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095f994ba6
Besides, this relates it more obviously to the VirtRegAuxInfo::calculateSpillWeightAndHint. No functionnal change. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194404 91177308-0d34-0410-b5e6-96231b3b80d8
69 lines
2.5 KiB
C++
69 lines
2.5 KiB
C++
//===---------------- lib/CodeGen/CalcSpillWeights.h ------------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_CODEGEN_CALCSPILLWEIGHTS_H
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#define LLVM_CODEGEN_CALCSPILLWEIGHTS_H
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#include "llvm/ADT/DenseMap.h"
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#include "llvm/CodeGen/SlotIndexes.h"
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namespace llvm {
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class LiveInterval;
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class LiveIntervals;
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class MachineBlockFrequencyInfo;
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class MachineLoopInfo;
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/// \brief Normalize the spill weight of a live interval
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///
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/// The spill weight of a live interval is computed as:
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///
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/// (sum(use freq) + sum(def freq)) / (K + size)
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///
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/// @param UseDefFreq Expected number of executed use and def instructions
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/// per function call. Derived from block frequencies.
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/// @param Size Size of live interval as returnexd by getSize()
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///
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static inline float normalizeSpillWeight(float UseDefFreq, unsigned Size) {
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// The constant 25 instructions is added to avoid depending too much on
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// accidental SlotIndex gaps for small intervals. The effect is that small
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// intervals have a spill weight that is mostly proportional to the number
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// of uses, while large intervals get a spill weight that is closer to a use
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// density.
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return UseDefFreq / (Size + 25*SlotIndex::InstrDist);
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}
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/// \brief Calculate auxiliary information for a virtual register such as its
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/// spill weight and allocation hint.
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class VirtRegAuxInfo {
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MachineFunction &MF;
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LiveIntervals &LIS;
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const MachineLoopInfo &Loops;
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const MachineBlockFrequencyInfo &MBFI;
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DenseMap<unsigned, float> Hint;
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public:
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VirtRegAuxInfo(MachineFunction &mf, LiveIntervals &lis,
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const MachineLoopInfo &loops,
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const MachineBlockFrequencyInfo &mbfi)
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: MF(mf), LIS(lis), Loops(loops), MBFI(mbfi) {}
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/// \brief (re)compute li's spill weight and allocation hint.
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void calculateSpillWeightAndHint(LiveInterval &li);
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};
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/// \brief Compute spill weights and allocation hints for all virtual register
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/// live intervals.
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void calculateSpillWeightsAndHints(LiveIntervals &LIS, MachineFunction &MF,
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const MachineLoopInfo &MLI,
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const MachineBlockFrequencyInfo &MBFI);
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}
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#endif // LLVM_CODEGEN_CALCSPILLWEIGHTS_H
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