ghc-7.7.20120902: The GHC API

Safe HaskellNone

RegAlloc.Graph.ArchBase

Description

Utils for calculating general worst, bound, squeese and free, functions.

as per: A Generalized Algorithm for Graph-Coloring Register Allocation Michael Smith, Normal Ramsey, Glenn Holloway. PLDI 2004

These general versions are not used in GHC proper because they are too slow. Instead, hand written optimised versions are provided for each architecture in MachRegs*.hs

This code is here because we can test the architecture specific code against it.

Synopsis

Documentation

data Reg Source

A register of some class

Constructors

Reg RegClass Int 
RegSub RegSub Reg 

Instances

Eq Reg 
Show Reg 
Uniquable Reg

so we can put regs in UniqSets

data RegSub Source

A subcomponent of another register

Constructors

SubL16 
SubL8 
SubL8H 

worst :: (RegClass -> UniqSet Reg) -> (Reg -> UniqSet Reg) -> Int -> RegClass -> RegClass -> IntSource

Worst case displacement

a node N of classN has some number of neighbors, all of which are from classC.

(worst neighbors classN classC) is the maximum number of potential colors for N that can be lost by coloring its neighbors.

bound :: (RegClass -> UniqSet Reg) -> (Reg -> UniqSet Reg) -> RegClass -> [RegClass] -> IntSource

For a node N of classN and neighbors of classesC (bound classN classesC) is the maximum number of potential colors for N that can be lost by coloring its neighbors.

squeese :: (RegClass -> UniqSet Reg) -> (Reg -> UniqSet Reg) -> RegClass -> [(Int, RegClass)] -> IntSource

The total squeese on a particular node with a list of neighbors.

A version of this should be constructed for each particular architecture, possibly including uses of bound, so that alised registers don't get counted twice, as per the paper.