X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FCodeGen%2FLiveRangeEdit.cpp;h=7793e96c354096d770d458f166fa370818aadbeb;hb=46abfcf4187432da728cbe452c32143da077e07f;hp=4ecb2d9a60a45ffab46ae457ac258cc795c8a49f;hpb=2e267ae7b8caf7192a3793eb3b78937ff83f794d;p=oota-llvm.git diff --git a/lib/CodeGen/LiveRangeEdit.cpp b/lib/CodeGen/LiveRangeEdit.cpp index 4ecb2d9a60a..7793e96c354 100644 --- a/lib/CodeGen/LiveRangeEdit.cpp +++ b/lib/CodeGen/LiveRangeEdit.cpp @@ -12,16 +12,16 @@ //===----------------------------------------------------------------------===// #define DEBUG_TYPE "regalloc" -#include "VirtRegMap.h" +#include "llvm/CodeGen/LiveRangeEdit.h" #include "llvm/ADT/SetVector.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; @@ -38,7 +38,7 @@ LiveInterval &LiveRangeEdit::createFrom(unsigned OldReg) { VRM->setIsSplitFromReg(VReg, VRM->getOriginal(OldReg)); } LiveInterval &LI = LIS.getOrCreateInterval(VReg); - newRegs_.push_back(&LI); + NewRegs.push_back(&LI); return LI; } @@ -46,16 +46,16 @@ 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 +64,45 @@ 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 +112,10 @@ 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. @@ -136,13 +147,13 @@ 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); } @@ -173,6 +184,19 @@ 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, 0, SawStore)) + return false; + DEBUG(dbgs() << "Try to fold single def: " << *DefMI << " into single use: " << *UseMI); @@ -220,14 +244,22 @@ void LiveRangeEdit::eliminateDeadDefs(SmallVectorImpl &Dead, DEBUG(dbgs() << "Deleting dead def " << Idx << '\t' << *MI); + // 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)) + if (!TargetRegisterInfo::isVirtualRegister(Reg)) { + // Check if MI reads any unreserved physregs. + if (Reg && MOI->readsReg() && !MRI.isReserved(Reg)) + ReadsPhysRegs = true; continue; + } LiveInterval &LI = LIS.getInterval(Reg); // Shrink read registers, unless it is likely to be expensive and @@ -242,22 +274,49 @@ void LiveRangeEdit::eliminateDeadDefs(SmallVectorImpl &Dead, // Remove defined value. if (MOI->isDef()) { if (VNInfo *VNI = LI.getVNInfoAt(Idx)) { - if (delegate_) - delegate_->LRE_WillShrinkVirtReg(LI.reg); + if (TheDelegate) + TheDelegate->LRE_WillShrinkVirtReg(LI.reg); LI.removeValNo(VNI); - if (LI.empty()) { - ToShrink.remove(&LI); - eraseVirtReg(Reg); - } + 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); + } + } } if (ToShrink.empty()) @@ -268,8 +327,8 @@ 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; @@ -286,7 +345,6 @@ void LiveRangeEdit::eliminateDeadDefs(SmallVectorImpl &Dead, } if (BeingSpilled) continue; - if (!VRM) continue; // LI may have been separated, create new intervals. LI->RenumberValues(LIS); @@ -305,10 +363,14 @@ void LiveRangeEdit::eliminateDeadDefs(SmallVectorImpl &Dead, // 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'; + }); } }