gbuoy/lib/regalloc.ts

import { createGraph, Graph } from "./data/graph"

import type { Loc } from "./ir/loc"
import type { SSA } from "./ir/ssa"

export type LivenessInfo = Array<Set<Loc>>

export const liveness = (block: Array<SSA>): LivenessInfo => {
    const info: LivenessInfo = []

    info[block.length] = new Set()
    for (let i = block.length - 1; i >= 0; --i) {
        const insn = block[i]
        const last = info[i + 1]

        info[i] = new Set()

        if (typeof insn.source !== "number") {
            info[i].add(insn.source)
        }

        if ("source1" in insn && typeof insn.source1 !== "number") {
            info[i].add(insn.source1)
        }

        last.forEach(loc => {
            if (loc.toString() === insn.dest.toString()) {
                return
            }

            info[i].add(loc)
        })
    }

    return info
}

export const locations = (block: Array<SSA>): Set<Loc> => {
    const ls: Set<Loc> = new Set()

    block.forEach(ssa => {
        if ("source1" in ssa && typeof ssa.source1 !== "number") {
            ls.add(ssa.source1)
        } else if (typeof ssa.source !== "number") {
            ls.add(ssa.source)
        }
    })

    return ls
}

export const interference = (block: Array<SSA>, live: LivenessInfo): Graph<Loc> =>
    createGraph((v, e) => {
        block.forEach((ssa, i) =>
            live[i + 1].forEach(u => {
                if (ssa.dest.toString() !== u.toString()) {
                    v(ssa.dest.toString(), ssa.dest)
                    v(u.toString(), u)
                    e(ssa.dest.toString(), u.toString())
                }
            })
        )
    })