import type { SSA, SSABinary, SSACopy, SSAUnary } from "./ir"
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const reg8 = ["B", "C", "D", "E"] as const
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type R8 = typeof reg8[number]
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class ASMState {
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regs: { [r in R8]: string | null }
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syms: { [s: string]: R8 }
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stack_offsets: { [s: string]: number }
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cur_offset: number
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insns: Array<string>
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constructor() {
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this.regs = { "B": null, "C": null, "D": null, "E": null }
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this.syms = {}
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this.stack_offsets = {}
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this.cur_offset = 0
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this.insns = []
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}
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// TODO: Generalize for u16
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get_sym_loc(sym: string): R8 | number | null {
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// return register if already allocated
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if (typeof this.syms[sym] !== "undefined") {
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return this.syms[sym]
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}
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// return stack offset if already allocated
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if (typeof this.stack_offsets[sym] !== "undefined") {
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return this.cur_offset - this.stack_offsets[sym]
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}
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return null
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}
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alloc_sym_loc(sym: string): R8 | number {
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const existing_loc = this.get_sym_loc(sym)
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if (existing_loc !== null) {
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return existing_loc
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}
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// look for free register
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for (const r8 of reg8) {
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if (this.regs[r8] === null) {
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this.regs[r8] = sym
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this.syms[sym] = r8
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return r8
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}
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}
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// allocate space on stack
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this.cur_offset++
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this.stack_offsets[sym] = this.cur_offset
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this.insns.push("ADD SP, -1")
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return this.stack_offsets[sym]
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}
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}
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export const convertASM = (ir: Array<SSA>): Array<string> => {
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const state = new ASMState()
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ir.forEach(ssa => convertASM_SSA(state, ssa))
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for (let sym of Object.keys(state.syms)) {
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if (sym.startsWith("temp")) {
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continue
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}
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state.insns.push(
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`LD A, ${state.syms[sym]}`,
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`LD (${sym}), A`
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)
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}
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for (let sym of Object.keys(state.stack_offsets)) {
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if (sym.startsWith("temp")) {
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continue
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}
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state.insns.push(
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`LD HL, SP + (${state.cur_offset - state.stack_offsets[sym]})`,
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`LD A, (HL)`,
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`LD (${sym}), A`
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)
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}
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if (state.cur_offset !== 0) {
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state.insns.push(`ADD SP, ${state.cur_offset}`)
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}
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return state.insns
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}
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// TODO: Track liveness
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const convertASM_SSA = (state: ASMState, ssa: SSA): void => {
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if ("source1" in ssa) { // Binary
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convertASM_SSA_Binary(state, ssa)
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} else if ("op" in ssa) { // Unary
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convertASM_SSA_Unary(state, ssa)
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} else { // Copy
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convertASM_SSA_Copy(state, ssa)
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}
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}
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export const convertASM_SSA_Binary = (state: ASMState, ssa: SSABinary): void => {
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const dest = state.alloc_sym_loc(ssa.dest)
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}
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export const convertASM_SSA_Unary = (state: ASMState, ssa: SSAUnary): void => {
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const dest = state.alloc_sym_loc(ssa.dest)
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if (typeof ssa.source == "number") {
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state.insns.push(`LD A, ${ssa.source}`)
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} else {
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const loc = state.get_sym_loc(ssa.source)
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if (loc === null) {
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state.insns.push(`LD A, (${ssa.source})`)
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} else if (typeof loc === "string") {
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state.insns.push(`LD A, ${loc}`)
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} else {
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state.insns.push(
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`LD HL, SP + (${loc})`,
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`LD A, (HL)`
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)
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}
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}
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switch (ssa.op) {
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case 'arith_negate':
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state.insns.push(
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`CPL`,
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`INC A`,
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)
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break
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case 'bit_negate':
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state.insns.push(
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`CPL`
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)
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break
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default:
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throw new Error(`unsupported unary op \`'${ssa.op}`)
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}
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if (typeof dest === "string") {
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state.insns.push(`LD ${dest}, A`)
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} else {
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state.insns.push(
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`LD HL, SP + (${dest})`,
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`LD (HL), A`
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)
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}
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}
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export const convertASM_SSA_Copy = (state: ASMState, ssa: SSACopy): void => {
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const dest = state.alloc_sym_loc(ssa.dest)
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let source = ""
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if (typeof ssa.source == "number") {
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source = ssa.source.toString()
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} else {
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const loc = state.get_sym_loc(ssa.source)
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if (loc === null) {
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state.insns.push(`LD A, (${ssa.source})`)
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source = "A"
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} else if (typeof loc === "string") {
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source = loc
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} else {
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state.insns.push(
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`LD HL, SP + (${loc})`,
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`LD A, (HL)`
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)
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source = "A"
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}
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}
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if (typeof dest === "string") {
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state.insns.push(`LD ${dest}, ${source}`)
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} else {
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state.insns.push(
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`LD HL, SP + (${dest})`,
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`LD (HL), ${source}`
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)
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}
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}
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