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-rw-r--r--lib/CodeGen/SimpleRegisterCoalescing.cpp177
1 files changed, 48 insertions, 129 deletions
diff --git a/lib/CodeGen/SimpleRegisterCoalescing.cpp b/lib/CodeGen/SimpleRegisterCoalescing.cpp
index 58763718f9b5..ed407eb40cb2 100644
--- a/lib/CodeGen/SimpleRegisterCoalescing.cpp
+++ b/lib/CodeGen/SimpleRegisterCoalescing.cpp
@@ -130,7 +130,8 @@ bool SimpleRegisterCoalescing::AdjustCopiesBackFrom(LiveInterval &IntA,
// 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>,
+ // 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>
@@ -281,12 +282,12 @@ TransferImplicitOps(MachineInstr *MI, MachineInstr *NewMI) {
}
}
-/// RemoveCopyByCommutingDef - We found a non-trivially-coalescable copy with IntA
-/// being the source and IntB being the dest, thus this defines a value number
-/// in IntB. If the source value number (in IntA) is defined by a commutable
-/// instruction and its other operand is coalesced to the copy dest register,
-/// see if we can transform the copy into a noop by commuting the definition. For
-/// example,
+/// RemoveCopyByCommutingDef - We found a non-trivially-coalescable copy with
+/// IntA being the source and IntB being the dest, thus this defines a value
+/// number in IntB. If the source value number (in IntA) is defined by a
+/// commutable instruction and its other operand is coalesced to the copy dest
+/// register, see if we can transform the copy into a noop by commuting the
+/// definition. For example,
///
/// A3 = op A2 B0<kill>
/// ...
@@ -508,7 +509,8 @@ bool SimpleRegisterCoalescing::RemoveCopyByCommutingDef(LiveInterval &IntA,
if (BHasSubRegs) {
for (const unsigned *SR = tri_->getSubRegisters(IntB.reg); *SR; ++SR) {
LiveInterval &SRLI = li_->getInterval(*SR);
- SRLI.MergeInClobberRange(*li_, AI->start, End, li_->getVNInfoAllocator());
+ SRLI.MergeInClobberRange(*li_, AI->start, End,
+ li_->getVNInfoAllocator());
}
}
}
@@ -708,7 +710,8 @@ bool SimpleRegisterCoalescing::ReMaterializeTrivialDef(LiveInterval &SrcInt,
checkForDeadDef = true;
}
- MachineBasicBlock::iterator MII = next(MachineBasicBlock::iterator(CopyMI));
+ MachineBasicBlock::iterator MII =
+ llvm::next(MachineBasicBlock::iterator(CopyMI));
tii_->reMaterialize(*MBB, MII, DstReg, DstSubIdx, DefMI, tri_);
MachineInstr *NewMI = prior(MII);
@@ -1314,7 +1317,13 @@ bool SimpleRegisterCoalescing::JoinCopy(CopyRec &TheCopy, bool &Again) {
"coalesced to another register.\n");
return false; // Not coalescable.
}
- } else if (!tii_->isMoveInstr(*CopyMI, SrcReg, DstReg, SrcSubIdx, DstSubIdx)){
+ } else if (tii_->isMoveInstr(*CopyMI, SrcReg, DstReg, SrcSubIdx, DstSubIdx)) {
+ if (SrcSubIdx && DstSubIdx && SrcSubIdx != DstSubIdx) {
+ // e.g. %reg16404:1<def> = MOV8rr %reg16412:2<kill>
+ Again = true;
+ return false; // Not coalescable.
+ }
+ } else {
llvm_unreachable("Unrecognized copy instruction!");
}
@@ -1611,9 +1620,9 @@ bool SimpleRegisterCoalescing::JoinCopy(CopyRec &TheCopy, bool &Again) {
}
}
} else {
- // 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.
+ // If the virtual register live interval is long but it has low use
+ // density, do not join them, instead mark the physical register as its
+ // allocation preference.
LiveInterval &JoinVInt = SrcIsPhys ? DstInt : SrcInt;
unsigned JoinVReg = SrcIsPhys ? DstReg : SrcReg;
unsigned JoinPReg = SrcIsPhys ? SrcReg : DstReg;
@@ -1938,6 +1947,10 @@ bool SimpleRegisterCoalescing::SimpleJoin(LiveInterval &LHS, LiveInterval &RHS){
if (Overlaps) {
// If we haven't already recorded that this value # is safe, check it.
if (!InVector(LHSIt->valno, EliminatedLHSVals)) {
+ // If it's re-defined by an early clobber somewhere in the live range,
+ // then conservatively abort coalescing.
+ if (LHSIt->valno->hasRedefByEC())
+ return false;
// Copy from the RHS?
if (!RangeIsDefinedByCopyFromReg(LHS, LHSIt, RHS.reg))
return false; // Nope, bail out.
@@ -1977,6 +1990,10 @@ bool SimpleRegisterCoalescing::SimpleJoin(LiveInterval &LHS, LiveInterval &RHS){
// if coalescing succeeds. Just skip the liverange.
if (++LHSIt == LHSEnd) break;
} else {
+ // If it's re-defined by an early clobber somewhere in the live range,
+ // then conservatively abort coalescing.
+ if (LHSIt->valno->hasRedefByEC())
+ return false;
// Otherwise, if this is a copy from the RHS, mark it as being merged
// in.
if (RangeIsDefinedByCopyFromReg(LHS, LHSIt, RHS.reg)) {
@@ -2316,6 +2333,10 @@ SimpleRegisterCoalescing::JoinIntervals(LiveInterval &LHS, LiveInterval &RHS,
if (LHSValNoAssignments[I->valno->id] !=
RHSValNoAssignments[J->valno->id])
return false;
+ // If it's re-defined by an early clobber somewhere in the live range,
+ // then conservatively abort coalescing.
+ if (NewVNInfo[LHSValNoAssignments[I->valno->id]]->hasRedefByEC())
+ return false;
}
if (I->end < J->end) {
@@ -2401,9 +2422,15 @@ void SimpleRegisterCoalescing::CopyCoalesceInMBB(MachineBasicBlock *MBB,
// If this isn't a copy nor a extract_subreg, we can't join intervals.
unsigned SrcReg, DstReg, SrcSubIdx, DstSubIdx;
+ bool isInsUndef = false;
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();
+ if (Inst->getOperand(1).isUndef())
+ isInsUndef = true;
} else if (Inst->getOpcode() == TargetInstrInfo::INSERT_SUBREG ||
Inst->getOpcode() == TargetInstrInfo::SUBREG_TO_REG) {
DstReg = Inst->getOperand(0).getReg();
@@ -2413,7 +2440,8 @@ void SimpleRegisterCoalescing::CopyCoalesceInMBB(MachineBasicBlock *MBB,
bool SrcIsPhys = TargetRegisterInfo::isPhysicalRegister(SrcReg);
bool DstIsPhys = TargetRegisterInfo::isPhysicalRegister(DstReg);
- if (li_->hasInterval(SrcReg) && li_->getInterval(SrcReg).empty())
+ if (isInsUndef ||
+ (li_->hasInterval(SrcReg) && li_->getInterval(SrcReg).empty()))
ImpDefCopies.push_back(CopyRec(Inst, 0));
else if (SrcIsPhys || DstIsPhys)
PhysCopies.push_back(CopyRec(Inst, 0));
@@ -2421,9 +2449,9 @@ void SimpleRegisterCoalescing::CopyCoalesceInMBB(MachineBasicBlock *MBB,
VirtCopies.push_back(CopyRec(Inst, 0));
}
- // Try coalescing implicit copies first, followed by copies to / from
- // physical registers, then finally copies from virtual registers to
- // virtual registers.
+ // Try coalescing implicit copies and insert_subreg <undef> first,
+ // followed by copies to / from physical registers, then finally copies
+ // from virtual registers to virtual registers.
for (unsigned i = 0, e = ImpDefCopies.size(); i != e; ++i) {
CopyRec &TheCopy = ImpDefCopies[i];
bool Again = false;
@@ -2594,114 +2622,6 @@ void SimpleRegisterCoalescing::releaseMemory() {
ReMatDefs.clear();
}
-/// Returns true if the given live interval is zero length.
-static bool isZeroLengthInterval(LiveInterval *li, LiveIntervals *li_) {
- for (LiveInterval::Ranges::const_iterator
- i = li->ranges.begin(), e = li->ranges.end(); i != e; ++i)
- if (i->end.getPrevIndex() > i->start)
- return false;
- return true;
-}
-
-
-void SimpleRegisterCoalescing::CalculateSpillWeights() {
- SmallSet<unsigned, 4> Processed;
- for (MachineFunction::iterator mbbi = mf_->begin(), mbbe = mf_->end();
- mbbi != mbbe; ++mbbi) {
- MachineBasicBlock* MBB = mbbi;
- SlotIndex MBBEnd = li_->getMBBEndIdx(MBB);
- MachineLoop* loop = loopInfo->getLoopFor(MBB);
- unsigned loopDepth = loop ? loop->getLoopDepth() : 0;
- bool isExiting = loop ? loop->isLoopExiting(MBB) : false;
-
- for (MachineBasicBlock::const_iterator mii = MBB->begin(), mie = MBB->end();
- mii != mie; ++mii) {
- const MachineInstr *MI = mii;
- if (tii_->isIdentityCopy(*MI))
- continue;
-
- if (MI->getOpcode() == TargetInstrInfo::IMPLICIT_DEF)
- continue;
-
- for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
- const MachineOperand &mopi = MI->getOperand(i);
- if (!mopi.isReg() || mopi.getReg() == 0)
- continue;
- unsigned Reg = mopi.getReg();
- if (!TargetRegisterInfo::isVirtualRegister(mopi.getReg()))
- continue;
- // Multiple uses of reg by the same instruction. It should not
- // contribute to spill weight again.
- if (!Processed.insert(Reg))
- continue;
-
- bool HasDef = mopi.isDef();
- bool HasUse = !HasDef;
- for (unsigned j = i+1; j != e; ++j) {
- const MachineOperand &mopj = MI->getOperand(j);
- if (!mopj.isReg() || mopj.getReg() != Reg)
- continue;
- HasDef |= mopj.isDef();
- HasUse |= mopj.isUse();
- if (HasDef && HasUse)
- break;
- }
-
- LiveInterval &RegInt = li_->getInterval(Reg);
- float Weight = li_->getSpillWeight(HasDef, HasUse, loopDepth);
- if (HasDef && isExiting) {
- // Looks like this is a loop count variable update.
- SlotIndex DefIdx = li_->getInstructionIndex(MI).getDefIndex();
- const LiveRange *DLR =
- li_->getInterval(Reg).getLiveRangeContaining(DefIdx);
- if (DLR->end > MBBEnd)
- Weight *= 3.0F;
- }
- RegInt.weight += Weight;
- }
- Processed.clear();
- }
- }
-
- for (LiveIntervals::iterator I = li_->begin(), E = li_->end(); I != E; ++I) {
- 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
- // it and hope it will be easier to allocate for this li.
- if (isZeroLengthInterval(&LI, li_)) {
- LI.weight = HUGE_VALF;
- continue;
- }
-
- bool isLoad = false;
- 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.
- // FIXME: this gets much more complicated once we support non-trivial
- // re-materialization.
- if (isLoad)
- LI.weight *= 0.9F;
- else
- LI.weight *= 0.5F;
- }
-
- // Slightly prefer live interval that has been assigned a preferred reg.
- std::pair<unsigned, unsigned> Hint = mri_->getRegAllocationHint(LI.reg);
- if (Hint.first || Hint.second)
- LI.weight *= 1.01F;
-
- // 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_->getApproximateInstructionCount(LI) * InstrSlots::NUM;
- }
- }
-}
-
-
bool SimpleRegisterCoalescing::runOnMachineFunction(MachineFunction &fn) {
mf_ = &fn;
mri_ = &fn.getRegInfo();
@@ -2727,7 +2647,8 @@ bool SimpleRegisterCoalescing::runOnMachineFunction(MachineFunction &fn) {
joinIntervals();
DEBUG({
errs() << "********** INTERVALS POST JOINING **********\n";
- for (LiveIntervals::iterator I = li_->begin(), E = li_->end(); I != E; ++I){
+ for (LiveIntervals::iterator I = li_->begin(), E = li_->end();
+ I != E; ++I){
I->second->print(errs(), tri_);
errs() << "\n";
}
@@ -2768,7 +2689,7 @@ bool SimpleRegisterCoalescing::runOnMachineFunction(MachineFunction &fn) {
DoDelete = true;
}
if (!DoDelete)
- mii = next(mii);
+ mii = llvm::next(mii);
else {
li_->RemoveMachineInstrFromMaps(MI);
mii = mbbi->erase(mii);
@@ -2831,8 +2752,6 @@ bool SimpleRegisterCoalescing::runOnMachineFunction(MachineFunction &fn) {
}
}
- CalculateSpillWeights();
-
DEBUG(dump());
return true;
}
generated by cgit v1.3 (git 2.53.0) at 2026-04-08 15:56:18 +0000