaker::ScanInstruction(MachineInstr *MI,
unsigned Count) {
// Update liveness.
- // Proceding upwards, registers that are defed but not used in this
+ // Proceeding upwards, registers that are defed but not used in this
// instruction are now dead.
if (!TII->isPredicated(MI)) {
// address updates.
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
MachineOperand &MO = MI->getOperand(i);
+
+ if (MO.isRegMask())
+ for (unsigned i = 0, e = TRI->getNumRegs(); i != e; ++i)
+ if (MO.clobbersPhysReg(i)) {
+ DefIndices[i] = Count;
+ KillIndices[i] = ~0u;
+ KeepRegs.reset(i);
+ Classes[i] = 0;
+ RegRefs.erase(i);
+ }
+
if (!MO.isReg()) continue;
unsigned Reg = MO.getReg();
if (Reg == 0) continue;
assert(((KillIndices[Reg] == ~0u) !=
(DefIndices[Reg] == ~0u)) &&
"Kill and Def maps aren't consistent for Reg!");
- KeepRegs.erase(Reg);
+ KeepRegs.reset(Reg);
Classes[Reg] = 0;
RegRefs.erase(Reg);
// Repeat, for all subregs.
- for (const unsigned *Subreg = TRI->getSubRegisters(Reg);
- *Subreg; ++Subreg) {
- unsigned SubregReg = *Subreg;
+ for (MCSubRegIterator SubRegs(Reg, TRI); SubRegs.isValid(); ++SubRegs) {
+ unsigned SubregReg = *SubRegs;
DefIndices[SubregReg] = Count;
KillIndices[SubregReg] = ~0u;
- KeepRegs.erase(SubregReg);
+ KeepRegs.reset(SubregReg);
Classes[SubregReg] = 0;
RegRefs.erase(SubregReg);
}
// Conservatively mark super-registers as unusable.
- for (const unsigned *Super = TRI->getSuperRegisters(Reg);
- *Super; ++Super) {
- unsigned SuperReg = *Super;
- Classes[SuperReg] = reinterpret_cast<TargetRegisterClass *>(-1);
- }
+ for (MCSuperRegIterator SR(Reg, TRI); SR.isValid(); ++SR)
+ Classes[*SR] = reinterpret_cast<TargetRegisterClass *>(-1);
}
}
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
const TargetRegisterClass *NewRC = 0;
if (i < MI->getDesc().getNumOperands())
- NewRC = MI->getDesc().OpInfo[i].getRegClass(TRI);
+ NewRC = TII->getRegClass(MI->getDesc(), i, TRI, MF);
// For now, only allow the register to be changed if its register
// class is consistent across all uses.
"Kill and Def maps aren't consistent for Reg!");
}
// Repeat, for all aliases.
- for (const unsigned *Alias = TRI->getAliasSet(Reg); *Alias; ++Alias) {
- unsigned AliasReg = *Alias;
+ for (MCRegAliasIterator AI(Reg, TRI, false); AI.isValid(); ++AI) {
+ unsigned AliasReg = *AI;
if (KillIndices[AliasReg] == ~0u) {
KillIndices[AliasReg] = Count;
DefIndices[AliasReg] = ~0u;
}
}
-// Check all machine instructions that define the antidependent register.
-// Return true if any of these instructions define the new register.
+// Check all machine operands that reference the antidependent register and must
+// be replaced by NewReg. Return true if any of their parent instructions may
+// clobber the new register.
+//
+// Note: AntiDepReg may be referenced by a two-address instruction such that
+// it's use operand is tied to a def operand. We guard against the case in which
+// the two-address instruction also defines NewReg, as may happen with
+// pre/postincrement loads. In this case, both the use and def operands are in
+// RegRefs because the def is inserted by PrescanInstruction and not erased
+// during ScanInstruction. So checking for an instructions with definitions of
+// both NewReg and AntiDepReg covers it.
bool
-CriticalAntiDepBreaker::isNewRegModifiedByRefs(RegRefIter RegRefBegin,
- RegRefIter RegRefEnd,
- unsigned NewReg)
+CriticalAntiDepBreaker::isNewRegClobberedByRefs(RegRefIter RegRefBegin,
+ RegRefIter RegRefEnd,
+ unsigned NewReg)
{
for (RegRefIter I = RegRefBegin; I != RegRefEnd; ++I ) {
- MachineOperand *MO = I->second;
- if (MO->isDef()) continue;
- if (MO->getParent()->modifiesRegister(NewReg, TRI))
+ MachineOperand *RefOper = I->second;
+
+ // Don't allow the instruction defining AntiDepReg to earlyclobber its
+ // operands, in case they may be assigned to NewReg. In this case antidep
+ // breaking must fail, but it's too rare to bother optimizing.
+ if (RefOper->isDef() && RefOper->isEarlyClobber())
return true;
+
+ // Handle cases in which this instructions defines NewReg.
+ MachineInstr *MI = RefOper->getParent();
+ for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
+ const MachineOperand &CheckOper = MI->getOperand(i);
+
+ if (CheckOper.isRegMask() && CheckOper.clobbersPhysReg(NewReg))
+ return true;
+
+ if (!CheckOper.isReg() || !CheckOper.isDef() ||
+ CheckOper.getReg() != NewReg)
+ continue;
+
+ // Don't allow the instruction to define NewReg and AntiDepReg.
+ // When AntiDepReg is renamed it will be an illegal op.
+ if (RefOper->isDef())
+ return true;
+
+ // Don't allow an instruction using AntiDepReg to be earlyclobbered by
+ // NewReg
+ if (CheckOper.isEarlyClobber())
+ return true;
+
+ // Don't allow inline asm to define NewReg at all. Who know what it's
+ // doing with it.
+ if (MI->isInlineAsm())
+ return true;
+ }
}
return false;
}
-unsigned
-CriticalAntiDepBreaker::findSuitableFreeRegister(RegRefIter RegRefBegin,
- RegRefIter RegRefEnd,
- unsigned AntiDepReg,
- unsigned LastNewReg,
- const TargetRegisterClass *RC)
+unsigned CriticalAntiDepBreaker::
+findSuitableFreeRegister(RegRefIter RegRefBegin,
+ RegRefIter RegRefEnd,
+ unsigned AntiDepReg,
+ unsigned LastNewReg,
+ const TargetRegisterClass *RC,
+ SmallVectorImpl<unsigned> &Forbid)
{
- for (TargetRegisterClass::iterator R = RC->allocation_order_begin(MF),
- RE = RC->allocation_order_end(MF); R != RE; ++R) {
- unsigned NewReg = *R;
- // Don't consider non-allocatable registers
- if (!AllocatableSet.test(NewReg)) continue;
+ ArrayRef<MCPhysReg> Order = RegClassInfo.getOrder(RC);
+ for (unsigned i = 0; i != Order.size(); ++i) {
+ unsigned NewReg = Order[i];
// Don't replace a register with itself.
if (NewReg == AntiDepReg) continue;
// Don't replace a register with one that was recently used to repair
// If any instructions that define AntiDepReg also define the NewReg, it's
// not suitable. For example, Instruction with multiple definitions can
// result in this condition.
- if (isNewRegModifiedByRefs(RegRefBegin, RegRefEnd, NewReg)) continue;
+ if (isNewRegClobberedByRefs(RegRefBegin, RegRefEnd, NewReg)) continue;
// If NewReg is dead and NewReg's most recent def is not before
// AntiDepReg's kill, it's safe to replace AntiDepReg with NewReg.
assert(((KillIndices[AntiDepReg] == ~0u) != (DefIndices[AntiDepReg] == ~0u))
Classes[NewReg] == reinterpret_cast<TargetRegisterClass *>(-1) ||
KillIndices[AntiDepReg] > DefIndices[NewReg])
continue;
+ // If NewReg overlaps any of the forbidden registers, we can't use it.
+ bool Forbidden = false;
+ for (SmallVectorImpl<unsigned>::iterator it = Forbid.begin(),
+ ite = Forbid.end(); it != ite; ++it)
+ if (TRI->regsOverlap(NewReg, *it)) {
+ Forbidden = true;
+ break;
+ }
+ if (Forbidden) continue;
return NewReg;
}
BreakAntiDependencies(const std::vector<SUnit>& SUnits,
MachineBasicBlock::iterator Begin,
MachineBasicBlock::iterator End,
- unsigned InsertPosIndex) {
+ unsigned InsertPosIndex,
+ DbgValueVector &DbgValues) {
// The code below assumes that there is at least one instruction,
// so just duck out immediately if the block is empty.
if (SUnits.empty()) return 0;
// Keep a map of the MachineInstr*'s back to the SUnit representing them.
// This is used for updating debug information.
+ //
+ // FIXME: Replace this with the existing map in ScheduleDAGInstrs::MISUnitMap
DenseMap<MachineInstr*,const SUnit*> MISUnitMap;
// Find the node at the bottom of the critical path.
if (Edge->getKind() == SDep::Anti) {
AntiDepReg = Edge->getReg();
assert(AntiDepReg != 0 && "Anti-dependence on reg0?");
- if (!AllocatableSet.test(AntiDepReg))
+ if (!MRI.isAllocatable(AntiDepReg))
// Don't break anti-dependencies on non-allocatable registers.
AntiDepReg = 0;
- else if (KeepRegs.count(AntiDepReg))
+ else if (KeepRegs.test(AntiDepReg))
// Don't break anti-dependencies if an use down below requires
// this exact register.
AntiDepReg = 0;
PrescanInstruction(MI);
+ SmallVector<unsigned, 2> ForbidRegs;
+
// If MI's defs have a special allocation requirement, don't allow
// any def registers to be changed. Also assume all registers
// defined in a call must not be changed (ABI).
- if (MI->getDesc().isCall() || MI->getDesc().hasExtraDefRegAllocReq() ||
+ if (MI->isCall() || MI->hasExtraDefRegAllocReq() ||
TII->isPredicated(MI))
// If this instruction's defs have special allocation requirement, don't
// break this anti-dependency.
AntiDepReg = 0;
else if (AntiDepReg) {
// If this instruction has a use of AntiDepReg, breaking it
- // is invalid.
+ // is invalid. If the instruction defines other registers,
+ // save a list of them so that we don't pick a new register
+ // that overlaps any of them.
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
MachineOperand &MO = MI->getOperand(i);
if (!MO.isReg()) continue;
AntiDepReg = 0;
break;
}
+ if (MO.isDef() && Reg != AntiDepReg)
+ ForbidRegs.push_back(Reg);
}
}
if (unsigned NewReg = findSuitableFreeRegister(Range.first, Range.second,
AntiDepReg,
LastNewReg[AntiDepReg],
- RC)) {
+ RC, ForbidRegs)) {
DEBUG(dbgs() << "Breaking anti-dependence edge on "
<< TRI->getName(AntiDepReg)
<< " with " << RegRefs.count(AntiDepReg) << " references"
// as well.
const SUnit *SU = MISUnitMap[Q->second->getParent()];
if (!SU) continue;
- for (unsigned i = 0, e = SU->DbgInstrList.size() ; i < e ; ++i) {
- MachineInstr *DI = SU->DbgInstrList[i];
- assert (DI->getNumOperands()==3 && DI->getOperand(0).isReg() &&
- DI->getOperand(0).getReg()
- && "Non register dbg_value attached to SUnit!");
- if (DI->getOperand(0).getReg() == AntiDepReg)
- DI->getOperand(0).setReg(NewReg);
- }
+ for (DbgValueVector::iterator DVI = DbgValues.begin(),
+ DVE = DbgValues.end(); DVI != DVE; ++DVI)
+ if (DVI->second == Q->second->getParent())
+ UpdateDbgValue(DVI->first, AntiDepReg, NewReg);
}
// We just went back in time and modified history; the
projects / oota-llvm.git / blobdiff