#include "llvm/CodeGen/RegisterCoalescer.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetOptions.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/ADT/SmallSet.h"
using namespace llvm;
STATISTIC(numJoins , "Number of interval joins performed");
+STATISTIC(numCrossRCs , "Number of cross class joins performed");
STATISTIC(numCommutes , "Number of instruction commuting performed");
STATISTIC(numExtends , "Number of copies extended");
+STATISTIC(NumReMats , "Number of instructions re-materialized");
STATISTIC(numPeep , "Number of identity moves eliminated after coalescing");
STATISTIC(numAborts , "Number of times interval joining aborted");
+STATISTIC(numDeadValNo, "Number of valno def marked dead");
char SimpleRegisterCoalescing::ID = 0;
static cl::opt<bool>
static cl::opt<bool>
NewHeuristic("new-coalescer-heuristic",
- cl::desc("Use new coalescer heuristic"),
- cl::init(false));
+ cl::desc("Use new coalescer heuristic"),
+ cl::init(false), cl::Hidden);
+
+static cl::opt<bool>
+CrossClassJoin("join-cross-class-copies",
+ cl::desc("Coalesce cross register class copies"),
+ cl::init(false), cl::Hidden);
static RegisterPass<SimpleRegisterCoalescing>
X("simple-register-coalescing", "Simple Register Coalescing");
const PassInfo *const llvm::SimpleRegisterCoalescingID = &X;
void SimpleRegisterCoalescing::getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.addRequired<LiveIntervals>();
AU.addPreserved<LiveIntervals>();
+ AU.addRequired<MachineLoopInfo>();
AU.addPreserved<MachineLoopInfo>();
AU.addPreservedID(MachineDominatorsID);
- AU.addPreservedID(PHIEliminationID);
+ if (StrongPHIElim)
+ AU.addPreservedID(StrongPHIEliminationID);
+ else
+ AU.addPreservedID(PHIEliminationID);
AU.addPreservedID(TwoAddressInstructionPassID);
- AU.addRequired<LiveIntervals>();
- AU.addRequired<MachineLoopInfo>();
MachineFunctionPass::getAnalysisUsage(AU);
}
// BValNo is a value number in B that is defined by a copy from A. 'B3' in
// the example above.
LiveInterval::iterator BLR = IntB.FindLiveRangeContaining(CopyIdx);
- if (BLR == IntB.end()) // Should never happen!
- return false;
+ assert(BLR != IntB.end() && "Live range not found!");
VNInfo *BValNo = BLR->valno;
// Get the location that B is defined at. Two options: either this value has
// AValNo is the value number in A that defines the copy, A3 in the example.
LiveInterval::iterator ALR = IntA.FindLiveRangeContaining(CopyIdx-1);
- if (ALR == IntA.end()) // Should never happen!
- return false;
+ assert(ALR != IntA.end() && "Live range not found!");
VNInfo *AValNo = ALR->valno;
+ // If it's re-defined by an early clobber somewhere in the live range, then
+ // it's not safe to eliminate the copy. FIXME: This is a temporary workaround.
+ // See PR3149:
+ // 172 %ECX<def> = MOV32rr %reg1039<kill>
+ // 180 INLINEASM <es:subl $5,$1
+ // sbbl $3,$0>, 10, %EAX<def>, 14, %ECX<earlyclobber,def>, 9, %EAX<kill>,
+ // 36, <fi#0>, 1, %reg0, 0, 9, %ECX<kill>, 36, <fi#1>, 1, %reg0, 0
+ // 188 %EAX<def> = MOV32rr %EAX<kill>
+ // 196 %ECX<def> = MOV32rr %ECX<kill>
+ // 204 %ECX<def> = MOV32rr %ECX<kill>
+ // 212 %EAX<def> = MOV32rr %EAX<kill>
+ // 220 %EAX<def> = MOV32rr %EAX
+ // 228 %reg1039<def> = MOV32rr %ECX<kill>
+ // The early clobber operand ties ECX input to the ECX def.
+ //
+ // The live interval of ECX is represented as this:
+ // %reg20,inf = [46,47:1)[174,230:0) 0@174-(230) 1@46-(47)
+ // The coalescer has no idea there was a def in the middle of [174,230].
+ if (AValNo->redefByEC)
+ return false;
// If AValNo is defined as a copy from IntB, we can potentially process this.
// Get the instruction that defines this value number.
// Get the LiveRange in IntB that this value number starts with.
LiveInterval::iterator ValLR = IntB.FindLiveRangeContaining(AValNo->def-1);
- if (ValLR == IntB.end()) // Should never happen!
- return false;
+ assert(ValLR != IntB.end() && "Live range not found!");
// Make sure that the end of the live range is inside the same block as
// CopyMI.
IntB.addRange(LiveRange(FillerStart, FillerEnd, BValNo));
// If the IntB live range is assigned to a physical register, and if that
- // physreg has aliases,
+ // physreg has sub-registers, update their live intervals as well.
if (TargetRegisterInfo::isPhysicalRegister(IntB.reg)) {
- // Update the liveintervals of sub-registers.
- for (const unsigned *AS = tri_->getSubRegisters(IntB.reg); *AS; ++AS) {
- LiveInterval &AliasLI = li_->getInterval(*AS);
- AliasLI.addRange(LiveRange(FillerStart, FillerEnd,
- AliasLI.getNextValue(FillerStart, 0, li_->getVNInfoAllocator())));
+ for (const unsigned *SR = tri_->getSubRegisters(IntB.reg); *SR; ++SR) {
+ LiveInterval &SRLI = li_->getInterval(*SR);
+ SRLI.addRange(LiveRange(FillerStart, FillerEnd,
+ SRLI.getNextValue(FillerStart, 0, li_->getVNInfoAllocator())));
}
}
// Okay, merge "B1" into the same value number as "B0".
- if (BValNo != ValLR->valno)
+ if (BValNo != ValLR->valno) {
+ IntB.addKills(ValLR->valno, BValNo->kills);
IntB.MergeValueNumberInto(BValNo, ValLR->valno);
+ }
DOUT << " result = "; IntB.print(DOUT, tri_);
DOUT << "\n";
// If the source instruction was killing the source register before the
// merge, unset the isKill marker given the live range has been extended.
int UIdx = ValLREndInst->findRegisterUseOperandIdx(IntB.reg, true);
- if (UIdx != -1)
+ if (UIdx != -1) {
ValLREndInst->getOperand(UIdx).setIsKill(false);
+ IntB.removeKill(ValLR->valno, FillerStart);
+ }
++numExtends;
return true;
// BValNo is a value number in B that is defined by a copy from A. 'B3' in
// the example above.
LiveInterval::iterator BLR = IntB.FindLiveRangeContaining(CopyIdx);
- if (BLR == IntB.end()) // Should never happen!
- return false;
+ assert(BLR != IntB.end() && "Live range not found!");
VNInfo *BValNo = BLR->valno;
// Get the location that B is defined at. Two options: either this value has
// AValNo is the value number in A that defines the copy, A3 in the example.
LiveInterval::iterator ALR = IntA.FindLiveRangeContaining(CopyIdx-1);
- if (ALR == IntA.end()) // Should never happen!
- return false;
+ assert(ALR != IntA.end() && "Live range not found!");
VNInfo *AValNo = ALR->valno;
// If other defs can reach uses of this def, then it's not safe to perform
// the optimization.
BExtend[ALR->end] = BLR->end;
// Update uses of IntA of the specific Val# with IntB.
+ bool BHasSubRegs = false;
+ if (TargetRegisterInfo::isPhysicalRegister(IntB.reg))
+ BHasSubRegs = *tri_->getSubRegisters(IntB.reg);
for (MachineRegisterInfo::use_iterator UI = mri_->use_begin(IntA.reg),
UE = mri_->use_end(); UI != UE;) {
MachineOperand &UseMO = UI.getOperand();
else
BKills.push_back(li_->getUseIndex(UseIdx)+1);
}
- unsigned SrcReg, DstReg;
- if (!tii_->isMoveInstr(*UseMI, SrcReg, DstReg))
+ unsigned SrcReg, DstReg, SrcSubIdx, DstSubIdx;
+ if (!tii_->isMoveInstr(*UseMI, SrcReg, DstReg, SrcSubIdx, DstSubIdx))
continue;
if (DstReg == IntB.reg) {
// This copy will become a noop. If it's defining a new val#,
// simply extend BLR if CopyMI doesn't end the range.
DOUT << "\nExtending: "; IntB.print(DOUT, tri_);
- IntB.removeValNo(BValNo);
- for (unsigned i = 0, e = BDeadValNos.size(); i != e; ++i)
+ // Remove val#'s defined by copies that will be coalesced away.
+ for (unsigned i = 0, e = BDeadValNos.size(); i != e; ++i) {
+ VNInfo *DeadVNI = BDeadValNos[i];
+ if (BHasSubRegs) {
+ for (const unsigned *SR = tri_->getSubRegisters(IntB.reg); *SR; ++SR) {
+ LiveInterval &SRLI = li_->getInterval(*SR);
+ const LiveRange *SRLR = SRLI.getLiveRangeContaining(DeadVNI->def);
+ SRLI.removeValNo(SRLR->valno);
+ }
+ }
IntB.removeValNo(BDeadValNos[i]);
- VNInfo *ValNo = IntB.getNextValue(AValNo->def, 0, li_->getVNInfoAllocator());
+ }
+
+ // Extend BValNo by merging in IntA live ranges of AValNo. Val# definition
+ // is updated. Kills are also updated.
+ VNInfo *ValNo = BValNo;
+ ValNo->def = AValNo->def;
+ ValNo->copy = NULL;
+ for (unsigned j = 0, ee = ValNo->kills.size(); j != ee; ++j) {
+ unsigned Kill = ValNo->kills[j];
+ if (Kill != BLR->end)
+ BKills.push_back(Kill);
+ }
+ ValNo->kills.clear();
for (LiveInterval::iterator AI = IntA.begin(), AE = IntA.end();
AI != AE; ++AI) {
if (AI->valno != AValNo) continue;
if (EI != BExtend.end())
End = EI->second;
IntB.addRange(LiveRange(AI->start, End, ValNo));
+
+ // If the IntB live range is assigned to a physical register, and if that
+ // physreg has sub-registers, update their live intervals as well.
+ if (BHasSubRegs) {
+ for (const unsigned *SR = tri_->getSubRegisters(IntB.reg); *SR; ++SR) {
+ LiveInterval &SRLI = li_->getInterval(*SR);
+ SRLI.MergeInClobberRange(AI->start, End, li_->getVNInfoAllocator());
+ }
+ }
}
IntB.addKills(ValNo, BKills);
ValNo->hasPHIKill = BHasPHIKill;
return true;
}
+/// isSameOrFallThroughBB - Return true if MBB == SuccMBB or MBB simply
+/// fallthoughs to SuccMBB.
+static bool isSameOrFallThroughBB(MachineBasicBlock *MBB,
+ MachineBasicBlock *SuccMBB,
+ const TargetInstrInfo *tii_) {
+ if (MBB == SuccMBB)
+ return true;
+ MachineBasicBlock *TBB = 0, *FBB = 0;
+ SmallVector<MachineOperand, 4> Cond;
+ return !tii_->AnalyzeBranch(*MBB, TBB, FBB, Cond) && !TBB && !FBB &&
+ MBB->isSuccessor(SuccMBB);
+}
+
+/// removeRange - Wrapper for LiveInterval::removeRange. This removes a range
+/// from a physical register live interval as well as from the live intervals
+/// of its sub-registers.
+static void removeRange(LiveInterval &li, unsigned Start, unsigned End,
+ LiveIntervals *li_, const TargetRegisterInfo *tri_) {
+ li.removeRange(Start, End, true);
+ if (TargetRegisterInfo::isPhysicalRegister(li.reg)) {
+ for (const unsigned* SR = tri_->getSubRegisters(li.reg); *SR; ++SR) {
+ if (!li_->hasInterval(*SR))
+ continue;
+ LiveInterval &sli = li_->getInterval(*SR);
+ unsigned RemoveEnd = Start;
+ while (RemoveEnd != End) {
+ LiveInterval::iterator LR = sli.FindLiveRangeContaining(Start);
+ if (LR == sli.end())
+ break;
+ RemoveEnd = (LR->end < End) ? LR->end : End;
+ sli.removeRange(Start, RemoveEnd, true);
+ Start = RemoveEnd;
+ }
+ }
+ }
+}
+
+/// TrimLiveIntervalToLastUse - If there is a last use in the same basic block
+/// as the copy instruction, trim the live interval to the last use and return
+/// true.
+bool
+SimpleRegisterCoalescing::TrimLiveIntervalToLastUse(unsigned CopyIdx,
+ MachineBasicBlock *CopyMBB,
+ LiveInterval &li,
+ const LiveRange *LR) {
+ unsigned MBBStart = li_->getMBBStartIdx(CopyMBB);
+ unsigned LastUseIdx;
+ MachineOperand *LastUse = lastRegisterUse(LR->start, CopyIdx-1, li.reg,
+ LastUseIdx);
+ if (LastUse) {
+ MachineInstr *LastUseMI = LastUse->getParent();
+ if (!isSameOrFallThroughBB(LastUseMI->getParent(), CopyMBB, tii_)) {
+ // r1024 = op
+ // ...
+ // BB1:
+ // = r1024
+ //
+ // BB2:
+ // r1025<dead> = r1024<kill>
+ if (MBBStart < LR->end)
+ removeRange(li, MBBStart, LR->end, li_, tri_);
+ return true;
+ }
+
+ // There are uses before the copy, just shorten the live range to the end
+ // of last use.
+ LastUse->setIsKill();
+ removeRange(li, li_->getDefIndex(LastUseIdx), LR->end, li_, tri_);
+ li.addKill(LR->valno, LastUseIdx+1);
+ unsigned SrcReg, DstReg, SrcSubIdx, DstSubIdx;
+ if (tii_->isMoveInstr(*LastUseMI, SrcReg, DstReg, SrcSubIdx, DstSubIdx) &&
+ DstReg == li.reg) {
+ // Last use is itself an identity code.
+ int DeadIdx = LastUseMI->findRegisterDefOperandIdx(li.reg, false, tri_);
+ LastUseMI->getOperand(DeadIdx).setIsDead();
+ }
+ return true;
+ }
+
+ // Is it livein?
+ if (LR->start <= MBBStart && LR->end > MBBStart) {
+ if (LR->start == 0) {
+ assert(TargetRegisterInfo::isPhysicalRegister(li.reg));
+ // Live-in to the function but dead. Remove it from entry live-in set.
+ mf_->begin()->removeLiveIn(li.reg);
+ }
+ // FIXME: Shorten intervals in BBs that reaches this BB.
+ }
+
+ return false;
+}
+
+/// ReMaterializeTrivialDef - If the source of a copy is defined by a trivial
+/// computation, replace the copy by rematerialize the definition.
+bool SimpleRegisterCoalescing::ReMaterializeTrivialDef(LiveInterval &SrcInt,
+ unsigned DstReg,
+ MachineInstr *CopyMI) {
+ unsigned CopyIdx = li_->getUseIndex(li_->getInstructionIndex(CopyMI));
+ LiveInterval::iterator SrcLR = SrcInt.FindLiveRangeContaining(CopyIdx);
+ assert(SrcLR != SrcInt.end() && "Live range not found!");
+ VNInfo *ValNo = SrcLR->valno;
+ // If other defs can reach uses of this def, then it's not safe to perform
+ // the optimization.
+ if (ValNo->def == ~0U || ValNo->def == ~1U || ValNo->hasPHIKill)
+ return false;
+ MachineInstr *DefMI = li_->getInstructionFromIndex(ValNo->def);
+ const TargetInstrDesc &TID = DefMI->getDesc();
+ if (!TID.isAsCheapAsAMove())
+ return false;
+ if (!DefMI->getDesc().isRematerializable() ||
+ !tii_->isTriviallyReMaterializable(DefMI))
+ return false;
+ bool SawStore = false;
+ if (!DefMI->isSafeToMove(tii_, SawStore))
+ return false;
+
+ unsigned DefIdx = li_->getDefIndex(CopyIdx);
+ const LiveRange *DLR= li_->getInterval(DstReg).getLiveRangeContaining(DefIdx);
+ DLR->valno->copy = NULL;
+ // Don't forget to update sub-register intervals.
+ if (TargetRegisterInfo::isPhysicalRegister(DstReg)) {
+ for (const unsigned* SR = tri_->getSubRegisters(DstReg); *SR; ++SR) {
+ if (!li_->hasInterval(*SR))
+ continue;
+ DLR = li_->getInterval(*SR).getLiveRangeContaining(DefIdx);
+ if (DLR && DLR->valno->copy == CopyMI)
+ DLR->valno->copy = NULL;
+ }
+ }
+
+ // If copy kills the source register, find the last use and propagate
+ // kill.
+ MachineBasicBlock *MBB = CopyMI->getParent();
+ if (CopyMI->killsRegister(SrcInt.reg))
+ TrimLiveIntervalToLastUse(CopyIdx, MBB, SrcInt, SrcLR);
+
+ MachineBasicBlock::iterator MII = next(MachineBasicBlock::iterator(CopyMI));
+ CopyMI->removeFromParent();
+ tii_->reMaterialize(*MBB, MII, DstReg, DefMI);
+ MachineInstr *NewMI = prior(MII);
+ // CopyMI may have implicit operands, transfer them over to the newly
+ // rematerialized instruction. And update implicit def interval valnos.
+ for (unsigned i = CopyMI->getDesc().getNumOperands(),
+ e = CopyMI->getNumOperands(); i != e; ++i) {
+ MachineOperand &MO = CopyMI->getOperand(i);
+ if (MO.isReg() && MO.isImplicit())
+ NewMI->addOperand(MO);
+ if (MO.isDef() && li_->hasInterval(MO.getReg())) {
+ unsigned Reg = MO.getReg();
+ DLR = li_->getInterval(Reg).getLiveRangeContaining(DefIdx);
+ if (DLR && DLR->valno->copy == CopyMI)
+ DLR->valno->copy = NULL;
+ }
+ }
+
+ li_->ReplaceMachineInstrInMaps(CopyMI, NewMI);
+ MBB->getParent()->DeleteMachineInstr(CopyMI);
+ ReMatCopies.insert(CopyMI);
+ ReMatDefs.insert(DefMI);
+ ++NumReMats;
+ return true;
+}
+
/// isBackEdgeCopy - Returns true if CopyMI is a back edge copy.
///
bool SimpleRegisterCoalescing::isBackEdgeCopy(MachineInstr *CopyMI,
LI.FindLiveRangeContaining(li_->getDefIndex(DefIdx));
if (DstLR == LI.end())
return false;
- unsigned KillIdx = li_->getInstructionIndex(&MBB->back()) + InstrSlots::NUM;
+ unsigned KillIdx = li_->getMBBEndIdx(MBB) + 1;
if (DstLR->valno->kills.size() == 1 &&
DstLR->valno->kills[0] == KillIdx && DstLR->valno->hasPHIKill)
return true;
unsigned UseDstReg = DstReg;
if (OldSubIdx)
UseDstReg = tri_->getSubReg(DstReg, OldSubIdx);
+
+ unsigned CopySrcReg, CopyDstReg, CopySrcSubIdx, CopyDstSubIdx;
+ if (tii_->isMoveInstr(*UseMI, CopySrcReg, CopyDstReg,
+ CopySrcSubIdx, CopyDstSubIdx) &&
+ CopySrcReg != CopyDstReg &&
+ CopySrcReg == SrcReg && CopyDstReg != UseDstReg) {
+ // If the use is a copy and it won't be coalesced away, and its source
+ // is defined by a trivial computation, try to rematerialize it instead.
+ if (ReMaterializeTrivialDef(li_->getInterval(SrcReg), CopyDstReg,UseMI))
+ continue;
+ }
+
O.setReg(UseDstReg);
O.setSubReg(0);
- } else {
- // Sub-register indexes goes from small to large. e.g.
- // RAX: 1 -> AL, 2 -> AX, 3 -> EAX
- // EAX: 1 -> AL, 2 -> AX
- // So RAX's sub-register 2 is AX, RAX's sub-regsiter 3 is EAX, whose
- // sub-register 2 is also AX.
- if (SubIdx && OldSubIdx && SubIdx != OldSubIdx)
- assert(OldSubIdx < SubIdx && "Conflicting sub-register index!");
- else if (SubIdx)
- O.setSubReg(SubIdx);
- // Remove would-be duplicated kill marker.
- if (O.isKill() && UseMI->killsRegister(DstReg))
- O.setIsKill(false);
- O.setReg(DstReg);
+ continue;
+ }
+
+ // Sub-register indexes goes from small to large. e.g.
+ // RAX: 1 -> AL, 2 -> AX, 3 -> EAX
+ // EAX: 1 -> AL, 2 -> AX
+ // So RAX's sub-register 2 is AX, RAX's sub-regsiter 3 is EAX, whose
+ // sub-register 2 is also AX.
+ if (SubIdx && OldSubIdx && SubIdx != OldSubIdx)
+ assert(OldSubIdx < SubIdx && "Conflicting sub-register index!");
+ else if (SubIdx)
+ O.setSubReg(SubIdx);
+ // Remove would-be duplicated kill marker.
+ if (O.isKill() && UseMI->killsRegister(DstReg))
+ O.setIsKill(false);
+ O.setReg(DstReg);
+
+ // After updating the operand, check if the machine instruction has
+ // become a copy. If so, update its val# information.
+ const TargetInstrDesc &TID = UseMI->getDesc();
+ unsigned CopySrcReg, CopyDstReg, CopySrcSubIdx, CopyDstSubIdx;
+ if (TID.getNumDefs() == 1 && TID.getNumOperands() > 2 &&
+ tii_->isMoveInstr(*UseMI, CopySrcReg, CopyDstReg,
+ CopySrcSubIdx, CopyDstSubIdx) &&
+ CopySrcReg != CopyDstReg &&
+ (TargetRegisterInfo::isVirtualRegister(CopyDstReg) ||
+ allocatableRegs_[CopyDstReg])) {
+ LiveInterval &LI = li_->getInterval(CopyDstReg);
+ unsigned DefIdx = li_->getDefIndex(li_->getInstructionIndex(UseMI));
+ const LiveRange *DLR = LI.getLiveRangeContaining(DefIdx);
+ if (DLR->valno->def == DefIdx)
+ DLR->valno->copy = UseMI;
}
}
}
MachineOperand &UseMO = UI.getOperand();
if (UseMO.isKill()) {
MachineInstr *UseMI = UseMO.getParent();
- unsigned SReg, DReg;
- if (!tii_->isMoveInstr(*UseMI, SReg, DReg))
- continue;
unsigned UseIdx = li_->getUseIndex(li_->getInstructionIndex(UseMI));
if (JoinedCopies.count(UseMI))
continue;
const LiveRange *UI = LI.getLiveRangeContaining(UseIdx);
- if (!LI.isKill(UI->valno, UseIdx+1))
+ if (!UI || !LI.isKill(UI->valno, UseIdx+1))
UseMO.setIsKill(false);
}
}
}
-/// removeRange - Wrapper for LiveInterval::removeRange. This removes a range
-/// from a physical register live interval as well as from the live intervals
-/// of its sub-registers.
-static void removeRange(LiveInterval &li, unsigned Start, unsigned End,
- LiveIntervals *li_, const TargetRegisterInfo *tri_) {
- li.removeRange(Start, End, true);
- if (TargetRegisterInfo::isPhysicalRegister(li.reg)) {
- for (const unsigned* SR = tri_->getSubRegisters(li.reg); *SR; ++SR) {
- if (!li_->hasInterval(*SR))
- continue;
- LiveInterval &sli = li_->getInterval(*SR);
- unsigned RemoveEnd = Start;
- while (RemoveEnd != End) {
- LiveInterval::iterator LR = sli.FindLiveRangeContaining(Start);
- if (LR == sli.end())
- break;
- RemoveEnd = (LR->end < End) ? LR->end : End;
- sli.removeRange(Start, RemoveEnd, true);
- Start = RemoveEnd;
- }
- }
- }
-}
-
/// removeIntervalIfEmpty - Check if the live interval of a physical register
/// is empty, if so remove it and also remove the empty intervals of its
/// sub-registers. Return true if live interval is removed.
return false;
}
+/// RemoveDeadDef - If a def of a live interval is now determined dead, remove
+/// the val# it defines. If the live interval becomes empty, remove it as well.
+bool SimpleRegisterCoalescing::RemoveDeadDef(LiveInterval &li,
+ MachineInstr *DefMI) {
+ unsigned DefIdx = li_->getDefIndex(li_->getInstructionIndex(DefMI));
+ LiveInterval::iterator MLR = li.FindLiveRangeContaining(DefIdx);
+ if (DefIdx != MLR->valno->def)
+ return false;
+ li.removeValNo(MLR->valno);
+ return removeIntervalIfEmpty(li, li_, tri_);
+}
+
/// PropagateDeadness - Propagate the dead marker to the instruction which
/// defines the val#.
static void PropagateDeadness(LiveInterval &li, MachineInstr *CopyMI,
}
}
-/// isSameOrFallThroughBB - Return true if MBB == SuccMBB or MBB simply
-/// fallthoughs to SuccMBB.
-static bool isSameOrFallThroughBB(MachineBasicBlock *MBB,
- MachineBasicBlock *SuccMBB,
- const TargetInstrInfo *tii_) {
- if (MBB == SuccMBB)
- return true;
- MachineBasicBlock *TBB = 0, *FBB = 0;
- std::vector<MachineOperand> Cond;
- return !tii_->AnalyzeBranch(*MBB, TBB, FBB, Cond) && !TBB && !FBB &&
- MBB->isSuccessor(SuccMBB);
-}
-
/// ShortenDeadCopySrcLiveRange - Shorten a live range as it's artificially
/// extended by a dead copy. Mark the last use (if any) of the val# as kill as
/// ends the live range there. If there isn't another use, then this live range
// More uses past this copy? Nothing to do.
return false;
+ // If there is a last use in the same bb, we can't remove the live range.
+ // Shorten the live interval and return.
MachineBasicBlock *CopyMBB = CopyMI->getParent();
- unsigned MBBStart = li_->getMBBStartIdx(CopyMBB);
- unsigned LastUseIdx;
- MachineOperand *LastUse = lastRegisterUse(LR->start, CopyIdx-1, li.reg,
- LastUseIdx);
- if (LastUse) {
- MachineInstr *LastUseMI = LastUse->getParent();
- if (!isSameOrFallThroughBB(LastUseMI->getParent(), CopyMBB, tii_)) {
- // r1024 = op
- // ...
- // BB1:
- // = r1024
- //
- // BB2:
- // r1025<dead> = r1024<kill>
- if (MBBStart < LR->end)
- removeRange(li, MBBStart, LR->end, li_, tri_);
- return false;
- }
-
- // There are uses before the copy, just shorten the live range to the end
- // of last use.
- LastUse->setIsKill();
- removeRange(li, li_->getDefIndex(LastUseIdx), LR->end, li_, tri_);
- unsigned SrcReg, DstReg;
- if (tii_->isMoveInstr(*LastUseMI, SrcReg, DstReg) &&
- DstReg == li.reg) {
- // Last use is itself an identity code.
- int DeadIdx = LastUseMI->findRegisterDefOperandIdx(li.reg, false, tri_);
- LastUseMI->getOperand(DeadIdx).setIsDead();
- }
+ if (TrimLiveIntervalToLastUse(CopyIdx, CopyMBB, li, LR))
return false;
- }
- // Is it livein?
- if (LR->start <= MBBStart && LR->end > MBBStart) {
- if (LR->start == 0) {
- assert(TargetRegisterInfo::isPhysicalRegister(li.reg));
- // Live-in to the function but dead. Remove it from entry live-in set.
- mf_->begin()->removeLiveIn(li.reg);
+ MachineBasicBlock *StartMBB = li_->getMBBFromIndex(RemoveStart);
+ if (!isSameOrFallThroughBB(StartMBB, CopyMBB, tii_))
+ // If the live range starts in another mbb and the copy mbb is not a fall
+ // through mbb, then we can only cut the range from the beginning of the
+ // copy mbb.
+ RemoveStart = li_->getMBBStartIdx(CopyMBB) + 1;
+
+ if (LR->valno->def == RemoveStart) {
+ // If the def MI defines the val# and this copy is the only kill of the
+ // val#, then propagate the dead marker.
+ if (li.isOnlyLROfValNo(LR)) {
+ PropagateDeadness(li, CopyMI, RemoveStart, li_, tri_);
+ ++numDeadValNo;
}
- // FIXME: Shorten intervals in BBs that reaches this BB.
+ if (li.isKill(LR->valno, RemoveEnd))
+ li.removeKill(LR->valno, RemoveEnd);
}
- if (LR->valno->def == RemoveStart)
- // If the def MI defines the val#, propagate the dead marker.
- PropagateDeadness(li, CopyMI, RemoveStart, li_, tri_);
-
- removeRange(li, RemoveStart, LR->end, li_, tri_);
+ removeRange(li, RemoveStart, RemoveEnd, li_, tri_);
return removeIntervalIfEmpty(li, li_, tri_);
}
if (ULR == li.end() || ULR->valno != LR->valno)
continue;
// If the use is not a use, then it's not safe to coalesce the move.
- unsigned SrcReg, DstReg;
- if (!tii_->isMoveInstr(*UseMI, SrcReg, DstReg)) {
+ unsigned SrcReg, DstReg, SrcSubIdx, DstSubIdx;
+ if (!tii_->isMoveInstr(*UseMI, SrcReg, DstReg, SrcSubIdx, DstSubIdx)) {
if (UseMI->getOpcode() == TargetInstrInfo::INSERT_SUBREG &&
UseMI->getOperand(1).getReg() == li.reg)
continue;
if (ULR == li.end() || ULR->valno != VNI)
continue;
// If the use is a copy, turn it into an identity copy.
- unsigned SrcReg, DstReg;
- if (tii_->isMoveInstr(*MI, SrcReg, DstReg) && SrcReg == li.reg) {
+ unsigned SrcReg, DstReg, SrcSubIdx, DstSubIdx;
+ if (tii_->isMoveInstr(*MI, SrcReg, DstReg, SrcSubIdx, DstSubIdx) &&
+ SrcReg == li.reg) {
// Each use MI may have multiple uses of this register. Change them all.
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
MachineOperand &MO = MI->getOperand(i);
LastUse = MO;
}
}
- if (LastUse)
+ if (LastUse) {
LastUse->setIsKill();
- else {
+ li.addKill(VNI, LastUseIdx+1);
+ } else {
// Remove dead implicit_def's.
while (!ImpDefs.empty()) {
MachineInstr *ImpDef = ImpDefs.back();
}
}
+/// getMatchingSuperReg - Return a super-register of the specified register
+/// Reg so its sub-register of index SubIdx is Reg.
static unsigned getMatchingSuperReg(unsigned Reg, unsigned SubIdx,
const TargetRegisterClass *RC,
const TargetRegisterInfo* TRI) {
return 0;
}
+/// isWinToJoinCrossClass - Return true if it's profitable to coalesce
+/// two virtual registers from different register classes.
+bool
+SimpleRegisterCoalescing::isWinToJoinCrossClass(unsigned LargeReg,
+ unsigned SmallReg,
+ unsigned Threshold) {
+ // Then make sure the intervals are *short*.
+ LiveInterval &LargeInt = li_->getInterval(LargeReg);
+ LiveInterval &SmallInt = li_->getInterval(SmallReg);
+ unsigned LargeSize = li_->getApproximateInstructionCount(LargeInt);
+ unsigned SmallSize = li_->getApproximateInstructionCount(SmallInt);
+ if (SmallSize > Threshold || LargeSize > Threshold)
+ if ((float)std::distance(mri_->use_begin(SmallReg),
+ mri_->use_end()) / SmallSize <
+ (float)std::distance(mri_->use_begin(LargeReg),
+ mri_->use_end()) / LargeSize)
+ return false;
+ return true;
+}
+
+/// HasIncompatibleSubRegDefUse - If we are trying to coalesce a virtual
+/// register with a physical register, check if any of the virtual register
+/// operand is a sub-register use or def. If so, make sure it won't result
+/// in an illegal extract_subreg or insert_subreg instruction. e.g.
+/// vr1024 = extract_subreg vr1025, 1
+/// ...
+/// vr1024 = mov8rr AH
+/// If vr1024 is coalesced with AH, the extract_subreg is now illegal since
+/// AH does not have a super-reg whose sub-register 1 is AH.
+bool
+SimpleRegisterCoalescing::HasIncompatibleSubRegDefUse(MachineInstr *CopyMI,
+ unsigned VirtReg,
+ unsigned PhysReg) {
+ for (MachineRegisterInfo::reg_iterator I = mri_->reg_begin(VirtReg),
+ E = mri_->reg_end(); I != E; ++I) {
+ MachineOperand &O = I.getOperand();
+ MachineInstr *MI = &*I;
+ if (MI == CopyMI || JoinedCopies.count(MI))
+ continue;
+ unsigned SubIdx = O.getSubReg();
+ if (SubIdx && !tri_->getSubReg(PhysReg, SubIdx))
+ return true;
+ if (MI->getOpcode() == TargetInstrInfo::EXTRACT_SUBREG) {
+ SubIdx = MI->getOperand(2).getImm();
+ if (O.isUse() && !tri_->getSubReg(PhysReg, SubIdx))
+ return true;
+ if (O.isDef()) {
+ unsigned SrcReg = MI->getOperand(1).getReg();
+ const TargetRegisterClass *RC =
+ TargetRegisterInfo::isPhysicalRegister(SrcReg)
+ ? tri_->getPhysicalRegisterRegClass(SrcReg)
+ : mri_->getRegClass(SrcReg);
+ if (!getMatchingSuperReg(PhysReg, SubIdx, RC, tri_))
+ return true;
+ }
+ }
+ if (MI->getOpcode() == TargetInstrInfo::INSERT_SUBREG) {
+ SubIdx = MI->getOperand(3).getImm();
+ if (VirtReg == MI->getOperand(0).getReg()) {
+ if (!tri_->getSubReg(PhysReg, SubIdx))
+ return true;
+ } else {
+ unsigned DstReg = MI->getOperand(0).getReg();
+ const TargetRegisterClass *RC =
+ TargetRegisterInfo::isPhysicalRegister(DstReg)
+ ? tri_->getPhysicalRegisterRegClass(DstReg)
+ : mri_->getRegClass(DstReg);
+ if (!getMatchingSuperReg(PhysReg, SubIdx, RC, tri_))
+ return true;
+ }
+ }
+ }
+ return false;
+}
+
+
+/// CanJoinExtractSubRegToPhysReg - Return true if it's possible to coalesce
+/// an extract_subreg where dst is a physical register, e.g.
+/// cl = EXTRACT_SUBREG reg1024, 1
+bool
+SimpleRegisterCoalescing::CanJoinExtractSubRegToPhysReg(unsigned DstReg,
+ unsigned SrcReg, unsigned SubIdx,
+ unsigned &RealDstReg) {
+ const TargetRegisterClass *RC = mri_->getRegClass(SrcReg);
+ RealDstReg = getMatchingSuperReg(DstReg, SubIdx, RC, tri_);
+ assert(RealDstReg && "Invalid extract_subreg instruction!");
+
+ // For this type of EXTRACT_SUBREG, conservatively
+ // check if the live interval of the source register interfere with the
+ // actual super physical register we are trying to coalesce with.
+ LiveInterval &RHS = li_->getInterval(SrcReg);
+ if (li_->hasInterval(RealDstReg) &&
+ RHS.overlaps(li_->getInterval(RealDstReg))) {
+ DOUT << "Interfere with register ";
+ DEBUG(li_->getInterval(RealDstReg).print(DOUT, tri_));
+ return false; // Not coalescable
+ }
+ for (const unsigned* SR = tri_->getSubRegisters(RealDstReg); *SR; ++SR)
+ if (li_->hasInterval(*SR) && RHS.overlaps(li_->getInterval(*SR))) {
+ DOUT << "Interfere with sub-register ";
+ DEBUG(li_->getInterval(*SR).print(DOUT, tri_));
+ return false; // Not coalescable
+ }
+ return true;
+}
+
+/// CanJoinInsertSubRegToPhysReg - Return true if it's possible to coalesce
+/// an insert_subreg where src is a physical register, e.g.
+/// reg1024 = INSERT_SUBREG reg1024, c1, 0
+bool
+SimpleRegisterCoalescing::CanJoinInsertSubRegToPhysReg(unsigned DstReg,
+ unsigned SrcReg, unsigned SubIdx,
+ unsigned &RealSrcReg) {
+ const TargetRegisterClass *RC = mri_->getRegClass(DstReg);
+ RealSrcReg = getMatchingSuperReg(SrcReg, SubIdx, RC, tri_);
+ assert(RealSrcReg && "Invalid extract_subreg instruction!");
+
+ LiveInterval &RHS = li_->getInterval(DstReg);
+ if (li_->hasInterval(RealSrcReg) &&
+ RHS.overlaps(li_->getInterval(RealSrcReg))) {
+ DOUT << "Interfere with register ";
+ DEBUG(li_->getInterval(RealSrcReg).print(DOUT, tri_));
+ return false; // Not coalescable
+ }
+ for (const unsigned* SR = tri_->getSubRegisters(RealSrcReg); *SR; ++SR)
+ if (li_->hasInterval(*SR) && RHS.overlaps(li_->getInterval(*SR))) {
+ DOUT << "Interfere with sub-register ";
+ DEBUG(li_->getInterval(*SR).print(DOUT, tri_));
+ return false; // Not coalescable
+ }
+ return true;
+}
+
/// JoinCopy - Attempt to join intervals corresponding to SrcReg/DstReg,
/// which are the src/dst of the copy instruction CopyMI. This returns true
/// if the copy was successfully coalesced away. If it is not currently
MachineInstr *CopyMI = TheCopy.MI;
Again = false;
- if (JoinedCopies.count(CopyMI))
+ if (JoinedCopies.count(CopyMI) || ReMatCopies.count(CopyMI))
return false; // Already done.
DOUT << li_->getInstructionIndex(CopyMI) << '\t' << *CopyMI;
- unsigned SrcReg;
- unsigned DstReg;
+ unsigned SrcReg, DstReg, SrcSubIdx, DstSubIdx;
bool isExtSubReg = CopyMI->getOpcode() == TargetInstrInfo::EXTRACT_SUBREG;
bool isInsSubReg = CopyMI->getOpcode() == TargetInstrInfo::INSERT_SUBREG;
unsigned SubIdx = 0;
}
DstReg = CopyMI->getOperand(0).getReg();
SrcReg = CopyMI->getOperand(2).getReg();
- } else if (!tii_->isMoveInstr(*CopyMI, SrcReg, DstReg)) {
+ } else if (!tii_->isMoveInstr(*CopyMI, SrcReg, DstReg, SrcSubIdx, DstSubIdx)){
assert(0 && "Unrecognized copy instruction!");
return false;
}
return false; // Not coalescable.
}
+ // Should be non-null only when coalescing to a sub-register class.
+ bool CrossRC = false;
+ const TargetRegisterClass *NewRC = NULL;
+ MachineBasicBlock *CopyMBB = CopyMI->getParent();
unsigned RealDstReg = 0;
unsigned RealSrcReg = 0;
if (isExtSubReg || isInsSubReg) {
DstReg = tri_->getSubReg(DstReg, SubIdx);
SubIdx = 0;
} else if ((DstIsPhys && isExtSubReg) || (SrcIsPhys && isInsSubReg)) {
- // If this is a extract_subreg where dst is a physical register, e.g.
- // cl = EXTRACT_SUBREG reg1024, 1
- // then create and update the actual physical register allocated to RHS.
- // Ditto for
- // reg1024 = INSERT_SUBREG r1024, cl, 1
if (CopyMI->getOperand(1).getSubReg()) {
- DOUT << "\tSrc of extract_ / insert_subreg already coalesced with reg"
+ DOUT << "\tSrc of extract_subreg already coalesced with reg"
<< " of a super-class.\n";
return false; // Not coalescable.
}
- const TargetRegisterClass *RC =
- mri_->getRegClass(isExtSubReg ? SrcReg : DstReg);
+
if (isExtSubReg) {
- RealDstReg = getMatchingSuperReg(DstReg, SubIdx, RC, tri_);
- assert(RealDstReg && "Invalid extra_subreg instruction!");
+ if (!CanJoinExtractSubRegToPhysReg(DstReg, SrcReg, SubIdx, RealDstReg))
+ return false; // Not coalescable
} else {
- RealSrcReg = getMatchingSuperReg(SrcReg, SubIdx, RC, tri_);
- assert(RealSrcReg && "Invalid extra_subreg instruction!");
- }
-
- // For this type of EXTRACT_SUBREG, conservatively
- // check if the live interval of the source register interfere with the
- // actual super physical register we are trying to coalesce with.
- unsigned PhysReg = isExtSubReg ? RealDstReg : RealSrcReg;
- LiveInterval &RHS = li_->getInterval(isExtSubReg ? SrcReg : DstReg);
- if (li_->hasInterval(PhysReg) &&
- RHS.overlaps(li_->getInterval(PhysReg))) {
- DOUT << "Interfere with register ";
- DEBUG(li_->getInterval(PhysReg).print(DOUT, tri_));
- return false; // Not coalescable
- }
- for (const unsigned* SR = tri_->getSubRegisters(PhysReg); *SR; ++SR)
- if (li_->hasInterval(*SR) && RHS.overlaps(li_->getInterval(*SR))) {
- DOUT << "Interfere with sub-register ";
- DEBUG(li_->getInterval(*SR).print(DOUT, tri_));
+ if (!CanJoinInsertSubRegToPhysReg(DstReg, SrcReg, SubIdx, RealSrcReg))
return false; // Not coalescable
- }
+ }
SubIdx = 0;
} else {
unsigned OldSubIdx = isExtSubReg ? CopyMI->getOperand(0).getSubReg()
if (SubIdx) {
unsigned LargeReg = isExtSubReg ? SrcReg : DstReg;
unsigned SmallReg = isExtSubReg ? DstReg : SrcReg;
- unsigned LargeRegSize =
- li_->getInterval(LargeReg).getSize() / InstrSlots::NUM;
- unsigned SmallRegSize =
- li_->getInterval(SmallReg).getSize() / InstrSlots::NUM;
- const TargetRegisterClass *RC = mri_->getRegClass(SmallReg);
- unsigned Threshold = allocatableRCRegs_[RC].count();
- // Be conservative. If both sides are virtual registers, do not coalesce
- // if this will cause a high use density interval to target a smaller
- // set of registers.
- if (SmallRegSize > Threshold || LargeRegSize > Threshold) {
- if ((float)std::distance(mri_->use_begin(SmallReg),
- mri_->use_end()) / SmallRegSize <
- (float)std::distance(mri_->use_begin(LargeReg),
- mri_->use_end()) / LargeRegSize) {
- Again = true; // May be possible to coalesce later.
- return false;
- }
+ unsigned Limit= allocatableRCRegs_[mri_->getRegClass(SmallReg)].count();
+ if (!isWinToJoinCrossClass(LargeReg, SmallReg, Limit)) {
+ Again = true; // May be possible to coalesce later.
+ return false;
}
}
}
} else if (differingRegisterClasses(SrcReg, DstReg)) {
- // FIXME: What if the resul of a EXTRACT_SUBREG is then coalesced
+ if (!CrossClassJoin)
+ return false;
+ CrossRC = true;
+
+ // FIXME: What if the result of a EXTRACT_SUBREG is then coalesced
// with another? If it's the resulting destination register, then
// the subidx must be propagated to uses (but only those defined
// by the EXTRACT_SUBREG). If it's being coalesced into another
// register, it should be safe because register is assumed to have
// the register class of the super-register.
- // If they are not of the same register class, we cannot join them.
- DOUT << "\tSrc/Dest are different register classes.\n";
- // Allow the coalescer to try again in case either side gets coalesced to
- // a physical register that's compatible with the other side. e.g.
- // r1024 = MOV32to32_ r1025
- // but later r1024 is assigned EAX then r1025 may be coalesced with EAX.
- Again = true; // May be possible to coalesce later.
- return false;
+ // Process moves where one of the registers have a sub-register index.
+ MachineOperand *DstMO = CopyMI->findRegisterDefOperand(DstReg);
+ if (DstMO->getSubReg())
+ // FIXME: Can we handle this?
+ return false;
+ MachineOperand *SrcMO = CopyMI->findRegisterUseOperand(SrcReg);
+ SubIdx = SrcMO->getSubReg();
+ if (SubIdx) {
+ // This is not a extract_subreg but it looks like one.
+ // e.g. %cl = MOV16rr %reg1024:2
+ isExtSubReg = true;
+ if (DstIsPhys) {
+ if (!CanJoinExtractSubRegToPhysReg(DstReg, SrcReg, SubIdx,RealDstReg))
+ return false; // Not coalescable
+ SubIdx = 0;
+ }
+ }
+
+ const TargetRegisterClass *SrcRC= SrcIsPhys ? 0 : mri_->getRegClass(SrcReg);
+ const TargetRegisterClass *DstRC= DstIsPhys ? 0 : mri_->getRegClass(DstReg);
+ unsigned LargeReg = SrcReg;
+ unsigned SmallReg = DstReg;
+ unsigned Limit = 0;
+
+ // Now determine the register class of the joined register.
+ if (isExtSubReg) {
+ if (SubIdx && DstRC && DstRC->isASubClass()) {
+ // This is a move to a sub-register class. However, the source is a
+ // sub-register of a larger register class. We don't know what should
+ // the register class be. FIXME.
+ Again = true;
+ return false;
+ }
+ Limit = allocatableRCRegs_[DstRC].count();
+ } else if (!SrcIsPhys && !SrcIsPhys) {
+ unsigned SrcSize = SrcRC->getSize();
+ unsigned DstSize = DstRC->getSize();
+ if (SrcSize < DstSize)
+ // For example X86::MOVSD2PDrr copies from FR64 to VR128.
+ NewRC = DstRC;
+ else if (DstSize > SrcSize) {
+ NewRC = SrcRC;
+ std::swap(LargeReg, SmallReg);
+ } else {
+ unsigned SrcNumRegs = SrcRC->getNumRegs();
+ unsigned DstNumRegs = DstRC->getNumRegs();
+ if (DstNumRegs < SrcNumRegs)
+ // Sub-register class?
+ NewRC = DstRC;
+ else if (SrcNumRegs < DstNumRegs) {
+ NewRC = SrcRC;
+ std::swap(LargeReg, SmallReg);
+ } else
+ // No idea what's the right register class to use.
+ return false;
+ }
+ }
+
+ // If we are joining two virtual registers and the resulting register
+ // class is more restrictive (fewer register, smaller size). Check if it's
+ // worth doing the merge.
+ if (!SrcIsPhys && !DstIsPhys &&
+ (isExtSubReg || DstRC->isASubClass()) &&
+ !isWinToJoinCrossClass(LargeReg, SmallReg,
+ allocatableRCRegs_[NewRC].count())) {
+ DOUT << "\tSrc/Dest are different register classes.\n";
+ // Allow the coalescer to try again in case either side gets coalesced to
+ // a physical register that's compatible with the other side. e.g.
+ // r1024 = MOV32to32_ r1025
+ // But later r1024 is assigned EAX then r1025 may be coalesced with EAX.
+ Again = true; // May be possible to coalesce later.
+ return false;
+ }
}
+
+ // Will it create illegal extract_subreg / insert_subreg?
+ if (SrcIsPhys && HasIncompatibleSubRegDefUse(CopyMI, DstReg, SrcReg))
+ return false;
+ if (DstIsPhys && HasIncompatibleSubRegDefUse(CopyMI, SrcReg, DstReg))
+ return false;
LiveInterval &SrcInt = li_->getInterval(SrcReg);
LiveInterval &DstInt = li_->getInterval(DstReg);
DOUT << " and "; DstInt.print(DOUT, tri_);
DOUT << ": ";
+ // Save a copy of the virtual register live interval. We'll manually
+ // merge this into the "real" physical register live interval this is
+ // coalesced with.
+ LiveInterval *SavedLI = 0;
+ if (RealDstReg)
+ SavedLI = li_->dupInterval(&SrcInt);
+ else if (RealSrcReg)
+ SavedLI = li_->dupInterval(&DstInt);
+
// Check if it is necessary to propagate "isDead" property.
if (!isExtSubReg && !isInsSubReg) {
MachineOperand *mopd = CopyMI->findRegisterDefOperand(DstReg, false);
// If the virtual register live interval is long but it has low use desity,
// do not join them, instead mark the physical register as its allocation
// preference.
- unsigned Length = JoinVInt.getSize() / InstrSlots::NUM;
+ unsigned Length = li_->getApproximateInstructionCount(JoinVInt);
if (Length > Threshold &&
- (((float)std::distance(mri_->use_begin(JoinVReg),
- mri_->use_end()) / Length) < (1.0 / Threshold))) {
+ (((float)std::distance(mri_->use_begin(JoinVReg), mri_->use_end())
+ / Length) < (1.0 / Threshold))) {
JoinVInt.preference = JoinPReg;
++numAborts;
DOUT << "\tMay tie down a physical register, abort!\n";
if (!isEmpty && !JoinIntervals(DstInt, SrcInt, Swapped)) {
// Coalescing failed.
+
+ // If definition of source is defined by trivial computation, try
+ // rematerializing it.
+ if (!isExtSubReg && !isInsSubReg &&
+ ReMaterializeTrivialDef(SrcInt, DstInt.reg, CopyMI))
+ return true;
// If we can eliminate the copy without merging the live ranges, do so now.
if (!isExtSubReg && !isInsSubReg &&
assert(TargetRegisterInfo::isVirtualRegister(SrcReg) &&
"LiveInterval::join didn't work right!");
- // If we're about to merge live ranges into a physical register live range,
+ // If we're about to merge live ranges into a physical register live interval,
// we have to update any aliased register's live ranges to indicate that they
// have clobbered values for this range.
if (TargetRegisterInfo::isPhysicalRegister(DstReg)) {
if (RealDstReg || RealSrcReg) {
LiveInterval &RealInt =
li_->getOrCreateInterval(RealDstReg ? RealDstReg : RealSrcReg);
- SmallSet<const VNInfo*, 4> CopiedValNos;
- for (LiveInterval::Ranges::const_iterator I = ResSrcInt->ranges.begin(),
- E = ResSrcInt->ranges.end(); I != E; ++I) {
- const LiveRange *DstLR = ResDstInt->getLiveRangeContaining(I->start);
- assert(DstLR && "Invalid joined interval!");
- const VNInfo *DstValNo = DstLR->valno;
- if (CopiedValNos.insert(DstValNo)) {
- VNInfo *ValNo = RealInt.getNextValue(DstValNo->def, DstValNo->copy,
- li_->getVNInfoAllocator());
- ValNo->hasPHIKill = DstValNo->hasPHIKill;
- RealInt.addKills(ValNo, DstValNo->kills);
- RealInt.MergeValueInAsValue(*ResDstInt, DstValNo, ValNo);
- }
+ for (LiveInterval::const_vni_iterator I = SavedLI->vni_begin(),
+ E = SavedLI->vni_end(); I != E; ++I) {
+ const VNInfo *ValNo = *I;
+ VNInfo *NewValNo = RealInt.getNextValue(ValNo->def, ValNo->copy,
+ li_->getVNInfoAllocator());
+ NewValNo->hasPHIKill = ValNo->hasPHIKill;
+ NewValNo->redefByEC = ValNo->redefByEC;
+ RealInt.addKills(NewValNo, ValNo->kills);
+ RealInt.MergeValueInAsValue(*SavedLI, ValNo, NewValNo);
}
-
+ RealInt.weight += SavedLI->weight;
DstReg = RealDstReg ? RealDstReg : RealSrcReg;
}
}
}
+ // Coalescing to a virtual register that is of a sub-register class of the
+ // other. Make sure the resulting register is set to the right register class.
+ if (CrossRC) {
+ ++numCrossRCs;
+ if (NewRC)
+ mri_->setRegClass(DstReg, NewRC);
+ }
+
if (NewHeuristic) {
// Add all copies that define val# in the source interval into the queue.
for (LiveInterval::const_vni_iterator i = ResSrcInt->vni_begin(),
if (!vni->def || vni->def == ~1U || vni->def == ~0U)
continue;
MachineInstr *CopyMI = li_->getInstructionFromIndex(vni->def);
- unsigned NewSrcReg, NewDstReg;
+ unsigned NewSrcReg, NewDstReg, NewSrcSubIdx, NewDstSubIdx;
if (CopyMI &&
JoinedCopies.count(CopyMI) == 0 &&
- tii_->isMoveInstr(*CopyMI, NewSrcReg, NewDstReg)) {
- unsigned LoopDepth = loopInfo->getLoopDepth(CopyMI->getParent());
+ tii_->isMoveInstr(*CopyMI, NewSrcReg, NewDstReg,
+ NewSrcSubIdx, NewDstSubIdx)) {
+ unsigned LoopDepth = loopInfo->getLoopDepth(CopyMBB);
JoinQueue->push(CopyRec(CopyMI, LoopDepth,
isBackEdgeCopy(CopyMI, DstReg)));
}
if (TargetRegisterInfo::isVirtualRegister(DstReg))
RemoveUnnecessaryKills(DstReg, *ResDstInt);
- // SrcReg is guarateed to be the register whose live interval that is
- // being merged.
- li_->removeInterval(SrcReg);
if (isInsSubReg)
// Avoid:
// r1024 = op
RemoveDeadImpDef(DstReg, *ResDstInt);
UpdateRegDefsUses(SrcReg, DstReg, SubIdx);
+ // SrcReg is guarateed to be the register whose live interval that is
+ // being merged.
+ li_->removeInterval(SrcReg);
+
+ // Manually deleted the live interval copy.
+ if (SavedLI) {
+ SavedLI->clear();
+ delete SavedLI;
+ }
+
if (isEmpty) {
// Now the copy is being coalesced away, the val# previously defined
// by the copy is being defined by an IMPLICIT_DEF which defines a zero
}
}
+ // If resulting interval has a preference that no longer fits because of subreg
+ // coalescing, just clear the preference.
+ if (ResDstInt->preference && (isExtSubReg || isInsSubReg) &&
+ TargetRegisterInfo::isVirtualRegister(ResDstInt->reg)) {
+ const TargetRegisterClass *RC = mri_->getRegClass(ResDstInt->reg);
+ if (!RC->contains(ResDstInt->preference))
+ ResDstInt->preference = 0;
+ }
+
DOUT << "\n\t\tJoined. Result = "; ResDstInt->print(DOUT, tri_);
DOUT << "\n";
// It's a sub-register live interval, we may not have precise information.
// Re-compute it.
MachineInstr *DefMI = li_->getInstructionFromIndex(LR->start);
- unsigned SrcReg, DstReg;
- if (tii_->isMoveInstr(*DefMI, SrcReg, DstReg) &&
+ unsigned SrcReg, DstReg, SrcSubIdx, DstSubIdx;
+ if (DefMI &&
+ tii_->isMoveInstr(*DefMI, SrcReg, DstReg, SrcSubIdx, DstSubIdx) &&
DstReg == li.reg && SrcReg == Reg) {
// Cache computed info.
LR->valno->def = LR->start;
// vr1024 = op
// = vr1025
// Even though vr1025 is copied from vr1024, it's not safe to
- // coalesced them since live range of vr1025 intersects the
+ // coalesce them since the live range of vr1025 intersects the
// def of vr1024. This happens because vr1025 is assigned the
// value of the previous iteration of vr1024.
return false;
// optimize for it: if there is more than one value, we merge them all into
// the lowest numbered one, then handle the interval as if we were merging
// with one value number.
- VNInfo *LHSValNo;
+ VNInfo *LHSValNo = NULL;
if (EliminatedLHSVals.size() > 1) {
// Loop through all the equal value numbers merging them into the smallest
// one.
/// physreg, this method always canonicalizes LHS to be it. The output
/// "RHS" will not have been modified, so we can use this information
/// below to update aliases.
-bool SimpleRegisterCoalescing::JoinIntervals(LiveInterval &LHS,
- LiveInterval &RHS, bool &Swapped) {
+bool
+SimpleRegisterCoalescing::JoinIntervals(LiveInterval &LHS, LiveInterval &RHS,
+ bool &Swapped) {
// Compute the final value assignment, assuming that the live ranges can be
// coalesced.
SmallVector<int, 16> LHSValNoAssignments;
DenseMap<VNInfo*, VNInfo*> LHSValsDefinedFromRHS;
DenseMap<VNInfo*, VNInfo*> RHSValsDefinedFromLHS;
SmallVector<VNInfo*, 16> NewVNInfo;
-
+
// If a live interval is a physical register, conservatively check if any
// of its sub-registers is overlapping the live interval of the virtual
// register. If so, do not coalesce.
if (TargetRegisterInfo::isPhysicalRegister(LHS.reg) &&
*tri_->getSubRegisters(LHS.reg)) {
- for (const unsigned* SR = tri_->getSubRegisters(LHS.reg); *SR; ++SR)
- if (li_->hasInterval(*SR) && RHS.overlaps(li_->getInterval(*SR))) {
- DOUT << "Interfere with sub-register ";
- DEBUG(li_->getInterval(*SR).print(DOUT, tri_));
+ // If it's coalescing a virtual register to a physical register, estimate
+ // its live interval length. This is the *cost* of scanning an entire live
+ // interval. If the cost is low, we'll do an exhaustive check instead.
+
+ // If this is something like this:
+ // BB1:
+ // v1024 = op
+ // ...
+ // BB2:
+ // ...
+ // RAX = v1024
+ //
+ // That is, the live interval of v1024 crosses a bb. Then we can't rely on
+ // less conservative check. It's possible a sub-register is defined before
+ // v1024 (or live in) and live out of BB1.
+ if (RHS.containsOneValue() &&
+ li_->intervalIsInOneMBB(RHS) &&
+ li_->getApproximateInstructionCount(RHS) <= 10) {
+ // Perform a more exhaustive check for some common cases.
+ if (li_->conflictsWithPhysRegRef(RHS, LHS.reg, true, JoinedCopies))
return false;
- }
+ } else {
+ for (const unsigned* SR = tri_->getSubRegisters(LHS.reg); *SR; ++SR)
+ if (li_->hasInterval(*SR) && RHS.overlaps(li_->getInterval(*SR))) {
+ DOUT << "Interfere with sub-register ";
+ DEBUG(li_->getInterval(*SR).print(DOUT, tri_));
+ return false;
+ }
+ }
} else if (TargetRegisterInfo::isPhysicalRegister(RHS.reg) &&
*tri_->getSubRegisters(RHS.reg)) {
- for (const unsigned* SR = tri_->getSubRegisters(RHS.reg); *SR; ++SR)
- if (li_->hasInterval(*SR) && LHS.overlaps(li_->getInterval(*SR))) {
- DOUT << "Interfere with sub-register ";
- DEBUG(li_->getInterval(*SR).print(DOUT, tri_));
+ if (LHS.containsOneValue() &&
+ li_->getApproximateInstructionCount(LHS) <= 10) {
+ // Perform a more exhaustive check for some common cases.
+ if (li_->conflictsWithPhysRegRef(LHS, RHS.reg, false, JoinedCopies))
return false;
- }
+ } else {
+ for (const unsigned* SR = tri_->getSubRegisters(RHS.reg); *SR; ++SR)
+ if (li_->hasInterval(*SR) && LHS.overlaps(li_->getInterval(*SR))) {
+ DOUT << "Interfere with sub-register ";
+ DEBUG(li_->getInterval(*SR).print(DOUT, tri_));
+ return false;
+ }
+ }
}
// Compute ultimate value numbers for the LHS and RHS values.
VNInfo *RHSValNoInfo = NULL;
VNInfo *RHSValNoInfo0 = RHS.getValNumInfo(0);
unsigned RHSSrcReg = li_->getVNInfoSourceReg(RHSValNoInfo0);
- if ((RHSSrcReg == 0 || RHSSrcReg != LHS.reg)) {
+ if (RHSSrcReg == 0 || RHSSrcReg != LHS.reg) {
// If RHS is not defined as a copy from the LHS, we can use simpler and
// faster checks to see if the live ranges are coalescable. This joiner
// can't swap the LHS/RHS intervals though.
MachineInstr *Inst = MII++;
// If this isn't a copy nor a extract_subreg, we can't join intervals.
- unsigned SrcReg, DstReg;
+ unsigned SrcReg, DstReg, SrcSubIdx, DstSubIdx;
if (Inst->getOpcode() == TargetInstrInfo::EXTRACT_SUBREG) {
DstReg = Inst->getOperand(0).getReg();
SrcReg = Inst->getOperand(1).getReg();
} else if (Inst->getOpcode() == TargetInstrInfo::INSERT_SUBREG) {
DstReg = Inst->getOperand(0).getReg();
SrcReg = Inst->getOperand(2).getReg();
- } else if (!tii_->isMoveInstr(*Inst, SrcReg, DstReg))
+ } else if (!tii_->isMoveInstr(*Inst, SrcReg, DstReg, SrcSubIdx, DstSubIdx))
continue;
bool SrcIsPhys = TargetRegisterInfo::isPhysicalRegister(SrcReg);
JoinQueue = new JoinPriorityQueue<CopyRecSort>(this);
std::vector<CopyRec> TryAgainList;
- if (loopInfo->begin() == loopInfo->end()) {
+ if (loopInfo->empty()) {
// If there are no loops in the function, join intervals in function order.
for (MachineFunction::iterator I = mf_->begin(), E = mf_->end();
I != E; ++I)
/// Return true if the two specified registers belong to different register
/// classes. The registers may be either phys or virt regs.
-bool SimpleRegisterCoalescing::differingRegisterClasses(unsigned RegA,
- unsigned RegB) const {
-
+bool
+SimpleRegisterCoalescing::differingRegisterClasses(unsigned RegA,
+ unsigned RegB) const {
// Get the register classes for the first reg.
if (TargetRegisterInfo::isPhysicalRegister(RegA)) {
assert(TargetRegisterInfo::isVirtualRegister(RegB) &&
}
// Compare against the regclass for the second reg.
- const TargetRegisterClass *RegClass = mri_->getRegClass(RegA);
- if (TargetRegisterInfo::isVirtualRegister(RegB))
- return RegClass != mri_->getRegClass(RegB);
- else
- return !RegClass->contains(RegB);
+ const TargetRegisterClass *RegClassA = mri_->getRegClass(RegA);
+ if (TargetRegisterInfo::isVirtualRegister(RegB)) {
+ const TargetRegisterClass *RegClassB = mri_->getRegClass(RegB);
+ return RegClassA != RegClassB;
+ }
+ return !RegClassA->contains(RegB);
}
/// lastRegisterUse - Returns the last use of the specific register between
E = mri_->use_end(); I != E; ++I) {
MachineOperand &Use = I.getOperand();
MachineInstr *UseMI = Use.getParent();
- unsigned SrcReg, DstReg;
- if (tii_->isMoveInstr(*UseMI, SrcReg, DstReg) && SrcReg == DstReg)
+ unsigned SrcReg, DstReg, SrcSubIdx, DstSubIdx;
+ if (tii_->isMoveInstr(*UseMI, SrcReg, DstReg, SrcSubIdx, DstSubIdx) &&
+ SrcReg == DstReg)
// Ignore identity copies.
continue;
unsigned Idx = li_->getInstructionIndex(UseMI);
if (Idx >= Start && Idx < End && Idx >= UseIdx) {
LastUse = &Use;
- UseIdx = Idx;
+ UseIdx = li_->getUseIndex(Idx);
}
}
return LastUse;
return NULL;
// Ignore identity copies.
- unsigned SrcReg, DstReg;
- if (!(tii_->isMoveInstr(*MI, SrcReg, DstReg) && SrcReg == DstReg))
+ unsigned SrcReg, DstReg, SrcSubIdx, DstSubIdx;
+ if (!(tii_->isMoveInstr(*MI, SrcReg, DstReg, SrcSubIdx, DstSubIdx) &&
+ SrcReg == DstReg))
for (unsigned i = 0, NumOps = MI->getNumOperands(); i != NumOps; ++i) {
MachineOperand &Use = MI->getOperand(i);
- if (Use.isRegister() && Use.isUse() && Use.getReg() &&
+ if (Use.isReg() && Use.isUse() && Use.getReg() &&
tri_->regsOverlap(Use.getReg(), Reg)) {
- UseIdx = e;
+ UseIdx = li_->getUseIndex(e);
return &Use;
}
}
void SimpleRegisterCoalescing::releaseMemory() {
JoinedCopies.clear();
+ ReMatCopies.clear();
+ ReMatDefs.clear();
}
static bool isZeroLengthInterval(LiveInterval *li) {
CopyMI->setDesc(tii_->get(TargetInstrInfo::IMPLICIT_DEF));
for (int i = CopyMI->getNumOperands() - 1, e = 0; i > e; --i)
CopyMI->RemoveOperand(i);
- bool NoUse = mri_->use_begin(SrcReg) == mri_->use_end();
+ bool NoUse = mri_->use_empty(SrcReg);
if (NoUse) {
for (MachineRegisterInfo::reg_iterator I = mri_->reg_begin(SrcReg),
E = mri_->reg_end(); I != E; ) {
// Join (coalesce) intervals if requested.
if (EnableJoining) {
joinIntervals();
- DOUT << "********** INTERVALS POST JOINING **********\n";
- for (LiveIntervals::iterator I = li_->begin(), E = li_->end(); I != E; ++I){
- I->second.print(DOUT, tri_);
- DOUT << "\n";
- }
+ DEBUG({
+ DOUT << "********** INTERVALS POST JOINING **********\n";
+ for (LiveIntervals::iterator I = li_->begin(), E = li_->end(); I != E; ++I){
+ I->second->print(DOUT, tri_);
+ DOUT << "\n";
+ }
+ });
}
// Perform a final pass over the instructions and compute spill weights
// and remove identity moves.
+ SmallVector<unsigned, 4> DeadDefs;
for (MachineFunction::iterator mbbi = mf_->begin(), mbbe = mf_->end();
mbbi != mbbe; ++mbbi) {
MachineBasicBlock* mbb = mbbi;
for (MachineBasicBlock::iterator mii = mbb->begin(), mie = mbb->end();
mii != mie; ) {
MachineInstr *MI = mii;
- unsigned SrcReg, DstReg;
+ unsigned SrcReg, DstReg, SrcSubIdx, DstSubIdx;
if (JoinedCopies.count(MI)) {
// Delete all coalesced copies.
- if (!tii_->isMoveInstr(*MI, SrcReg, DstReg)) {
+ if (!tii_->isMoveInstr(*MI, SrcReg, DstReg, SrcSubIdx, DstSubIdx)) {
assert((MI->getOpcode() == TargetInstrInfo::EXTRACT_SUBREG ||
MI->getOpcode() == TargetInstrInfo::INSERT_SUBREG) &&
"Unrecognized copy instruction");
continue;
}
+ // Now check if this is a remat'ed def instruction which is now dead.
+ if (ReMatDefs.count(MI)) {
+ bool isDead = true;
+ for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
+ const MachineOperand &MO = MI->getOperand(i);
+ if (!MO.isReg())
+ continue;
+ unsigned Reg = MO.getReg();
+ if (!Reg)
+ continue;
+ if (TargetRegisterInfo::isVirtualRegister(Reg))
+ DeadDefs.push_back(Reg);
+ if (MO.isDead())
+ continue;
+ if (TargetRegisterInfo::isPhysicalRegister(Reg) ||
+ !mri_->use_empty(Reg)) {
+ isDead = false;
+ break;
+ }
+ }
+ if (isDead) {
+ while (!DeadDefs.empty()) {
+ unsigned DeadDef = DeadDefs.back();
+ DeadDefs.pop_back();
+ RemoveDeadDef(li_->getInterval(DeadDef), MI);
+ }
+ li_->RemoveMachineInstrFromMaps(mii);
+ mii = mbbi->erase(mii);
+ continue;
+ } else
+ DeadDefs.clear();
+ }
+
// If the move will be an identity move delete it
- bool isMove = tii_->isMoveInstr(*mii, SrcReg, DstReg);
+ bool isMove= tii_->isMoveInstr(*MI, SrcReg, DstReg, SrcSubIdx, DstSubIdx);
if (isMove && SrcReg == DstReg) {
if (li_->hasInterval(SrcReg)) {
LiveInterval &RegInt = li_->getInterval(SrcReg);
// If def of this move instruction is dead, remove its live range
// from the dstination register's live interval.
- if (mii->registerDefIsDead(DstReg)) {
- if (!ShortenDeadCopySrcLiveRange(RegInt, mii))
- ShortenDeadCopyLiveRange(RegInt, mii);
+ if (MI->registerDefIsDead(DstReg)) {
+ if (!ShortenDeadCopySrcLiveRange(RegInt, MI))
+ ShortenDeadCopyLiveRange(RegInt, MI);
}
}
- li_->RemoveMachineInstrFromMaps(mii);
+ li_->RemoveMachineInstrFromMaps(MI);
mii = mbbi->erase(mii);
++numPeep;
} else if (!isMove || !TurnCopyIntoImpDef(mii, mbb, DstReg, SrcReg)) {
SmallSet<unsigned, 4> UniqueUses;
- for (unsigned i = 0, e = mii->getNumOperands(); i != e; ++i) {
- const MachineOperand &mop = mii->getOperand(i);
- if (mop.isRegister() && mop.getReg() &&
+ for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
+ const MachineOperand &mop = MI->getOperand(i);
+ if (mop.isReg() && mop.getReg() &&
TargetRegisterInfo::isVirtualRegister(mop.getReg())) {
unsigned reg = mop.getReg();
// Multiple uses of reg by the same instruction. It should not
}
for (LiveIntervals::iterator I = li_->begin(), E = li_->end(); I != E; ++I) {
- LiveInterval &LI = I->second;
+ LiveInterval &LI = *I->second;
if (TargetRegisterInfo::isVirtualRegister(LI.reg)) {
// If the live interval length is essentially zero, i.e. in every live
// range the use follows def immediately, it doesn't make sense to spill
LI.weight = HUGE_VALF;
else {
bool isLoad = false;
- if (li_->isReMaterializable(LI, isLoad)) {
+ SmallVector<LiveInterval*, 4> SpillIs;
+ if (li_->isReMaterializable(LI, SpillIs, isLoad)) {
// If all of the definitions of the interval are re-materializable,
// it is a preferred candidate for spilling. If non of the defs are
// loads, then it's potentially very cheap to re-materialize.
// Divide the weight of the interval by its size. This encourages
// spilling of intervals that are large and have few uses, and
// discourages spilling of small intervals with many uses.
- LI.weight /= LI.getSize();
+ LI.weight /= li_->getApproximateInstructionCount(LI) * InstrSlots::NUM;
}
}
projects / oota-llvm.git / blobdiff