ghc-9.4.0.20220721: The GHC API
Safe HaskellSafe-Inferred
LanguageHaskell2010

GHC.CmmToAsm.Reg.Graph.Base

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

Instances details
Show Reg Source # 
Instance details

Defined in GHC.CmmToAsm.Reg.Graph.Base

Uniquable Reg Source #

so we can put regs in UniqSets

Instance details

Defined in GHC.CmmToAsm.Reg.Graph.Base

Methods

getUnique :: Reg -> Unique Source #

Eq Reg Source # 
Instance details

Defined in GHC.CmmToAsm.Reg.Graph.Base

Methods

(==) :: Reg -> Reg -> Bool #

(/=) :: Reg -> Reg -> Bool #

data RegSub Source #

A subcomponent of another register

Constructors

SubL16 
SubL8 
SubL8H 

worst :: (RegClass -> UniqSet Reg) -> (Reg -> UniqSet Reg) -> Int -> RegClass -> RegClass -> Int Source #

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.

This should be hand coded/cached for each particular architecture, because the compute time is very long..

bound :: (RegClass -> UniqSet Reg) -> (Reg -> UniqSet Reg) -> RegClass -> [RegClass] -> Int Source #

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)] -> Int Source #

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 aliased registers don't get counted twice, as per the paper.