X-Git-Url: http://plrg.eecs.uci.edu/git/?p=oota-llvm.git;a=blobdiff_plain;f=lib%2FCodeGen%2FCalcSpillWeights.cpp;h=bf3882a6e3451b5fdf63fe7adc8eb8b70b663da2;hp=e5894b8cca9da558ad03970a17b3fad62cb85af6;hb=ab08da75d70c76fd946483e29366264c92cc092b;hpb=1394e6d9252ed188dbd73a59bcb4f15526641363 diff --git a/lib/CodeGen/CalcSpillWeights.cpp b/lib/CodeGen/CalcSpillWeights.cpp index e5894b8cca9..bf3882a6e34 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. @@ -86,17 +71,38 @@ static unsigned copyHint(const MachineInstr *mi, unsigned reg, return tri.getMatchingSuperReg(hreg, sub, rc); } -void VirtRegAuxInfo::CalculateWeightAndHint(LiveInterval &li) { +// 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.getTarget().getRegisterInfo(); - MachineBasicBlock *mbb = 0; - MachineLoop *loop = 0; - unsigned loopDepth = 0; + const TargetRegisterInfo &tri = *MF.getSubtarget().getRegisterInfo(); + MachineBasicBlock *mbb = nullptr; + MachineLoop *loop = nullptr; bool isExiting = false; float totalWeight = 0; 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; @@ -106,8 +112,10 @@ void VirtRegAuxInfo::CalculateWeightAndHint(LiveInterval &li) { // Don't recompute spill weight for an unspillable register. bool Spillable = li.isSpillable(); - for (MachineRegisterInfo::reg_iterator I = mri.reg_begin(li.reg); - MachineInstr *mi = I.skipInstruction();) { + for (MachineRegisterInfo::reg_instr_iterator + I = mri.reg_instr_begin(li.reg), E = mri.reg_instr_end(); + I != E; ) { + MachineInstr *mi = &*(I++); if (mi->isIdentityCopy() || mi->isImplicitDef() || mi->isDebugValue()) continue; if (!visited.insert(mi)) @@ -119,14 +127,14 @@ void VirtRegAuxInfo::CalculateWeightAndHint(LiveInterval &li) { if (mi->getParent() != mbb) { mbb = mi->getParent(); loop = Loops.getLoopFor(mbb); - loopDepth = loop ? loop->getLoopDepth() : 0; isExiting = loop ? loop->isLoopExiting(mbb) : false; } // Calculate instr weight. bool reads, writes; - tie(reads, writes) = mi->readsWritesVirtualRegister(li.reg); - weight = LiveIntervals::getSpillWeight(writes, reads, loopDepth); + 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)) @@ -141,9 +149,13 @@ void VirtRegAuxInfo::CalculateWeightAndHint(LiveInterval &li) { 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) @@ -165,51 +177,17 @@ void VirtRegAuxInfo::CalculateWeightAndHint(LiveInterval &li) { 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; - if (LIS.isReMaterializable(li, 0, isLoad)) { - if (isLoad) - totalWeight *= 0.9F; - else - totalWeight *= 0.5F; - } - - li.weight = normalizeSpillWeight(totalWeight, li.getSize()); -} + if (isRematerializable(li, LIS, *MF.getSubtarget().getInstrInfo())) + totalWeight *= 0.5F; -void VirtRegAuxInfo::CalculateRegClass(unsigned reg) { - MachineRegisterInfo &MRI = MF.getRegInfo(); - const TargetRegisterInfo *TRI = MF.getTarget().getRegisterInfo(); - const TargetRegisterClass *OldRC = MRI.getRegClass(reg); - const TargetRegisterClass *NewRC = TRI->getLargestLegalSuperClass(OldRC); - - // Stop early if there is no room to grow. - if (NewRC == OldRC) - return; - - // Accumulate constraints from all uses. - for (MachineRegisterInfo::reg_nodbg_iterator I = MRI.reg_nodbg_begin(reg), - E = MRI.reg_nodbg_end(); I != E; ++I) { - // TRI doesn't have accurate enough information to model this yet. - if (I.getOperand().getSubReg()) - return; - const TargetRegisterClass *OpRC = - I->getDesc().getRegClass(I.getOperandNo(), TRI); - if (OpRC) - NewRC = getCommonSubClass(NewRC, OpRC); - if (!NewRC || NewRC == OldRC) - return; - } - DEBUG(dbgs() << "Inflating " << OldRC->getName() << ':' << PrintReg(reg) - << " to " << NewRC->getName() <<".\n"); - MRI.setRegClass(reg, NewRC); + li.weight = normalize(totalWeight, li.getSize()); }