Sync to upstream/release/624 (#1245)

# What's changed?

* Optimize table.maxn.  This function is now 5-14x faster
* Reserve Luau stack space for error message.

## New Solver

* Globals can be type-stated, but only if they are already in scope
* Fix a stack overflow that could occur when normalizing certain kinds
of recursive unions of intersections (of unions of intersections...)
* Fix an assertion failure that would trigger when the __iter metamethod
has a bad signature

## Native Codegen

* Type propagation and temporary register type hints
* Direct vector property access should only happen for names of right
length
* BytecodeAnalysis will only predict that some of the vector value
fields are numbers

---

## Internal Contributors

Co-authored-by: Alexander McCord <amccord@roblox.com>
Co-authored-by: Andy Friesen <afriesen@roblox.com>
Co-authored-by: Aviral Goel <agoel@roblox.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>

Analysis/include/Luau/Normalize.h

@@ -395,6 +395,7 @@ class Normalizer
     TypeId negate(TypeId there);
     void subtractPrimitive(NormalizedType& here, TypeId ty);
     void subtractSingleton(NormalizedType& here, TypeId ty);
+    NormalizationResult intersectNormalWithNegationTy(TypeId toNegate, NormalizedType& intersect, bool useDeprecated = false);
 
     // ------- Normalizing intersections
     TypeId intersectionOfTops(TypeId here, TypeId there);

Analysis/src/ConstraintGenerator.cpp

@@ -1900,10 +1900,7 @@ Inference ConstraintGenerator::check(const ScopePtr& scope, AstExprGlobal* globa
         return Inference{*ty, refinementArena.proposition(key, builtinTypes->truthyType)};
     }
     else
-    {
-        reportError(global->location, UnknownSymbol{global->name.value, UnknownSymbol::Binding});
         return Inference{builtinTypes->errorRecoveryType()};
-    }
 }
 
 Inference ConstraintGenerator::checkIndexName(const ScopePtr& scope, const RefinementKey* key, AstExpr* indexee, const std::string& index, Location indexLocation)
@@ -2453,7 +2450,12 @@ ConstraintGenerator::LValueBounds ConstraintGenerator::checkLValue(const ScopePt
 {
     std::optional<TypeId> annotatedTy = scope->lookup(Symbol{global->name});
     if (annotatedTy)
-        return {annotatedTy, arena->addType(BlockedType{})};
+    {
+        DefId def = dfg->getDef(global);
+        TypeId assignedTy = arena->addType(BlockedType{});
+        rootScope->lvalueTypes[def] = assignedTy;
+        return {annotatedTy, assignedTy};
+    }
     else
         return {annotatedTy, std::nullopt};
 }

Analysis/src/ConstraintSolver.cpp

@@ -1619,9 +1619,7 @@ std::pair<bool, std::optional<TypeId>> ConstraintSolver::tryDispatchSetIndexer(
     {
         if (tt->indexer)
         {
-            if (isBlocked(tt->indexer->indexType))
-                return {block(tt->indexer->indexType, constraint), std::nullopt};
-            else if (isBlocked(tt->indexer->indexResultType))
+            if (isBlocked(tt->indexer->indexResultType))
                 return {block(tt->indexer->indexResultType, constraint), std::nullopt};
 
             unify(constraint, indexType, tt->indexer->indexType);
@@ -2014,10 +2012,14 @@ bool ConstraintSolver::tryDispatchIterableTable(TypeId iteratorTy, const Iterabl
                 if (std::optional<TypeId> instantiatedNextFn = instantiate(builtinTypes, arena, NotNull{&limits}, constraint->scope, nextFn))
                 {
                     const FunctionType* nextFn = get<FunctionType>(*instantiatedNextFn);
-                    LUAU_ASSERT(nextFn);
-                    const TypePackId nextRetPack = nextFn->retTypes;
 
-                    pushConstraint(constraint->scope, constraint->location, UnpackConstraint{c.variables, nextRetPack, /* resultIsLValue=*/true});
+                    // If nextFn is nullptr, then the iterator function has an improper signature.
+                    if (nextFn)
+                    {
+                        const TypePackId nextRetPack = nextFn->retTypes;
+                        pushConstraint(constraint->scope, constraint->location, UnpackConstraint{c.variables, nextRetPack, /* resultIsLValue=*/true});
+                    }
+
                     return true;
                 }
                 else

Analysis/src/Normalize.cpp

@@ -20,6 +20,7 @@ LUAU_FASTFLAGVARIABLE(LuauNormalizeAwayUninhabitableTables, false)
 LUAU_FASTFLAGVARIABLE(LuauFixNormalizeCaching, false);
 LUAU_FASTFLAGVARIABLE(LuauNormalizeNotUnknownIntersection, false);
 LUAU_FASTFLAGVARIABLE(LuauFixCyclicUnionsOfIntersections, false);
+LUAU_FASTFLAGVARIABLE(LuauFixReduceStackPressure, false);
 
 // This could theoretically be 2000 on amd64, but x86 requires this.
 LUAU_FASTINTVARIABLE(LuauNormalizeIterationLimit, 1200);
@@ -36,6 +37,11 @@ static bool fixCyclicUnionsOfIntersections()
     return FFlag::LuauFixCyclicUnionsOfIntersections || FFlag::DebugLuauDeferredConstraintResolution;
 }
 
+static bool fixReduceStackPressure()
+{
+    return FFlag::LuauFixReduceStackPressure || FFlag::DebugLuauDeferredConstraintResolution;
+}
+
 namespace Luau
 {
 
@@ -45,6 +51,14 @@ static bool normalizeAwayUninhabitableTables()
     return FFlag::LuauNormalizeAwayUninhabitableTables || FFlag::DebugLuauDeferredConstraintResolution;
 }
 
+static bool shouldEarlyExit(NormalizationResult res)
+{
+    // if res is hit limits, return control flow
+    if (res == NormalizationResult::HitLimits || res == NormalizationResult::False)
+        return true;
+    return false;
+}
+
 TypeIds::TypeIds(std::initializer_list<TypeId> tys)
 {
     for (TypeId ty : tys)
@@ -1729,6 +1743,27 @@ bool Normalizer::withinResourceLimits()
     return true;
 }
 
+NormalizationResult Normalizer::intersectNormalWithNegationTy(TypeId toNegate, NormalizedType& intersect, bool useDeprecated)
+{
+
+    std::optional<NormalizedType> negated;
+    if (useDeprecated)
+    {
+        const NormalizedType* normal = DEPRECATED_normalize(toNegate);
+        negated = negateNormal(*normal);
+    }
+    else
+    {
+        std::shared_ptr<const NormalizedType> normal = normalize(toNegate);
+        negated = negateNormal(*normal);
+    }
+
+    if (!negated)
+        return NormalizationResult::False;
+    intersectNormals(intersect, *negated);
+    return NormalizationResult::True;
+}
+
 // See above for an explaination of `ignoreSmallerTyvars`.
 NormalizationResult Normalizer::unionNormalWithTy(NormalizedType& here, TypeId there, Set<TypeId>& seenSetTypes, int ignoreSmallerTyvars)
 {
@@ -2541,8 +2576,8 @@ std::optional<TypeId> Normalizer::intersectionOfTables(TypeId here, TypeId there
         state = tttv->state;
 
     TypeLevel level = max(httv->level, tttv->level);
-    TableType result{state, level};
 
+    std::unique_ptr<TableType> result = nullptr;
     bool hereSubThere = true;
     bool thereSubHere = true;
 
@@ -2563,8 +2598,18 @@ std::optional<TypeId> Normalizer::intersectionOfTables(TypeId here, TypeId there
                     if (tprop.readTy.has_value())
                     {
                         // if the intersection of the read types of a property is uninhabited, the whole table is `never`.
-                        if (normalizeAwayUninhabitableTables() && NormalizationResult::False == isIntersectionInhabited(*hprop.readTy, *tprop.readTy))
-                            return {builtinTypes->neverType};
+                        if (fixReduceStackPressure())
+                        {
+                            if (normalizeAwayUninhabitableTables() &&
+                                NormalizationResult::True != isIntersectionInhabited(*hprop.readTy, *tprop.readTy))
+                                return {builtinTypes->neverType};
+                        }
+                        else
+                        {
+                            if (normalizeAwayUninhabitableTables() &&
+                                NormalizationResult::False == isIntersectionInhabited(*hprop.readTy, *tprop.readTy))
+                                return {builtinTypes->neverType};
+                        }
 
                         TypeId ty = simplifyIntersection(builtinTypes, NotNull{arena}, *hprop.readTy, *tprop.readTy).result;
                         prop.readTy = ty;
@@ -2614,14 +2659,21 @@ std::optional<TypeId> Normalizer::intersectionOfTables(TypeId here, TypeId there
         // TODO: string indexers
 
         if (prop.readTy || prop.writeTy)
-            result.props[name] = prop;
+        {
+            if (!result.get())
+                result = std::make_unique<TableType>(TableType{state, level});
+            result->props[name] = prop;
+        }
     }
 
     for (const auto& [name, tprop] : tttv->props)
     {
         if (httv->props.count(name) == 0)
         {
-            result.props[name] = tprop;
+            if (!result.get())
+                result = std::make_unique<TableType>(TableType{state, level});
+
+            result->props[name] = tprop;
             hereSubThere = false;
         }
     }
@@ -2631,18 +2683,24 @@ std::optional<TypeId> Normalizer::intersectionOfTables(TypeId here, TypeId there
         // TODO: What should intersection of indexes be?
         TypeId index = unionType(httv->indexer->indexType, tttv->indexer->indexType);
         TypeId indexResult = intersectionType(httv->indexer->indexResultType, tttv->indexer->indexResultType);
-        result.indexer = {index, indexResult};
+        if (!result.get())
+            result = std::make_unique<TableType>(TableType{state, level});
+        result->indexer = {index, indexResult};
         hereSubThere &= (httv->indexer->indexType == index) && (httv->indexer->indexResultType == indexResult);
         thereSubHere &= (tttv->indexer->indexType == index) && (tttv->indexer->indexResultType == indexResult);
     }
     else if (httv->indexer)
     {
-        result.indexer = httv->indexer;
+        if (!result.get())
+            result = std::make_unique<TableType>(TableType{state, level});
+        result->indexer = httv->indexer;
         thereSubHere = false;
     }
     else if (tttv->indexer)
     {
-        result.indexer = tttv->indexer;
+        if (!result.get())
+            result = std::make_unique<TableType>(TableType{state, level});
+        result->indexer = tttv->indexer;
         hereSubThere = false;
     }
 
@@ -2652,7 +2710,12 @@ std::optional<TypeId> Normalizer::intersectionOfTables(TypeId here, TypeId there
     else if (thereSubHere)
         table = ttable;
     else
-        table = arena->addType(std::move(result));
+    {
+        if (result.get())
+            table = arena->addType(std::move(*result));
+        else
+            table = arena->addType(TableType{state, level});
+    }
 
     if (tmtable && hmtable)
     {
@@ -3150,19 +3213,15 @@ NormalizationResult Normalizer::intersectNormalWithTy(NormalizedType& here, Type
         {
             if (fixNormalizeCaching())
             {
-                std::shared_ptr<const NormalizedType> normal = normalize(t);
-                std::optional<NormalizedType> negated = negateNormal(*normal);
-                if (!negated)
-                    return NormalizationResult::False;
-                intersectNormals(here, *negated);
+                NormalizationResult res = intersectNormalWithNegationTy(t, here);
+                if (shouldEarlyExit(res))
+                    return res;
             }
             else
             {
-                const NormalizedType* normal = DEPRECATED_normalize(t);
-                std::optional<NormalizedType> negated = negateNormal(*normal);
-                if (!negated)
-                    return NormalizationResult::False;
-                intersectNormals(here, *negated);
+                NormalizationResult res = intersectNormalWithNegationTy(t, here, /* useDeprecated */ true);
+                if (shouldEarlyExit(res))
+                    return res;
             }
         }
         else if (const UnionType* itv = get<UnionType>(t))
@@ -3171,11 +3230,9 @@ NormalizationResult Normalizer::intersectNormalWithTy(NormalizedType& here, Type
             {
                 for (TypeId part : itv->options)
                 {
-                    std::shared_ptr<const NormalizedType> normalPart = normalize(part);
-                    std::optional<NormalizedType> negated = negateNormal(*normalPart);
-                    if (!negated)
-                        return NormalizationResult::False;
-                    intersectNormals(here, *negated);
+                    NormalizationResult res = intersectNormalWithNegationTy(part, here);
+                    if (shouldEarlyExit(res))
+                        return res;
                 }
             }
             else
@@ -3184,22 +3241,18 @@ NormalizationResult Normalizer::intersectNormalWithTy(NormalizedType& here, Type
                 {
                     for (TypeId part : itv->options)
                     {
-                        std::shared_ptr<const NormalizedType> normalPart = normalize(part);
-                        std::optional<NormalizedType> negated = negateNormal(*normalPart);
-                        if (!negated)
-                            return NormalizationResult::False;
-                        intersectNormals(here, *negated);
+                        NormalizationResult res = intersectNormalWithNegationTy(part, here);
+                        if (shouldEarlyExit(res))
+                            return res;
                     }
                 }
                 else
                 {
                     for (TypeId part : itv->options)
                     {
-                        const NormalizedType* normalPart = DEPRECATED_normalize(part);
-                        std::optional<NormalizedType> negated = negateNormal(*normalPart);
-                        if (!negated)
-                            return NormalizationResult::False;
-                        intersectNormals(here, *negated);
+                        NormalizationResult res = intersectNormalWithNegationTy(part, here, /* useDeprecated */ true);
+                        if (shouldEarlyExit(res))
+                            return res;
                     }
                 }
             }

Analysis/src/TypeChecker2.cpp

@@ -1280,7 +1280,9 @@ struct TypeChecker2
 
     void visit(AstExprGlobal* expr)
     {
-        // TODO!
+        NotNull<Scope> scope = stack.back();
+        if (!scope->lookup(expr->name))
+            reportError(UnknownSymbol{expr->name.value, UnknownSymbol::Binding}, expr->location);
     }
 
     void visit(AstExprVarargs* expr)

CLI/Compile.cpp

@@ -317,6 +317,7 @@ static bool compileFile(const char* name, CompileFormat format, Luau::CodeGen::A
         {
             options.includeAssembly = format != CompileFormat::CodegenIr;
             options.includeIr = format != CompileFormat::CodegenAsm;
+            options.includeIrTypes = format != CompileFormat::CodegenAsm;
             options.includeOutlinedCode = format == CompileFormat::CodegenVerbose;
         }
 

CMakeLists.txt

@@ -229,6 +229,7 @@ if(LUAU_BUILD_TESTS)
     target_link_libraries(Luau.UnitTest PRIVATE Luau.Analysis Luau.Compiler Luau.CodeGen)
 
     target_compile_options(Luau.Conformance PRIVATE ${LUAU_OPTIONS})
+    target_compile_definitions(Luau.Conformance PRIVATE DOCTEST_CONFIG_DOUBLE_STRINGIFY)
     target_include_directories(Luau.Conformance PRIVATE extern)
     target_link_libraries(Luau.Conformance PRIVATE Luau.Analysis Luau.Compiler Luau.CodeGen Luau.VM)
     if(CMAKE_SYSTEM_NAME MATCHES "Android|iOS")

CodeGen/include/Luau/CodeGen.h

@@ -40,8 +40,12 @@ enum class CodeGenCompilationResult
     CodeGenAssemblerFinalizationFailure = 7,  // Failure during assembler finalization
     CodeGenLoweringFailure = 8,               // Lowering failed
     AllocationFailed = 9,                     // Native codegen failed due to an allocation error
+
+    Count = 10,
 };
 
+std::string toString(const CodeGenCompilationResult& result);
+
 struct ProtoCompilationFailure
 {
     CodeGenCompilationResult result = CodeGenCompilationResult::Success;

CodeGen/src/BytecodeAnalysis.cpp

@@ -6,13 +6,17 @@
 #include "Luau/IrUtils.h"
 
 #include "lobject.h"
+#include "lstate.h"
+
+#include <algorithm>
 
 #include <algorithm>
 
 LUAU_FASTFLAG(LuauCodegenDirectUserdataFlow)
 LUAU_FASTFLAG(LuauLoadTypeInfo)                   // Because new VM typeinfo load changes the format used by Codegen, same flag is used
 LUAU_FASTFLAGVARIABLE(LuauCodegenTypeInfo, false) // New analysis is flagged separately
 LUAU_FASTFLAG(LuauTypeInfoLookupImprovement)
+LUAU_FASTFLAGVARIABLE(LuauCodegenVectorMispredictFix, false)
 
 namespace Luau
 {
@@ -771,10 +775,30 @@ void analyzeBytecodeTypes(IrFunction& function)
 
                 regTags[ra] = LBC_TYPE_ANY;
 
-                // Assuming that vector component is being indexed
-                // TODO: check what key is used
-                if (bcType.a == LBC_TYPE_VECTOR)
-                    regTags[ra] = LBC_TYPE_NUMBER;
+                if (FFlag::LuauCodegenVectorMispredictFix)
+                {
+                    if (bcType.a == LBC_TYPE_VECTOR)
+                    {
+                        TString* str = gco2ts(function.proto->k[kc].value.gc);
+                        const char* field = getstr(str);
+
+                        if (str->len == 1)
+                        {
+                            // Same handling as LOP_GETTABLEKS block in lvmexecute.cpp - case-insensitive comparison with "X" / "Y" / "Z"
+                            char ch = field[0] | ' ';
+
+                            if (ch == 'x' || ch == 'y' || ch == 'z')
+                                regTags[ra] = LBC_TYPE_NUMBER;
+                        }
+                    }
+                }
+                else
+                {
+                    // Assuming that vector component is being indexed
+                    // TODO: check what key is used
+                    if (bcType.a == LBC_TYPE_VECTOR)
+                        regTags[ra] = LBC_TYPE_NUMBER;
+                }
 
                 bcType.result = regTags[ra];
                 break;