[llvm-commits] [llvm] r131524 - in /llvm/trunk/lib/CodeGen: SimpleRegisterCoalescing.cpp SimpleRegisterCoalescing.h
Jakob Stoklund Olesen
stoklund at 2pi.dk
Tue May 17 21:51:15 PDT 2011
Author: stoklund
Date: Tue May 17 23:51:15 2011
New Revision: 131524
URL: http://llvm.org/viewvc/llvm-project?rev=131524&view=rev
Log:
Eliminate dead dead code elimination code.
Modified:
llvm/trunk/lib/CodeGen/SimpleRegisterCoalescing.cpp
llvm/trunk/lib/CodeGen/SimpleRegisterCoalescing.h
Modified: llvm/trunk/lib/CodeGen/SimpleRegisterCoalescing.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SimpleRegisterCoalescing.cpp?rev=131524&r1=131523&r2=131524&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SimpleRegisterCoalescing.cpp (original)
+++ llvm/trunk/lib/CodeGen/SimpleRegisterCoalescing.cpp Tue May 17 23:51:15 2011
@@ -47,7 +47,6 @@
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 @@
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 @@
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 @@
}
}
-/// 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 @@
}
}
-/// 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();
Modified: llvm/trunk/lib/CodeGen/SimpleRegisterCoalescing.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SimpleRegisterCoalescing.h?rev=131524&r1=131523&r2=131524&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SimpleRegisterCoalescing.h (original)
+++ llvm/trunk/lib/CodeGen/SimpleRegisterCoalescing.h Tue May 17 23:51:15 2011
@@ -103,10 +103,6 @@
/// 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 @@
/// 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 @@
/// 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 @@
/// 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);
};
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