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107 lines
2.9 KiB
107 lines
2.9 KiB
import { colorGreedy, createGraph, Graph, maxCardinalitySearch } from "./data/graph"
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import { setEquals, union } from "./data/set"
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import { BasicBlock } from "./ir/block"
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import { Loc } from "./ir/loc"
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import { StackOffset } from "./sm83/cpu"
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export type LivenessInfo = Array<Set<Loc>>
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export const liveness = (block: BasicBlock): LivenessInfo => {
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const info: LivenessInfo = []
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info[block.insns.length] = new Set()
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for (let i = block.insns.length - 1; i >= 0; --i) {
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const insn = block.insns[i]
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const last = info[i + 1]
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info[i] = new Set()
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if (insn.type === "goto") {
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continue
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}
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if ("source" in insn && typeof insn.source !== "number") {
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info[i].add(insn.source)
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}
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last.forEach(loc => {
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if (insn.dest instanceof Loc && loc.ppName() === insn.dest.ppName()) {
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return
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}
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info[i].add(loc)
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})
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}
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let dirty = true
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while (dirty) {
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dirty = false
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for (let i = block.insns.length - 1; i >= 0; --i) {
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if (block.insns[i].type !== "goto") {
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continue
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}
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const labelSet = info[block.labels[block.insns[i].dest as string]]
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if (setEquals(info[i], labelSet)) {
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continue
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}
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dirty = true
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info[i] = union(info[i], labelSet)
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}
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}
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return info
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}
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export const interference = (block: BasicBlock, live: LivenessInfo): Graph<Loc> =>
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createGraph((v, e) => {
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block.locs().forEach(loc => {
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v(loc.ppName(), loc)
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})
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block.insns.forEach((insn, i) =>
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live[i + 1].forEach(u => {
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if (insn.dest instanceof Loc && insn.dest.ppName() !== u.ppName()) {
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e(insn.dest.ppName(), u.ppName())
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}
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})
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)
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})
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export type RegAlloc = {
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[s: string]: string | StackOffset,
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}
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export const allocateRegisters = (block: BasicBlock, registers: Array<string>): RegAlloc => {
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const info = liveness(block)
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const graph = interference(block, info)
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const ordering = maxCardinalitySearch(graph)
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const coloring = colorGreedy(graph, ordering)
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const allocation: RegAlloc = {}
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const availableRegisters = new Set(registers)
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const colorMap: { [c: number]: string | StackOffset } = {}
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let nextStackOffset = 0
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Object.entries(coloring.colors).forEach(([vertex, color]) => {
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if (typeof colorMap[color] !== 'undefined') {
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allocation[vertex] = colorMap[color]
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return
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}
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let value = null
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if (availableRegisters.size == 0) {
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value = { offset: nextStackOffset++ }
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} else {
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const result = availableRegisters.values().next()
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value = result.value
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availableRegisters.delete(value)
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}
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allocation[vertex] = value
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colorMap[color] = value
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})
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return allocation
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}
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