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Diffstat (limited to 'contrib/llvm/lib/CodeGen/InlineSpiller.cpp')
| -rw-r--r-- | contrib/llvm/lib/CodeGen/InlineSpiller.cpp | 480 |
1 files changed, 480 insertions, 0 deletions
diff --git a/contrib/llvm/lib/CodeGen/InlineSpiller.cpp b/contrib/llvm/lib/CodeGen/InlineSpiller.cpp new file mode 100644 index 0000000..b965bfd --- /dev/null +++ b/contrib/llvm/lib/CodeGen/InlineSpiller.cpp @@ -0,0 +1,480 @@ +//===-------- InlineSpiller.cpp - Insert spills and restores inline -------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// The inline spiller modifies the machine function directly instead of +// inserting spills and restores in VirtRegMap. +// +//===----------------------------------------------------------------------===// + +#define DEBUG_TYPE "spiller" +#include "Spiller.h" +#include "SplitKit.h" +#include "VirtRegMap.h" +#include "llvm/CodeGen/LiveIntervalAnalysis.h" +#include "llvm/CodeGen/MachineFrameInfo.h" +#include "llvm/CodeGen/MachineFunction.h" +#include "llvm/CodeGen/MachineLoopInfo.h" +#include "llvm/CodeGen/MachineRegisterInfo.h" +#include "llvm/Target/TargetMachine.h" +#include "llvm/Target/TargetInstrInfo.h" +#include "llvm/Support/Debug.h" +#include "llvm/Support/raw_ostream.h" + +using namespace llvm; + +namespace { +class InlineSpiller : public Spiller { + MachineFunctionPass &pass_; + MachineFunction &mf_; + LiveIntervals &lis_; + MachineLoopInfo &loops_; + VirtRegMap &vrm_; + MachineFrameInfo &mfi_; + MachineRegisterInfo &mri_; + const TargetInstrInfo &tii_; + const TargetRegisterInfo &tri_; + const BitVector reserved_; + + SplitAnalysis splitAnalysis_; + + // Variables that are valid during spill(), but used by multiple methods. + LiveInterval *li_; + SmallVectorImpl<LiveInterval*> *newIntervals_; + const TargetRegisterClass *rc_; + int stackSlot_; + const SmallVectorImpl<LiveInterval*> *spillIs_; + + // Values of the current interval that can potentially remat. + SmallPtrSet<VNInfo*, 8> reMattable_; + + // Values in reMattable_ that failed to remat at some point. + SmallPtrSet<VNInfo*, 8> usedValues_; + + ~InlineSpiller() {} + +public: + InlineSpiller(MachineFunctionPass &pass, + MachineFunction &mf, + VirtRegMap &vrm) + : pass_(pass), + mf_(mf), + lis_(pass.getAnalysis<LiveIntervals>()), + loops_(pass.getAnalysis<MachineLoopInfo>()), + vrm_(vrm), + mfi_(*mf.getFrameInfo()), + mri_(mf.getRegInfo()), + tii_(*mf.getTarget().getInstrInfo()), + tri_(*mf.getTarget().getRegisterInfo()), + reserved_(tri_.getReservedRegs(mf_)), + splitAnalysis_(mf, lis_, loops_) {} + + void spill(LiveInterval *li, + SmallVectorImpl<LiveInterval*> &newIntervals, + SmallVectorImpl<LiveInterval*> &spillIs); + +private: + bool split(); + + bool allUsesAvailableAt(const MachineInstr *OrigMI, SlotIndex OrigIdx, + SlotIndex UseIdx); + bool reMaterializeFor(MachineBasicBlock::iterator MI); + void reMaterializeAll(); + + bool coalesceStackAccess(MachineInstr *MI); + bool foldMemoryOperand(MachineBasicBlock::iterator MI, + const SmallVectorImpl<unsigned> &Ops); + void insertReload(LiveInterval &NewLI, MachineBasicBlock::iterator MI); + void insertSpill(LiveInterval &NewLI, MachineBasicBlock::iterator MI); +}; +} + +namespace llvm { +Spiller *createInlineSpiller(MachineFunctionPass &pass, + MachineFunction &mf, + VirtRegMap &vrm) { + return new InlineSpiller(pass, mf, vrm); +} +} + +/// split - try splitting the current interval into pieces that may allocate +/// separately. Return true if successful. +bool InlineSpiller::split() { + splitAnalysis_.analyze(li_); + + if (const MachineLoop *loop = splitAnalysis_.getBestSplitLoop()) { + // We can split, but li_ may be left intact with fewer uses. + if (SplitEditor(splitAnalysis_, lis_, vrm_, *newIntervals_) + .splitAroundLoop(loop)) + return true; + } + + // Try splitting into single block intervals. + SplitAnalysis::BlockPtrSet blocks; + if (splitAnalysis_.getMultiUseBlocks(blocks)) { + if (SplitEditor(splitAnalysis_, lis_, vrm_, *newIntervals_) + .splitSingleBlocks(blocks)) + return true; + } + + // Try splitting inside a basic block. + if (const MachineBasicBlock *MBB = splitAnalysis_.getBlockForInsideSplit()) { + if (SplitEditor(splitAnalysis_, lis_, vrm_, *newIntervals_) + .splitInsideBlock(MBB)) + return true; + } + + // We may have been able to split out some uses, but the original interval is + // intact, and it should still be spilled. + return false; +} + +/// allUsesAvailableAt - Return true if all registers used by OrigMI at +/// OrigIdx are also available with the same value at UseIdx. +bool InlineSpiller::allUsesAvailableAt(const MachineInstr *OrigMI, + SlotIndex OrigIdx, + SlotIndex UseIdx) { + OrigIdx = OrigIdx.getUseIndex(); + UseIdx = UseIdx.getUseIndex(); + for (unsigned i = 0, e = OrigMI->getNumOperands(); i != e; ++i) { + const MachineOperand &MO = OrigMI->getOperand(i); + if (!MO.isReg() || !MO.getReg() || MO.getReg() == li_->reg) + continue; + // Reserved registers are OK. + if (MO.isUndef() || !lis_.hasInterval(MO.getReg())) + continue; + // We don't want to move any defs. + if (MO.isDef()) + return false; + // We cannot depend on virtual registers in spillIs_. They will be spilled. + for (unsigned si = 0, se = spillIs_->size(); si != se; ++si) + if ((*spillIs_)[si]->reg == MO.getReg()) + return false; + + LiveInterval &LI = lis_.getInterval(MO.getReg()); + const VNInfo *OVNI = LI.getVNInfoAt(OrigIdx); + if (!OVNI) + continue; + if (OVNI != LI.getVNInfoAt(UseIdx)) + return false; + } + return true; +} + +/// reMaterializeFor - Attempt to rematerialize li_->reg before MI instead of +/// reloading it. +bool InlineSpiller::reMaterializeFor(MachineBasicBlock::iterator MI) { + SlotIndex UseIdx = lis_.getInstructionIndex(MI).getUseIndex(); + VNInfo *OrigVNI = li_->getVNInfoAt(UseIdx); + if (!OrigVNI) { + DEBUG(dbgs() << "\tadding <undef> flags: "); + for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) { + MachineOperand &MO = MI->getOperand(i); + if (MO.isReg() && MO.isUse() && MO.getReg() == li_->reg) + MO.setIsUndef(); + } + DEBUG(dbgs() << UseIdx << '\t' << *MI); + return true; + } + if (!reMattable_.count(OrigVNI)) { + DEBUG(dbgs() << "\tusing non-remat valno " << OrigVNI->id << ": " + << UseIdx << '\t' << *MI); + return false; + } + MachineInstr *OrigMI = lis_.getInstructionFromIndex(OrigVNI->def); + if (!allUsesAvailableAt(OrigMI, OrigVNI->def, UseIdx)) { + usedValues_.insert(OrigVNI); + DEBUG(dbgs() << "\tcannot remat for " << UseIdx << '\t' << *MI); + return false; + } + + // If the instruction also writes li_->reg, it had better not require the same + // register for uses and defs. + bool Reads, Writes; + SmallVector<unsigned, 8> Ops; + tie(Reads, Writes) = MI->readsWritesVirtualRegister(li_->reg, &Ops); + if (Writes) { + for (unsigned i = 0, e = Ops.size(); i != e; ++i) { + MachineOperand &MO = MI->getOperand(Ops[i]); + if (MO.isUse() ? MI->isRegTiedToDefOperand(Ops[i]) : MO.getSubReg()) { + usedValues_.insert(OrigVNI); + DEBUG(dbgs() << "\tcannot remat tied reg: " << UseIdx << '\t' << *MI); + return false; + } + } + } + + // Alocate a new register for the remat. + unsigned NewVReg = mri_.createVirtualRegister(rc_); + vrm_.grow(); + LiveInterval &NewLI = lis_.getOrCreateInterval(NewVReg); + NewLI.markNotSpillable(); + newIntervals_->push_back(&NewLI); + + // Finally we can rematerialize OrigMI before MI. + MachineBasicBlock &MBB = *MI->getParent(); + tii_.reMaterialize(MBB, MI, NewLI.reg, 0, OrigMI, tri_); + MachineBasicBlock::iterator RematMI = MI; + SlotIndex DefIdx = lis_.InsertMachineInstrInMaps(--RematMI).getDefIndex(); + DEBUG(dbgs() << "\tremat: " << DefIdx << '\t' << *RematMI); + + // Replace operands + for (unsigned i = 0, e = Ops.size(); i != e; ++i) { + MachineOperand &MO = MI->getOperand(Ops[i]); + if (MO.isReg() && MO.isUse() && MO.getReg() == li_->reg) { + MO.setReg(NewVReg); + MO.setIsKill(); + } + } + DEBUG(dbgs() << "\t " << UseIdx << '\t' << *MI); + + VNInfo *DefVNI = NewLI.getNextValue(DefIdx, 0, true, + lis_.getVNInfoAllocator()); + NewLI.addRange(LiveRange(DefIdx, UseIdx.getDefIndex(), DefVNI)); + DEBUG(dbgs() << "\tinterval: " << NewLI << '\n'); + return true; +} + +/// reMaterializeAll - Try to rematerialize as many uses of li_ as possible, +/// and trim the live ranges after. +void InlineSpiller::reMaterializeAll() { + // Do a quick scan of the interval values to find if any are remattable. + reMattable_.clear(); + usedValues_.clear(); + for (LiveInterval::const_vni_iterator I = li_->vni_begin(), + E = li_->vni_end(); I != E; ++I) { + VNInfo *VNI = *I; + if (VNI->isUnused() || !VNI->isDefAccurate()) + continue; + MachineInstr *DefMI = lis_.getInstructionFromIndex(VNI->def); + if (!DefMI || !tii_.isTriviallyReMaterializable(DefMI)) + continue; + reMattable_.insert(VNI); + } + + // Often, no defs are remattable. + if (reMattable_.empty()) + return; + + // Try to remat before all uses of li_->reg. + bool anyRemat = false; + for (MachineRegisterInfo::use_nodbg_iterator + RI = mri_.use_nodbg_begin(li_->reg); + MachineInstr *MI = RI.skipInstruction();) + anyRemat |= reMaterializeFor(MI); + + if (!anyRemat) + return; + + // Remove any values that were completely rematted. + bool anyRemoved = false; + for (SmallPtrSet<VNInfo*, 8>::iterator I = reMattable_.begin(), + E = reMattable_.end(); I != E; ++I) { + VNInfo *VNI = *I; + if (VNI->hasPHIKill() || usedValues_.count(VNI)) + continue; + MachineInstr *DefMI = lis_.getInstructionFromIndex(VNI->def); + DEBUG(dbgs() << "\tremoving dead def: " << VNI->def << '\t' << *DefMI); + lis_.RemoveMachineInstrFromMaps(DefMI); + vrm_.RemoveMachineInstrFromMaps(DefMI); + DefMI->eraseFromParent(); + VNI->setIsDefAccurate(false); + anyRemoved = true; + } + + if (!anyRemoved) + return; + + // Removing values may cause debug uses where li_ is not live. + for (MachineRegisterInfo::use_iterator RI = mri_.use_begin(li_->reg); + MachineInstr *MI = RI.skipInstruction();) { + if (!MI->isDebugValue()) + continue; + // Try to preserve the debug value if li_ is live immediately after it. + MachineBasicBlock::iterator NextMI = MI; + ++NextMI; + if (NextMI != MI->getParent()->end() && !lis_.isNotInMIMap(NextMI)) { + VNInfo *VNI = li_->getVNInfoAt(lis_.getInstructionIndex(NextMI)); + if (VNI && (VNI->hasPHIKill() || usedValues_.count(VNI))) + continue; + } + DEBUG(dbgs() << "Removing debug info due to remat:" << "\t" << *MI); + MI->eraseFromParent(); + } +} + +/// If MI is a load or store of stackSlot_, it can be removed. +bool InlineSpiller::coalesceStackAccess(MachineInstr *MI) { + int FI = 0; + unsigned reg; + if (!(reg = tii_.isLoadFromStackSlot(MI, FI)) && + !(reg = tii_.isStoreToStackSlot(MI, FI))) + return false; + + // We have a stack access. Is it the right register and slot? + if (reg != li_->reg || FI != stackSlot_) + return false; + + DEBUG(dbgs() << "Coalescing stack access: " << *MI); + lis_.RemoveMachineInstrFromMaps(MI); + MI->eraseFromParent(); + return true; +} + +/// foldMemoryOperand - Try folding stack slot references in Ops into MI. +/// Return true on success, and MI will be erased. +bool InlineSpiller::foldMemoryOperand(MachineBasicBlock::iterator MI, + const SmallVectorImpl<unsigned> &Ops) { + // TargetInstrInfo::foldMemoryOperand only expects explicit, non-tied + // operands. + SmallVector<unsigned, 8> FoldOps; + for (unsigned i = 0, e = Ops.size(); i != e; ++i) { + unsigned Idx = Ops[i]; + MachineOperand &MO = MI->getOperand(Idx); + if (MO.isImplicit()) + continue; + // FIXME: Teach targets to deal with subregs. + if (MO.getSubReg()) + return false; + // Tied use operands should not be passed to foldMemoryOperand. + if (!MI->isRegTiedToDefOperand(Idx)) + FoldOps.push_back(Idx); + } + + MachineInstr *FoldMI = tii_.foldMemoryOperand(MI, FoldOps, stackSlot_); + if (!FoldMI) + return false; + lis_.ReplaceMachineInstrInMaps(MI, FoldMI); + vrm_.addSpillSlotUse(stackSlot_, FoldMI); + MI->eraseFromParent(); + DEBUG(dbgs() << "\tfolded: " << *FoldMI); + return true; +} + +/// insertReload - Insert a reload of NewLI.reg before MI. +void InlineSpiller::insertReload(LiveInterval &NewLI, + MachineBasicBlock::iterator MI) { + MachineBasicBlock &MBB = *MI->getParent(); + SlotIndex Idx = lis_.getInstructionIndex(MI).getDefIndex(); + tii_.loadRegFromStackSlot(MBB, MI, NewLI.reg, stackSlot_, rc_, &tri_); + --MI; // Point to load instruction. + SlotIndex LoadIdx = lis_.InsertMachineInstrInMaps(MI).getDefIndex(); + vrm_.addSpillSlotUse(stackSlot_, MI); + DEBUG(dbgs() << "\treload: " << LoadIdx << '\t' << *MI); + VNInfo *LoadVNI = NewLI.getNextValue(LoadIdx, 0, true, + lis_.getVNInfoAllocator()); + NewLI.addRange(LiveRange(LoadIdx, Idx, LoadVNI)); +} + +/// insertSpill - Insert a spill of NewLI.reg after MI. +void InlineSpiller::insertSpill(LiveInterval &NewLI, + MachineBasicBlock::iterator MI) { + MachineBasicBlock &MBB = *MI->getParent(); + SlotIndex Idx = lis_.getInstructionIndex(MI).getDefIndex(); + tii_.storeRegToStackSlot(MBB, ++MI, NewLI.reg, true, stackSlot_, rc_, &tri_); + --MI; // Point to store instruction. + SlotIndex StoreIdx = lis_.InsertMachineInstrInMaps(MI).getDefIndex(); + vrm_.addSpillSlotUse(stackSlot_, MI); + DEBUG(dbgs() << "\tspilled: " << StoreIdx << '\t' << *MI); + VNInfo *StoreVNI = NewLI.getNextValue(Idx, 0, true, + lis_.getVNInfoAllocator()); + NewLI.addRange(LiveRange(Idx, StoreIdx, StoreVNI)); +} + +void InlineSpiller::spill(LiveInterval *li, + SmallVectorImpl<LiveInterval*> &newIntervals, + SmallVectorImpl<LiveInterval*> &spillIs) { + DEBUG(dbgs() << "Inline spilling " << *li << "\n"); + assert(li->isSpillable() && "Attempting to spill already spilled value."); + assert(!li->isStackSlot() && "Trying to spill a stack slot."); + + li_ = li; + newIntervals_ = &newIntervals; + rc_ = mri_.getRegClass(li->reg); + spillIs_ = &spillIs; + + if (split()) + return; + + reMaterializeAll(); + + // Remat may handle everything. + if (li_->empty()) + return; + + stackSlot_ = vrm_.getStackSlot(li->reg); + if (stackSlot_ == VirtRegMap::NO_STACK_SLOT) + stackSlot_ = vrm_.assignVirt2StackSlot(li->reg); + + // Iterate over instructions using register. + for (MachineRegisterInfo::reg_iterator RI = mri_.reg_begin(li->reg); + MachineInstr *MI = RI.skipInstruction();) { + + // Debug values are not allowed to affect codegen. + if (MI->isDebugValue()) { + // Modify DBG_VALUE now that the value is in a spill slot. + uint64_t Offset = MI->getOperand(1).getImm(); + const MDNode *MDPtr = MI->getOperand(2).getMetadata(); + DebugLoc DL = MI->getDebugLoc(); + if (MachineInstr *NewDV = tii_.emitFrameIndexDebugValue(mf_, stackSlot_, + Offset, MDPtr, DL)) { + DEBUG(dbgs() << "Modifying debug info due to spill:" << "\t" << *MI); + MachineBasicBlock *MBB = MI->getParent(); + MBB->insert(MBB->erase(MI), NewDV); + } else { + DEBUG(dbgs() << "Removing debug info due to spill:" << "\t" << *MI); + MI->eraseFromParent(); + } + continue; + } + + // Stack slot accesses may coalesce away. + if (coalesceStackAccess(MI)) + continue; + + // Analyze instruction. + bool Reads, Writes; + SmallVector<unsigned, 8> Ops; + tie(Reads, Writes) = MI->readsWritesVirtualRegister(li->reg, &Ops); + + // Attempt to fold memory ops. + if (foldMemoryOperand(MI, Ops)) + continue; + + // Allocate interval around instruction. + // FIXME: Infer regclass from instruction alone. + unsigned NewVReg = mri_.createVirtualRegister(rc_); + vrm_.grow(); + LiveInterval &NewLI = lis_.getOrCreateInterval(NewVReg); + NewLI.markNotSpillable(); + + if (Reads) + insertReload(NewLI, MI); + + // Rewrite instruction operands. + bool hasLiveDef = false; + for (unsigned i = 0, e = Ops.size(); i != e; ++i) { + MachineOperand &MO = MI->getOperand(Ops[i]); + MO.setReg(NewVReg); + if (MO.isUse()) { + if (!MI->isRegTiedToDefOperand(Ops[i])) + MO.setIsKill(); + } else { + if (!MO.isDead()) + hasLiveDef = true; + } + } + + // FIXME: Use a second vreg if instruction has no tied ops. + if (Writes && hasLiveDef) + insertSpill(NewLI, MI); + + DEBUG(dbgs() << "\tinterval: " << NewLI << '\n'); + newIntervals.push_back(&NewLI); + } +} |
