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Eliminate dead dead code elimination code.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@131524 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jakob Stoklund Olesen 2011-05-18 04:51:15 +00:00
parent c6b9ebdd64
commit 54f0d1e021
2 changed files with 0 additions and 292 deletions
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266
lib/CodeGen/SimpleRegisterCoalescing.cpp
View File

@ -47,7 +47,6 @@ 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>
@ -503,98 +502,6 @@ bool SimpleRegisterCoalescing::RemoveCopyByCommutingDef(const CoalescerPair &CP,
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,
SlotIndex Start, SlotIndex 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);
SlotIndex RemoveStart = Start;
SlotIndex RemoveEnd = Start;
while (RemoveEnd != End) {
LiveInterval::iterator LR = sli.FindLiveRangeContaining(RemoveStart);
if (LR == sli.end())
break;
RemoveEnd = (LR->end < End) ? LR->end : End;
sli.removeRange(RemoveStart, RemoveEnd, true);
RemoveStart = 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(SlotIndex CopyIdx,
MachineBasicBlock *CopyMBB,
LiveInterval &li,
const LiveRange *LR) {
SlotIndex MBBStart = li_->getMBBStartIdx(CopyMBB);
SlotIndex LastUseIdx;
MachineOperand *LastUse =
lastRegisterUse(LR->start, CopyIdx.getPrevSlot(), 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, LastUseIdx.getDefIndex(), LR->end, li_, tri_);
if (LastUseMI->isCopy()) {
MachineOperand &DefMO = LastUseMI->getOperand(0);
if (DefMO.getReg() == li.reg && !DefMO.getSubReg())
DefMO.setIsDead();
}
return true;
}
// Is it livein?
if (LR->start <= MBBStart && LR->end > MBBStart) {
if (LR->start == li_->getZeroIndex()) {
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,
@ -781,26 +688,6 @@ static bool removeIntervalIfEmpty(LiveInterval &li, LiveIntervals *li_,
return false;
}
/// ShortenDeadCopyLiveRange - Shorten a live range defined by a dead copy.
/// Return true if live interval is removed.
bool SimpleRegisterCoalescing::ShortenDeadCopyLiveRange(LiveInterval &li,
MachineInstr *CopyMI) {
SlotIndex CopyIdx = li_->getInstructionIndex(CopyMI);
LiveInterval::iterator MLR =
li.FindLiveRangeContaining(CopyIdx.getDefIndex());
if (MLR == li.end())
return false; // Already removed by ShortenDeadCopySrcLiveRange.
SlotIndex RemoveStart = MLR->start;
SlotIndex RemoveEnd = MLR->end;
SlotIndex DefIdx = CopyIdx.getDefIndex();
// Remove the liverange that's defined by this.
if (RemoveStart == DefIdx && RemoveEnd == DefIdx.getStoreIndex()) {
removeRange(li, RemoveStart, RemoveEnd, li_, tri_);
return removeIntervalIfEmpty(li, li_, tri_);
}
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,
@ -834,84 +721,6 @@ void SimpleRegisterCoalescing::RemoveCopyFlag(unsigned DstReg,
}
}
/// PropagateDeadness - Propagate the dead marker to the instruction which
/// defines the val#.
static void PropagateDeadness(LiveInterval &li, MachineInstr *CopyMI,
SlotIndex &LRStart, LiveIntervals *li_,
const TargetRegisterInfo* tri_) {
MachineInstr *DefMI =
li_->getInstructionFromIndex(LRStart.getDefIndex());
if (DefMI && DefMI != CopyMI) {
int DeadIdx = DefMI->findRegisterDefOperandIdx(li.reg);
if (DeadIdx != -1)
DefMI->getOperand(DeadIdx).setIsDead();
else
DefMI->addOperand(MachineOperand::CreateReg(li.reg,
/*def*/true, /*implicit*/true, /*kill*/false, /*dead*/true));
LRStart = LRStart.getNextSlot();
}
}
/// 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
/// is dead. Return true if live interval is removed.
bool
SimpleRegisterCoalescing::ShortenDeadCopySrcLiveRange(LiveInterval &li,
MachineInstr *CopyMI) {
SlotIndex CopyIdx = li_->getInstructionIndex(CopyMI);
if (CopyIdx == SlotIndex()) {
// FIXME: special case: function live in. It can be a general case if the
// first instruction index starts at > 0 value.
assert(TargetRegisterInfo::isPhysicalRegister(li.reg));
// Live-in to the function but dead. Remove it from entry live-in set.
if (mf_->begin()->isLiveIn(li.reg))
mf_->begin()->removeLiveIn(li.reg);
if (const LiveRange *LR = li.getLiveRangeContaining(CopyIdx))
removeRange(li, LR->start, LR->end, li_, tri_);
return removeIntervalIfEmpty(li, li_, tri_);
}
LiveInterval::iterator LR =
li.FindLiveRangeContaining(CopyIdx.getPrevIndex().getStoreIndex());
if (LR == li.end())
// Livein but defined by a phi.
return false;
SlotIndex RemoveStart = LR->start;
SlotIndex RemoveEnd = CopyIdx.getStoreIndex();
if (LR->end > RemoveEnd)
// 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();
if (TrimLiveIntervalToLastUse(CopyIdx, CopyMBB, li, LR))
return false;
// There are other kills of the val#. Nothing to do.
if (!li.isOnlyLROfValNo(LR))
return false;
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).getNextIndex().getBaseIndex();
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.
PropagateDeadness(li, CopyMI, RemoveStart, li_, tri_);
++numDeadValNo;
}
removeRange(li, RemoveStart, RemoveEnd, li_, tri_);
return removeIntervalIfEmpty(li, li_, tri_);
}
/// shouldJoinPhys - Return true if a copy involving a physreg should be joined.
/// We need to be careful about coalescing a source physical register with a
/// virtual register. Once the coalescing is done, it cannot be broken and these
@ -1558,81 +1367,6 @@ void SimpleRegisterCoalescing::joinIntervals() {
}
}
/// 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 {
// Get the register classes for the first reg.
if (TargetRegisterInfo::isPhysicalRegister(RegA)) {
assert(TargetRegisterInfo::isVirtualRegister(RegB) &&
"Shouldn't consider two physregs!");
return !mri_->getRegClass(RegB)->contains(RegA);
}
// Compare against the regclass for the second reg.
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 (non-debug) use of the specific register
/// between cycles Start and End or NULL if there are no uses.
MachineOperand *
SimpleRegisterCoalescing::lastRegisterUse(SlotIndex Start,
SlotIndex End,
unsigned Reg,
SlotIndex &UseIdx) const{
UseIdx = SlotIndex();
if (TargetRegisterInfo::isVirtualRegister(Reg)) {
MachineOperand *LastUse = NULL;
for (MachineRegisterInfo::use_nodbg_iterator I = mri_->use_nodbg_begin(Reg),
E = mri_->use_nodbg_end(); I != E; ++I) {
MachineOperand &Use = I.getOperand();
MachineInstr *UseMI = Use.getParent();
if (UseMI->isIdentityCopy())
continue;
SlotIndex Idx = li_->getInstructionIndex(UseMI);
if (Idx >= Start && Idx < End && (!UseIdx.isValid() || Idx >= UseIdx)) {
LastUse = &Use;
UseIdx = Idx.getUseIndex();
}
}
return LastUse;
}
SlotIndex s = Start;
SlotIndex e = End.getPrevSlot().getBaseIndex();
while (e >= s) {
// Skip deleted instructions
MachineInstr *MI = li_->getInstructionFromIndex(e);
while (e != SlotIndex() && e.getPrevIndex() >= s && !MI) {
e = e.getPrevIndex();
MI = li_->getInstructionFromIndex(e);
}
if (e < s || MI == NULL)
return NULL;
// Ignore identity copies.
if (!MI->isIdentityCopy())
for (unsigned i = 0, NumOps = MI->getNumOperands(); i != NumOps; ++i) {
MachineOperand &Use = MI->getOperand(i);
if (Use.isReg() && Use.isUse() && Use.getReg() &&
tri_->regsOverlap(Use.getReg(), Reg)) {
UseIdx = e.getUseIndex();
return &Use;
}
}
e = e.getPrevIndex();
}
return NULL;
}
void SimpleRegisterCoalescing::releaseMemory() {
JoinedCopies.clear();
ReMatCopies.clear();

26
lib/CodeGen/SimpleRegisterCoalescing.h
View File

@ -103,10 +103,6 @@ namespace llvm {
/// use this information below to update aliases.
bool JoinIntervals(CoalescerPair &CP);
/// Return true if the two specified registers belong to different register
/// classes. The registers may be either phys or virt regs.
bool differingRegisterClasses(unsigned RegA, unsigned RegB) const;
/// AdjustCopiesBackFrom - We found a non-trivially-coalescable copy. If
/// the source value number is defined by a copy from the destination reg
/// see if we can merge these two destination reg valno# into a single
@ -124,13 +120,6 @@ namespace llvm {
/// can transform the copy into a noop by commuting the definition.
bool RemoveCopyByCommutingDef(const CoalescerPair &CP,MachineInstr *CopyMI);
/// TrimLiveIntervalToLastUse - If there is a last use in the same basic
/// block as the copy instruction, trim the ive interval to the last use
/// and return true.
bool TrimLiveIntervalToLastUse(SlotIndex CopyIdx,
MachineBasicBlock *CopyMBB,
LiveInterval &li, const LiveRange *LR);
/// ReMaterializeTrivialDef - If the source of a copy is defined by a trivial
/// computation, replace the copy by rematerialize the definition.
/// If PreserveSrcInt is true, make sure SrcInt is valid after the call.
@ -156,16 +145,6 @@ namespace llvm {
/// subregister.
void UpdateRegDefsUses(const CoalescerPair &CP);
/// ShortenDeadCopyLiveRange - Shorten a live range defined by a dead copy.
/// Return true if live interval is removed.
bool ShortenDeadCopyLiveRange(LiveInterval &li, MachineInstr *CopyMI);
/// ShortenDeadCopyLiveRange - 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 is dead. Return true if live interval is removed.
bool ShortenDeadCopySrcLiveRange(LiveInterval &li, MachineInstr *CopyMI);
/// 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.
@ -175,11 +154,6 @@ namespace llvm {
/// VNInfo copy flag for DstReg and all aliases.
void RemoveCopyFlag(unsigned DstReg, const MachineInstr *CopyMI);
/// lastRegisterUse - Returns the last use of the specific register between
/// cycles Start and End or NULL if there are no uses.
MachineOperand *lastRegisterUse(SlotIndex Start, SlotIndex End,
unsigned Reg, SlotIndex &LastUseIdx) const;
/// markAsJoined - Remember that CopyMI has already been joined.
void markAsJoined(MachineInstr *CopyMI);
};