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When splitting a live range, the new registers have fewer uses and the permissible register class may be less constrained. Recompute the register class constraint from the uses of new registers created for a split. This may let them be allocated from a larger set, possibly avoiding a spill. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@110703 91177308-0d34-0410-b5e6-96231b3b80d8
65 lines
2.0 KiB
C++
65 lines
2.0 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/CodeGen/MachineFunctionPass.h"
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#include "llvm/ADT/DenseMap.h"
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namespace llvm {
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class LiveInterval;
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class LiveIntervals;
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class MachineLoopInfo;
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/// VirtRegAuxInfo - Calculate auxiliary information for a virtual
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/// register such as its 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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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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mf_(mf), lis_(lis), loops_(loops) {}
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/// CalculateRegClass - recompute the register class for reg from its uses.
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/// Since the register class can affect the allocation hint, this function
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/// should be called before CalculateWeightAndHint if both are called.
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void CalculateRegClass(unsigned reg);
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/// CalculateWeightAndHint - (re)compute li's spill weight and allocation
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/// hint.
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void CalculateWeightAndHint(LiveInterval &li);
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};
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/// CalculateSpillWeights - Compute spill weights for all virtual register
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/// live intervals.
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class CalculateSpillWeights : public MachineFunctionPass {
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public:
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static char ID;
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CalculateSpillWeights() : MachineFunctionPass(ID) {}
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virtual void getAnalysisUsage(AnalysisUsage &au) const;
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virtual bool runOnMachineFunction(MachineFunction &fn);
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private:
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/// Returns true if the given live interval is zero length.
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bool isZeroLengthInterval(LiveInterval *li) const;
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};
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}
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#endif // LLVM_CODEGEN_CALCSPILLWEIGHTS_H
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