X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FCodeGen%2FCalcSpillWeights.cpp;h=d08fae09323ca16c4a6bb2c3b614a86cc1ba894c;hb=12232769b3379924a24bf34a80770879ff2fb284;hp=5ace76c393ef8d91116f368588557fc9467608cd;hpb=2ab36d350293c77fc8941ce1023e4899df7e3a82;p=oota-llvm.git diff --git a/lib/CodeGen/CalcSpillWeights.cpp b/lib/CodeGen/CalcSpillWeights.cpp index 5ace76c393e..d08fae09323 100644 --- a/lib/CodeGen/CalcSpillWeights.cpp +++ b/lib/CodeGen/CalcSpillWeights.cpp @@ -7,52 +7,37 @@ // //===----------------------------------------------------------------------===// -#define DEBUG_TYPE "calcspillweights" - -#include "llvm/Function.h" -#include "llvm/ADT/SmallSet.h" #include "llvm/CodeGen/CalcSpillWeights.h" #include "llvm/CodeGen/LiveIntervalAnalysis.h" +#include "llvm/CodeGen/MachineBlockFrequencyInfo.h" #include "llvm/CodeGen/MachineFunction.h" #include "llvm/CodeGen/MachineLoopInfo.h" #include "llvm/CodeGen/MachineRegisterInfo.h" -#include "llvm/CodeGen/SlotIndexes.h" #include "llvm/Support/Debug.h" #include "llvm/Support/raw_ostream.h" #include "llvm/Target/TargetInstrInfo.h" -#include "llvm/Target/TargetMachine.h" #include "llvm/Target/TargetRegisterInfo.h" +#include "llvm/Target/TargetSubtargetInfo.h" using namespace llvm; -char CalculateSpillWeights::ID = 0; -INITIALIZE_PASS_BEGIN(CalculateSpillWeights, "calcspillweights", - "Calculate spill weights", false, false) -INITIALIZE_PASS_DEPENDENCY(LiveIntervals) -INITIALIZE_PASS_DEPENDENCY(MachineLoopInfo) -INITIALIZE_PASS_END(CalculateSpillWeights, "calcspillweights", - "Calculate spill weights", false, false) - -void CalculateSpillWeights::getAnalysisUsage(AnalysisUsage &au) const { - au.addRequired(); - au.addRequired(); - au.setPreservesAll(); - MachineFunctionPass::getAnalysisUsage(au); -} - -bool CalculateSpillWeights::runOnMachineFunction(MachineFunction &fn) { +#define DEBUG_TYPE "calcspillweights" +void llvm::calculateSpillWeightsAndHints(LiveIntervals &LIS, + MachineFunction &MF, + const MachineLoopInfo &MLI, + const MachineBlockFrequencyInfo &MBFI, + VirtRegAuxInfo::NormalizingFn norm) { DEBUG(dbgs() << "********** Compute Spill Weights **********\n" - << "********** Function: " - << fn.getFunction()->getName() << '\n'); - - LiveIntervals &lis = getAnalysis(); - VirtRegAuxInfo vrai(fn, lis, getAnalysis()); - for (LiveIntervals::iterator I = lis.begin(), E = lis.end(); I != E; ++I) { - LiveInterval &li = *I->second; - if (TargetRegisterInfo::isVirtualRegister(li.reg)) - vrai.CalculateWeightAndHint(li); + << "********** Function: " << MF.getName() << '\n'); + + MachineRegisterInfo &MRI = MF.getRegInfo(); + VirtRegAuxInfo VRAI(MF, LIS, MLI, MBFI, norm); + for (unsigned i = 0, e = MRI.getNumVirtRegs(); i != e; ++i) { + unsigned Reg = TargetRegisterInfo::index2VirtReg(i); + if (MRI.reg_nodbg_empty(Reg)) + continue; + VRAI.calculateSpillWeightAndHint(LIS.getInterval(Reg)); } - return false; } // Return the preferred allocation register for reg, given a COPY instruction. @@ -86,58 +71,93 @@ static unsigned copyHint(const MachineInstr *mi, unsigned reg, return tri.getMatchingSuperReg(hreg, sub, rc); } -void VirtRegAuxInfo::CalculateWeightAndHint(LiveInterval &li) { - MachineRegisterInfo &mri = mf_.getRegInfo(); - const TargetRegisterInfo &tri = *mf_.getTarget().getRegisterInfo(); - MachineBasicBlock *mbb = 0; - MachineLoop *loop = 0; - unsigned loopDepth = 0; +// Check if all values in LI are rematerializable +static bool isRematerializable(const LiveInterval &LI, + const LiveIntervals &LIS, + const TargetInstrInfo &TII) { + for (LiveInterval::const_vni_iterator I = LI.vni_begin(), E = LI.vni_end(); + I != E; ++I) { + const VNInfo *VNI = *I; + if (VNI->isUnused()) + continue; + if (VNI->isPHIDef()) + return false; + + MachineInstr *MI = LIS.getInstructionFromIndex(VNI->def); + assert(MI && "Dead valno in interval"); + + if (!TII.isTriviallyReMaterializable(MI, LIS.getAliasAnalysis())) + return false; + } + return true; +} + +void +VirtRegAuxInfo::calculateSpillWeightAndHint(LiveInterval &li) { + MachineRegisterInfo &mri = MF.getRegInfo(); + const TargetRegisterInfo &tri = *MF.getSubtarget().getRegisterInfo(); + MachineBasicBlock *mbb = nullptr; + MachineLoop *loop = nullptr; bool isExiting = false; float totalWeight = 0; + unsigned numInstr = 0; // Number of instructions using li SmallPtrSet visited; - // Find the best physreg hist and the best virtreg hint. + // Find the best physreg hint and the best virtreg hint. float bestPhys = 0, bestVirt = 0; unsigned hintPhys = 0, hintVirt = 0; // Don't recompute a target specific hint. bool noHint = mri.getRegAllocationHint(li.reg).first != 0; - for (MachineRegisterInfo::reg_iterator I = mri.reg_begin(li.reg); - MachineInstr *mi = I.skipInstruction();) { + // Don't recompute spill weight for an unspillable register. + bool Spillable = li.isSpillable(); + + for (MachineRegisterInfo::reg_instr_iterator + I = mri.reg_instr_begin(li.reg), E = mri.reg_instr_end(); + I != E; ) { + MachineInstr *mi = &*(I++); + numInstr++; if (mi->isIdentityCopy() || mi->isImplicitDef() || mi->isDebugValue()) continue; - if (!visited.insert(mi)) + if (!visited.insert(mi).second) continue; - // Get loop info for mi. - if (mi->getParent() != mbb) { - mbb = mi->getParent(); - loop = loops_.getLoopFor(mbb); - loopDepth = loop ? loop->getLoopDepth() : 0; - isExiting = loop ? loop->isLoopExiting(mbb) : false; + float weight = 1.0f; + if (Spillable) { + // Get loop info for mi. + if (mi->getParent() != mbb) { + mbb = mi->getParent(); + loop = Loops.getLoopFor(mbb); + isExiting = loop ? loop->isLoopExiting(mbb) : false; + } + + // Calculate instr weight. + bool reads, writes; + std::tie(reads, writes) = mi->readsWritesVirtualRegister(li.reg); + weight = LiveIntervals::getSpillWeight( + writes, reads, &MBFI, mi); + + // Give extra weight to what looks like a loop induction variable update. + if (writes && isExiting && LIS.isLiveOutOfMBB(li, mbb)) + weight *= 3; + + totalWeight += weight; } - // Calculate instr weight. - bool reads, writes; - tie(reads, writes) = mi->readsWritesVirtualRegister(li.reg); - float weight = LiveIntervals::getSpillWeight(writes, reads, loopDepth); - - // Give extra weight to what looks like a loop induction variable update. - if (writes && isExiting && lis_.isLiveOutOfMBB(li, mbb)) - weight *= 3; - - totalWeight += weight; - // Get allocation hints from copies. if (noHint || !mi->isCopy()) continue; unsigned hint = copyHint(mi, li.reg, tri, mri); if (!hint) continue; - float hweight = hint_[hint] += weight; + // Force hweight onto the stack so that x86 doesn't add hidden precision, + // making the comparison incorrectly pass (i.e., 1 > 1 == true??). + // + // FIXME: we probably shouldn't use floats at all. + volatile float hweight = Hint[hint] += weight; if (TargetRegisterInfo::isPhysicalRegister(hint)) { - if (hweight > bestPhys && lis_.isAllocatable(hint)) + if (hweight > bestPhys && mri.isAllocatable(hint)) bestPhys = hweight, hintPhys = hint; } else { if (hweight > bestVirt) @@ -145,84 +165,31 @@ void VirtRegAuxInfo::CalculateWeightAndHint(LiveInterval &li) { } } - hint_.clear(); + Hint.clear(); // Always prefer the physreg hint. if (unsigned hint = hintPhys ? hintPhys : hintVirt) { mri.setRegAllocationHint(li.reg, 0, hint); - // Weakly boost the spill weifght of hinted registers. + // Weakly boost the spill weight of hinted registers. totalWeight *= 1.01F; } + // If the live interval was already unspillable, leave it that way. + if (!Spillable) + return; + // Mark li as unspillable if all live ranges are tiny. - if (li.isZeroLength()) { + if (li.isZeroLength(LIS.getSlotIndexes())) { li.markNotSpillable(); return; } // If all of the definitions of the interval are re-materializable, - // it is a preferred candidate for spilling. If none of the defs are - // loads, then it's potentially very cheap to re-materialize. + // it is a preferred candidate for spilling. // FIXME: this gets much more complicated once we support non-trivial // re-materialization. - bool isLoad = false; - SmallVector spillIs; - if (lis_.isReMaterializable(li, spillIs, isLoad)) { - if (isLoad) - totalWeight *= 0.9F; - else - totalWeight *= 0.5F; - } + if (isRematerializable(li, LIS, *MF.getSubtarget().getInstrInfo())) + totalWeight *= 0.5F; - li.weight = totalWeight; - lis_.normalizeSpillWeight(li); -} - -void VirtRegAuxInfo::CalculateRegClass(unsigned reg) { - MachineRegisterInfo &mri = mf_.getRegInfo(); - const TargetRegisterInfo *tri = mf_.getTarget().getRegisterInfo(); - const TargetRegisterClass *orc = mri.getRegClass(reg); - SmallPtrSet rcs; - - for (MachineRegisterInfo::reg_nodbg_iterator I = mri.reg_nodbg_begin(reg), - E = mri.reg_nodbg_end(); I != E; ++I) { - // The targets don't have accurate enough regclass descriptions that we can - // handle subregs. We need something similar to - // TRI::getMatchingSuperRegClass, but returning a super class instead of a - // sub class. - if (I.getOperand().getSubReg()) { - DEBUG(dbgs() << "Cannot handle subregs: " << I.getOperand() << '\n'); - return; - } - if (const TargetRegisterClass *rc = - I->getDesc().getRegClass(I.getOperandNo(), tri)) - rcs.insert(rc); - } - - // If we found no regclass constraints, just leave reg as is. - // In theory, we could inflate to the largest superclass of reg's existing - // class, but that might not be legal for the current cpu setting. - // This could happen if reg is only used by COPY instructions, so we may need - // to improve on this. - if (rcs.empty()) { - return; - } - - // Compute the intersection of all classes in rcs. - // This ought to be independent of iteration order, but if the target register - // classes don't form a proper algebra, it is possible to get different - // results. The solution is to make sure the intersection of any two register - // classes is also a register class or the null set. - const TargetRegisterClass *rc = 0; - for (SmallPtrSet::iterator I = rcs.begin(), - E = rcs.end(); I != E; ++I) { - rc = rc ? getCommonSubClass(rc, *I) : *I; - assert(rc && "Incompatible regclass constraints found"); - } - - if (rc == orc) - return; - DEBUG(dbgs() << "Inflating " << orc->getName() << ":%reg" << reg << " to " - << rc->getName() <<".\n"); - mri.setRegClass(reg, rc); + li.weight = normalize(totalWeight, li.getSize(), numInstr); }