Add basic intraprocedural flow-sensitive analysis for optimization by LPTK · Pull Request #481 · hkust-taco/mlscript

LPTK · 2026-04-25T15:59:05Z

For now, this is mostly for propagating transitive variable assignments and folding constants. We can later fully leverage the results to simplify pattern matching expressions, remove dead assignments, etc.

# Conflicts: # hkmc2/shared/src/test/mlscript/codegen/SwitchSpecialization.mls

Agent-Logs-Url: https://github.com/LPTK/mlscript/sessions/63b4fea7-7c56-467f-81c1-6c8561e8ea62 Co-authored-by: LPTK <2545083+LPTK@users.noreply.github.com>

… prevent incorrect constant folding in nested while loops Agent-Logs-Url: https://github.com/LPTK/mlscript/sessions/63b4fea7-7c56-467f-81c1-6c8561e8ea62 Co-authored-by: LPTK <2545083+LPTK@users.noreply.github.com>

# Conflicts: # hkmc2/shared/src/main/scala/hkmc2/MLsCompiler.scala # hkmc2/shared/src/test/mlscript/codegen/Inliner.mls # hkmc2/shared/src/test/mlscript/deforest/simple.mls # hkmc2/shared/src/test/mlscript/handlers/Debugging.mls # hkmc2/shared/src/test/mlscript/handlers/SavedVars.mls # hkmc2/shared/src/test/mlscript/wasm/Basics.mls # hkmc2/shared/src/test/mlscript/wasm/MainFunctions.mls # hkmc2/shared/src/test/mlscript/wasm/ScopedLocals.mls # hkmc2/shared/src/test/mlscript/wasm/SingletonUnit.mls # hkmc2/shared/src/test/mlscript/wasm/Strings.mls # hkmc2DiffTests/src/test/scala/hkmc2/JSBackendDiffMaker.scala

# Conflicts: # hkmc2/shared/src/main/scala/hkmc2/MLsCompiler.scala # hkmc2/shared/src/main/scala/hkmc2/codegen/Block.scala # hkmc2/shared/src/test/mlscript/codegen/FirstClassFunctionTransform.mls # hkmc2/shared/src/test/mlscript/dead-param-elim/class-in-fun.mls # hkmc2/shared/src/test/mlscript/handlers/EffectsHygiene.mls # hkmc2/shared/src/test/mlscript/tailrec/TailRecOpt.mls # hkmc2DiffTests/src/test/scala/hkmc2/JSBackendDiffMaker.scala

…mpiled)

# Conflicts: # hkmc2/shared/src/test/mlscript-compile/Runtime.mjs # hkmc2/shared/src/test/mlscript/basics/Assert.mls # hkmc2/shared/src/test/mlscript/codegen/SanityChecks.mls

# Conflicts: # hkmc2/shared/src/main/scala/hkmc2/MLsCompiler.scala # hkmc2/shared/src/main/scala/hkmc2/codegen/BlockTransformer.scala # hkmc2/shared/src/test/mlscript/wasm/SingletonUnit.mls

# Conflicts: # hkmc2/shared/src/main/scala/hkmc2/codegen/Block.scala # hkmc2/shared/src/main/scala/hkmc2/codegen/BlockSimplifier.scala # hkmc2/shared/src/main/scala/hkmc2/package.scala # hkmc2/shared/src/test/mlscript-compile/Predef.mjs # hkmc2/shared/src/test/mlscript-compile/Runtime.mjs # hkmc2/shared/src/test/mlscript/basics/Indentation.mls # hkmc2/shared/src/test/mlscript/basics/LazySpreads.mls # hkmc2/shared/src/test/mlscript/basics/ShortcircuitingOps.mls # hkmc2/shared/src/test/mlscript/block-staging/Functions.mls # hkmc2/shared/src/test/mlscript/codegen/NestedScoped.mls # hkmc2/shared/src/test/mlscript/codegen/PartialApps.mls # hkmc2/shared/src/test/mlscript/codegen/SanityChecks.mls # hkmc2/shared/src/test/mlscript/codegen/TraceLogIndent.mls # hkmc2/shared/src/test/mlscript/deforest/simple.mls # hkmc2/shared/src/test/mlscript/invalml/InvalMLCodeGen.mls # hkmc2/shared/src/test/mlscript/invalml/InvalMLGetters.mls

# Conflicts: # hkmc2/shared/src/test/mlscript/wasm/Basics.mls

LPTK · 2026-05-09T14:59:17Z

I still have to clean up the OptScratch files, but other than that, the PR is ready to review (not commit by commit, obviously).

Copilot

Pull request overview

Adds a basic intraprocedural, flow-sensitive optimization pass (variable/constant propagation and related simplifications) and wires it into the compiler and diff-test harness, with extensive golden-output updates and new optimization-focused test cases.

Changes:

Integrate optimization pipeline updates (BlockSimplifier + DeadParamElim) with optional debugging/disable switches in diff tests and compiler entrypoints.
Add new config toggles (e.g., deadBranchRemoval) and sanity-check behavior (runtime trapping on Unreachable when enabled).
Update/add many .mls golden tests to reflect optimized IR/JS output.

Reviewed changes

Copilot reviewed 125 out of 126 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
hkmc2DiffTests/src/test/scala/hkmc2/Watcher.scala	Always prints watcher exception stack traces for easier debugging.
hkmc2DiffTests/src/test/scala/hkmc2/MLsDiffMaker.scala	Adds `:dopt`/`:noOpt` commands; tweaks sanity-check config wiring.
hkmc2DiffTests/src/test/scala/hkmc2/JSBackendDiffMaker.scala	Adds optimization tracing/logging hooks and `:noOpt` gating.
hkmc2DiffTests/src/test/scala/hkmc2/DiffTestRunner.scala	Refactors timeout behavior to shared base; tweaks local time limit.
hkmc2/shared/src/test/mlscript/wasm/VirtualMethods.mls	Golden output update for optimized Wasm codegen.
hkmc2/shared/src/test/mlscript/wasm/Strings.mls	Golden output update for optimized Wasm codegen.
hkmc2/shared/src/test/mlscript/wasm/SingletonUnit.mls	Golden output update for optimized Wasm codegen.
hkmc2/shared/src/test/mlscript/wasm/ScopedLocals.mls	Golden output update for optimized Wasm codegen.
hkmc2/shared/src/test/mlscript/wasm/ReplImports.mls	Golden output update for optimized Wasm codegen.
hkmc2/shared/src/test/mlscript/wasm/Matching.mls	Golden output update for optimized Wasm codegen.
hkmc2/shared/src/test/mlscript/wasm/MainFunctions.mls	Golden output update for optimized Wasm codegen.
hkmc2/shared/src/test/mlscript/wasm/ClassInheritance.mls	Golden output update (incl. diagnostic line numbers).
hkmc2/shared/src/test/mlscript/wasm/Basics.mls	Golden output update (incl. diagnostic expectations).
hkmc2/shared/src/test/mlscript/ups/syntax/MixedParameters.mls	Updates expected runtime/compile behavior outputs.
hkmc2/shared/src/test/mlscript/ups/SimpleTransform.mls	Adds note + spacing; keeps test intent.
hkmc2/shared/src/test/mlscript/ups/RecursiveTransformations.mls	Updates expected outputs and diagnostic locations.
hkmc2/shared/src/test/mlscript/ups/examples/PrecedenceClimbStackParse.mls	Updates expected outputs and diagnostic locations.
hkmc2/shared/src/test/mlscript/ups/examples/Extraction.mls	Adds `:noOpt` to keep a known IR rebinding failure visible.
hkmc2/shared/src/test/mlscript/ups/examples/BadRecStackParse.mls	Golden output update.
hkmc2/shared/src/test/mlscript/ucs/patterns/RestTuple.mls	Golden JS update reflecting propagation/simplification.
hkmc2/shared/src/test/mlscript/ucs/patterns/Parameters.mls	Golden output update for pattern parameter handling.
hkmc2/shared/src/test/mlscript/ucs/normalization/ExcessiveDeduplication.mls	Golden JS update for dedup/branch simplification changes.
hkmc2/shared/src/test/mlscript/ucs/normalization/DeduplicationWhile.mls	Golden JS update for while/dedup simplification changes.
hkmc2/shared/src/test/mlscript/ucs/normalization/Deduplication.mls	Golden JS update for dedup/constant propagation.
hkmc2/shared/src/test/mlscript/ucs/general/LogicalConnectives.mls	Golden output update + diagnostic location tweaks.
hkmc2/shared/src/test/mlscript/tailrec/TailRecOpt.mls	Golden JS update for renamed params / simplification.
hkmc2/shared/src/test/mlscript/syntax/BasicIfs.mls	Updates expected output values.
hkmc2/shared/src/test/mlscript/std/FingerTreeListTest.mls	Golden JS update reflecting propagation/simplification.
hkmc2/shared/src/test/mlscript/parser/PrefixOps.mls	Golden JS/output update for folded prefix ops.
hkmc2/shared/src/test/mlscript/opt/ValPropag.mls	New optimization test for val/let propagation behavior.
hkmc2/shared/src/test/mlscript/opt/OptScratch3.mls	New scratch/regression tests for optimizer behavior.
hkmc2/shared/src/test/mlscript/opt/OptScratch2.mls	New scratch/regression tests for optimizer behavior.
hkmc2/shared/src/test/mlscript/opt/OptScratch.mls	New scratch/regression tests for optimizer behavior.
hkmc2/shared/src/test/mlscript/opt/MatchSimplification.mls	New test for match/if simplification under optimization.
hkmc2/shared/src/test/mlscript/opt/LoopOpt.mls	New test for loop-related optimization behavior.
hkmc2/shared/src/test/mlscript/opt/IllFormedAccesses.mls	New test documenting optimizer effects on UB (uninitialized access).
hkmc2/shared/src/test/mlscript/opt/DeadVarRemoval.mls	Golden IR update for dead var removal behavior.
hkmc2/shared/src/test/mlscript/opt/DeadSelRemoval.mls	Golden IR update for dead selection elimination behavior.
hkmc2/shared/src/test/mlscript/opt/DeadObjRemoval.mls	Golden JS/IR update for dead object elimination behavior.
hkmc2/shared/src/test/mlscript/opt/DeadBranchRemoval.mls	New tests for dead-branch removal feature flag.
hkmc2/shared/src/test/mlscript/opt/DeadAssignmentRemoval.mls	New tests for dead assignment elimination behavior.
hkmc2/shared/src/test/mlscript/opt/ConstantFolding.mls	New tests covering constant folding and iteration behavior.
hkmc2/shared/src/test/mlscript/opt/BasicVarPropag.mls	New comprehensive tests for variable propagation + folding.
hkmc2/shared/src/test/mlscript/opt/AbortivePrefix.mls	Golden outputs updated for abortive-prefix simplification.
hkmc2/shared/src/test/mlscript/invalml/InvalMLGetters.mls	Golden output/diagnostic location updates.
hkmc2/shared/src/test/mlscript/invalml/InvalMLCodeGen.mls	Golden JS update reflecting propagation/simplification.
hkmc2/shared/src/test/mlscript/handlers/SetInHandlers.mls	Golden JS update reflecting propagation/simplification.
hkmc2/shared/src/test/mlscript/handlers/SavedVars.mls	Golden JS update reflecting propagation/simplification.
hkmc2/shared/src/test/mlscript/handlers/RecursiveHandlers.mls	Golden JS update reflecting propagation/simplification.
hkmc2/shared/src/test/mlscript/handlers/NoStackSafety.mls	Golden JS update reflecting propagation/simplification.
hkmc2/shared/src/test/mlscript/handlers/Fallthrough.mls	Golden JS update reflecting propagation/simplification.
hkmc2/shared/src/test/mlscript/handlers/EffectsHygiene.mls	Golden JS update reflecting propagation/simplification.
hkmc2/shared/src/test/mlscript/handlers/Debugging.mls	Golden JS update reflecting propagation/simplification.
hkmc2/shared/src/test/mlscript/deforest/simple.mls	Golden output update for deforest-related naming changes.
hkmc2/shared/src/test/mlscript/deforest/relaxedPrograms.mls	Golden output update (includes expected JS syntax error caret).
hkmc2/shared/src/test/mlscript/deforest/nestedMatch.mls	Golden output update for deforest-related naming changes.
hkmc2/shared/src/test/mlscript/dead-param-elim/ups.mls	Golden output update for dead-param-elim tracing.
hkmc2/shared/src/test/mlscript/dead-param-elim/lambda.mls	Adds optimized IR section to dead-param-elim test.
hkmc2/shared/src/test/mlscript/dead-param-elim/clash.mls	Golden output update for eliminable param set changes.
hkmc2/shared/src/test/mlscript/ctx/Summon.mls	Diagnostic location updates.
hkmc2/shared/src/test/mlscript/codegen/WhileDefaults.mls	Golden JS update reflecting propagation/simplification.
hkmc2/shared/src/test/mlscript/codegen/While.mls	Golden JS update reflecting propagation/simplification.
hkmc2/shared/src/test/mlscript/codegen/TraceLogIndent.mls	Golden REPL trace output update reflecting simplification.
hkmc2/shared/src/test/mlscript/codegen/Throw.mls	Golden JS update reflecting propagation/simplification.
hkmc2/shared/src/test/mlscript/codegen/SwitchSpecialization.mls	Golden JS update reflecting propagation/simplification.
hkmc2/shared/src/test/mlscript/codegen/SetIn.mls	Golden JS update reflecting propagation/simplification.
hkmc2/shared/src/test/mlscript/codegen/ScopedBlocksAndHandlers.mls	Golden JS update reflecting propagation/simplification.
hkmc2/shared/src/test/mlscript/codegen/ScopedBlocks.mls	Golden JS update reflecting propagation/simplification.
hkmc2/shared/src/test/mlscript/codegen/SanityChecks.mls	Golden JS update reflecting propagation/simplification.
hkmc2/shared/src/test/mlscript/codegen/Repl.mls	Golden REPL output update reflecting constant folding.
hkmc2/shared/src/test/mlscript/codegen/RandomStuff.mls	Golden JS update reflecting propagation/simplification.
hkmc2/shared/src/test/mlscript/codegen/Quasiquotes.mls	Golden JS update reflecting propagation/simplification.
hkmc2/shared/src/test/mlscript/codegen/PartialApps.mls	Golden JS update reflecting propagation/simplification.
hkmc2/shared/src/test/mlscript/codegen/ParamClasses.mls	Golden JS/diagnostic location updates.
hkmc2/shared/src/test/mlscript/codegen/NestedScoped.mls	Golden IR/JS updates reflecting optimization effects.
hkmc2/shared/src/test/mlscript/codegen/NestedLoops.mls	New test for nested-loop optimized IR behavior.
hkmc2/shared/src/test/mlscript/codegen/Formatting.mls	Golden JS formatting updates due to propagation/simplification.
hkmc2/shared/src/test/mlscript/codegen/Functions.mls	Golden REPL output update reflecting propagation/simplification.
hkmc2/shared/src/test/mlscript/codegen/Misc.mls	Golden JS update reflecting constant folding.
hkmc2/shared/src/test/mlscript/codegen/MergeMatchArms.mls	Golden JS/IR updates reflecting match/branch simplification.
hkmc2/shared/src/test/mlscript/codegen/Lambdas.mls	Golden JS update reflecting lambda simplification.
hkmc2/shared/src/test/mlscript/codegen/Inliner.mls	Golden IR update + enables deadBranchRemoval for inliner tests.
hkmc2/shared/src/test/mlscript/codegen/Hygiene.mls	Golden output update reflecting propagation/simplification.
hkmc2/shared/src/test/mlscript/codegen/GlobalThis.mls	Golden JS update reflecting propagation/simplification.
hkmc2/shared/src/test/mlscript/codegen/FunInClass.mls	Golden JS update reflecting propagation/simplification.
hkmc2/shared/src/test/mlscript/codegen/ConsoleLog.mls	Golden JS update reflecting constant folding/propagation.
hkmc2/shared/src/test/mlscript/codegen/ConfigDirective.mls	Moves dead-param-elim trace output to match new behavior.
hkmc2/shared/src/test/mlscript/codegen/ClassMatching.mls	Golden JS/IR updates reflecting propagation/simplification.
hkmc2/shared/src/test/mlscript/codegen/CaseShorthand.mls	Golden JS update reflecting propagation/simplification.
hkmc2/shared/src/test/mlscript/codegen/CaseOfCase.mls	Golden JS update reflecting propagation/simplification.
hkmc2/shared/src/test/mlscript/codegen/BuiltinSymbols.mls	Golden IR update reflecting propagation/simplification.
hkmc2/shared/src/test/mlscript/codegen/BuiltinOps.mls	Golden JS update reflecting constant folding.
hkmc2/shared/src/test/mlscript/block-staging/Functions.mls	Adds `:noOpt` to preserve known IR rebinding failure visibility.
hkmc2/shared/src/test/mlscript/basics/StrTest.mls	Golden JS update reflecting propagation/simplification.
hkmc2/shared/src/test/mlscript/basics/ShortcircuitingOps.mls	Golden JS update reflecting propagation/simplification.
hkmc2/shared/src/test/mlscript/basics/PureTermStatements.mls	Golden JS update reflecting DCE/sequence simplification.
hkmc2/shared/src/test/mlscript/basics/MultilineExpressions.mls	Golden JS/diagnostic location updates reflecting folding.
hkmc2/shared/src/test/mlscript/basics/MemberProjections.mls	Golden JS update reflecting propagation/simplification.
hkmc2/shared/src/test/mlscript/basics/LazySpreads.mls	Golden JS/diagnostic location updates reflecting propagation.
hkmc2/shared/src/test/mlscript/basics/Indentation.mls	Adds optimized IR section for an indentation-related case.
hkmc2/shared/src/test/mlscript/basics/FunnyRecordKeys.mls	Golden JS update reflecting propagation/simplification.
hkmc2/shared/src/test/mlscript/basics/DynamicSelection.mls	Golden diagnostic output updates.
hkmc2/shared/src/test/mlscript/basics/Drop.mls	Golden JS update reflecting constant folding.
hkmc2/shared/src/test/mlscript/basics/Assert.mls	Golden JS/diagnostic location updates reflecting folding.
hkmc2/shared/src/test/mlscript/backlog/Lifter.mls	Golden runtime output text updates reflecting renaming.
hkmc2/shared/src/test/mlscript/backlog/ForLLM.mls	Adds additional parser/backlog repro cases and expected errors.
hkmc2/shared/src/test/mlscript-compile/Predef.mls	Adds `hide`/`maybe` helpers to stabilize tests against optimization.
hkmc2/shared/src/test/mlscript-compile/Predef.mjs	Updates generated Predef JS to include new helpers and simplifications.
hkmc2/shared/src/main/scala/hkmc2/utils/utils.scala	Adds `filterConserve` to preserve list identity when unchanged.
hkmc2/shared/src/main/scala/hkmc2/semantics/Symbol.scala	Adds `showDbg`; introduces `LocalVarSymbol` and refines symbol hierarchy.
hkmc2/shared/src/main/scala/hkmc2/package.scala	Adds `abbreviate` helper; minor naming tweak in extension.
hkmc2/shared/src/main/scala/hkmc2/MLsCompiler.scala	Integrates optimizer pipeline and adds optimization trace logger.
hkmc2/shared/src/main/scala/hkmc2/Config.scala	Adds `deadBranchRemoval`; extends sanity checks; parses new config field.
hkmc2/shared/src/main/scala/hkmc2/codegen/Printer.scala	Minor formatting tweak.
hkmc2/shared/src/main/scala/hkmc2/codegen/js/JSBuilder.scala	Adds `resultQual`; emits runtime traps for `Unreachable` under sanity checks.
hkmc2/shared/src/main/scala/hkmc2/codegen/BlockTraverser.scala	Refactors class-like def traversal into helper.
hkmc2/shared/src/main/scala/hkmc2/codegen/BlockTransformer.scala	Refactors class-like def transformation into helper.
hkmc2/shared/src/main/scala/hkmc2/codegen/Block.scala	Adds debug renderers; fixes `Scoped` free-vars; match simplification tweak.
hkmc2/jvm/src/test/scala/hkmc2/TimeOutTests.scala	New shared timeout base for ScalaTest suites.
hkmc2/jvm/src/test/scala/hkmc2/CompileTestRunnerBase.scala	Switches to shared timeout base; adds timeLimit.
.github/skills/hkmc2-difftests/references/commands-and-policies.md	Documents new/related debugging commands.

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+  var testName: Str = "‹unknown›"
+  override def withFixture(test: NoArgTest) =
+    testName = test.name
+    super.withFixture(test)
+  override val defaultTestSignaler: Signaler = new Signaler:
+    @annotation.nowarn("msg=method stop in class Thread is deprecated") def apply(testThread: Thread): Unit =
+      println(s"[${Thread.currentThread().getName}] running ${testThread.getName} has run out of time!")
+      println(s"!! Test $testName at $testThread has run out out time !! stopping..." +
+        "\n\tNote: you can increase this limit by changing DiffTests.TimeLimit")


CAG2Mark · 2026-05-09T16:17:28Z

I can have a look in the coming day or two.

CAG2Mark · 2026-05-11T07:26:03Z

I've just done a high-level review of the new DataFlowAnalysis and the changes seem reasonable at first glance. I need to work on some other things, so I will take a closer look at the details tomorrow.

# Conflicts: # hkmc2/shared/src/main/scala/hkmc2/MLsCompiler.scala # hkmc2/shared/src/test/mlscript/deforest/nestedMatch.mls

AnsonYeung

I think the loop logic is missing a merge for the loop start.

AnsonYeung · 2026-05-11T10:49:52Z

-  private var changed = true
+  val deadBranchRemoval = config.deadBranchRemoval
+
+  val MaxIterations = 10


Why is this variable name capitalized

AnsonYeung · 2026-05-11T10:55:18Z

      // * Replace with `undefined` those references to local variables that are never assigned
      case Value.Ref(loc, N) if localVars.contains(loc) && !definedVars.contains(loc) =>
-        registerChange
+        registerChange("TODO: description")


Seems there are many TODOs in registerChange

AnsonYeung · 2026-05-11T11:15:56Z

+      def merge(that: AssignInfo): AssignInfo =
+        if this is that then this
+        else that match
+          case Unknown => that
+          case Uninitialized => this
+          // case Merge(l, r) => Merge(merge(this, l), r)
+          case _: Assigned | _: Merge => Merge(this, that)
+


If this is Unknown | Uninitialized then a Merge will be created

AnsonYeung · 2026-05-11T11:52:40Z

+      assignedResults = oldAssignedResults
+      res
+
+    val atLabelBegin: MutMap[LabelSymbol, AssignedResults] = MutMap.empty.withDefaultValue(emptyAssignedResults)


It seems to me that atLabelBegin is effectively unused, the only usage only put the result back into the same map

AnsonYeung · 2026-05-11T12:20:50Z

+            @inline def regChange =
+              registerChange(s"Arm ${pat.showDbg} is unreachable because")
+              false
+            pat match
+            case Case.Lit(lit) => 
+              shapes.contains(lit) && { shapes -= lit; true } || regChange
+            case Case.Cls(sym, _) =>
+
+              // FIXME: take inheritance into account
+              // FIXME: take lit <: virual-cls into account (such as true <: Bool)
+
+              shapes.contains(sym) && { shapes -= sym; true } || regChange


Suggested change

@inline def regChange =

registerChange(s"Arm ${pat.showDbg} is unreachable because")

false

pat match

case Case.Lit(lit) =>

shapes.contains(lit) && { shapes -= lit; true } || regChange

case Case.Cls(sym, _) =>

// FIXME: take inheritance into account

// FIXME: take lit <: virual-cls into account (such as true <: Bool)

shapes.contains(sym) && { shapes -= sym; true } || regChange

@inline def regChange(reason: Str) =

registerChange(s"Arm ${pat.showDbg} is unreachable. Reason: ${reason}")

false

pat match

case Case.Lit(lit) =>

shapes.contains(lit) && { shapes -= lit; true } || regChange("Impossible literal")

case Case.Cls(sym, _) =>

// FIXME: take inheritance into account

// FIXME: take lit <: virual-cls into account (such as true <: Bool)

shapes.contains(sym) && { shapes -= sym; true } || regChange("Impossible instanceof")

AnsonYeung · 2026-05-11T15:49:14Z


 fun f(x) = if x is str as AtPrec as prec then [str, prec]
 f("+")
-//│ = ["+", 2]


This seems like some weird diff

AnsonYeung · 2026-05-11T15:49:59Z

 // * Notice: wrong assoc.
 parse("a" :: "+" :: "(" :: "b" :: "+" :: "x" :: "+" :: "y" :: ")" :: Nil)
-//│ = {Success: Op(Id("a"), "+", Op(Id("b"), "+", Op(Id("x"), "+", Id("y"))))}


AnsonYeung · 2026-05-11T15:50:19Z

-//│ = ["+", 5]
 f("*")


AnsonYeung · 2026-05-11T15:50:27Z

 f("+")
-//│ = ["+", 5]


same as above

AnsonYeung · 2026-05-11T15:55:21Z

 arr is MultiSet(1, _)
-//│ = true
 arr is MultiSet(0, _)
-//│ = false
 arr is MultiSet(3, _)
-//│ = true
 arr is MultiSet(3, MultiSet(1, MultiSet(2, Nil)))
-//│ = true
 arr is MultiSet(3, MultiSet(0, _))
 //│ = false


seems like ups use this broken style of test a lot which breaks on this pr a lot

LPTK and others added 30 commits April 11, 2026 11:56

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# Conflicts: # hkmc2/shared/src/test/mlscript/codegen/SwitchSpecialization.mls

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Diagnose WASM timeout: x constant-folded due to ValuePropagation bug

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Agent-Logs-Url: https://github.com/LPTK/mlscript/sessions/63b4fea7-7c56-467f-81c1-6c8561e8ea62 Co-authored-by: LPTK <2545083+LPTK@users.noreply.github.com>

W

1de5023

LPTK added 13 commits April 25, 2026 16:18

WW run tests with existing Rendering.mjs (too many failures when reco…

b793ab9

…mpiled)

WW min

93f8a5e

WW fix

7c61ac0

WW no sanity checks in :js

6db76c2

WW missing class-inheritance reasoning

ba3d0e7

W disable DBE for now

d4518e6

Merge remote-tracking branch 'hkust-taco/hkmc2' into value-propag

6fa4ffd

# Conflicts: # hkmc2/shared/src/test/mlscript-compile/Runtime.mjs # hkmc2/shared/src/test/mlscript/basics/Assert.mls # hkmc2/shared/src/test/mlscript/codegen/SanityChecks.mls

WIP cleanup, renaming

6f89e76

More cleanup

524c25d

WIP untrack mjs files

b4324dd

WIP More cleanups

bcad3c2

Merge branch 'hkmc2' into data-flow-analysis

2ef2d37

# Conflicts: # hkmc2/shared/src/main/scala/hkmc2/MLsCompiler.scala # hkmc2/shared/src/main/scala/hkmc2/codegen/BlockTransformer.scala # hkmc2/shared/src/test/mlscript/wasm/SingletonUnit.mls

LPTK closed this May 6, 2026

LPTK force-pushed the data-flow-analysis branch from e0773b1 to 54054c6 Compare May 6, 2026 04:33

LPTK reopened this May 6, 2026

LPTK added 2 commits May 9, 2026 18:54

Merge remote-tracking branch 'hkust-taco/hkmc2' into data-flow-analysis

c5451c5

# Conflicts: # hkmc2/shared/src/test/mlscript/wasm/Basics.mls

Cleanup

dacc827

LPTK marked this pull request as ready for review May 9, 2026 14:58

LPTK requested review from AnsonYeung, CAG2Mark and Copilot May 9, 2026 14:59

Copilot started reviewing on behalf of LPTK May 9, 2026 14:59 View session

Copilot AI reviewed May 9, 2026

View reviewed changes

Merge branch 'hkmc2' into data-flow-analysis

0e12aa6

# Conflicts: # hkmc2/shared/src/main/scala/hkmc2/MLsCompiler.scala # hkmc2/shared/src/test/mlscript/deforest/nestedMatch.mls

AnsonYeung reviewed May 11, 2026

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