struct SpillPlacement::Node

Declaration

struct SpillPlacement::Node { /* full declaration omitted */ };

Description

Node - Each edge bundle corresponds to a Hopfield node. The node contains precomputed frequency data that only depends on the CFG, but Bias and Links are computed each time placeSpills is called. The node Value is positive when the variable should be in a register. The value can change when linked nodes change, but convergence is very fast because all weights are positive.

Declared at: llvm/lib/CodeGen/SpillPlacement.cpp:79

Member Variables

public llvm::BlockFrequency BiasN

BiasN - Sum of blocks that prefer a spill.

public llvm::BlockFrequency BiasP

BiasP - Sum of blocks that prefer a register.

public int Value

Value - Output value of this node computed from the Bias and links. This is always on of the values {-1, 0, 1}. A positive number means the variable should go in a register through this bundle.

public llvm::SpillPlacement::Node::LinkVector Links

Links - (Weight, BundleNo) for all transparent blocks connecting to other bundles. The weights are all positive block frequencies.

public llvm::BlockFrequency SumLinkWeights

SumLinkWeights - Cached sum of the weights of all links + ThresHold.

Method Overview

• public void addBias(llvm::BlockFrequency freq, llvm::SpillPlacement::BorderConstraint direction)
• public void addLink(unsigned int b, llvm::BlockFrequency w)
• public void clear(const llvm::BlockFrequency & Threshold)
• public void getDissentingNeighbors(SparseSet<unsigned int> & List, const llvm::SpillPlacement::Node * nodes) const
• public bool mustSpill() const
• public bool preferReg() const
• public bool update(const llvm::SpillPlacement::Node * nodes, const llvm::BlockFrequency & Threshold)

Methods

¶void addBias(
    llvm::BlockFrequency freq,
    llvm::SpillPlacement::BorderConstraint
        direction)

Description

addBias - Bias this node.

Declared at: llvm/lib/CodeGen/SpillPlacement.cpp:138

Parameters

llvm::BlockFrequency freq

llvm::SpillPlacement::BorderConstraint direction

¶void addLink(unsigned int b,
             llvm::BlockFrequency w)

Description

addLink - Add a link to bundle b with weight w.

Declared at: llvm/lib/CodeGen/SpillPlacement.cpp:123

Parameters

unsigned int b

llvm::BlockFrequency w

¶void clear(const llvm::BlockFrequency& Threshold)

Description

clear - Reset per-query data, but preserve frequencies that only depend on the CFG.

Declared at: llvm/lib/CodeGen/SpillPlacement.cpp:116

Parameters

const llvm::BlockFrequency& Threshold

¶void getDissentingNeighbors(
    SparseSet<unsigned int>& List,
    const llvm::SpillPlacement::Node* nodes) const

Declared at: llvm/lib/CodeGen/SpillPlacement.cpp:185

Parameters

SparseSet<unsigned int>& List

const llvm::SpillPlacement::Node* nodes

¶bool mustSpill() const

Description

mustSpill - Return True if this node is so biased that it must spill.

Declared at: llvm/lib/CodeGen/SpillPlacement.cpp:107

¶bool preferReg() const

Description

preferReg - Return true when this node prefers to be in a register.

Declared at: llvm/lib/CodeGen/SpillPlacement.cpp:101

¶bool update(
    const llvm::SpillPlacement::Node* nodes,
    const llvm::BlockFrequency& Threshold)

Description

update - Recompute Value from Bias and Links. Return true when node preference changes.

Declared at: llvm/lib/CodeGen/SpillPlacement.cpp:156

Parameters

const llvm::SpillPlacement::Node* nodes

const llvm::BlockFrequency& Threshold