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boots: prepare for allocating temporary registers
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@dinfuehr
dinfuehr committed Aug 30, 2023
1 parent d5155d6 commit 24723bf
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Showing 2 changed files with 150 additions and 44 deletions.
12 changes: 12 additions & 0 deletions dora-boots/graph.dora
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Original file line number Diff line number Diff line change
Expand Up @@ -1055,6 +1055,14 @@ impl LocationData {
self.output = Some(Location::fixedRegister(register));
}

pub fn requireTempRegister() {
self.temps.push(Location::someRegister());
}

pub fn requireTempFixedRegister(register: Register) {
self.output = Some(Location::fixedRegister(register));
}

pub fn requireOutputSameAsFirstInput() {
self.output = Some(Location::sameAsFirstInput());
}
Expand All @@ -1075,6 +1083,10 @@ impl LocationData {
self.inputs.get(idx).getOrPanic()
}

pub fn getTemps(): Vec[Location] {
self.temps
}

pub fn addTemp(temp: Location) {
self.temps.push(temp);
}
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182 changes: 138 additions & 44 deletions dora-boots/regalloc.dora
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Original file line number Diff line number Diff line change
Expand Up @@ -43,55 +43,22 @@ impl SimpleRegisterAllocator {

fn allocateRegisters() {
for block in self.graph.reversePostOrderIterator() {
self.setupTracker(block);
self.initializeInstTracker(block);
block.setTrackerIn(self.tracker.clone());

for inst in block.phisIterator() {
let loc = inst.getLocationData();

// pick a register
let register = self.tracker.allocateRegister(inst).getOrPanic();
loc.getOutput().setRegister(register);
self.allocatePhi(inst);
}

for inst in block.instructionsIterator() {
let loc = inst.getLocationData();
let mut idx = 0;

for input in inst.getInputs() {
let register = self.tracker.getRegister(input.getValue());
loc.getInput(idx).setRegister(register);
idx = idx + 1;
}

if loc.hasOutput() {
let output = loc.getOutput();

if output.hasRegister() {
// fixed register was already assigned
self.tracker.allocateFixedRegister(output.getRegister(), inst);
} else {
// pick a register
let register = self.tracker.allocateRegister(inst).getOrPanic();
output.setRegister(register);
}
}

for input in inst.getInputs() {
let value = input.getValue();

if value.getLastUse() === input {
self.tracker.free(value);
}
}

self.allocateInstruction(inst);
}

block.setTrackerOut(self.tracker);
}
}

fn setupTracker(block: Block) {
fn initializeInstTracker(block: Block) {
let dominator = block.getDominator();

if dominator.isNone() {
Expand All @@ -103,6 +70,100 @@ impl SimpleRegisterAllocator {
self.tracker = dominator.getTrackerOut().clone();
self.tracker.unionWithLiveIn(block);
}

fn allocatePhi(inst: Inst) {
// pick a register
let register = self.allocateArbitraryRegister(inst);
inst.getLocationData().getOutput().setRegister(register);
}

fn allocateInstruction(inst: Inst) {
self.allocateFixedRegisterInputs(inst);
self.allocateArbitraryRegisterInputs(inst);
self.allocateOutputRegister(inst);
self.freeDeadValues(inst);
}

fn allocateFixedRegisterInputs(inst: Inst) {
let loc = inst.getLocationData();

for input in inst.getInputs() {
let idx = input.getIdx().toInt64();

if loc.getInput(idx).hasRegister() {
unreachable[()]();
}
}

for temp in loc.getTemps() {
if temp.hasRegister() {
unreachable[()]();
}
}
}

fn allocateArbitraryRegisterInputs(inst: Inst) {
let loc = inst.getLocationData();

for input in inst.getInputs() {
let idx = input.getIdx().toInt64();

if !loc.getInput(idx).hasRegister() {
let register = self.allocateArbitraryRegister(input.getValue());
loc.getInput(idx).setRegister(register);
}
}

for temp in loc.getTemps() {
if !temp.hasRegister() {
unreachable[()]();
}
}
}

fn allocateOutputRegister(inst: Inst) {
let loc = inst.getLocationData();

if loc.hasOutput() {
let output = loc.getOutput();

if output.hasRegister() {
// fixed register was already assigned
self.allocateFixedRegister(inst, output.getRegister());
} else {
// pick a register
let register = self.tracker.allocateRegister(inst).getOrPanic();
output.setRegister(register);
}
}
}

fn freeDeadValues(inst: Inst) {
for input in inst.getInputs() {
let value = input.getValue();

if value.getLastUse() === input {
self.tracker.free(value);
}
}
}

fn ensureRegister(value: Inst): Register {
self.tracker.getRegister(value).getOrPanic()
}

fn allocateArbitraryRegister(inst: Inst): Register {
let register = self.tracker.getRegister(inst);
if register.isSome() {
return register.getOrPanic();
}
self.tracker.allocateRegister(inst).getOrPanic()
}

fn allocateFixedRegister(inst: Inst, reg: Register) {
assert(self.tracker.free.contains(reg));
self.tracker.allocateFixedRegister(reg, inst);
}
}

fn ssaDestruction(graph: Graph, codegen: CodeGen) {
Expand All @@ -129,7 +190,9 @@ fn ssaDestruction(graph: Graph, codegen: CodeGen) {
for inst in block.getLiveIn() {
let inst = inst.toInt32();
let sourceRegister = predecessorTracker.locations.get(inst).getOrPanic();
let sourceRegister = sourceRegister.toRegister().getOrPanic();
let destRegister = blockTracker.locations.get(inst).getOrPanic();
let destRegister = destRegister.toRegister().getOrPanic();
assert(sourceRegister == destRegister);
moves.add(destRegister, sourceRegister);
}
Expand All @@ -144,7 +207,7 @@ pub class InstTracker {
allocatable: RegSet,
free: RegSet,
data: RegMap[Int32],
locations: HashMap[Int32, Register],
locations: HashMap[Int32, InstLocation],
}

impl InstTracker {
Expand All @@ -153,7 +216,7 @@ impl InstTracker {
allocatable,
allocatable.clone(),
RegMap[Int32]::new(allocatable),
HashMap[Int32, Register]::new(),
HashMap[Int32, InstLocation]::new(),
)
}

Expand All @@ -172,26 +235,42 @@ impl InstTracker {
}
}

fn getRegister(inst: Inst): Register {
fn getLocation(inst: Inst): InstLocation {
self.locations.get(inst.id()).getOrPanic()
}

fn getRegister(inst: Inst): Option[Register] {
let location = self.locations.get(inst.id());

if location.isSome() {
location.getOrPanic().toRegister()
} else {
None[Register]
}
}

fn allocateFixedRegister(reg: Register, value: Inst) {
self.data.pick(reg, value.id());
self.locations.insert(value.id(), reg);
self.locations.insert(value.id(), InstLocation::Register(reg));
}

fn allocateRegister(value: Inst): Option[Register] {
let result = self.data.acquire(value.id());

if result.isSome() {
self.locations.insert(value.id(), result.getOrPanic());
let location = InstLocation::Register(result.getOrPanic());
self.locations.insert(value.id(), location);
}

result
}

fn free(inst: Inst) {
let reg = self.getRegister(inst);
self.data.free(reg);
if reg.isSome() {
self.data.free(reg.getOrPanic());
}

self.locations.remove(inst.id());
}

Expand All @@ -206,11 +285,26 @@ impl InstTracker {
}

enum InstLocation {
None,
Register(Register),
Stack(Int32),
}

impl InstLocation {
fn isRegister(): Bool {
match self {
InstLocation::Register(reg) => true,
InstLocation::Stack(stack) => false,
}
}

fn toRegister(): Option[Register] {
match self {
InstLocation::Register(reg) => Some(reg),
InstLocation::Stack(stack) => None,
}
}
}

class ParallelMoveResolver {
moves: Vec[(Register, Register)],
orderedMoves: Vec[(Register, Register)],
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