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Merged
LPTK merged 3 commits into from
Dec 10, 2025
Merged

Improve codegen slightly #362

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aaabc6f
Use switch whenver possible
AnsonYeung Dec 9, 2025
ab7b2f9
Do not convert simple equality checks to switches
LPTK Dec 9, 2025
b2a65b5
Add a couple of smart constructors without much effect
LPTK Dec 9, 2025
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30 changes: 30 additions & 0 deletions hkmc2/shared/src/main/scala/hkmc2/codegen/Block.scala
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Expand Up @@ -29,6 +29,19 @@ sealed abstract class Block extends Product:
case _: End => true
case _ => false

lazy val isAbortive: Bool = this match
case _: End => false
case _: Throw | _: Break | _: Continue => true
case ret: Return => !ret.implct
case Begin(sub, rst) => sub.isAbortive || rst.isAbortive
case Assign(_, _, rst) => rst.isAbortive
case AssignField(_, _, _, rst) => rst.isAbortive
case AssignDynField(_, _, _, _, rst) => rst.isAbortive
case Match(_, arms, dflt, rst) => rst.isAbortive
case Define(_, rst) => rst.isAbortive
case TryBlock(sub, fin, rst) => rst.isAbortive || sub.isAbortive || fin.isAbortive
case Label(_, _, bod, rst) => rst.isAbortive
case HandleBlock(_, _, _, _, _, handlers, body, rst) => rst.isAbortive

lazy val definedVars: Set[Local] = this match
case _: Return | _: Throw => Set.empty
Expand Down Expand Up @@ -287,6 +300,23 @@ case class AssignDynField(lhs: Path, fld: Path, arrayIdx: Bool, rhs: Result, res
case class Define(defn: Defn, rest: Block) extends Block with ProductWithTail


object Match:
def apply(scrut: Path, arms: Ls[Case -> Block], dflt: Opt[Block], rest: Block): Block = dflt match
case S(Match(`scrut`, arms2, dflt2, _: End)) => // TODO: also handle non-End rest (may require a join point)
// * Currently, this branch does not seem used, because the UCS already does a good job at merging matches
Match(scrut, arms ::: arms2, dflt2, rest)
case _ =>
if !rest.isEmpty && arms.forall(_._2.isAbortive) && dflt.exists(_.isAbortive)
then new Match(scrut, arms, dflt, End("unreachable"))
else new Match(scrut, arms, dflt, rest)

object Begin:
def apply(sub: Block, rest: Block): Block =
if sub.isEmpty then rest
else if sub.isAbortive then sub
else new Begin(sub, rest)


case class HandleBlock(
lhs: Local,
res: Local,
Expand Down
11 changes: 11 additions & 0 deletions hkmc2/shared/src/main/scala/hkmc2/codegen/js/JSBuilder.scala
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Expand Up @@ -447,6 +447,17 @@ class JSBuilder(using TL, State, Ctx) extends CodeBuilder:
case S(el) => returningTerm(el, endSemi = true)
case N => doc""
e :: returningTerm(rest, endSemi)
case Match(scrut, arms, els, rest)
if arms.sizeCompare(1) > 0 && arms.forall(_._1.isInstanceOf[Case.Lit]) =>
val l = arms.foldLeft(doc""): (acc, arm) =>
acc :: doc" # case ${arm._1.asInstanceOf[Case.Lit].lit.idStr}: #{ ${
returningTerm(arm._2, endSemi = true)
} # break; #} "
val e = els match
case S(el) =>
doc" # default: #{ ${ returningTerm(el, endSemi = true) } # break; #} "
case N => doc""
doc" # switch (${result(scrut)}) { #{ ${l :: e} #} # }" :: returningTerm(rest, endSemi)
case Match(scrut, hd :: tl, els, rest) =>
val sd = result(scrut)
def cond(cse: Case) = cse match
Expand Down
16 changes: 10 additions & 6 deletions hkmc2/shared/src/test/mlscript/bbml/bbCodeGen.mls
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Expand Up @@ -176,12 +176,16 @@ fun nott = case
//│ nott = function nott() {
//│ let lambda1;
//│ lambda1 = (undefined, function (caseScrut) {
//│ if (caseScrut === true) {
//│ return false
//│ } else if (caseScrut === false) {
//│ return true
//│ } else {
//│ throw globalThis.Object.freeze(new globalThis.Error("match error"))
//│ switch (caseScrut) {
//│ case true:
//│ return false;
//│ break;
//│ case false:
//│ return true;
//│ break;
//│ default:
//│ throw globalThis.Object.freeze(new globalThis.Error("match error"));
//│ break;
//│ }
//│ });
//│ return lambda1
Expand Down
22 changes: 11 additions & 11 deletions hkmc2/shared/src/test/mlscript/codegen/IfThenElse.mls
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Expand Up @@ -9,12 +9,12 @@ if true then 1 else 0
:sjs
let f = x => if x then print("ok") else print("ko")
//│ JS (unsanitized):
//│ let f, lambda;
//│ lambda = (undefined, function (x) {
//│ let f, f1;
//│ f1 = function f(x) {
//│ if (x === true) { return Predef.print("ok") } else { return Predef.print("ko") }
//│ });
//│ f = lambda;
//│ f = fun
//│ };
//│ f = f1;
//│ f = fun f

f(true)
//│ > ok
Expand All @@ -26,31 +26,31 @@ f(false)
:sjs
let f = x => print((if x then "ok" else "ko") + "!")
//│ JS (unsanitized):
//│ let f1, lambda1;
//│ lambda1 = (undefined, function (x) {
//│ let f2, lambda;
//│ lambda = (undefined, function (x) {
//│ let tmp, tmp1;
//│ if (x === true) {
//│ tmp = "ok";
//│ } else { tmp = "ko"; }
//│ tmp1 = tmp + "!";
//│ return Predef.print(tmp1)
//│ });
//│ f1 = lambda1;
//│ f2 = lambda;
//│ f = fun

:sjs
let f = x => print((if x and x then "ok" else "ko") + "!")
//│ JS (unsanitized):
//│ let f2, lambda2;
//│ lambda2 = (undefined, function (x) {
//│ let f3, lambda1;
//│ lambda1 = (undefined, function (x) {
//│ let tmp, tmp1;
//│ if (x === true) {
//│ tmp = "ok";
//│ } else { tmp = "ko"; }
//│ tmp1 = tmp + "!";
//│ return Predef.print(tmp1)
//│ });
//│ f2 = lambda2;
//│ f3 = lambda1;
//│ f = fun
// --- TODO: What we want ---
// this.f = (x) => {
Expand Down
8 changes: 4 additions & 4 deletions hkmc2/shared/src/test/mlscript/codegen/PartialApps.mls
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Expand Up @@ -225,17 +225,17 @@ _ - _ of 1, 2
:sjs
1 \ (_ - 2)
//│ JS (unsanitized):
//│ let lambda38; lambda38 = (undefined, function (_0) { return _0 - 2 }); Predef.passTo(1, lambda38)
//│ let lambda37; lambda37 = (undefined, function (_0) { return _0 - 2 }); Predef.passTo(1, lambda37)
//│ = fun

:sjs
1 \ (_ - 2)()
//│ JS (unsanitized):
//│ let lambda39, tmp19;
//│ lambda39 = (undefined, function (_0) {
//│ let lambda38, tmp19;
//│ lambda38 = (undefined, function (_0) {
//│ return _0 - 2
//│ });
//│ tmp19 = Predef.passTo(1, lambda39);
//│ tmp19 = Predef.passTo(1, lambda38);
//│ runtime.safeCall(tmp19())
//│ = -1

Expand Down
16 changes: 16 additions & 0 deletions hkmc2/shared/src/test/mlscript/codegen/Throw.mls
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Expand Up @@ -47,3 +47,19 @@ f(false)
//│ };
//│ f3(false)
//│ ═══[RUNTIME ERROR] Error: y


:re
:sjs
if false then throw 0
throw 1
//│ JS (unsanitized):
//│ let scrut;
//│ scrut = false;
//│ if (scrut === true) {
//│ throw 0
//│ } else { throw globalThis.Object.freeze(new globalThis.Error("match error")) }
//│ /* unreachable */
//│ ═══[RUNTIME ERROR] Error: match error


2 changes: 1 addition & 1 deletion hkmc2/shared/src/test/mlscript/codegen/While.mls
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Expand Up @@ -17,7 +17,7 @@
//│ } else {
//│ throw globalThis.Object.freeze(new globalThis.Error("match error"))
//│ }
//│ return runtime.LoopEnd
//│ /* unreachable */
//│ });
//│ tmp1 = while1();
//│ tmp2 = tmp1 !== runtime.LoopEnd;
Expand Down
103 changes: 58 additions & 45 deletions hkmc2/shared/src/test/mlscript/handlers/Debugging.mls
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Expand Up @@ -53,44 +53,53 @@ fun f() =
//│ this.pc = pc;
//│ }
//│ resume(value$) {
//│ if (this.pc === 1) {
//│ scrut = value$;
//│ } else if (this.pc === 2) {
//│ tmp = value$;
//│ } else if (this.pc === 3) {
//│ tmp1 = value$;
//│ switch (this.pc) {
//│ case 1:
//│ scrut = value$;
//│ break;
//│ case 2:
//│ tmp = value$;
//│ break;
//│ case 3:
//│ tmp1 = value$;
//│ break;
//│ }
//│ contLoop: while (true) {
//│ if (this.pc === 4) {
//│ return j / i
//│ } else if (this.pc === 1) {
//│ if (scrut === true) {
//│ tmp = Predef.raiseUnhandledEffect();
//│ if (tmp instanceof runtime.EffectSig.class) {
//│ return this.doUnwind(tmp, 2)
//│ switch (this.pc) {
//│ case 4:
//│ return j / i;
//│ break;
//│ case 1:
//│ if (scrut === true) {
//│ tmp = Predef.raiseUnhandledEffect();
//│ if (tmp instanceof runtime.EffectSig.class) {
//│ return this.doUnwind(tmp, 2)
//│ }
//│ this.pc = 2;
//│ continue contLoop
//│ } else {
//│ tmp1 = runtime.Unit;
//│ this.pc = 4;
//│ continue contLoop
//│ }
//│ this.pc = 2;
//│ continue contLoop
//│ } else {
//│ tmp1 = runtime.Unit;
//│ /* unreachable */
//│ break;
//│ case 5:
//│ tmp1 = Predef.print(tmp);
//│ if (tmp1 instanceof runtime.EffectSig.class) {
//│ return this.doUnwind(tmp1, 3)
//│ }
//│ this.pc = 3;
//│ continue contLoop;
//│ break;
//│ case 2:
//│ this.pc = 5;
//│ continue contLoop;
//│ break;
//│ case 3:
//│ this.pc = 4;
//│ continue contLoop
//│ }
//│ this.pc = 4;
//│ continue contLoop
//│ } else if (this.pc === 5) {
//│ tmp1 = Predef.print(tmp);
//│ if (tmp1 instanceof runtime.EffectSig.class) {
//│ return this.doUnwind(tmp1, 3)
//│ }
//│ this.pc = 3;
//│ continue contLoop
//│ } else if (this.pc === 2) {
//│ this.pc = 5;
//│ continue contLoop
//│ } else if (this.pc === 3) {
//│ this.pc = 4;
//│ continue contLoop
//│ continue contLoop;
//│ break;
//│ }
//│ break;
//│ }
Expand All @@ -99,12 +108,16 @@ fun f() =
//│ return getLocals3();
//│ }
//│ get getLoc() {
//│ if (this.pc === 1) {
//│ return "Debugging.mls:16:6"
//│ } else if (this.pc === 2) {
//│ return "Debugging.mls:17:14"
//│ } else if (this.pc === 3) {
//│ return "Debugging.mls:17:5"
//│ switch (this.pc) {
//│ case 1:
//│ return "Debugging.mls:16:6";
//│ break;
//│ case 2:
//│ return "Debugging.mls:17:14";
//│ break;
//│ case 3:
//│ return "Debugging.mls:17:5";
//│ break;
//│ }
//│ }
//│ toString() { return runtime.render(this); }
Expand Down Expand Up @@ -148,8 +161,8 @@ lambda_test(() =>
raiseUnhandledEffect()
100)
//│ ═══[RUNTIME ERROR] Error: Unhandled effect FatalEffect
//│ at lambda (Debugging.mls:148:3)
//│ at lambda_test (Debugging.mls:145:3)
//│ at lambda (Debugging.mls:161:3)
//│ at lambda_test (Debugging.mls:158:3)


import "../../mlscript-compile/Runtime.mls"
Expand Down Expand Up @@ -228,9 +241,9 @@ fun f() =
f()
//│ > [FnLocalsInfo("‹top level›", [LocalVarInfo("i", 100)]), FnLocalsInfo("f", [LocalVarInfo("j", 200)])]
//│ > Stack Trace:
//│ > at f (Debugging.mls:221:3) with locals: j=200
//│ > at f (Debugging.mls:234:3) with locals: j=200
//│ > Stack Trace:
//│ > at f (Debugging.mls:223:3)
//│ > at f (Debugging.mls:236:3)
//│ > Stack Trace:
//│ > at f (Debugging.mls:224:3) with locals: j=300
//│ > at f (Debugging.mls:237:3) with locals: j=300
//│ > [FnLocalsInfo("‹top level›", [LocalVarInfo("i", 100)]), FnLocalsInfo("f", [LocalVarInfo("j", 300)])]
46 changes: 27 additions & 19 deletions hkmc2/shared/src/test/mlscript/handlers/EffectsInClasses.mls
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Expand Up @@ -31,27 +31,35 @@ data class Lol(h) with
//│ this.pc = pc;
//│ }
//│ resume(value$) {
//│ if (this.pc === 1) {
//│ tmp = value$;
//│ } else if (this.pc === 2) {
//│ res = value$;
//│ switch (this.pc) {
//│ case 1:
//│ tmp = value$;
//│ break;
//│ case 2:
//│ res = value$;
//│ break;
//│ }
//│ contLoop: while (true) {
//│ if (this.pc === 3) {
//│ return this$Lol
//│ } else if (this.pc === 4) {
//│ res = Predef.print(tmp);
//│ if (res instanceof runtime.EffectSig.class) {
//│ return this.doUnwind(res, 2)
//│ }
//│ this.pc = 2;
//│ continue contLoop
//│ } else if (this.pc === 1) {
//│ this.pc = 4;
//│ continue contLoop
//│ } else if (this.pc === 2) {
//│ this.pc = 3;
//│ continue contLoop
//│ switch (this.pc) {
//│ case 3:
//│ return this$Lol;
//│ break;
//│ case 4:
//│ res = Predef.print(tmp);
//│ if (res instanceof runtime.EffectSig.class) {
//│ return this.doUnwind(res, 2)
//│ }
//│ this.pc = 2;
//│ continue contLoop;
//│ break;
//│ case 1:
//│ this.pc = 4;
//│ continue contLoop;
//│ break;
//│ case 2:
//│ this.pc = 3;
//│ continue contLoop;
//│ break;
//│ }
//│ break;
//│ }
Expand Down
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