X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FCodeGen%2FLiveRangeEdit.cpp;h=c27d6309fe9fed47d5a039976ca8e791297e8eba;hb=049ffbbdf2a43d5529cb56b6bb696d20d28ff217;hp=4ecb2d9a60a45ffab46ae457ac258cc795c8a49f;hpb=2e267ae7b8caf7192a3793eb3b78937ff83f794d;p=oota-llvm.git diff --git a/lib/CodeGen/LiveRangeEdit.cpp b/lib/CodeGen/LiveRangeEdit.cpp index 4ecb2d9a60a..c27d6309fe9 100644 --- a/lib/CodeGen/LiveRangeEdit.cpp +++ b/lib/CodeGen/LiveRangeEdit.cpp @@ -11,51 +11,57 @@ // is spilled or split. //===----------------------------------------------------------------------===// -#define DEBUG_TYPE "regalloc" -#include "VirtRegMap.h" -#include "llvm/ADT/SetVector.h" +#include "llvm/CodeGen/LiveRangeEdit.h" #include "llvm/ADT/Statistic.h" #include "llvm/CodeGen/CalcSpillWeights.h" #include "llvm/CodeGen/LiveIntervalAnalysis.h" -#include "llvm/CodeGen/LiveRangeEdit.h" #include "llvm/CodeGen/MachineRegisterInfo.h" -#include "llvm/Target/TargetInstrInfo.h" +#include "llvm/CodeGen/VirtRegMap.h" #include "llvm/Support/Debug.h" #include "llvm/Support/raw_ostream.h" +#include "llvm/Target/TargetInstrInfo.h" using namespace llvm; +#define DEBUG_TYPE "regalloc" + STATISTIC(NumDCEDeleted, "Number of instructions deleted by DCE"); STATISTIC(NumDCEFoldedLoads, "Number of single use loads folded after DCE"); STATISTIC(NumFracRanges, "Number of live ranges fractured by DCE"); void LiveRangeEdit::Delegate::anchor() { } -LiveInterval &LiveRangeEdit::createFrom(unsigned OldReg) { +LiveInterval &LiveRangeEdit::createEmptyIntervalFrom(unsigned OldReg) { unsigned VReg = MRI.createVirtualRegister(MRI.getRegClass(OldReg)); if (VRM) { - VRM->grow(); VRM->setIsSplitFromReg(VReg, VRM->getOriginal(OldReg)); } - LiveInterval &LI = LIS.getOrCreateInterval(VReg); - newRegs_.push_back(&LI); + LiveInterval &LI = LIS.createEmptyInterval(VReg); return LI; } +unsigned LiveRangeEdit::createFrom(unsigned OldReg) { + unsigned VReg = MRI.createVirtualRegister(MRI.getRegClass(OldReg)); + if (VRM) { + VRM->setIsSplitFromReg(VReg, VRM->getOriginal(OldReg)); + } + return VReg; +} + bool LiveRangeEdit::checkRematerializable(VNInfo *VNI, const MachineInstr *DefMI, AliasAnalysis *aa) { assert(DefMI && "Missing instruction"); - scannedRemattable_ = true; + ScannedRemattable = true; if (!TII.isTriviallyReMaterializable(DefMI, aa)) return false; - remattable_.insert(VNI); + Remattable.insert(VNI); return true; } void LiveRangeEdit::scanRemattable(AliasAnalysis *aa) { - for (LiveInterval::vni_iterator I = parent_.vni_begin(), - E = parent_.vni_end(); I != E; ++I) { + for (LiveInterval::vni_iterator I = getParent().vni_begin(), + E = getParent().vni_end(); I != E; ++I) { VNInfo *VNI = *I; if (VNI->isUnused()) continue; @@ -64,34 +70,45 @@ void LiveRangeEdit::scanRemattable(AliasAnalysis *aa) { continue; checkRematerializable(VNI, DefMI, aa); } - scannedRemattable_ = true; + ScannedRemattable = true; } bool LiveRangeEdit::anyRematerializable(AliasAnalysis *aa) { - if (!scannedRemattable_) + if (!ScannedRemattable) scanRemattable(aa); - return !remattable_.empty(); + return !Remattable.empty(); } /// allUsesAvailableAt - Return true if all registers used by OrigMI at /// OrigIdx are also available with the same value at UseIdx. bool LiveRangeEdit::allUsesAvailableAt(const MachineInstr *OrigMI, SlotIndex OrigIdx, - SlotIndex UseIdx) { + SlotIndex UseIdx) const { OrigIdx = OrigIdx.getRegSlot(true); UseIdx = UseIdx.getRegSlot(true); for (unsigned i = 0, e = OrigMI->getNumOperands(); i != e; ++i) { const MachineOperand &MO = OrigMI->getOperand(i); - if (!MO.isReg() || !MO.getReg() || MO.isDef()) - continue; - // Reserved registers are OK. - if (MO.isUndef() || !LIS.hasInterval(MO.getReg())) + if (!MO.isReg() || !MO.getReg() || !MO.readsReg()) continue; + // We can't remat physreg uses, unless it is a constant. + if (TargetRegisterInfo::isPhysicalRegister(MO.getReg())) { + if (MRI.isConstantPhysReg(MO.getReg(), *OrigMI->getParent()->getParent())) + continue; + return false; + } + LiveInterval &li = LIS.getInterval(MO.getReg()); const VNInfo *OVNI = li.getVNInfoAt(OrigIdx); if (!OVNI) continue; + + // Don't allow rematerialization immediately after the original def. + // It would be incorrect if OrigMI redefines the register. + // See PR14098. + if (SlotIndex::isSameInstr(OrigIdx, UseIdx)) + return false; + if (OVNI != li.getVNInfoAt(UseIdx)) return false; } @@ -101,10 +118,10 @@ bool LiveRangeEdit::allUsesAvailableAt(const MachineInstr *OrigMI, bool LiveRangeEdit::canRematerializeAt(Remat &RM, SlotIndex UseIdx, bool cheapAsAMove) { - assert(scannedRemattable_ && "Call anyRematerializable first"); + assert(ScannedRemattable && "Call anyRematerializable first"); // Use scanRemattable info. - if (!remattable_.count(RM.ParentVNI)) + if (!Remattable.count(RM.ParentVNI)) return false; // No defining instruction provided. @@ -118,7 +135,7 @@ bool LiveRangeEdit::canRematerializeAt(Remat &RM, } // If only cheap remats were requested, bail out early. - if (cheapAsAMove && !RM.OrigMI->isAsCheapAsAMove()) + if (cheapAsAMove && !TII.isAsCheapAsAMove(RM.OrigMI)) return false; // Verify that all used registers are available with the same values. @@ -136,24 +153,22 @@ SlotIndex LiveRangeEdit::rematerializeAt(MachineBasicBlock &MBB, bool Late) { assert(RM.OrigMI && "Invalid remat"); TII.reMaterialize(MBB, MI, DestReg, 0, RM.OrigMI, tri); - rematted_.insert(RM.ParentVNI); + Rematted.insert(RM.ParentVNI); return LIS.getSlotIndexes()->insertMachineInstrInMaps(--MI, Late) .getRegSlot(); } void LiveRangeEdit::eraseVirtReg(unsigned Reg) { - if (delegate_ && delegate_->LRE_CanEraseVirtReg(Reg)) + if (TheDelegate && TheDelegate->LRE_CanEraseVirtReg(Reg)) LIS.removeInterval(Reg); } bool LiveRangeEdit::foldAsLoad(LiveInterval *LI, SmallVectorImpl &Dead) { - MachineInstr *DefMI = 0, *UseMI = 0; + MachineInstr *DefMI = nullptr, *UseMI = nullptr; // Check that there is a single def and a single use. - for (MachineRegisterInfo::reg_nodbg_iterator I = MRI.reg_nodbg_begin(LI->reg), - E = MRI.reg_nodbg_end(); I != E; ++I) { - MachineOperand &MO = I.getOperand(); + for (MachineOperand &MO : MRI.reg_nodbg_operands(LI->reg)) { MachineInstr *MI = MO.getParent(); if (MO.isDef()) { if (DefMI && DefMI != MI) @@ -173,6 +188,19 @@ bool LiveRangeEdit::foldAsLoad(LiveInterval *LI, if (!DefMI || !UseMI) return false; + // Since we're moving the DefMI load, make sure we're not extending any live + // ranges. + if (!allUsesAvailableAt(DefMI, + LIS.getInstructionIndex(DefMI), + LIS.getInstructionIndex(UseMI))) + return false; + + // We also need to make sure it is safe to move the load. + // Assume there are stores between DefMI and UseMI. + bool SawStore = true; + if (!DefMI->isSafeToMove(&TII, nullptr, SawStore)) + return false; + DEBUG(dbgs() << "Try to fold single def: " << *DefMI << " into single use: " << *UseMI); @@ -186,79 +214,128 @@ bool LiveRangeEdit::foldAsLoad(LiveInterval *LI, DEBUG(dbgs() << " folded: " << *FoldMI); LIS.ReplaceMachineInstrInMaps(UseMI, FoldMI); UseMI->eraseFromParent(); - DefMI->addRegisterDead(LI->reg, 0); + DefMI->addRegisterDead(LI->reg, nullptr); Dead.push_back(DefMI); ++NumDCEFoldedLoads; return true; } -void LiveRangeEdit::eliminateDeadDefs(SmallVectorImpl &Dead, - ArrayRef RegsBeingSpilled) { - SetVector, - SmallPtrSet > ToShrink; +/// Find all live intervals that need to shrink, then remove the instruction. +void LiveRangeEdit::eliminateDeadDef(MachineInstr *MI, ToShrinkSet &ToShrink) { + assert(MI->allDefsAreDead() && "Def isn't really dead"); + SlotIndex Idx = LIS.getInstructionIndex(MI).getRegSlot(); - for (;;) { - // Erase all dead defs. - while (!Dead.empty()) { - MachineInstr *MI = Dead.pop_back_val(); - assert(MI->allDefsAreDead() && "Def isn't really dead"); - SlotIndex Idx = LIS.getInstructionIndex(MI).getRegSlot(); - - // Never delete inline asm. - if (MI->isInlineAsm()) { - DEBUG(dbgs() << "Won't delete: " << Idx << '\t' << *MI); - continue; - } + // Never delete a bundled instruction. + if (MI->isBundled()) { + return; + } + // Never delete inline asm. + if (MI->isInlineAsm()) { + DEBUG(dbgs() << "Won't delete: " << Idx << '\t' << *MI); + return; + } - // Use the same criteria as DeadMachineInstructionElim. - bool SawStore = false; - if (!MI->isSafeToMove(&TII, 0, SawStore)) { - DEBUG(dbgs() << "Can't delete: " << Idx << '\t' << *MI); - continue; - } + // Use the same criteria as DeadMachineInstructionElim. + bool SawStore = false; + if (!MI->isSafeToMove(&TII, nullptr, SawStore)) { + DEBUG(dbgs() << "Can't delete: " << Idx << '\t' << *MI); + return; + } + + DEBUG(dbgs() << "Deleting dead def " << Idx << '\t' << *MI); - DEBUG(dbgs() << "Deleting dead def " << Idx << '\t' << *MI); - - // Check for live intervals that may shrink - for (MachineInstr::mop_iterator MOI = MI->operands_begin(), - MOE = MI->operands_end(); MOI != MOE; ++MOI) { - if (!MOI->isReg()) - continue; - unsigned Reg = MOI->getReg(); - if (!TargetRegisterInfo::isVirtualRegister(Reg)) - continue; - LiveInterval &LI = LIS.getInterval(Reg); - - // Shrink read registers, unless it is likely to be expensive and - // unlikely to change anything. We typically don't want to shrink the - // PIC base register that has lots of uses everywhere. - // Always shrink COPY uses that probably come from live range splitting. - if (MI->readsVirtualRegister(Reg) && - (MI->isCopy() || MOI->isDef() || MRI.hasOneNonDBGUse(Reg) || - LI.killedAt(Idx))) - ToShrink.insert(&LI); - - // Remove defined value. - if (MOI->isDef()) { - if (VNInfo *VNI = LI.getVNInfoAt(Idx)) { - if (delegate_) - delegate_->LRE_WillShrinkVirtReg(LI.reg); - LI.removeValNo(VNI); - if (LI.empty()) { - ToShrink.remove(&LI); - eraseVirtReg(Reg); - } + // Collect virtual registers to be erased after MI is gone. + SmallVector RegsToErase; + bool ReadsPhysRegs = false; + + // Check for live intervals that may shrink + for (MachineInstr::mop_iterator MOI = MI->operands_begin(), + MOE = MI->operands_end(); MOI != MOE; ++MOI) { + if (!MOI->isReg()) + continue; + unsigned Reg = MOI->getReg(); + if (!TargetRegisterInfo::isVirtualRegister(Reg)) { + // Check if MI reads any unreserved physregs. + if (Reg && MOI->readsReg() && !MRI.isReserved(Reg)) + ReadsPhysRegs = true; + else if (MOI->isDef()) { + for (MCRegUnitIterator Units(Reg, MRI.getTargetRegisterInfo()); + Units.isValid(); ++Units) { + if (LiveRange *LR = LIS.getCachedRegUnit(*Units)) { + if (VNInfo *VNI = LR->getVNInfoAt(Idx)) + LR->removeValNo(VNI); } } } + continue; + } + LiveInterval &LI = LIS.getInterval(Reg); + + // Shrink read registers, unless it is likely to be expensive and + // unlikely to change anything. We typically don't want to shrink the + // PIC base register that has lots of uses everywhere. + // Always shrink COPY uses that probably come from live range splitting. + if (MI->readsVirtualRegister(Reg) && + (MI->isCopy() || MOI->isDef() || MRI.hasOneNonDBGUse(Reg) || + LI.Query(Idx).isKill())) + ToShrink.insert(&LI); + + // Remove defined value. + if (MOI->isDef()) { + if (VNInfo *VNI = LI.getVNInfoAt(Idx)) { + if (TheDelegate) + TheDelegate->LRE_WillShrinkVirtReg(LI.reg); + LI.removeValNo(VNI); + if (LI.empty()) + RegsToErase.push_back(Reg); + } + } + } - if (delegate_) - delegate_->LRE_WillEraseInstruction(MI); - LIS.RemoveMachineInstrFromMaps(MI); - MI->eraseFromParent(); - ++NumDCEDeleted; + // Currently, we don't support DCE of physreg live ranges. If MI reads + // any unreserved physregs, don't erase the instruction, but turn it into + // a KILL instead. This way, the physreg live ranges don't end up + // dangling. + // FIXME: It would be better to have something like shrinkToUses() for + // physregs. That could potentially enable more DCE and it would free up + // the physreg. It would not happen often, though. + if (ReadsPhysRegs) { + MI->setDesc(TII.get(TargetOpcode::KILL)); + // Remove all operands that aren't physregs. + for (unsigned i = MI->getNumOperands(); i; --i) { + const MachineOperand &MO = MI->getOperand(i-1); + if (MO.isReg() && TargetRegisterInfo::isPhysicalRegister(MO.getReg())) + continue; + MI->RemoveOperand(i-1); } + DEBUG(dbgs() << "Converted physregs to:\t" << *MI); + } else { + if (TheDelegate) + TheDelegate->LRE_WillEraseInstruction(MI); + LIS.RemoveMachineInstrFromMaps(MI); + MI->eraseFromParent(); + ++NumDCEDeleted; + } + + // Erase any virtregs that are now empty and unused. There may be + // uses around. Keep the empty live range in that case. + for (unsigned i = 0, e = RegsToErase.size(); i != e; ++i) { + unsigned Reg = RegsToErase[i]; + if (LIS.hasInterval(Reg) && MRI.reg_nodbg_empty(Reg)) { + ToShrink.remove(&LIS.getInterval(Reg)); + eraseVirtReg(Reg); + } + } +} + +void LiveRangeEdit::eliminateDeadDefs(SmallVectorImpl &Dead, + ArrayRef RegsBeingSpilled) { + ToShrinkSet ToShrink; + + for (;;) { + // Erase all dead defs. + while (!Dead.empty()) + eliminateDeadDef(Dead.pop_back_val(), ToShrink); if (ToShrink.empty()) break; @@ -268,11 +345,11 @@ void LiveRangeEdit::eliminateDeadDefs(SmallVectorImpl &Dead, ToShrink.pop_back(); if (foldAsLoad(LI, Dead)) continue; - if (delegate_) - delegate_->LRE_WillShrinkVirtReg(LI->reg); + if (TheDelegate) + TheDelegate->LRE_WillShrinkVirtReg(LI->reg); if (!LIS.shrinkToUses(LI, &Dead)) continue; - + // Don't create new intervals for a register being spilled. // The new intervals would have to be spilled anyway so its not worth it. // Also they currently aren't spilled so creating them and not spilling @@ -284,12 +361,11 @@ void LiveRangeEdit::eliminateDeadDefs(SmallVectorImpl &Dead, break; } } - + if (BeingSpilled) continue; - if (!VRM) continue; // LI may have been separated, create new intervals. - LI->RenumberValues(LIS); + LI->RenumberValues(); ConnectedVNInfoEqClasses ConEQ(LIS); unsigned NumComp = ConEQ.Classify(LI); if (NumComp <= 1) @@ -299,27 +375,44 @@ void LiveRangeEdit::eliminateDeadDefs(SmallVectorImpl &Dead, DEBUG(dbgs() << NumComp << " components: " << *LI << '\n'); SmallVector Dups(1, LI); for (unsigned i = 1; i != NumComp; ++i) { - Dups.push_back(&createFrom(LI->reg)); + Dups.push_back(&createEmptyIntervalFrom(LI->reg)); // If LI is an original interval that hasn't been split yet, make the new // intervals their own originals instead of referring to LI. The original // interval must contain all the split products, and LI doesn't. if (IsOriginal) VRM->setIsSplitFromReg(Dups.back()->reg, 0); - if (delegate_) - delegate_->LRE_DidCloneVirtReg(Dups.back()->reg, LI->reg); + if (TheDelegate) + TheDelegate->LRE_DidCloneVirtReg(Dups.back()->reg, LI->reg); } ConEQ.Distribute(&Dups[0], MRI); + DEBUG({ + for (unsigned i = 0; i != NumComp; ++i) + dbgs() << '\t' << *Dups[i] << '\n'; + }); } } -void LiveRangeEdit::calculateRegClassAndHint(MachineFunction &MF, - const MachineLoopInfo &Loops) { - VirtRegAuxInfo VRAI(MF, LIS, Loops); - for (iterator I = begin(), E = end(); I != E; ++I) { - LiveInterval &LI = **I; +// Keep track of new virtual registers created via +// MachineRegisterInfo::createVirtualRegister. +void +LiveRangeEdit::MRI_NoteNewVirtualRegister(unsigned VReg) +{ + if (VRM) + VRM->grow(); + + NewRegs.push_back(VReg); +} + +void +LiveRangeEdit::calculateRegClassAndHint(MachineFunction &MF, + const MachineLoopInfo &Loops, + const MachineBlockFrequencyInfo &MBFI) { + VirtRegAuxInfo VRAI(MF, LIS, Loops, MBFI); + for (unsigned I = 0, Size = size(); I < Size; ++I) { + LiveInterval &LI = LIS.getInterval(get(I)); if (MRI.recomputeRegClass(LI.reg, MF.getTarget())) DEBUG(dbgs() << "Inflated " << PrintReg(LI.reg) << " to " << MRI.getRegClass(LI.reg)->getName() << '\n'); - VRAI.CalculateWeightAndHint(LI); + VRAI.calculateSpillWeightAndHint(LI); } }