/// @param UseDefFreq Expected number of executed use and def instructions
/// per function call. Derived from block frequencies.
/// @param Size Size of live interval as returnexd by getSize()
+ /// @param NumInstr Number of instructions using this live interval
///
- static inline float normalizeSpillWeight(float UseDefFreq, unsigned Size) {
+ static inline float normalizeSpillWeight(float UseDefFreq, unsigned Size,
+ unsigned NumInstr) {
// The constant 25 instructions is added to avoid depending too much on
// accidental SlotIndex gaps for small intervals. The effect is that small
// intervals have a spill weight that is mostly proportional to the number
/// spill weight and allocation hint.
class VirtRegAuxInfo {
public:
- typedef float (*NormalizingFn)(float, unsigned);
+ typedef float (*NormalizingFn)(float, unsigned, unsigned);
private:
MachineFunction &MF;
MachineLoop *loop = nullptr;
bool isExiting = false;
float totalWeight = 0;
+ unsigned numInstr = 0; // Number of instructions using li
SmallPtrSet<MachineInstr*, 8> visited;
// Find the best physreg hint and the best virtreg hint.
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 (isRematerializable(li, LIS, *MF.getSubtarget().getInstrInfo()))
totalWeight *= 0.5F;
- li.weight = normalize(totalWeight, li.getSize());
+ li.weight = normalize(totalWeight, li.getSize(), numInstr);
}
// instructions.
//
// Try to guess the size of the new interval.
- const float EstWeight = normalizeSpillWeight(blockFreq * (NewGaps + 1),
- Uses[SplitBefore].distance(Uses[SplitAfter]) +
- (LiveBefore + LiveAfter)*SlotIndex::InstrDist);
+ const float EstWeight = normalizeSpillWeight(
+ blockFreq * (NewGaps + 1),
+ Uses[SplitBefore].distance(Uses[SplitAfter]) +
+ (LiveBefore + LiveAfter) * SlotIndex::InstrDist,
+ 1);
// Would this split be possible to allocate?
// Never allocate all gaps, we wouldn't be making progress.
DEBUG(dbgs() << " w=" << EstWeight);
void apply(PBQPRAGraph &G) override {
LiveIntervals &LIS = G.getMetadata().LIS;
+ // A minimum spill costs, so that register constraints can can be set
+ // without normalization in the [0.0:MinSpillCost( interval.
+ const PBQP::PBQPNum MinSpillCost = 10.0;
+
for (auto NId : G.nodeIds()) {
PBQP::PBQPNum SpillCost =
LIS.getInterval(G.getNodeMetadata(NId).getVReg()).weight;
if (SpillCost == 0.0)
SpillCost = std::numeric_limits<PBQP::PBQPNum>::min();
+ else
+ SpillCost += MinSpillCost;
PBQPRAGraph::RawVector NodeCosts(G.getNodeCosts(NId));
NodeCosts[PBQP::RegAlloc::getSpillOptionIdx()] = SpillCost;
G.setNodeCosts(NId, std::move(NodeCosts));
unsigned DstReg = CP.getDstReg();
unsigned SrcReg = CP.getSrcReg();
- const float CopyFactor = 0.5; // Cost of copy relative to load. Current
- // value plucked randomly out of the air.
-
- PBQP::PBQPNum CBenefit =
- CopyFactor * LiveIntervals::getSpillWeight(false, true, &MBFI, &MI);
+ const float Scale = 1.0f / MBFI.getEntryFreq();
+ PBQP::PBQPNum CBenefit = MBFI.getBlockFreq(&MBB).getFrequency() * Scale;
if (CP.isPhys()) {
if (!MF.getRegInfo().isAllocatable(DstReg))
}
}
+static inline float normalizePBQPSpillWeight(float UseDefFreq, unsigned Size,
+ unsigned NumInstr) {
+ // All intervals have a spill weight that is mostly proportional to the number
+ // of uses, with uses in loops having a bigger weight.
+ return NumInstr * normalizeSpillWeight(UseDefFreq, Size, 1);
+}
+
bool RegAllocPBQP::runOnMachineFunction(MachineFunction &MF) {
LiveIntervals &LIS = getAnalysis<LiveIntervals>();
MachineBlockFrequencyInfo &MBFI =
getAnalysis<MachineBlockFrequencyInfo>();
- calculateSpillWeightsAndHints(LIS, MF, getAnalysis<MachineLoopInfo>(), MBFI);
+ calculateSpillWeightsAndHints(LIS, MF, getAnalysis<MachineLoopInfo>(), MBFI,
+ normalizePBQPSpillWeight);
VirtRegMap &VRM = getAnalysis<VirtRegMap>();