Sync to upstream/release/559 (#804)

* Fix autocompletion of if-then-else expressions
* Fix a potential crash surrounding improper use of `%*` in a string
format specifier
* All Python scripts now invoke Python via `python3` rather than
`python`.
* Improved error handling for string interpolation with too many
arguments.

Co-authored-by: Arseny Kapoulkine <arseny.kapoulkine@gmail.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>

Analysis/include/Luau/Predicate.h

@@ -57,11 +57,7 @@ struct AndPredicate
     PredicateVec lhs;
     PredicateVec rhs;
 
-    AndPredicate(PredicateVec&& lhs, PredicateVec&& rhs)
+    AndPredicate(PredicateVec&& lhs, PredicateVec&& rhs);
-        : lhs(std::move(lhs))
-        , rhs(std::move(rhs))
-    {
-    }
 };
 
 struct OrPredicate
@@ -69,11 +65,7 @@ struct OrPredicate
     PredicateVec lhs;
     PredicateVec rhs;
 
-    OrPredicate(PredicateVec&& lhs, PredicateVec&& rhs)
+    OrPredicate(PredicateVec&& lhs, PredicateVec&& rhs);
-        : lhs(std::move(lhs))
-        , rhs(std::move(rhs))
-    {
-    }
 };
 
 struct NotPredicate
@@ -81,6 +73,19 @@ struct NotPredicate
     PredicateVec predicates;
 };
 
+// Outside definition works around clang 15 issue where vector instantiation is triggered while Predicate is still incomplete
+inline AndPredicate::AndPredicate(PredicateVec&& lhs, PredicateVec&& rhs)
+    : lhs(std::move(lhs))
+    , rhs(std::move(rhs))
+{
+}
+
+inline OrPredicate::OrPredicate(PredicateVec&& lhs, PredicateVec&& rhs)
+    : lhs(std::move(lhs))
+    , rhs(std::move(rhs))
+{
+}
+
 template<typename T>
 const T* get(const Predicate& predicate)
 {

Analysis/include/Luau/ToString.h

@@ -45,7 +45,6 @@ struct ToStringOptions
     bool hideTableKind = false;                   // If true, all tables will be surrounded with plain '{}'
     bool hideNamedFunctionTypeParameters = false; // If true, type parameters of functions will be hidden at top-level.
     bool hideFunctionSelfArgument = false;        // If true, `self: X` will be omitted from the function signature if the function has self
-    bool DEPRECATED_indent = false;               // TODO Deprecated field, prune when clipping flag FFlagLuauLineBreaksDeterminIndents
     size_t maxTableLength = size_t(FInt::LuauTableTypeMaximumStringifierLength); // Only applied to TableTypes
     size_t maxTypeLength = size_t(FInt::LuauTypeMaximumStringifierLength);
     ToStringNameMap nameMap;

Analysis/include/Luau/TypeReduction.h

@@ -27,8 +27,8 @@ private:
     DenseHashMap<TypeId, TypeId> cachedTypes{nullptr};
     DenseHashMap<TypePackId, TypePackId> cachedTypePacks{nullptr};
 
-    std::optional<TypeId> reduceImpl(TypeId ty);
+    std::pair<std::optional<TypeId>, bool> reduceImpl(TypeId ty);
-    std::optional<TypePackId> reduceImpl(TypePackId tp);
+    std::pair<std::optional<TypePackId>, bool> reduceImpl(TypePackId tp);
 
     // Computes an *estimated length* of the cartesian product of the given type.
     size_t cartesianProductSize(TypeId ty) const;

Analysis/src/Autocomplete.cpp

@@ -13,6 +13,7 @@
 #include <utility>
 
 LUAU_FASTFLAGVARIABLE(LuauCompleteTableKeysBetter, false);
+LUAU_FASTFLAGVARIABLE(LuauFixAutocompleteInIf, false);
 
 static const std::unordered_set<std::string> kStatementStartingKeywords = {
     "while", "if", "local", "repeat", "function", "do", "for", "return", "break", "continue", "type", "export"};
@@ -1487,8 +1488,22 @@ static AutocompleteResult autocomplete(const SourceModule& sourceModule, const M
             return {{{"then", AutocompleteEntry{AutocompleteEntryKind::Keyword}}}, ancestry, AutocompleteContext::Keyword};
     }
     else if (AstStatIf* statIf = extractStat<AstStatIf>(ancestry);
-             statIf && (!statIf->thenLocation || statIf->thenLocation->containsClosed(position)))
+             statIf && (!statIf->thenLocation || statIf->thenLocation->containsClosed(position)) && 
+             (!FFlag::LuauFixAutocompleteInIf || (statIf->condition && !statIf->condition->location.containsClosed(position))))
+    {
+        if (FFlag::LuauFixAutocompleteInIf)
+        {
+            AutocompleteEntryMap ret;
+            ret["then"] = {AutocompleteEntryKind::Keyword};
+            ret["and"] = {AutocompleteEntryKind::Keyword};
+            ret["or"] = {AutocompleteEntryKind::Keyword};
+            return {std::move(ret), ancestry, AutocompleteContext::Keyword};
+        }
+        else
+        {
             return {{{"then", AutocompleteEntry{AutocompleteEntryKind::Keyword}}}, ancestry, AutocompleteContext::Keyword};
+        }
+    }
     else if (AstStatRepeat* statRepeat = node->as<AstStatRepeat>(); statRepeat && statRepeat->condition->is<AstExprError>())
         return autocompleteExpression(sourceModule, *module, builtinTypes, typeArena, ancestry, position);
     else if (AstStatRepeat* statRepeat = extractStat<AstStatRepeat>(ancestry); statRepeat)

Analysis/src/ToString.cpp

@@ -15,10 +15,8 @@
 
 LUAU_FASTFLAG(DebugLuauDeferredConstraintResolution)
 LUAU_FASTFLAG(LuauUnknownAndNeverType)
-LUAU_FASTFLAGVARIABLE(LuauLineBreaksDetermineIndents, false)
 LUAU_FASTFLAGVARIABLE(LuauFunctionReturnStringificationFixup, false)
 LUAU_FASTFLAGVARIABLE(LuauUnseeArrayTtv, false)
-LUAU_FASTFLAGVARIABLE(LuauSerializeNilUnionAsNil, false)
 
 /*
  * Prefix generic typenames with gen-
@@ -276,22 +274,12 @@ struct StringifierState
 
 private:
     void emitIndentation()
-    {
-        if (!FFlag::LuauLineBreaksDetermineIndents)
-        {
-            if (!opts.DEPRECATED_indent)
-                return;
-
-            emit(std::string(indentation, ' '));
-        }
-        else
     {
         if (!opts.useLineBreaks)
             return;
 
         emit(std::string(indentation, ' '));
     }
-    }
 };
 
 struct TypeStringifier
@@ -781,11 +769,8 @@ struct TypeStringifier
             if (results.size() > 1)
                 s = ")?";
 
-            if (FFlag::LuauSerializeNilUnionAsNil)
-            {
             if (!hasNonNilDisjunct)
                 s = "nil";
-            }
 
             state.emit(s);
         }

Analysis/src/TypeReduction.cpp

@@ -51,6 +51,16 @@ struct TypeReducer
     NotNull<BuiltinTypes> builtinTypes;
     NotNull<InternalErrorReporter> handle;
 
+    std::unordered_map<TypeId, TypeId> copies;
+    std::deque<const void*> seen;
+    int depth = 0;
+
+    // When we encounter _any type_ that which is usually mutated in-place, we need to not cache the result.
+    // e.g. `'a & {} T` may have an upper bound constraint `{}` placed upon `'a`, but this constraint was not
+    // known when we decided to reduce this intersection type. By not caching, we'll always be forced to perform
+    // the reduction calculus over again.
+    bool cacheOk = true;
+
     TypeId reduce(TypeId ty);
     TypePackId reduce(TypePackId tp);
 
@@ -60,13 +70,11 @@ struct TypeReducer
     TypeId functionType(TypeId ty);
     TypeId negationType(TypeId ty);
 
-    std::deque<const void*> seen;
-    int depth = 0;
-
     RecursionGuard guard(TypeId ty);
     RecursionGuard guard(TypePackId tp);
 
-    std::unordered_map<TypeId, TypeId> copies;
+    void checkCacheable(TypeId ty);
+    void checkCacheable(TypePackId tp);
 
     template<typename T>
     LUAU_NOINLINE std::pair<TypeId, T*> copy(TypeId ty, const T* t)
@@ -153,6 +161,7 @@ TypeId TypeReducer::reduce(TypeId ty)
         return ty;
 
     RecursionGuard rg = guard(ty);
+    checkCacheable(ty);
 
     if (auto i = get<IntersectionType>(ty))
         return foldl<IntersectionType>(begin(i), end(i), &TypeReducer::intersectionType);
@@ -176,6 +185,7 @@ TypePackId TypeReducer::reduce(TypePackId tp)
         return tp;
 
     RecursionGuard rg = guard(tp);
+    checkCacheable(tp);
 
     TypePackIterator it = begin(tp);
 
@@ -213,6 +223,14 @@ std::optional<TypeId> TypeReducer::intersectionType(TypeId left, TypeId right)
         return right; // any & T ~ T
     else if (get<AnyType>(right))
         return left; // T & any ~ T
+    else if (get<FreeType>(left))
+        return std::nullopt; // 'a & T ~ 'a & T
+    else if (get<FreeType>(right))
+        return std::nullopt; // T & 'a ~ T & 'a
+    else if (get<GenericType>(left))
+        return std::nullopt; // G & T ~ G & T
+    else if (get<GenericType>(right))
+        return std::nullopt; // T & G ~ T & G
     else if (get<ErrorType>(left))
         return std::nullopt; // error & T ~ error & T
     else if (get<ErrorType>(right))
@@ -701,6 +719,32 @@ RecursionGuard TypeReducer::guard(TypePackId tp)
     return RecursionGuard{&depth, FInt::LuauTypeReductionRecursionLimit, &seen};
 }
 
+void TypeReducer::checkCacheable(TypeId ty)
+{
+    if (!cacheOk)
+        return;
+
+    ty = follow(ty);
+
+    // Only does shallow check, the TypeReducer itself already does deep traversal.
+    if (get<FreeType>(ty) || get<BlockedType>(ty) || get<PendingExpansionType>(ty))
+        cacheOk = false;
+    else if (auto tt = get<TableType>(ty); tt && (tt->state == TableState::Free || tt->state == TableState::Unsealed))
+        cacheOk = false;
+}
+
+void TypeReducer::checkCacheable(TypePackId tp)
+{
+    if (!cacheOk)
+        return;
+
+    tp = follow(tp);
+
+    // Only does shallow check, the TypeReducer itself already does deep traversal.
+    if (get<FreeTypePack>(tp) || get<BlockedTypePack>(tp))
+        cacheOk = false;
+}
+
 } // namespace
 
 TypeReduction::TypeReduction(NotNull<TypeArena> arena, NotNull<BuiltinTypes> builtinTypes, NotNull<InternalErrorReporter> handle)
@@ -715,13 +759,11 @@ std::optional<TypeId> TypeReduction::reduce(TypeId ty)
     if (auto found = cachedTypes.find(ty))
         return *found;
 
-    if (auto reduced = reduceImpl(ty))
+    auto [reducedTy, cacheOk] = reduceImpl(ty);
-    {
+    if (cacheOk)
-        cachedTypes[ty] = *reduced;
+        cachedTypes[ty] = *reducedTy;
-        return *reduced;
-    }
 
-    return std::nullopt;
+    return reducedTy;
 }
 
 std::optional<TypePackId> TypeReduction::reduce(TypePackId tp)
@@ -729,50 +771,48 @@ std::optional<TypePackId> TypeReduction::reduce(TypePackId tp)
     if (auto found = cachedTypePacks.find(tp))
         return *found;
 
-    if (auto reduced = reduceImpl(tp))
+    auto [reducedTp, cacheOk] = reduceImpl(tp);
-    {
+    if (cacheOk)
-        cachedTypePacks[tp] = *reduced;
+        cachedTypePacks[tp] = *reducedTp;
-        return *reduced;
+
+    return reducedTp;
 }
 
-    return std::nullopt;
+std::pair<std::optional<TypeId>, bool> TypeReduction::reduceImpl(TypeId ty)
-}
-
-std::optional<TypeId> TypeReduction::reduceImpl(TypeId ty)
 {
     if (FFlag::DebugLuauDontReduceTypes)
-        return ty;
+        return {ty, false};
 
     if (hasExceededCartesianProductLimit(ty))
-        return std::nullopt;
+        return {std::nullopt, false};
 
     try
     {
         TypeReducer reducer{arena, builtinTypes, handle};
-        return reducer.reduce(ty);
+        return {reducer.reduce(ty), reducer.cacheOk};
     }
     catch (const RecursionLimitException&)
     {
-        return std::nullopt;
+        return {std::nullopt, false};
     }
 }
 
-std::optional<TypePackId> TypeReduction::reduceImpl(TypePackId tp)
+std::pair<std::optional<TypePackId>, bool> TypeReduction::reduceImpl(TypePackId tp)
 {
     if (FFlag::DebugLuauDontReduceTypes)
-        return tp;
+        return {tp, false};
 
     if (hasExceededCartesianProductLimit(tp))
-        return std::nullopt;
+        return {std::nullopt, false};
 
     try
     {
         TypeReducer reducer{arena, builtinTypes, handle};
-        return reducer.reduce(tp);
+        return {reducer.reduce(tp), reducer.cacheOk};
     }
     catch (const RecursionLimitException&)
     {
-        return std::nullopt;
+        return {std::nullopt, false};
     }
 }
 

Ast/src/Parser.cpp

@@ -14,11 +14,6 @@
 LUAU_FASTINTVARIABLE(LuauRecursionLimit, 1000)
 LUAU_FASTINTVARIABLE(LuauParseErrorLimit, 100)
 
-LUAU_FASTFLAGVARIABLE(LuauFixNamedFunctionParse, false)
-LUAU_DYNAMIC_FASTFLAGVARIABLE(LuaReportParseWrongNamedType, false)
-
-bool lua_telemetry_parsed_named_non_function_type = false;
-
 LUAU_FASTFLAGVARIABLE(LuauErrorDoubleHexPrefix, false)
 LUAU_DYNAMIC_FASTFLAGVARIABLE(LuaReportParseIntegerIssues, false)
 
@@ -1423,7 +1418,7 @@ AstTypeOrPack Parser::parseFunctionTypeAnnotation(bool allowPack)
 
     AstArray<AstType*> paramTypes = copy(params);
 
-    if (FFlag::LuauFixNamedFunctionParse && !names.empty())
+    if (!names.empty())
         forceFunctionType = true;
 
     bool returnTypeIntroducer = lexer.current().type == Lexeme::SkinnyArrow || lexer.current().type == ':';
@@ -1431,9 +1426,6 @@ AstTypeOrPack Parser::parseFunctionTypeAnnotation(bool allowPack)
     // Not a function at all. Just a parenthesized type. Or maybe a type pack with a single element
     if (params.size() == 1 && !varargAnnotation && !forceFunctionType && !returnTypeIntroducer)
     {
-        if (DFFlag::LuaReportParseWrongNamedType && !names.empty())
-            lua_telemetry_parsed_named_non_function_type = true;
-
         if (allowPack)
             return {{}, allocator.alloc<AstTypePackExplicit>(begin.location, AstTypeList{paramTypes, nullptr})};
         else
@@ -1441,12 +1433,7 @@ AstTypeOrPack Parser::parseFunctionTypeAnnotation(bool allowPack)
     }
 
     if (!forceFunctionType && !returnTypeIntroducer && allowPack)
-    {
-        if (DFFlag::LuaReportParseWrongNamedType && !names.empty())
-            lua_telemetry_parsed_named_non_function_type = true;
-
         return {{}, allocator.alloc<AstTypePackExplicit>(begin.location, AstTypeList{paramTypes, varargAnnotation})};
-    }
 
     AstArray<std::optional<AstArgumentName>> paramNames = copy(names);
 

CodeGen/include/Luau/AssemblyBuilderX64.h

@@ -78,6 +78,7 @@ public:
 
     void test(OperandX64 lhs, OperandX64 rhs);
     void lea(OperandX64 lhs, OperandX64 rhs);
+    void setcc(ConditionX64 cond, OperandX64 op);
 
     void push(OperandX64 op);
     void pop(OperandX64 op);
@@ -189,8 +190,8 @@ private:
         const char* name, OperandX64 dst, OperandX64 src1, OperandX64 src2, uint8_t imm8, uint8_t code, bool setW, uint8_t mode, uint8_t prefix);
 
     // Instruction components
-    void placeRegAndModRegMem(OperandX64 lhs, OperandX64 rhs);
+    void placeRegAndModRegMem(OperandX64 lhs, OperandX64 rhs, int32_t extraCodeBytes = 0);
-    void placeModRegMem(OperandX64 rhs, uint8_t regop);
+    void placeModRegMem(OperandX64 rhs, uint8_t regop, int32_t extraCodeBytes = 0);
     void placeRex(RegisterX64 op);
     void placeRex(OperandX64 op);
     void placeRexNoW(OperandX64 op);

CodeGen/src/AssemblyBuilderX64.cpp

@@ -17,9 +17,13 @@ static const uint8_t codeForCondition[] = {
     0x0, 0x1, 0x2, 0x3, 0x2, 0x6, 0x7, 0x3, 0x4, 0xc, 0xe, 0xf, 0xd, 0x3, 0x7, 0x6, 0x2, 0x5, 0xd, 0xf, 0xe, 0xc, 0x4, 0x5, 0xa, 0xb};
 static_assert(sizeof(codeForCondition) / sizeof(codeForCondition[0]) == size_t(ConditionX64::Count), "all conditions have to be covered");
 
-static const char* textForCondition[] = {"jo", "jno", "jc", "jnc", "jb", "jbe", "ja", "jae", "je", "jl", "jle", "jg", "jge", "jnb", "jnbe", "jna",
+static const char* jccTextForCondition[] = {"jo", "jno", "jc", "jnc", "jb", "jbe", "ja", "jae", "je", "jl", "jle", "jg", "jge", "jnb", "jnbe", "jna",
     "jnae", "jne", "jnl", "jnle", "jng", "jnge", "jz", "jnz", "jp", "jnp"};
-static_assert(sizeof(textForCondition) / sizeof(textForCondition[0]) == size_t(ConditionX64::Count), "all conditions have to be covered");
+static_assert(sizeof(jccTextForCondition) / sizeof(jccTextForCondition[0]) == size_t(ConditionX64::Count), "all conditions have to be covered");
+
+static const char* setccTextForCondition[] = {"seto", "setno", "setc", "setnc", "setb", "setbe", "seta", "setae", "sete", "setl", "setle", "setg",
+    "setge", "setnb", "setnbe", "setna", "setnae", "setne", "setnl", "setnle", "setng", "setnge", "setz", "setnz", "setp", "setnp"};
+static_assert(sizeof(setccTextForCondition) / sizeof(setccTextForCondition[0]) == size_t(ConditionX64::Count), "all conditions have to be covered");
 
 #define OP_PLUS_REG(op, reg) ((op) + (reg & 0x7))
 #define OP_PLUS_CC(op, cc) ((op) + uint8_t(cc))
@@ -169,7 +173,7 @@ void AssemblyBuilderX64::mov(OperandX64 lhs, OperandX64 rhs)
         if (size == SizeX64::byte)
         {
             place(0xc6);
-            placeModRegMem(lhs, 0);
+            placeModRegMem(lhs, 0, /*extraCodeBytes=*/1);
             placeImm8(rhs.imm);
         }
         else
@@ -177,7 +181,7 @@ void AssemblyBuilderX64::mov(OperandX64 lhs, OperandX64 rhs)
             LUAU_ASSERT(size == SizeX64::dword || size == SizeX64::qword);
 
             place(0xc7);
-            placeModRegMem(lhs, 0);
+            placeModRegMem(lhs, 0, /*extraCodeBytes=*/4);
             placeImm32(rhs.imm);
         }
     }
@@ -304,13 +308,13 @@ void AssemblyBuilderX64::imul(OperandX64 dst, OperandX64 lhs, int32_t rhs)
     if (int8_t(rhs) == rhs)
     {
         place(0x6b);
-        placeRegAndModRegMem(dst, lhs);
+        placeRegAndModRegMem(dst, lhs, /*extraCodeBytes=*/1);
         placeImm8(rhs);
     }
     else
     {
         place(0x69);
-        placeRegAndModRegMem(dst, lhs);
+        placeRegAndModRegMem(dst, lhs, /*extraCodeBytes=*/4);
         placeImm32(rhs);
     }
 
@@ -366,9 +370,24 @@ void AssemblyBuilderX64::ret()
     commit();
 }
 
+void AssemblyBuilderX64::setcc(ConditionX64 cond, OperandX64 op)
+{
+    SizeX64 size = op.cat == CategoryX64::reg ? op.base.size : op.memSize;
+    LUAU_ASSERT(size == SizeX64::byte);
+
+    if (logText)
+        log(setccTextForCondition[size_t(cond)], op);
+
+    placeRex(op);
+    place(0x0f);
+    place(0x90 | codeForCondition[size_t(cond)]);
+    placeModRegMem(op, 0);
+    commit();
+}
+
 void AssemblyBuilderX64::jcc(ConditionX64 cond, Label& label)
 {
-    placeJcc(textForCondition[size_t(cond)], label, codeForCondition[size_t(cond)]);
+    placeJcc(jccTextForCondition[size_t(cond)], label, codeForCondition[size_t(cond)]);
 }
 
 void AssemblyBuilderX64::jmp(Label& label)
@@ -866,7 +885,7 @@ void AssemblyBuilderX64::placeBinaryRegMemAndImm(OperandX64 lhs, OperandX64 rhs,
     if (size == SizeX64::byte)
     {
         place(code8);
-        placeModRegMem(lhs, opreg);
+        placeModRegMem(lhs, opreg, /*extraCodeBytes=*/1);
         placeImm8(rhs.imm);
     }
     else
@@ -876,13 +895,13 @@ void AssemblyBuilderX64::placeBinaryRegMemAndImm(OperandX64 lhs, OperandX64 rhs,
         if (int8_t(rhs.imm) == rhs.imm && code != codeImm8)
         {
             place(codeImm8);
-            placeModRegMem(lhs, opreg);
+            placeModRegMem(lhs, opreg, /*extraCodeBytes=*/1);
             placeImm8(rhs.imm);
         }
         else
         {
             place(code);
-            placeModRegMem(lhs, opreg);
+            placeModRegMem(lhs, opreg, /*extraCodeBytes=*/4);
             placeImm32(rhs.imm);
         }
     }
@@ -950,7 +969,7 @@ void AssemblyBuilderX64::placeShift(const char* name, OperandX64 lhs, OperandX64
         LUAU_ASSERT(int8_t(rhs.imm) == rhs.imm);
 
         place(size == SizeX64::byte ? 0xc0 : 0xc1);
-        placeModRegMem(lhs, opreg);
+        placeModRegMem(lhs, opreg, /*extraCodeBytes=*/1);
         placeImm8(rhs.imm);
     }
     else
@@ -1042,7 +1061,7 @@ void AssemblyBuilderX64::placeAvx(
 
     placeVex(dst, src1, src2, setW, mode, prefix);
     place(code);
-    placeRegAndModRegMem(dst, src2);
+    placeRegAndModRegMem(dst, src2, /*extraCodeBytes=*/1);
     placeImm8(imm8);
 
     commit();
@@ -1118,14 +1137,14 @@ static uint8_t getScaleEncoding(uint8_t scale)
     return scales[scale];
 }
 
-void AssemblyBuilderX64::placeRegAndModRegMem(OperandX64 lhs, OperandX64 rhs)
+void AssemblyBuilderX64::placeRegAndModRegMem(OperandX64 lhs, OperandX64 rhs, int32_t extraCodeBytes)
 {
     LUAU_ASSERT(lhs.cat == CategoryX64::reg);
 
-    placeModRegMem(rhs, lhs.base.index);
+    placeModRegMem(rhs, lhs.base.index, extraCodeBytes);
 }
 
-void AssemblyBuilderX64::placeModRegMem(OperandX64 rhs, uint8_t regop)
+void AssemblyBuilderX64::placeModRegMem(OperandX64 rhs, uint8_t regop, int32_t extraCodeBytes)
 {
     if (rhs.cat == CategoryX64::reg)
     {
@@ -1180,7 +1199,12 @@ void AssemblyBuilderX64::placeModRegMem(OperandX64 rhs, uint8_t regop)
         else if (base == rip)
         {
             place(MOD_RM(0b00, regop, 0b101));
-            placeImm32(-int32_t(getCodeSize() + 4) + rhs.imm);
+
+            // As a reminder: we do (getCodeSize() + 4) here to calculate the offset of the end of the current instruction we are placing.
+            // Since we have already placed all of the instruction bytes for this instruction, we add +4 to account for the imm32 displacement.
+            // Some instructions, however, are encoded such that an additional imm8 byte, or imm32 bytes, is placed after the ModRM byte, thus,
+            // we need to account for that case here as well.
+            placeImm32(-int32_t(getCodeSize() + 4 + extraCodeBytes) + rhs.imm);
         }
         else if (base != noreg)
         {

CodeGen/src/CodeGen.cpp

@@ -91,6 +91,9 @@ static int emitInst(AssemblyBuilderX64& build, NativeState& data, ModuleHelpers&
     case LOP_SETGLOBAL:
         emitInstSetGlobal(build, pc, i, next, fallback);
         break;
+    case LOP_NAMECALL:
+        emitInstNameCall(build, pc, i, proto->k, next, fallback);
+        break;
     case LOP_CALL:
         emitInstCall(build, helpers, pc, i);
         break;
@@ -270,6 +273,9 @@ static int emitInst(AssemblyBuilderX64& build, NativeState& data, ModuleHelpers&
     case LOP_CONCAT:
         emitInstConcat(build, pc, i, next);
         break;
+    case LOP_COVERAGE:
+        emitInstCoverage(build, i);
+        break;
     default:
         emitFallback(build, data, op, i);
         break;
@@ -298,6 +304,10 @@ static void emitInstFallback(AssemblyBuilderX64& build, NativeState& data, LuauO
     case LOP_SETTABLEN:
         emitInstSetTableNFallback(build, pc, i);
         break;
+    case LOP_NAMECALL:
+        // TODO: fast-paths that we've handled can be removed from the fallback
+        emitFallback(build, data, op, i);
+        break;
     case LOP_JUMPIFEQ:
         emitInstJumpIfEqFallback(build, pc, i, labelarr, /* not_ */ false);
         break;

CodeGen/src/EmitCommonX64.cpp

@@ -239,6 +239,22 @@ void callCheckGc(AssemblyBuilderX64& build, int pcpos, bool savepc, Label& skip)
     emitUpdateBase(build);
 }
 
+void callGetFastTmOrFallback(AssemblyBuilderX64& build, RegisterX64 table, TMS tm, Label& fallback)
+{
+    build.mov(rArg1, qword[table + offsetof(Table, metatable)]);
+    build.test(rArg1, rArg1);
+    build.jcc(ConditionX64::Zero, fallback); // no metatable
+
+    build.test(byte[rArg1 + offsetof(Table, tmcache)], 1 << tm);
+    build.jcc(ConditionX64::NotZero, fallback); // no tag method
+
+    // rArg1 is already prepared
+    build.mov(rArg2, tm);
+    build.mov(rax, qword[rState + offsetof(lua_State, global)]);
+    build.mov(rArg3, qword[rax + offsetof(global_State, tmname[tm])]);
+    build.call(qword[rNativeContext + offsetof(NativeContext, luaT_gettm)]);
+}
+
 void emitExit(AssemblyBuilderX64& build, bool continueInVm)
 {
     if (continueInVm)

CodeGen/src/EmitCommonX64.h

@@ -67,8 +67,10 @@ constexpr OperandX64 sArg6 = noreg;
 constexpr unsigned kTValueSizeLog2 = 4;
 constexpr unsigned kLuaNodeSizeLog2 = 5;
 constexpr unsigned kLuaNodeTagMask = 0xf;
+constexpr unsigned kNextBitOffset = 4;
 
 constexpr unsigned kOffsetOfLuaNodeTag = 12; // offsetof cannot be used on a bit field
+constexpr unsigned kOffsetOfLuaNodeNext = 12; // offsetof cannot be used on a bit field
 constexpr unsigned kOffsetOfInstructionC = 3;
 
 // Leaf functions that are placed in every module to perform common instruction sequences
@@ -168,6 +170,12 @@ inline void jumpIfTagIsNot(AssemblyBuilderX64& build, int ri, lua_Type tag, Labe
     build.jcc(ConditionX64::NotEqual, label);
 }
 
+inline void jumpIfTagIsNot(AssemblyBuilderX64& build, RegisterX64 reg, lua_Type tag, Label& label)
+{
+    build.cmp(dword[reg + offsetof(TValue, tt)], tag);
+    build.jcc(ConditionX64::NotEqual, label);
+}
+
 // Note: fallthrough label should be placed after this condition
 inline void jumpIfFalsy(AssemblyBuilderX64& build, int ri, Label& target, Label& fallthrough)
 {
@@ -224,6 +232,13 @@ inline void jumpIfNodeValueTagIs(AssemblyBuilderX64& build, RegisterX64 node, lu
     build.jcc(ConditionX64::Equal, label);
 }
 
+inline void jumpIfNodeHasNext(AssemblyBuilderX64& build, RegisterX64 node, Label& label)
+{
+    build.mov(ecx, dword[node + offsetof(LuaNode, key) + kOffsetOfLuaNodeNext]);
+    build.shr(ecx, kNextBitOffset);
+    build.jcc(ConditionX64::NotZero, label);
+}
+
 inline void jumpIfNodeKeyNotInExpectedSlot(AssemblyBuilderX64& build, RegisterX64 tmp, RegisterX64 node, OperandX64 expectedKey, Label& label)
 {
     jumpIfNodeKeyTagIsNot(build, tmp, node, LUA_TSTRING, label);
@@ -250,6 +265,7 @@ void callBarrierTable(AssemblyBuilderX64& build, RegisterX64 tmp, RegisterX64 ta
 void callBarrierObject(AssemblyBuilderX64& build, RegisterX64 tmp, RegisterX64 object, int ra, Label& skip);
 void callBarrierTableFast(AssemblyBuilderX64& build, RegisterX64 table, Label& skip);
 void callCheckGc(AssemblyBuilderX64& build, int pcpos, bool savepc, Label& skip);
+void callGetFastTmOrFallback(AssemblyBuilderX64& build, RegisterX64 table, TMS tm, Label& fallback);
 
 void emitExit(AssemblyBuilderX64& build, bool continueInVm);
 void emitUpdateBase(AssemblyBuilderX64& build);
@@ -258,7 +274,6 @@ void emitInterrupt(AssemblyBuilderX64& build, int pcpos);
 void emitFallback(AssemblyBuilderX64& build, NativeState& data, int op, int pcpos);
 
 void emitContinueCallInVm(AssemblyBuilderX64& build);
-void emitExitFromLastReturn(AssemblyBuilderX64& build);
 
 } // namespace CodeGen
 } // namespace Luau

CodeGen/src/EmitInstructionX64.cpp

@@ -69,6 +69,51 @@ void emitInstMove(AssemblyBuilderX64& build, const Instruction* pc)
     build.vmovups(luauReg(ra), xmm0);
 }
 
+void emitInstNameCall(AssemblyBuilderX64& build, const Instruction* pc, int pcpos, const TValue* k, Label& next, Label& fallback)
+{
+    int ra = LUAU_INSN_A(*pc);
+    int rb = LUAU_INSN_B(*pc);
+    uint32_t aux = pc[1];
+
+    Label secondfpath;
+
+    jumpIfTagIsNot(build, rb, LUA_TTABLE, fallback);
+
+    RegisterX64 table = r8;
+    build.mov(table, luauRegValue(rb));
+
+    // &h->node[tsvalue(kv)->hash & (sizenode(h) - 1)];
+    RegisterX64 node = rdx;
+    build.mov(node, qword[table + offsetof(Table, node)]);
+    build.mov(eax, 1);
+    build.mov(cl, byte[table + offsetof(Table, lsizenode)]);
+    build.shl(eax, cl);
+    build.dec(eax);
+    build.and_(eax, tsvalue(&k[aux])->hash);
+    build.shl(rax, kLuaNodeSizeLog2);
+    build.add(node, rax);
+
+    jumpIfNodeKeyNotInExpectedSlot(build, rax, node, luauConstantValue(aux), secondfpath);
+
+    setLuauReg(build, xmm0, ra + 1, luauReg(rb));
+    setLuauReg(build, xmm0, ra, luauNodeValue(node));
+    build.jmp(next);
+
+    build.setLabel(secondfpath);
+
+    jumpIfNodeHasNext(build, node, fallback);
+    callGetFastTmOrFallback(build, table, TM_INDEX, fallback);
+    jumpIfTagIsNot(build, rax, LUA_TTABLE, fallback);
+
+    build.mov(table, qword[rax + offsetof(TValue, value)]);
+
+    getTableNodeAtCachedSlot(build, rax, node, table, pcpos);
+    jumpIfNodeKeyNotInExpectedSlot(build, rax, node, luauConstantValue(aux), fallback);
+
+    setLuauReg(build, xmm0, ra + 1, luauReg(rb));
+    setLuauReg(build, xmm0, ra, luauNodeValue(node));
+}
+
 void emitInstCall(AssemblyBuilderX64& build, ModuleHelpers& helpers, const Instruction* pc, int pcpos)
 {
     int ra = LUAU_INSN_A(*pc);
@@ -1627,5 +1672,28 @@ void emitInstConcat(AssemblyBuilderX64& build, const Instruction* pc, int pcpos,
     callCheckGc(build, pcpos, /* savepc= */ false, next);
 }
 
+void emitInstCoverage(AssemblyBuilderX64& build, int pcpos)
+{
+    build.mov(rcx, sCode);
+    build.add(rcx, pcpos * sizeof(Instruction));
+
+    // hits = LUAU_INSN_E(*pc)
+    build.mov(edx, dword[rcx]);
+    build.sar(edx, 8);
+
+    // hits = (hits < (1 << 23) - 1) ? hits + 1 : hits;
+    build.xor_(eax, eax);
+    build.cmp(edx, (1 << 23) - 1);
+    build.setcc(ConditionX64::NotEqual, al);
+    build.add(edx, eax);
+
+
+    // VM_PATCH_E(pc, hits);
+    build.sal(edx, 8);
+    build.movzx(eax, byte[rcx]);
+    build.or_(eax, edx);
+    build.mov(dword[rcx], eax);
+}
+
 } // namespace CodeGen
 } // namespace Luau

CodeGen/src/EmitInstructionX64.h

@@ -17,6 +17,7 @@ class AssemblyBuilderX64;
 enum class ConditionX64 : uint8_t;
 struct Label;
 struct ModuleHelpers;
+struct NativeState;
 
 void emitInstLoadNil(AssemblyBuilderX64& build, const Instruction* pc);
 void emitInstLoadB(AssemblyBuilderX64& build, const Instruction* pc, int pcpos, Label* labelarr);
@@ -24,6 +25,7 @@ void emitInstLoadN(AssemblyBuilderX64& build, const Instruction* pc);
 void emitInstLoadK(AssemblyBuilderX64& build, const Instruction* pc);
 void emitInstLoadKX(AssemblyBuilderX64& build, const Instruction* pc);
 void emitInstMove(AssemblyBuilderX64& build, const Instruction* pc);
+void emitInstNameCall(AssemblyBuilderX64& build, const Instruction* pc, int pcpos, const TValue* k, Label& next, Label& fallback);
 void emitInstCall(AssemblyBuilderX64& build, ModuleHelpers& helpers, const Instruction* pc, int pcpos);
 void emitInstReturn(AssemblyBuilderX64& build, ModuleHelpers& helpers, const Instruction* pc, int pcpos);
 void emitInstJump(AssemblyBuilderX64& build, const Instruction* pc, int pcpos, Label* labelarr);
@@ -84,6 +86,7 @@ void emitInstSetTableKS(AssemblyBuilderX64& build, const Instruction* pc, int pc
 void emitInstGetGlobal(AssemblyBuilderX64& build, const Instruction* pc, int pcpos, Label& fallback);
 void emitInstSetGlobal(AssemblyBuilderX64& build, const Instruction* pc, int pcpos, Label& next, Label& fallback);
 void emitInstConcat(AssemblyBuilderX64& build, const Instruction* pc, int pcpos, Label& next);
+void emitInstCoverage(AssemblyBuilderX64& build, int pcpos);
 
 } // namespace CodeGen
 } // namespace Luau

CodeGen/src/Fallbacks.cpp

@@ -594,19 +594,6 @@ const Instruction* execute_LOP_PREPVARARGS(lua_State* L, const Instruction* pc,
     return pc;
 }
 
-const Instruction* execute_LOP_COVERAGE(lua_State* L, const Instruction* pc, StkId base, TValue* k)
-{
-    [[maybe_unused]] Closure* cl = clvalue(L->ci->func);
-    Instruction insn = *pc++;
-    int hits = LUAU_INSN_E(insn);
-
-    // update hits with saturated add and patch the instruction in place
-    hits = (hits < (1 << 23) - 1) ? hits + 1 : hits;
-    VM_PATCH_E(pc - 1, hits);
-
-    return pc;
-}
-
 const Instruction* execute_LOP_BREAK(lua_State* L, const Instruction* pc, StkId base, TValue* k)
 {
     LUAU_ASSERT(!"Unsupported deprecated opcode");

CodeGen/src/Fallbacks.h

@@ -20,5 +20,4 @@ const Instruction* execute_LOP_FORGPREP(lua_State* L, const Instruction* pc, Stk
 const Instruction* execute_LOP_GETVARARGS(lua_State* L, const Instruction* pc, StkId base, TValue* k);
 const Instruction* execute_LOP_DUPCLOSURE(lua_State* L, const Instruction* pc, StkId base, TValue* k);
 const Instruction* execute_LOP_PREPVARARGS(lua_State* L, const Instruction* pc, StkId base, TValue* k);
-const Instruction* execute_LOP_COVERAGE(lua_State* L, const Instruction* pc, StkId base, TValue* k);
 const Instruction* execute_LOP_BREAK(lua_State* L, const Instruction* pc, StkId base, TValue* k);

CodeGen/src/IrData.h

@@ -0,0 +1,280 @@
+// This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
+#pragma once
+
+#include "Luau/Label.h"
+#include "Luau/RegisterX64.h"
+#include "Luau/RegisterA64.h"
+
+#include <vector>
+
+#include <stdint.h>
+
+namespace Luau
+{
+namespace CodeGen
+{
+
+enum class IrCmd : uint8_t
+{
+    NOP,
+
+    LOAD_TAG,
+    LOAD_POINTER,
+    LOAD_DOUBLE,
+    LOAD_INT,
+    LOAD_TVALUE,
+    LOAD_NODE_VALUE_TV, // TODO: we should find a way to generalize LOAD_TVALUE
+    LOAD_ENV,
+
+    GET_ARR_ADDR,
+    GET_SLOT_NODE_ADDR,
+
+    STORE_TAG,
+    STORE_POINTER,
+    STORE_DOUBLE,
+    STORE_INT,
+    STORE_TVALUE,
+    STORE_NODE_VALUE_TV, // TODO: we should find a way to generalize STORE_TVALUE
+
+    ADD_INT,
+    SUB_INT,
+
+    ADD_NUM,
+    SUB_NUM,
+    MUL_NUM,
+    DIV_NUM,
+    MOD_NUM,
+    POW_NUM,
+
+    UNM_NUM,
+
+    NOT_ANY, // TODO: boolean specialization will be useful
+
+    JUMP,
+    JUMP_IF_TRUTHY,
+    JUMP_IF_FALSY,
+    JUMP_EQ_TAG,
+    JUMP_EQ_BOOLEAN,
+    JUMP_EQ_POINTER,
+
+    JUMP_CMP_NUM,
+    JUMP_CMP_STR,
+    JUMP_CMP_ANY,
+
+    TABLE_LEN,
+    NEW_TABLE,
+    DUP_TABLE,
+
+    NUM_TO_INDEX,
+
+    // Fallback functions
+    DO_ARITH,
+    DO_LEN,
+    GET_TABLE,
+    SET_TABLE,
+    GET_IMPORT,
+    CONCAT,
+    GET_UPVALUE,
+    SET_UPVALUE,
+
+    // Guards and checks
+    CHECK_TAG,
+    CHECK_READONLY,
+    CHECK_NO_METATABLE,
+    CHECK_SAFE_ENV,
+    CHECK_ARRAY_SIZE,
+    CHECK_SLOT_MATCH,
+
+    // Special operations
+    INTERRUPT,
+    CHECK_GC,
+    BARRIER_OBJ,
+    BARRIER_TABLE_BACK,
+    BARRIER_TABLE_FORWARD,
+    SET_SAVEDPC,
+    CLOSE_UPVALS,
+
+    // While capture is a no-op right now, it might be useful to track register/upvalue lifetimes
+    CAPTURE,
+
+    // Operations that don't have an IR representation yet
+    LOP_SETLIST,
+    LOP_CALL,
+    LOP_RETURN,
+    LOP_FASTCALL,
+    LOP_FASTCALL1,
+    LOP_FASTCALL2,
+    LOP_FASTCALL2K,
+    LOP_FORNPREP,
+    LOP_FORNLOOP,
+    LOP_FORGLOOP,
+    LOP_FORGLOOP_FALLBACK,
+    LOP_FORGPREP_NEXT,
+    LOP_FORGPREP_INEXT,
+    LOP_FORGPREP_XNEXT_FALLBACK,
+    LOP_AND,
+    LOP_ANDK,
+    LOP_OR,
+    LOP_ORK,
+
+    // Operations that have a translation, but use a full instruction fallback
+    FALLBACK_GETGLOBAL,
+    FALLBACK_SETGLOBAL,
+    FALLBACK_GETTABLEKS,
+    FALLBACK_SETTABLEKS,
+
+    // Operations that don't have assembly lowering at all
+    FALLBACK_NAMECALL,
+    FALLBACK_PREPVARARGS,
+    FALLBACK_GETVARARGS,
+    FALLBACK_NEWCLOSURE,
+    FALLBACK_DUPCLOSURE,
+    FALLBACK_FORGPREP,
+    FALLBACK_COVERAGE,
+};
+
+enum class IrConstKind : uint8_t
+{
+    Bool,
+    Int,
+    Uint,
+    Double,
+    Tag,
+};
+
+struct IrConst
+{
+    IrConstKind kind;
+
+    union
+    {
+        bool valueBool;
+        int valueInt;
+        unsigned valueUint;
+        double valueDouble;
+        uint8_t valueTag;
+    };
+};
+
+enum class IrCondition : uint8_t
+{
+    Equal,
+    NotEqual,
+    Less,
+    NotLess,
+    LessEqual,
+    NotLessEqual,
+    Greater,
+    NotGreater,
+    GreaterEqual,
+    NotGreaterEqual,
+
+    UnsignedLess,
+    UnsignedLessEqual,
+    UnsignedGreater,
+    UnsignedGreaterEqual,
+
+    Count
+};
+
+enum class IrOpKind : uint32_t
+{
+    None,
+
+    // To reference a constant value
+    Constant,
+
+    // To specify a condition code
+    Condition,
+
+    // To reference a result of a previous instruction
+    Inst,
+
+    // To reference a basic block in control flow
+    Block,
+
+    // To reference a VM register
+    VmReg,
+
+    // To reference a VM constant
+    VmConst,
+
+    // To reference a VM upvalue
+    VmUpvalue,
+};
+
+struct IrOp
+{
+    IrOpKind kind : 4;
+    uint32_t index : 28;
+
+    IrOp()
+        : kind(IrOpKind::None)
+        , index(0)
+    {
+    }
+
+    IrOp(IrOpKind kind, uint32_t index)
+        : kind(kind)
+        , index(index)
+    {
+    }
+};
+
+static_assert(sizeof(IrOp) == 4);
+
+struct IrInst
+{
+    IrCmd cmd;
+
+    // Operands
+    IrOp a;
+    IrOp b;
+    IrOp c;
+    IrOp d;
+    IrOp e;
+
+    uint32_t lastUse = 0;
+    uint16_t useCount = 0;
+
+    // Location of the result (optional)
+    RegisterX64 regX64 = noreg;
+    RegisterA64 regA64{KindA64::none, 0};
+    bool reusedReg = false;
+};
+
+enum class IrBlockKind : uint8_t
+{
+    Bytecode,
+    Fallback,
+    Internal,
+};
+
+struct IrBlock
+{
+    IrBlockKind kind;
+
+    // Start points to an instruction index in a stream
+    // End is implicit
+    uint32_t start;
+
+    Label label;
+};
+
+struct BytecodeMapping
+{
+    uint32_t irLocation;
+    uint32_t asmLocation;
+};
+
+struct IrFunction
+{
+    std::vector<IrBlock> blocks;
+    std::vector<IrInst> instructions;
+    std::vector<IrConst> constants;
+
+    std::vector<BytecodeMapping> bcMapping;
+};
+
+} // namespace CodeGen
+} // namespace Luau

CodeGen/src/IrDump.cpp

@@ -0,0 +1,379 @@
+// This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
+#include "IrDump.h"
+
+#include "IrUtils.h"
+
+#include "lua.h"
+
+#include <stdarg.h>
+
+namespace Luau
+{
+namespace CodeGen
+{
+
+static const char* textForCondition[] = {
+    "eq", "not_eq", "lt", "not_lt", "le", "not_le", "gt", "not_gt", "ge", "not_ge", "u_lt", "u_le", "u_gt", "u_ge"};
+static_assert(sizeof(textForCondition) / sizeof(textForCondition[0]) == size_t(IrCondition::Count), "all conditions have to be covered");
+
+const int kDetailsAlignColumn = 60;
+
+LUAU_PRINTF_ATTR(2, 3)
+static void append(std::string& result, const char* fmt, ...)
+{
+    char buf[256];
+    va_list args;
+    va_start(args, fmt);
+    vsnprintf(buf, sizeof(buf), fmt, args);
+    va_end(args);
+    result.append(buf);
+}
+
+static const char* getTagName(uint8_t tag)
+{
+    switch (tag)
+    {
+    case LUA_TNIL:
+        return "tnil";
+    case LUA_TBOOLEAN:
+        return "tboolean";
+    case LUA_TLIGHTUSERDATA:
+        return "tlightuserdata";
+    case LUA_TNUMBER:
+        return "tnumber";
+    case LUA_TVECTOR:
+        return "tvector";
+    case LUA_TSTRING:
+        return "tstring";
+    case LUA_TTABLE:
+        return "ttable";
+    case LUA_TFUNCTION:
+        return "tfunction";
+    case LUA_TUSERDATA:
+        return "tuserdata";
+    case LUA_TTHREAD:
+        return "tthread";
+    default:
+        LUAU_UNREACHABLE();
+    }
+}
+
+const char* getCmdName(IrCmd cmd)
+{
+    switch (cmd)
+    {
+    case IrCmd::NOP:
+        return "NOP";
+    case IrCmd::LOAD_TAG:
+        return "LOAD_TAG";
+    case IrCmd::LOAD_POINTER:
+        return "LOAD_POINTER";
+    case IrCmd::LOAD_DOUBLE:
+        return "LOAD_DOUBLE";
+    case IrCmd::LOAD_INT:
+        return "LOAD_INT";
+    case IrCmd::LOAD_TVALUE:
+        return "LOAD_TVALUE";
+    case IrCmd::LOAD_NODE_VALUE_TV:
+        return "LOAD_NODE_VALUE_TV";
+    case IrCmd::LOAD_ENV:
+        return "LOAD_ENV";
+    case IrCmd::GET_ARR_ADDR:
+        return "GET_ARR_ADDR";
+    case IrCmd::GET_SLOT_NODE_ADDR:
+        return "GET_SLOT_NODE_ADDR";
+    case IrCmd::STORE_TAG:
+        return "STORE_TAG";
+    case IrCmd::STORE_POINTER:
+        return "STORE_POINTER";
+    case IrCmd::STORE_DOUBLE:
+        return "STORE_DOUBLE";
+    case IrCmd::STORE_INT:
+        return "STORE_INT";
+    case IrCmd::STORE_TVALUE:
+        return "STORE_TVALUE";
+    case IrCmd::STORE_NODE_VALUE_TV:
+        return "STORE_NODE_VALUE_TV";
+    case IrCmd::ADD_INT:
+        return "ADD_INT";
+    case IrCmd::SUB_INT:
+        return "SUB_INT";
+    case IrCmd::ADD_NUM:
+        return "ADD_NUM";
+    case IrCmd::SUB_NUM:
+        return "SUB_NUM";
+    case IrCmd::MUL_NUM:
+        return "MUL_NUM";
+    case IrCmd::DIV_NUM:
+        return "DIV_NUM";
+    case IrCmd::MOD_NUM:
+        return "MOD_NUM";
+    case IrCmd::POW_NUM:
+        return "POW_NUM";
+    case IrCmd::UNM_NUM:
+        return "UNM_NUM";
+    case IrCmd::NOT_ANY:
+        return "NOT_ANY";
+    case IrCmd::JUMP:
+        return "JUMP";
+    case IrCmd::JUMP_IF_TRUTHY:
+        return "JUMP_IF_TRUTHY";
+    case IrCmd::JUMP_IF_FALSY:
+        return "JUMP_IF_FALSY";
+    case IrCmd::JUMP_EQ_TAG:
+        return "JUMP_EQ_TAG";
+    case IrCmd::JUMP_EQ_BOOLEAN:
+        return "JUMP_EQ_BOOLEAN";
+    case IrCmd::JUMP_EQ_POINTER:
+        return "JUMP_EQ_POINTER";
+    case IrCmd::JUMP_CMP_NUM:
+        return "JUMP_CMP_NUM";
+    case IrCmd::JUMP_CMP_STR:
+        return "JUMP_CMP_STR";
+    case IrCmd::JUMP_CMP_ANY:
+        return "JUMP_CMP_ANY";
+    case IrCmd::TABLE_LEN:
+        return "TABLE_LEN";
+    case IrCmd::NEW_TABLE:
+        return "NEW_TABLE";
+    case IrCmd::DUP_TABLE:
+        return "DUP_TABLE";
+    case IrCmd::NUM_TO_INDEX:
+        return "NUM_TO_INDEX";
+    case IrCmd::DO_ARITH:
+        return "DO_ARITH";
+    case IrCmd::DO_LEN:
+        return "DO_LEN";
+    case IrCmd::GET_TABLE:
+        return "GET_TABLE";
+    case IrCmd::SET_TABLE:
+        return "SET_TABLE";
+    case IrCmd::GET_IMPORT:
+        return "GET_IMPORT";
+    case IrCmd::CONCAT:
+        return "CONCAT";
+    case IrCmd::GET_UPVALUE:
+        return "GET_UPVALUE";
+    case IrCmd::SET_UPVALUE:
+        return "SET_UPVALUE";
+    case IrCmd::CHECK_TAG:
+        return "CHECK_TAG";
+    case IrCmd::CHECK_READONLY:
+        return "CHECK_READONLY";
+    case IrCmd::CHECK_NO_METATABLE:
+        return "CHECK_NO_METATABLE";
+    case IrCmd::CHECK_SAFE_ENV:
+        return "CHECK_SAFE_ENV";
+    case IrCmd::CHECK_ARRAY_SIZE:
+        return "CHECK_ARRAY_SIZE";
+    case IrCmd::CHECK_SLOT_MATCH:
+        return "CHECK_SLOT_MATCH";
+    case IrCmd::INTERRUPT:
+        return "INTERRUPT";
+    case IrCmd::CHECK_GC:
+        return "CHECK_GC";
+    case IrCmd::BARRIER_OBJ:
+        return "BARRIER_OBJ";
+    case IrCmd::BARRIER_TABLE_BACK:
+        return "BARRIER_TABLE_BACK";
+    case IrCmd::BARRIER_TABLE_FORWARD:
+        return "BARRIER_TABLE_FORWARD";
+    case IrCmd::SET_SAVEDPC:
+        return "SET_SAVEDPC";
+    case IrCmd::CLOSE_UPVALS:
+        return "CLOSE_UPVALS";
+    case IrCmd::CAPTURE:
+        return "CAPTURE";
+    case IrCmd::LOP_SETLIST:
+        return "LOP_SETLIST";
+    case IrCmd::LOP_CALL:
+        return "LOP_CALL";
+    case IrCmd::LOP_RETURN:
+        return "LOP_RETURN";
+    case IrCmd::LOP_FASTCALL:
+        return "LOP_FASTCALL";
+    case IrCmd::LOP_FASTCALL1:
+        return "LOP_FASTCALL1";
+    case IrCmd::LOP_FASTCALL2:
+        return "LOP_FASTCALL2";
+    case IrCmd::LOP_FASTCALL2K:
+        return "LOP_FASTCALL2K";
+    case IrCmd::LOP_FORNPREP:
+        return "LOP_FORNPREP";
+    case IrCmd::LOP_FORNLOOP:
+        return "LOP_FORNLOOP";
+    case IrCmd::LOP_FORGLOOP:
+        return "LOP_FORGLOOP";
+    case IrCmd::LOP_FORGLOOP_FALLBACK:
+        return "LOP_FORGLOOP_FALLBACK";
+    case IrCmd::LOP_FORGPREP_NEXT:
+        return "LOP_FORGPREP_NEXT";
+    case IrCmd::LOP_FORGPREP_INEXT:
+        return "LOP_FORGPREP_INEXT";
+    case IrCmd::LOP_FORGPREP_XNEXT_FALLBACK:
+        return "LOP_FORGPREP_XNEXT_FALLBACK";
+    case IrCmd::LOP_AND:
+        return "LOP_AND";
+    case IrCmd::LOP_ANDK:
+        return "LOP_ANDK";
+    case IrCmd::LOP_OR:
+        return "LOP_OR";
+    case IrCmd::LOP_ORK:
+        return "LOP_ORK";
+    case IrCmd::FALLBACK_GETGLOBAL:
+        return "FALLBACK_GETGLOBAL";
+    case IrCmd::FALLBACK_SETGLOBAL:
+        return "FALLBACK_SETGLOBAL";
+    case IrCmd::FALLBACK_GETTABLEKS:
+        return "FALLBACK_GETTABLEKS";
+    case IrCmd::FALLBACK_SETTABLEKS:
+        return "FALLBACK_SETTABLEKS";
+    case IrCmd::FALLBACK_NAMECALL:
+        return "FALLBACK_NAMECALL";
+    case IrCmd::FALLBACK_PREPVARARGS:
+        return "FALLBACK_PREPVARARGS";
+    case IrCmd::FALLBACK_GETVARARGS:
+        return "FALLBACK_GETVARARGS";
+    case IrCmd::FALLBACK_NEWCLOSURE:
+        return "FALLBACK_NEWCLOSURE";
+    case IrCmd::FALLBACK_DUPCLOSURE:
+        return "FALLBACK_DUPCLOSURE";
+    case IrCmd::FALLBACK_FORGPREP:
+        return "FALLBACK_FORGPREP";
+    case IrCmd::FALLBACK_COVERAGE:
+        return "FALLBACK_COVERAGE";
+    }
+
+    LUAU_UNREACHABLE();
+}
+
+const char* getBlockKindName(IrBlockKind kind)
+{
+    switch (kind)
+    {
+    case IrBlockKind::Bytecode:
+        return "bb_bytecode";
+    case IrBlockKind::Fallback:
+        return "bb_fallback";
+    case IrBlockKind::Internal:
+        return "bb";
+    }
+
+    LUAU_UNREACHABLE();
+}
+
+void toString(IrToStringContext& ctx, IrInst inst, uint32_t index)
+{
+    append(ctx.result, "  ");
+
+    // Instructions with a result display target virtual register
+    if (hasResult(inst.cmd))
+        append(ctx.result, "%%%u = ", index);
+
+    ctx.result.append(getCmdName(inst.cmd));
+
+    if (inst.a.kind != IrOpKind::None)
+    {
+        append(ctx.result, " ");
+        toString(ctx, inst.a);
+    }
+
+    if (inst.b.kind != IrOpKind::None)
+    {
+        append(ctx.result, ", ");
+        toString(ctx, inst.b);
+    }
+
+    if (inst.c.kind != IrOpKind::None)
+    {
+        append(ctx.result, ", ");
+        toString(ctx, inst.c);
+    }
+
+    if (inst.d.kind != IrOpKind::None)
+    {
+        append(ctx.result, ", ");
+        toString(ctx, inst.d);
+    }
+
+    if (inst.e.kind != IrOpKind::None)
+    {
+        append(ctx.result, ", ");
+        toString(ctx, inst.e);
+    }
+}
+
+void toString(IrToStringContext& ctx, IrOp op)
+{
+    switch (op.kind)
+    {
+    case IrOpKind::None:
+        break;
+    case IrOpKind::Constant:
+        toString(ctx.result, ctx.constants[op.index]);
+        break;
+    case IrOpKind::Condition:
+        LUAU_ASSERT(op.index < uint32_t(IrCondition::Count));
+        ctx.result.append(textForCondition[op.index]);
+        break;
+    case IrOpKind::Inst:
+        append(ctx.result, "%%%u", op.index);
+        break;
+    case IrOpKind::Block:
+        append(ctx.result, "%s_%u", getBlockKindName(ctx.blocks[op.index].kind), op.index);
+        break;
+    case IrOpKind::VmReg:
+        append(ctx.result, "R%u", op.index);
+        break;
+    case IrOpKind::VmConst:
+        append(ctx.result, "K%u", op.index);
+        break;
+    case IrOpKind::VmUpvalue:
+        append(ctx.result, "U%u", op.index);
+        break;
+    }
+}
+
+void toString(std::string& result, IrConst constant)
+{
+    switch (constant.kind)
+    {
+    case IrConstKind::Bool:
+        append(result, constant.valueBool ? "true" : "false");
+        break;
+    case IrConstKind::Int:
+        append(result, "%di", constant.valueInt);
+        break;
+    case IrConstKind::Uint:
+        append(result, "%uu", constant.valueUint);
+        break;
+    case IrConstKind::Double:
+        append(result, "%.17g", constant.valueDouble);
+        break;
+    case IrConstKind::Tag:
+        result.append(getTagName(constant.valueTag));
+        break;
+    }
+}
+
+void toStringDetailed(IrToStringContext& ctx, IrInst inst, uint32_t index)
+{
+    size_t start = ctx.result.size();
+
+    toString(ctx, inst, index);
+
+    int pad = kDetailsAlignColumn - int(ctx.result.size() - start);
+
+    if (pad > 0)
+        ctx.result.append(pad, ' ');
+
+    LUAU_ASSERT(inst.useCount == 0 || inst.lastUse != 0);
+
+    if (inst.useCount == 0 && hasSideEffects(inst.cmd))
+        append(ctx.result, "; %%%u, has side-effects\n", index);
+    else
+        append(ctx.result, "; useCount: %d, lastUse: %%%u\n", inst.useCount, inst.lastUse);
+}
+
+} // namespace CodeGen
+} // namespace Luau

CodeGen/src/IrDump.h

@@ -0,0 +1,32 @@
+// This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
+#pragma once
+
+#include "IrData.h"
+
+#include <string>
+#include <vector>
+
+namespace Luau
+{
+namespace CodeGen
+{
+
+const char* getCmdName(IrCmd cmd);
+const char* getBlockKindName(IrBlockKind kind);
+
+struct IrToStringContext
+{
+    std::string& result;
+    std::vector<IrBlock>& blocks;
+    std::vector<IrConst>& constants;
+};
+
+void toString(IrToStringContext& ctx, IrInst inst, uint32_t index);
+void toString(IrToStringContext& ctx, IrOp op);
+
+void toString(std::string& result, IrConst constant);
+
+void toStringDetailed(IrToStringContext& ctx, IrInst inst, uint32_t index);
+
+} // namespace CodeGen
+} // namespace Luau

CodeGen/src/IrUtils.h

@@ -0,0 +1,161 @@
+// This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
+#pragma once
+
+#include "Luau/Bytecode.h"
+#include "Luau/Common.h"
+
+#include "IrData.h"
+
+namespace Luau
+{
+namespace CodeGen
+{
+
+inline bool isJumpD(LuauOpcode op)
+{
+    switch (op)
+    {
+    case LOP_JUMP:
+    case LOP_JUMPIF:
+    case LOP_JUMPIFNOT:
+    case LOP_JUMPIFEQ:
+    case LOP_JUMPIFLE:
+    case LOP_JUMPIFLT:
+    case LOP_JUMPIFNOTEQ:
+    case LOP_JUMPIFNOTLE:
+    case LOP_JUMPIFNOTLT:
+    case LOP_FORNPREP:
+    case LOP_FORNLOOP:
+    case LOP_FORGPREP:
+    case LOP_FORGLOOP:
+    case LOP_FORGPREP_INEXT:
+    case LOP_FORGPREP_NEXT:
+    case LOP_JUMPBACK:
+    case LOP_JUMPXEQKNIL:
+    case LOP_JUMPXEQKB:
+    case LOP_JUMPXEQKN:
+    case LOP_JUMPXEQKS:
+        return true;
+
+    default:
+        return false;
+    }
+}
+
+inline bool isSkipC(LuauOpcode op)
+{
+    switch (op)
+    {
+    case LOP_LOADB:
+        return true;
+
+    default:
+        return false;
+    }
+}
+
+inline bool isFastCall(LuauOpcode op)
+{
+    switch (op)
+    {
+    case LOP_FASTCALL:
+    case LOP_FASTCALL1:
+    case LOP_FASTCALL2:
+    case LOP_FASTCALL2K:
+        return true;
+
+    default:
+        return false;
+    }
+}
+
+inline int getJumpTarget(uint32_t insn, uint32_t pc)
+{
+    LuauOpcode op = LuauOpcode(LUAU_INSN_OP(insn));
+
+    if (isJumpD(op))
+        return int(pc + LUAU_INSN_D(insn) + 1);
+    else if (isFastCall(op))
+        return int(pc + LUAU_INSN_C(insn) + 2);
+    else if (isSkipC(op) && LUAU_INSN_C(insn))
+        return int(pc + LUAU_INSN_C(insn) + 1);
+    else if (op == LOP_JUMPX)
+        return int(pc + LUAU_INSN_E(insn) + 1);
+    else
+        return -1;
+}
+
+inline bool isBlockTerminator(IrCmd cmd)
+{
+    switch (cmd)
+    {
+    case IrCmd::JUMP:
+    case IrCmd::JUMP_IF_TRUTHY:
+    case IrCmd::JUMP_IF_FALSY:
+    case IrCmd::JUMP_EQ_TAG:
+    case IrCmd::JUMP_EQ_BOOLEAN:
+    case IrCmd::JUMP_EQ_POINTER:
+    case IrCmd::JUMP_CMP_NUM:
+    case IrCmd::JUMP_CMP_STR:
+    case IrCmd::JUMP_CMP_ANY:
+    case IrCmd::LOP_RETURN:
+    case IrCmd::LOP_FORNPREP:
+    case IrCmd::LOP_FORNLOOP:
+    case IrCmd::LOP_FORGLOOP:
+    case IrCmd::LOP_FORGLOOP_FALLBACK:
+    case IrCmd::LOP_FORGPREP_NEXT:
+    case IrCmd::LOP_FORGPREP_INEXT:
+    case IrCmd::LOP_FORGPREP_XNEXT_FALLBACK:
+    case IrCmd::FALLBACK_FORGPREP:
+        return true;
+    default:
+        break;
+    }
+
+    return false;
+}
+
+inline bool hasResult(IrCmd cmd)
+{
+    switch (cmd)
+    {
+    case IrCmd::LOAD_TAG:
+    case IrCmd::LOAD_POINTER:
+    case IrCmd::LOAD_DOUBLE:
+    case IrCmd::LOAD_INT:
+    case IrCmd::LOAD_TVALUE:
+    case IrCmd::LOAD_NODE_VALUE_TV:
+    case IrCmd::LOAD_ENV:
+    case IrCmd::GET_ARR_ADDR:
+    case IrCmd::GET_SLOT_NODE_ADDR:
+    case IrCmd::ADD_INT:
+    case IrCmd::SUB_INT:
+    case IrCmd::ADD_NUM:
+    case IrCmd::SUB_NUM:
+    case IrCmd::MUL_NUM:
+    case IrCmd::DIV_NUM:
+    case IrCmd::MOD_NUM:
+    case IrCmd::POW_NUM:
+    case IrCmd::UNM_NUM:
+    case IrCmd::NOT_ANY:
+    case IrCmd::TABLE_LEN:
+    case IrCmd::NEW_TABLE:
+    case IrCmd::DUP_TABLE:
+    case IrCmd::NUM_TO_INDEX:
+        return true;
+    default:
+        break;
+    }
+
+    return false;
+}
+
+inline bool hasSideEffects(IrCmd cmd)
+{
+    // Instructions that don't produce a result most likely have other side-effects to make them useful
+    // Right now, a full switch would mirror the 'hasResult' function, so we use this simple condition
+    return !hasResult(cmd);
+}
+
+} // namespace CodeGen
+} // namespace Luau

CodeGen/src/NativeState.cpp

@@ -42,7 +42,6 @@ void initFallbackTable(NativeState& data)
     CODEGEN_SET_FALLBACK(LOP_GETVARARGS, 0);
     CODEGEN_SET_FALLBACK(LOP_DUPCLOSURE, 0);
     CODEGEN_SET_FALLBACK(LOP_PREPVARARGS, 0);
-    CODEGEN_SET_FALLBACK(LOP_COVERAGE, 0);
     CODEGEN_SET_FALLBACK(LOP_BREAK, 0);
 
     // Fallbacks that are called from partial implementation of an instruction
@@ -80,6 +79,8 @@ void initHelperFunctions(NativeState& data)
 
     data.context.luaF_close = luaF_close;
 
+    data.context.luaT_gettm = luaT_gettm;
+
     data.context.libm_exp = exp;
     data.context.libm_pow = pow;
     data.context.libm_fmod = fmod;

CodeGen/src/NativeState.h

@@ -78,6 +78,8 @@ struct NativeContext
 
     void (*luaF_close)(lua_State* L, StkId level) = nullptr;
 
+    const TValue* (*luaT_gettm)(Table* events, TMS event, TString* ename) = nullptr;
+
     double (*libm_exp)(double) = nullptr;
     double (*libm_pow)(double, double) = nullptr;
     double (*libm_fmod)(double, double) = nullptr;

Compiler/include/Luau/BytecodeBuilder.h

@@ -123,6 +123,8 @@ public:
     static uint32_t getImportId(int32_t id0, int32_t id1);
     static uint32_t getImportId(int32_t id0, int32_t id1, int32_t id2);
 
+    static int decomposeImportId(uint32_t ids, int32_t& id0, int32_t& id1, int32_t& id2);
+
     static uint32_t getStringHash(StringRef key);
 
     static std::string getError(const std::string& message);
@@ -243,6 +245,7 @@ private:
     std::vector<DebugUpval> debugUpvals;
 
     DenseHashMap<StringRef, unsigned int, StringRefHash> stringTable;
+    std::vector<StringRef> debugStrings;
 
     std::vector<std::pair<uint32_t, uint32_t>> debugRemarks;
     std::string debugRemarkBuffer;
@@ -261,6 +264,7 @@ private:
     void validateVariadic() const;
 
     std::string dumpCurrentFunction(std::vector<int>& dumpinstoffs) const;
+    void dumpConstant(std::string& result, int k) const;
     void dumpInstruction(const uint32_t* opcode, std::string& output, int targetLabel) const;
 
     void writeFunction(std::string& ss, uint32_t id) const;

Compiler/src/BytecodeBuilder.cpp

@@ -318,8 +318,13 @@ unsigned int BytecodeBuilder::addStringTableEntry(StringRef value)
 
     // note: bytecode serialization format uses 1-based table indices, 0 is reserved to mean nil
     if (index == 0)
+    {
         index = uint32_t(stringTable.size());
 
+        if ((dumpFlags & Dump_Code) != 0)
+            debugStrings.push_back(value);
+    }
+
     return index;
 }
 
@@ -870,6 +875,15 @@ uint32_t BytecodeBuilder::getImportId(int32_t id0, int32_t id1, int32_t id2)
     return (3u << 30) | (id0 << 20) | (id1 << 10) | id2;
 }
 
+int BytecodeBuilder::decomposeImportId(uint32_t ids, int32_t& id0, int32_t& id1, int32_t& id2)
+{
+    int count = ids >> 30;
+    id0 = count > 0 ? int(ids >> 20) & 1023 : -1;
+    id1 = count > 1 ? int(ids >> 10) & 1023 : -1;
+    id2 = count > 2 ? int(ids) & 1023 : -1;
+    return count;
+}
+
 uint32_t BytecodeBuilder::getStringHash(StringRef key)
 {
     // This hashing algorithm should match luaS_hash defined in VM/lstring.cpp for short inputs; we can't use that code directly to keep compiler and
@@ -1598,6 +1612,95 @@ void BytecodeBuilder::validateVariadic() const
 }
 #endif
 
+static bool printableStringConstant(const char* str, size_t len)
+{
+    for (size_t i = 0; i < len; ++i)
+    {
+        if (unsigned(str[i]) < ' ')
+            return false;
+    }
+
+    return true;
+}
+
+void BytecodeBuilder::dumpConstant(std::string& result, int k) const
+{
+    LUAU_ASSERT(unsigned(k) < constants.size());
+    const Constant& data = constants[k];
+
+    switch (data.type)
+    {
+    case Constant::Type_Nil:
+        formatAppend(result, "nil");
+        break;
+    case Constant::Type_Boolean:
+        formatAppend(result, "%s", data.valueBoolean ? "true" : "false");
+        break;
+    case Constant::Type_Number:
+        formatAppend(result, "%.17g", data.valueNumber);
+        break;
+    case Constant::Type_String:
+    {
+        const StringRef& str = debugStrings[data.valueString - 1];
+
+        if (printableStringConstant(str.data, str.length))
+        {
+            if (str.length < 32)
+                formatAppend(result, "'%.*s'", int(str.length), str.data);
+            else
+                formatAppend(result, "'%.*s'...", 32, str.data);
+        }
+        break;
+    }
+    case Constant::Type_Import:
+    {
+        int id0 = -1, id1 = -1, id2 = -1;
+        if (int count = decomposeImportId(data.valueImport, id0, id1, id2))
+        {
+            {
+                const Constant& id = constants[id0];
+                LUAU_ASSERT(id.type == Constant::Type_String && id.valueString <= debugStrings.size());
+
+                const StringRef& str = debugStrings[id.valueString - 1];
+                formatAppend(result, "%.*s", int(str.length), str.data);
+            }
+
+            if (count > 1)
+            {
+                const Constant& id = constants[id1];
+                LUAU_ASSERT(id.type == Constant::Type_String && id.valueString <= debugStrings.size());
+
+                const StringRef& str = debugStrings[id.valueString - 1];
+                formatAppend(result, ".%.*s", int(str.length), str.data);
+            }
+
+            if (count > 2)
+            {
+                const Constant& id = constants[id2];
+                LUAU_ASSERT(id.type == Constant::Type_String && id.valueString <= debugStrings.size());
+
+                const StringRef& str = debugStrings[id.valueString - 1];
+                formatAppend(result, ".%.*s", int(str.length), str.data);
+            }
+        }
+        break;
+    }
+    case Constant::Type_Table:
+        formatAppend(result, "{...}");
+        break;
+    case Constant::Type_Closure:
+    {
+        const Function& func = functions[data.valueClosure];
+
+        if (!func.dumpname.empty())
+            formatAppend(result, "'%s'", func.dumpname.c_str());
+        break;
+    }
+    default:
+        LUAU_UNREACHABLE();
+    }
+}
+
 void BytecodeBuilder::dumpInstruction(const uint32_t* code, std::string& result, int targetLabel) const
 {
     uint32_t insn = *code++;
@@ -1620,7 +1723,9 @@ void BytecodeBuilder::dumpInstruction(const uint32_t* code, std::string& result,
         break;
 
     case LOP_LOADK:
-        formatAppend(result, "LOADK R%d K%d\n", LUAU_INSN_A(insn), LUAU_INSN_D(insn));
+        formatAppend(result, "LOADK R%d K%d [", LUAU_INSN_A(insn), LUAU_INSN_D(insn));
+        dumpConstant(result, LUAU_INSN_D(insn));
+        result.append("]\n");
         break;
 
     case LOP_MOVE:
@@ -1628,11 +1733,17 @@ void BytecodeBuilder::dumpInstruction(const uint32_t* code, std::string& result,
         break;
 
     case LOP_GETGLOBAL:
-        formatAppend(result, "GETGLOBAL R%d K%d\n", LUAU_INSN_A(insn), *code++);
+        formatAppend(result, "GETGLOBAL R%d K%d [", LUAU_INSN_A(insn), *code);
+        dumpConstant(result, *code);
+        result.append("]\n");
+        code++;
         break;
 
     case LOP_SETGLOBAL:
-        formatAppend(result, "SETGLOBAL R%d K%d\n", LUAU_INSN_A(insn), *code++);
+        formatAppend(result, "SETGLOBAL R%d K%d [", LUAU_INSN_A(insn), *code);
+        dumpConstant(result, *code);
+        result.append("]\n");
+        code++;
         break;
 
     case LOP_GETUPVAL:
@@ -1648,7 +1759,9 @@ void BytecodeBuilder::dumpInstruction(const uint32_t* code, std::string& result,
         break;
 
     case LOP_GETIMPORT:
-        formatAppend(result, "GETIMPORT R%d %d\n", LUAU_INSN_A(insn), LUAU_INSN_D(insn));
+        formatAppend(result, "GETIMPORT R%d %d [", LUAU_INSN_A(insn), LUAU_INSN_D(insn));
+        dumpConstant(result, LUAU_INSN_D(insn));
+        result.append("]\n");
         code++; // AUX
         break;
 
@@ -1661,11 +1774,17 @@ void BytecodeBuilder::dumpInstruction(const uint32_t* code, std::string& result,
         break;
 
     case LOP_GETTABLEKS:
-        formatAppend(result, "GETTABLEKS R%d R%d K%d\n", LUAU_INSN_A(insn), LUAU_INSN_B(insn), *code++);
+        formatAppend(result, "GETTABLEKS R%d R%d K%d [", LUAU_INSN_A(insn), LUAU_INSN_B(insn), *code);
+        dumpConstant(result, *code);
+        result.append("]\n");
+        code++;
         break;
 
     case LOP_SETTABLEKS:
-        formatAppend(result, "SETTABLEKS R%d R%d K%d\n", LUAU_INSN_A(insn), LUAU_INSN_B(insn), *code++);
+        formatAppend(result, "SETTABLEKS R%d R%d K%d [", LUAU_INSN_A(insn), LUAU_INSN_B(insn), *code);
+        dumpConstant(result, *code);
+        result.append("]\n");
+        code++;
         break;
 
     case LOP_GETTABLEN:
@@ -1681,7 +1800,10 @@ void BytecodeBuilder::dumpInstruction(const uint32_t* code, std::string& result,
         break;
 
     case LOP_NAMECALL:
-        formatAppend(result, "NAMECALL R%d R%d K%d\n", LUAU_INSN_A(insn), LUAU_INSN_B(insn), *code++);
+        formatAppend(result, "NAMECALL R%d R%d K%d [", LUAU_INSN_A(insn), LUAU_INSN_B(insn), *code);
+        dumpConstant(result, *code);
+        result.append("]\n");
+        code++;
         break;
 
     case LOP_CALL:
@@ -1753,27 +1875,39 @@ void BytecodeBuilder::dumpInstruction(const uint32_t* code, std::string& result,
         break;
 
     case LOP_ADDK:
-        formatAppend(result, "ADDK R%d R%d K%d\n", LUAU_INSN_A(insn), LUAU_INSN_B(insn), LUAU_INSN_C(insn));
+        formatAppend(result, "ADDK R%d R%d K%d [", LUAU_INSN_A(insn), LUAU_INSN_B(insn), LUAU_INSN_C(insn));
+        dumpConstant(result, LUAU_INSN_C(insn));
+        result.append("]\n");
         break;
 
     case LOP_SUBK:
-        formatAppend(result, "SUBK R%d R%d K%d\n", LUAU_INSN_A(insn), LUAU_INSN_B(insn), LUAU_INSN_C(insn));
+        formatAppend(result, "SUBK R%d R%d K%d [", LUAU_INSN_A(insn), LUAU_INSN_B(insn), LUAU_INSN_C(insn));
+        dumpConstant(result, LUAU_INSN_C(insn));
+        result.append("]\n");
         break;
 
     case LOP_MULK:
-        formatAppend(result, "MULK R%d R%d K%d\n", LUAU_INSN_A(insn), LUAU_INSN_B(insn), LUAU_INSN_C(insn));
+        formatAppend(result, "MULK R%d R%d K%d [", LUAU_INSN_A(insn), LUAU_INSN_B(insn), LUAU_INSN_C(insn));
+        dumpConstant(result, LUAU_INSN_C(insn));
+        result.append("]\n");
         break;
 
     case LOP_DIVK:
-        formatAppend(result, "DIVK R%d R%d K%d\n", LUAU_INSN_A(insn), LUAU_INSN_B(insn), LUAU_INSN_C(insn));
+        formatAppend(result, "DIVK R%d R%d K%d [", LUAU_INSN_A(insn), LUAU_INSN_B(insn), LUAU_INSN_C(insn));
+        dumpConstant(result, LUAU_INSN_C(insn));
+        result.append("]\n");
         break;
 
     case LOP_MODK:
-        formatAppend(result, "MODK R%d R%d K%d\n", LUAU_INSN_A(insn), LUAU_INSN_B(insn), LUAU_INSN_C(insn));
+        formatAppend(result, "MODK R%d R%d K%d [", LUAU_INSN_A(insn), LUAU_INSN_B(insn), LUAU_INSN_C(insn));
+        dumpConstant(result, LUAU_INSN_C(insn));
+        result.append("]\n");
         break;
 
     case LOP_POWK:
-        formatAppend(result, "POWK R%d R%d K%d\n", LUAU_INSN_A(insn), LUAU_INSN_B(insn), LUAU_INSN_C(insn));
+        formatAppend(result, "POWK R%d R%d K%d [", LUAU_INSN_A(insn), LUAU_INSN_B(insn), LUAU_INSN_C(insn));
+        dumpConstant(result, LUAU_INSN_C(insn));
+        result.append("]\n");
         break;
 
     case LOP_AND:
@@ -1785,11 +1919,15 @@ void BytecodeBuilder::dumpInstruction(const uint32_t* code, std::string& result,
         break;
 
     case LOP_ANDK:
-        formatAppend(result, "ANDK R%d R%d K%d\n", LUAU_INSN_A(insn), LUAU_INSN_B(insn), LUAU_INSN_C(insn));
+        formatAppend(result, "ANDK R%d R%d K%d [", LUAU_INSN_A(insn), LUAU_INSN_B(insn), LUAU_INSN_C(insn));
+        dumpConstant(result, LUAU_INSN_C(insn));
+        result.append("]\n");
         break;
 
     case LOP_ORK:
-        formatAppend(result, "ORK R%d R%d K%d\n", LUAU_INSN_A(insn), LUAU_INSN_B(insn), LUAU_INSN_C(insn));
+        formatAppend(result, "ORK R%d R%d K%d [", LUAU_INSN_A(insn), LUAU_INSN_B(insn), LUAU_INSN_C(insn));
+        dumpConstant(result, LUAU_INSN_C(insn));
+        result.append("]\n");
         break;
 
     case LOP_CONCAT:
@@ -1850,7 +1988,9 @@ void BytecodeBuilder::dumpInstruction(const uint32_t* code, std::string& result,
         break;
 
     case LOP_DUPCLOSURE:
-        formatAppend(result, "DUPCLOSURE R%d K%d\n", LUAU_INSN_A(insn), LUAU_INSN_D(insn));
+        formatAppend(result, "DUPCLOSURE R%d K%d [", LUAU_INSN_A(insn), LUAU_INSN_D(insn));
+        dumpConstant(result, LUAU_INSN_D(insn));
+        result.append("]\n");
         break;
 
     case LOP_BREAK:
@@ -1862,7 +2002,10 @@ void BytecodeBuilder::dumpInstruction(const uint32_t* code, std::string& result,
         break;
 
     case LOP_LOADKX:
-        formatAppend(result, "LOADKX R%d K%d\n", LUAU_INSN_A(insn), *code++);
+        formatAppend(result, "LOADKX R%d K%d [", LUAU_INSN_A(insn), *code);
+        dumpConstant(result, *code);
+        result.append("]\n");
+        code++;
         break;
 
     case LOP_JUMPX:
@@ -1876,18 +2019,18 @@ void BytecodeBuilder::dumpInstruction(const uint32_t* code, std::string& result,
     case LOP_FASTCALL1:
         formatAppend(result, "FASTCALL1 %d R%d L%d\n", LUAU_INSN_A(insn), LUAU_INSN_B(insn), targetLabel);
         break;
+
     case LOP_FASTCALL2:
-    {
+        formatAppend(result, "FASTCALL2 %d R%d R%d L%d\n", LUAU_INSN_A(insn), LUAU_INSN_B(insn), *code, targetLabel);
-        uint32_t aux = *code++;
+        code++;
-        formatAppend(result, "FASTCALL2 %d R%d R%d L%d\n", LUAU_INSN_A(insn), LUAU_INSN_B(insn), aux, targetLabel);
         break;
-    }
+
     case LOP_FASTCALL2K:
-    {
+        formatAppend(result, "FASTCALL2K %d R%d K%d L%d [", LUAU_INSN_A(insn), LUAU_INSN_B(insn), *code, targetLabel);
-        uint32_t aux = *code++;
+        dumpConstant(result, *code);
-        formatAppend(result, "FASTCALL2K %d R%d K%d L%d\n", LUAU_INSN_A(insn), LUAU_INSN_B(insn), aux, targetLabel);
+        result.append("]\n");
+        code++;
         break;
-    }
 
     case LOP_COVERAGE:
         formatAppend(result, "COVERAGE\n");
@@ -1910,12 +2053,16 @@ void BytecodeBuilder::dumpInstruction(const uint32_t* code, std::string& result,
         break;
 
     case LOP_JUMPXEQKN:
-        formatAppend(result, "JUMPXEQKN R%d K%d L%d%s\n", LUAU_INSN_A(insn), *code & 0xffffff, targetLabel, *code >> 31 ? " NOT" : "");
+        formatAppend(result, "JUMPXEQKN R%d K%d L%d%s [", LUAU_INSN_A(insn), *code & 0xffffff, targetLabel, *code >> 31 ? " NOT" : "");
+        dumpConstant(result, *code & 0xffffff);
+        result.append("]\n");
         code++;
         break;
 
     case LOP_JUMPXEQKS:
-        formatAppend(result, "JUMPXEQKS R%d K%d L%d%s\n", LUAU_INSN_A(insn), *code & 0xffffff, targetLabel, *code >> 31 ? " NOT" : "");
+        formatAppend(result, "JUMPXEQKS R%d K%d L%d%s [", LUAU_INSN_A(insn), *code & 0xffffff, targetLabel, *code >> 31 ? " NOT" : "");
+        dumpConstant(result, *code & 0xffffff);
+        result.append("]\n");
         code++;
         break;
 

Compiler/src/Compiler.cpp

@@ -28,6 +28,7 @@ LUAU_FASTINTVARIABLE(LuauCompileInlineDepth, 5)
 LUAU_FASTFLAG(LuauInterpolatedStringBaseSupport)
 LUAU_FASTFLAGVARIABLE(LuauMultiAssignmentConflictFix, false)
 LUAU_FASTFLAGVARIABLE(LuauSelfAssignmentSkip, false)
+LUAU_FASTFLAGVARIABLE(LuauCompileInterpStringLimit, false)
 
 namespace Luau
 {
@@ -1580,7 +1581,8 @@ struct Compiler
 
         RegScope rs(this);
 
-        uint8_t baseReg = allocReg(expr, uint8_t(2 + expr->expressions.size));
+        uint8_t baseReg = FFlag::LuauCompileInterpStringLimit ? allocReg(expr, unsigned(2 + expr->expressions.size))
+                                                              : allocReg(expr, uint8_t(2 + expr->expressions.size));
 
         emitLoadK(baseReg, formatStringIndex);
 

Sources.cmake

@@ -82,6 +82,7 @@ target_sources(Luau.CodeGen PRIVATE
     CodeGen/src/EmitCommonX64.cpp
     CodeGen/src/EmitInstructionX64.cpp
     CodeGen/src/Fallbacks.cpp
+    CodeGen/src/IrDump.cpp
     CodeGen/src/NativeState.cpp
     CodeGen/src/UnwindBuilderDwarf2.cpp
     CodeGen/src/UnwindBuilderWin.cpp
@@ -95,6 +96,9 @@ target_sources(Luau.CodeGen PRIVATE
     CodeGen/src/EmitInstructionX64.h
     CodeGen/src/Fallbacks.h
     CodeGen/src/FallbacksProlog.h
+    CodeGen/src/IrDump.h
+    CodeGen/src/IrData.h
+    CodeGen/src/IrUtils.h
     CodeGen/src/NativeState.h
 )
 

VM/include/lualib.h

@@ -91,13 +91,13 @@ typedef struct luaL_Buffer luaL_Buffer;
 // all the buffer users we have in Luau match this pattern, but it's something to keep in mind for new uses of buffers
 
 #define luaL_addchar(B, c) ((void)((B)->p < (B)->end || luaL_extendbuffer(B, 1, -1)), (*(B)->p++ = (char)(c)))
-#define luaL_addstring(B, s) luaL_addlstring(B, s, strlen(s))
+#define luaL_addstring(B, s) luaL_addlstring(B, s, strlen(s), -1)
 
 LUALIB_API void luaL_buffinit(lua_State* L, luaL_Buffer* B);
 LUALIB_API char* luaL_buffinitsize(lua_State* L, luaL_Buffer* B, size_t size);
 LUALIB_API char* luaL_extendbuffer(luaL_Buffer* B, size_t additionalsize, int boxloc);
 LUALIB_API void luaL_reservebuffer(luaL_Buffer* B, size_t size, int boxloc);
-LUALIB_API void luaL_addlstring(luaL_Buffer* B, const char* s, size_t l);
+LUALIB_API void luaL_addlstring(luaL_Buffer* B, const char* s, size_t l, int boxloc);
 LUALIB_API void luaL_addvalue(luaL_Buffer* B);
 LUALIB_API void luaL_pushresult(luaL_Buffer* B);
 LUALIB_API void luaL_pushresultsize(luaL_Buffer* B, size_t size);

VM/src/laux.cpp

@@ -414,10 +414,10 @@ void luaL_reservebuffer(luaL_Buffer* B, size_t size, int boxloc)
         luaL_extendbuffer(B, size - (B->end - B->p), boxloc);
 }
 
-void luaL_addlstring(luaL_Buffer* B, const char* s, size_t len)
+void luaL_addlstring(luaL_Buffer* B, const char* s, size_t len, int boxloc)
 {
     if (size_t(B->end - B->p) < len)
-        luaL_extendbuffer(B, len - (B->end - B->p), -1);
+        luaL_extendbuffer(B, len - (B->end - B->p), boxloc);
 
     memcpy(B->p, s, len);
     B->p += len;

VM/src/ldblib.cpp

@@ -137,7 +137,7 @@ static int db_traceback(lua_State* L)
                 *--lineptr = '0' + (r % 10);
 
             luaL_addchar(&buf, ':');
-            luaL_addlstring(&buf, lineptr, lineend - lineptr);
+            luaL_addlstring(&buf, lineptr, lineend - lineptr, -1);
         }
 
         if (ar.name)

VM/src/loslib.cpp

@@ -151,7 +151,7 @@ static int os_date(lua_State* L)
                 char buff[200]; // should be big enough for any conversion result
                 cc[1] = *(++s);
                 reslen = strftime(buff, sizeof(buff), cc, stm);
-                luaL_addlstring(&b, buff, reslen);
+                luaL_addlstring(&b, buff, reslen, -1);
             }
         }
         luaL_pushresult(&b);

VM/src/lstrlib.cpp

@@ -8,6 +8,8 @@
 #include <string.h>
 #include <stdio.h>
 
+LUAU_FASTFLAGVARIABLE(LuauStringFormatAnyFix, false)
+
 // macro to `unsign' a character
 #define uchar(c) ((unsigned char)(c))
 
@@ -771,7 +773,7 @@ static void add_s(MatchState* ms, luaL_Buffer* b, const char* s, const char* e)
                 luaL_addchar(b, news[i]);
             }
             else if (news[i] == '0')
-                luaL_addlstring(b, s, e - s);
+                luaL_addlstring(b, s, e - s, -1);
             else
             {
                 push_onecapture(ms, news[i] - '1', s, e);
@@ -854,7 +856,7 @@ static int str_gsub(lua_State* L)
         if (anchor)
             break;
     }
-    luaL_addlstring(&b, src, ms.src_end - src);
+    luaL_addlstring(&b, src, ms.src_end - src, -1);
     luaL_pushresult(&b);
     lua_pushinteger(L, n); // number of substitutions
     return 2;
@@ -891,12 +893,12 @@ static void addquoted(lua_State* L, luaL_Buffer* b, int arg)
         }
         case '\r':
         {
-            luaL_addlstring(b, "\\r", 2);
+            luaL_addlstring(b, "\\r", 2, -1);
             break;
         }
         case '\0':
         {
-            luaL_addlstring(b, "\\000", 4);
+            luaL_addlstring(b, "\\000", 4, -1);
             break;
         }
         default:
@@ -1012,7 +1014,7 @@ static int str_format(lua_State* L)
             case 'q':
             {
                 addquoted(L, &b, arg);
-                continue; // skip the 'addsize' at the end
+                continue; // skip the 'luaL_addlstring' at the end
             }
             case 's':
             {
@@ -1024,7 +1026,7 @@ static int str_format(lua_State* L)
                        keep original string */
                     lua_pushvalue(L, arg);
                     luaL_addvalue(&b);
-                    continue; // skip the `addsize' at the end
+                    continue; // skip the `luaL_addlstring' at the end
                 }
                 else
                 {
@@ -1037,18 +1039,30 @@ static int str_format(lua_State* L)
                 if (formatItemSize != 1)
                     luaL_error(L, "'%%*' does not take a form");
 
+                if (FFlag::LuauStringFormatAnyFix)
+                {
                     size_t length;
                     const char* string = luaL_tolstring(L, arg, &length);
 
-                luaL_addlstring(&b, string, length);
+                    luaL_addlstring(&b, string, length, -2);
-                continue; // skip the `addsize' at the end
+                    lua_pop(L, 1);
+                }
+                else
+                {
+                    size_t length;
+                    const char* string = luaL_tolstring(L, arg, &length);
+
+                    luaL_addlstring(&b, string, length, -1);
+                }
+
+                continue; // skip the `luaL_addlstring' at the end
             }
             default:
             { // also treat cases `pnLlh'
                 luaL_error(L, "invalid option '%%%c' to 'format'", *(strfrmt - 1));
             }
             }
-            luaL_addlstring(&b, buff, strlen(buff));
+            luaL_addlstring(&b, buff, strlen(buff), -1);
         }
     }
     luaL_pushresult(&b);
@@ -1360,7 +1374,7 @@ static void packint(luaL_Buffer* b, unsigned long long n, int islittle, int size
         for (i = SZINT; i < size; i++) // correct extra bytes
             buff[islittle ? i : size - 1 - i] = (char)MC;
     }
-    luaL_addlstring(b, buff, size); // add result to buffer
+    luaL_addlstring(b, buff, size, -1); // add result to buffer
 }
 
 /*
@@ -1434,7 +1448,7 @@ static int str_pack(lua_State* L)
                 u.n = n;
             // move 'u' to final result, correcting endianness if needed
             copywithendian(buff, u.buff, size, h.islittle);
-            luaL_addlstring(&b, buff, size);
+            luaL_addlstring(&b, buff, size, -1);
             break;
         }
         case Kchar:
@@ -1442,7 +1456,7 @@ static int str_pack(lua_State* L)
             size_t len;
             const char* s = luaL_checklstring(L, arg, &len);
             luaL_argcheck(L, len <= (size_t)size, arg, "string longer than given size");
-            luaL_addlstring(&b, s, len); // add string
+            luaL_addlstring(&b, s, len, -1); // add string
             while (len++ < (size_t)size) // pad extra space
                 luaL_addchar(&b, LUAL_PACKPADBYTE);
             break;
@@ -1453,7 +1467,7 @@ static int str_pack(lua_State* L)
             const char* s = luaL_checklstring(L, arg, &len);
             luaL_argcheck(L, size >= (int)sizeof(size_t) || len < ((size_t)1 << (size * NB)), arg, "string length does not fit in given size");
             packint(&b, len, h.islittle, size, 0); // pack length
-            luaL_addlstring(&b, s, len);
+            luaL_addlstring(&b, s, len, -1);
             totalsize += len;
             break;
         }
@@ -1462,7 +1476,7 @@ static int str_pack(lua_State* L)
             size_t len;
             const char* s = luaL_checklstring(L, arg, &len);
             luaL_argcheck(L, strlen(s) == len, arg, "string contains zeros");
-            luaL_addlstring(&b, s, len);
+            luaL_addlstring(&b, s, len, -1);
             luaL_addchar(&b, '\0'); // add zero at the end
             totalsize += len + 1;
             break;

VM/src/ltablib.cpp

@@ -238,7 +238,7 @@ static int tconcat(lua_State* L)
     for (; i < last; i++)
     {
         addfield(L, &b, i);
-        luaL_addlstring(&b, sep, lsep);
+        luaL_addlstring(&b, sep, lsep, -1);
     }
     if (i == last) // add last value (if interval was not empty)
         addfield(L, &b, i);

VM/src/lutf8lib.cpp

@@ -175,7 +175,7 @@ static int utfchar(lua_State* L)
         for (int i = 1; i <= n; i++)
         {
             int l = buffutfchar(L, i, buff, &charstr);
-            luaL_addlstring(&b, charstr, l);
+            luaL_addlstring(&b, charstr, l, -1);
         }
         luaL_pushresult(&b);
     }

bench/bench.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/python3
 # This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
 import argparse
 import os

tests/AssemblyBuilderX64.test.cpp

@@ -243,6 +243,12 @@ TEST_CASE_FIXTURE(AssemblyBuilderX64Fixture, "FormsOfLea")
     SINGLE_COMPARE(lea(rax, addr[r13 + r12 * 4 + 4]), 0x4b, 0x8d, 0x44, 0xa5, 0x04);
 }
 
+TEST_CASE_FIXTURE(AssemblyBuilderX64Fixture, "FormsOfSetcc")
+{
+    SINGLE_COMPARE(setcc(ConditionX64::NotEqual, bl), 0x0f, 0x95, 0xc3);
+    SINGLE_COMPARE(setcc(ConditionX64::BelowEqual, byte[rcx]), 0x0f, 0x96, 0x01);
+}
+
 TEST_CASE_FIXTURE(AssemblyBuilderX64Fixture, "FormsOfAbsoluteJumps")
 {
     SINGLE_COMPARE(jmp(rax), 0xff, 0xe0);

tests/Autocomplete.test.cpp

@@ -15,6 +15,7 @@
 
 LUAU_FASTFLAG(LuauTraceTypesInNonstrictMode2)
 LUAU_FASTFLAG(LuauSetMetatableDoesNotTimeTravel)
+LUAU_FASTFLAG(LuauFixAutocompleteInIf)
 
 using namespace Luau;
 
@@ -789,6 +790,21 @@ TEST_CASE_FIXTURE(ACFixture, "autocomplete_if_middle_keywords")
     CHECK_EQ(ac2.entryMap.count("end"), 0);
     CHECK_EQ(ac2.context, AutocompleteContext::Keyword);
 
+    if (FFlag::LuauFixAutocompleteInIf)
+    {
+        check(R"(
+            if x t@1
+        )");
+
+        auto ac3 = autocomplete('1');
+        CHECK_EQ(3, ac3.entryMap.size());
+        CHECK_EQ(ac3.entryMap.count("then"), 1);
+        CHECK_EQ(ac3.entryMap.count("and"), 1);
+        CHECK_EQ(ac3.entryMap.count("or"), 1);
+        CHECK_EQ(ac3.context, AutocompleteContext::Keyword);
+    }
+    else
+    {
         check(R"(
             if x t@1
         )");
@@ -797,6 +813,7 @@ TEST_CASE_FIXTURE(ACFixture, "autocomplete_if_middle_keywords")
         CHECK_EQ(1, ac3.entryMap.size());
         CHECK_EQ(ac3.entryMap.count("then"), 1);
         CHECK_EQ(ac3.context, AutocompleteContext::Keyword);
+    }
 
     check(R"(
         if x then
@@ -839,6 +856,23 @@ TEST_CASE_FIXTURE(ACFixture, "autocomplete_if_middle_keywords")
     CHECK_EQ(ac5.entryMap.count("elseif"), 0);
     CHECK_EQ(ac5.entryMap.count("end"), 0);
     CHECK_EQ(ac5.context, AutocompleteContext::Statement);
+    
+    if (FFlag::LuauFixAutocompleteInIf)
+    {
+        check(R"(
+            if t@1
+        )");
+
+        auto ac6 = autocomplete('1');
+        CHECK_EQ(ac6.entryMap.count("true"), 1);
+        CHECK_EQ(ac6.entryMap.count("false"), 1);
+        CHECK_EQ(ac6.entryMap.count("then"), 0);
+        CHECK_EQ(ac6.entryMap.count("function"), 1);
+        CHECK_EQ(ac6.entryMap.count("else"), 0);
+        CHECK_EQ(ac6.entryMap.count("elseif"), 0);
+        CHECK_EQ(ac6.entryMap.count("end"), 0);
+        CHECK_EQ(ac6.context, AutocompleteContext::Expression);
+    }
 }
 
 TEST_CASE_FIXTURE(ACFixture, "autocomplete_until_in_repeat")

tests/Conformance.test.cpp

@@ -297,6 +297,8 @@ TEST_CASE("Clear")
 
 TEST_CASE("Strings")
 {
+    ScopedFastFlag luauStringFormatAnyFix{"LuauStringFormatAnyFix", true};
+
     runConformance("strings.lua");
 }
 

tests/Parser.test.cpp

@@ -2177,8 +2177,6 @@ type C<X...> = Packed<(number, X...)>
 
 TEST_CASE_FIXTURE(Fixture, "invalid_type_forms")
 {
-    ScopedFastFlag luauFixNamedFunctionParse{"LuauFixNamedFunctionParse", true};
-
     matchParseError("type A = (b: number)", "Expected '->' when parsing function type, got <eof>");
     matchParseError("type P<T...> = () -> T... type B = P<(x: number, y: string)>", "Expected '->' when parsing function type, got '>'");
     matchParseError("type F<T... = (a: string)> = (T...) -> ()", "Expected '->' when parsing function type, got '>'");

tests/ToString.test.cpp

@@ -83,7 +83,6 @@ TEST_CASE_FIXTURE(Fixture, "table_respects_use_line_break")
 
     ToStringOptions opts;
     opts.useLineBreaks = true;
-    opts.DEPRECATED_indent = true;
 
     //clang-format off
     CHECK_EQ("{|\n"
@@ -97,7 +96,6 @@ TEST_CASE_FIXTURE(Fixture, "table_respects_use_line_break")
 
 TEST_CASE_FIXTURE(Fixture, "nil_or_nil_is_nil_not_question_mark")
 {
-    ScopedFastFlag sff("LuauSerializeNilUnionAsNil", true);
     CheckResult result = check(R"(
       type nil_ty = nil | nil
       local a : nil_ty = nil
@@ -109,7 +107,6 @@ TEST_CASE_FIXTURE(Fixture, "nil_or_nil_is_nil_not_question_mark")
 
 TEST_CASE_FIXTURE(Fixture, "long_disjunct_of_nil_is_nil_not_question_mark")
 {
-    ScopedFastFlag sff("LuauSerializeNilUnionAsNil", true);
     CheckResult result = check(R"(
       type nil_ty = nil | nil | nil | nil | nil
       local a : nil_ty = nil

tests/TypeReduction.test.cpp

@@ -88,6 +88,96 @@ TEST_CASE_FIXTURE(ReductionFixture, "cartesian_product_is_zero")
     CHECK(ty);
 }
 
+TEST_CASE_FIXTURE(ReductionFixture, "stress_test_recursion_limits")
+{
+    TypeId ty = arena.addType(IntersectionType{{builtinTypes->numberType, builtinTypes->stringType}});
+    for (size_t i = 0; i < 20'000; ++i)
+    {
+        TableType table;
+        table.state = TableState::Sealed;
+        table.props["x"] = {ty};
+        ty = arena.addType(IntersectionType{{arena.addType(table), arena.addType(table)}});
+    }
+
+    CHECK(!reduction.reduce(ty));
+}
+
+TEST_CASE_FIXTURE(ReductionFixture, "caching")
+{
+    SUBCASE("free_tables")
+    {
+        TypeId ty1 = arena.addType(TableType{});
+        getMutable<TableType>(ty1)->state = TableState::Free;
+        getMutable<TableType>(ty1)->props["x"] = {builtinTypes->stringType};
+
+        TypeId ty2 = arena.addType(TableType{});
+        getMutable<TableType>(ty2)->state = TableState::Sealed;
+
+        TypeId intersectionTy = arena.addType(IntersectionType{{ty1, ty2}});
+
+        ToStringOptions opts;
+        opts.exhaustive = true;
+
+        CHECK("{- x: string -} & {|  |}" == toString(reductionof(intersectionTy)));
+
+        getMutable<TableType>(ty1)->state = TableState::Sealed;
+        CHECK("{| x: string |}" == toString(reductionof(intersectionTy)));
+    }
+
+    SUBCASE("unsealed_tables")
+    {
+        TypeId ty1 = arena.addType(TableType{});
+        getMutable<TableType>(ty1)->state = TableState::Unsealed;
+        getMutable<TableType>(ty1)->props["x"] = {builtinTypes->stringType};
+
+        TypeId ty2 = arena.addType(TableType{});
+        getMutable<TableType>(ty2)->state = TableState::Sealed;
+
+        TypeId intersectionTy = arena.addType(IntersectionType{{ty1, ty2}});
+
+        ToStringOptions opts;
+        opts.exhaustive = true;
+
+        CHECK("{| x: string |}" == toString(reductionof(intersectionTy)));
+
+        getMutable<TableType>(ty1)->state = TableState::Sealed;
+        CHECK("{| x: string |}" == toString(reductionof(intersectionTy)));
+    }
+
+    SUBCASE("free_types")
+    {
+        TypeId ty1 = arena.freshType(nullptr);
+        TypeId ty2 = arena.addType(TableType{});
+        getMutable<TableType>(ty2)->state = TableState::Sealed;
+
+        TypeId intersectionTy = arena.addType(IntersectionType{{ty1, ty2}});
+
+        ToStringOptions opts;
+        opts.exhaustive = true;
+
+        CHECK("a & {|  |}" == toString(reductionof(intersectionTy)));
+
+        *asMutable(ty1) = BoundType{ty2};
+        CHECK("{|  |}" == toString(reductionof(intersectionTy)));
+    }
+
+    SUBCASE("we_can_see_that_the_cache_works_if_we_mutate_a_normally_not_mutated_type")
+    {
+        TypeId ty1 = arena.addType(BoundType{builtinTypes->stringType});
+        TypeId ty2 = builtinTypes->numberType;
+
+        TypeId intersectionTy = arena.addType(IntersectionType{{ty1, ty2}});
+
+        ToStringOptions opts;
+        opts.exhaustive = true;
+
+        CHECK("never" == toString(reductionof(intersectionTy))); // Bound<string> & number ~ never
+
+        *asMutable(ty1) = BoundType{ty2};
+        CHECK("never" == toString(reductionof(intersectionTy))); // Bound<number> & number ~ number, but the cache is `never`.
+    }
+} // caching
+
 TEST_CASE_FIXTURE(ReductionFixture, "intersections_without_negations")
 {
     SUBCASE("string_and_string")
@@ -359,6 +449,34 @@ TEST_CASE_FIXTURE(ReductionFixture, "intersections_without_negations")
         TypeId ty = reductionof("{ p: string } & { p: string, [string]: number }");
         CHECK("{| [string]: number, p: string |}" == toString(ty));
     }
+
+    SUBCASE("fresh_type_and_string")
+    {
+        TypeId freshTy = arena.freshType(nullptr);
+        TypeId ty = reductionof(arena.addType(IntersectionType{{freshTy, builtinTypes->stringType}}));
+        CHECK("a & string" == toString(ty));
+    }
+
+    SUBCASE("string_and_fresh_type")
+    {
+        TypeId freshTy = arena.freshType(nullptr);
+        TypeId ty = reductionof(arena.addType(IntersectionType{{builtinTypes->stringType, freshTy}}));
+        CHECK("a & string" == toString(ty));
+    }
+
+    SUBCASE("generic_and_string")
+    {
+        TypeId genericTy = arena.addType(GenericType{"G"});
+        TypeId ty = reductionof(arena.addType(IntersectionType{{genericTy, builtinTypes->stringType}}));
+        CHECK("G & string" == toString(ty));
+    }
+
+    SUBCASE("string_and_generic")
+    {
+        TypeId genericTy = arena.addType(GenericType{"G"});
+        TypeId ty = reductionof(arena.addType(IntersectionType{{builtinTypes->stringType, genericTy}}));
+        CHECK("G & string" == toString(ty));
+    }
 } // intersections_without_negations
 
 TEST_CASE_FIXTURE(ReductionFixture, "intersections_with_negations")
@@ -1232,18 +1350,4 @@ TEST_CASE_FIXTURE(ReductionFixture, "cycles")
     }
 }
 
-TEST_CASE_FIXTURE(ReductionFixture, "stress_test_recursion_limits")
-{
-    TypeId ty = arena.addType(IntersectionType{{builtinTypes->numberType, builtinTypes->stringType}});
-    for (size_t i = 0; i < 20'000; ++i)
-    {
-        TableType table;
-        table.state = TableState::Sealed;
-        table.props["x"] = {ty};
-        ty = arena.addType(IntersectionType{{arena.addType(table), arena.addType(table)}});
-    }
-
-    CHECK(!reduction.reduce(ty));
-}
-
 TEST_SUITE_END();

tests/conformance/strings.lua

@@ -164,6 +164,16 @@ local ud = newproxy(true)
 getmetatable(ud).__tostring = function() return "good" end
 assert(string.format("%*", ud) == "good")
 
+assert(string.format(string.rep("%*", 100), table.unpack(table.create(100, 1))) == string.rep("1", 100))
+
+do
+	local a = "1234567890"
+	a = string.format("%*%*%*%*%*", a, a, a, a, a)
+	a = string.format("%*%*%*%*%*", a, a, a, a, a)
+	a = string.format("%*%*%*%*%*", a, a, a, a, a)
+	assert(a == string.rep("1234567890", 125))
+end
+
 assert(pcall(function()
 	string.format("%#*", "bad form")
 end) == false)

tests/conformance/tables.lua

@@ -686,4 +686,18 @@ do
   assert(pcall(table.clear, table.freeze({})) == false)
 end
 
+-- check that namecall lookup doesn't give up on entries missing from cached slot position
+do
+  for i = 1,10 do
+    local t = setmetatable({}, { __index = { foo = 1 }})
+
+    assert(t.foo == 1)
+
+    t[-i] = 2
+    t.foo = function(t, i) return -i end
+
+    assert(t:foo(i) == -i)
+  end
+end
+
 return"OK"

tools/faillist.txt

@@ -2,8 +2,6 @@ AnnotationTests.corecursive_types_error_on_tight_loop
 AnnotationTests.duplicate_type_param_name
 AnnotationTests.for_loop_counter_annotation_is_checked
 AnnotationTests.generic_aliases_are_cloned_properly
-AnnotationTests.instantiation_clone_has_to_follow
-AnnotationTests.luau_print_is_not_special_without_the_flag
 AnnotationTests.occurs_check_on_cyclic_intersection_type
 AnnotationTests.occurs_check_on_cyclic_union_type
 AnnotationTests.too_many_type_params
@@ -87,6 +85,8 @@ DefinitionTests.class_definition_overload_metamethods
 DefinitionTests.class_definition_string_props
 DefinitionTests.declaring_generic_functions
 DefinitionTests.definition_file_classes
+DefinitionTests.definitions_symbols_are_generated_for_recursively_referenced_types
+DefinitionTests.single_class_type_identity_in_global_types
 FrontendTest.environments
 FrontendTest.it_should_be_safe_to_stringify_errors_when_full_type_graph_is_discarded
 FrontendTest.nocheck_cycle_used_by_checked
@@ -140,6 +140,7 @@ NonstrictModeTests.parameters_having_type_any_are_optional
 NonstrictModeTests.table_dot_insert_and_recursive_calls
 NonstrictModeTests.table_props_are_any
 Normalize.cyclic_table_normalizes_sensibly
+Normalize.negations_of_classes
 ParseErrorRecovery.generic_type_list_recovery
 ParseErrorRecovery.recovery_of_parenthesized_expressions
 ParserTests.parse_nesting_based_end_detection_failsafe_earlier
@@ -165,8 +166,10 @@ RefinementTest.call_an_incompatible_function_after_using_typeguard
 RefinementTest.correctly_lookup_property_whose_base_was_previously_refined2
 RefinementTest.discriminate_on_properties_of_disjoint_tables_where_that_property_is_true_or_false
 RefinementTest.discriminate_tag
+RefinementTest.eliminate_subclasses_of_instance
 RefinementTest.else_with_no_explicit_expression_should_also_refine_the_tagged_union
 RefinementTest.falsiness_of_TruthyPredicate_narrows_into_nil
+RefinementTest.narrow_from_subclasses_of_instance_or_string_or_vector3
 RefinementTest.narrow_property_of_a_bounded_variable
 RefinementTest.nonoptional_type_can_narrow_to_nil_if_sense_is_true
 RefinementTest.refine_a_property_not_to_be_nil_through_an_intersection_table
@@ -176,6 +179,7 @@ RefinementTest.type_guard_narrowed_into_nothingness
 RefinementTest.type_narrow_for_all_the_userdata
 RefinementTest.type_narrow_to_vector
 RefinementTest.typeguard_cast_free_table_to_vector
+RefinementTest.typeguard_cast_instance_or_vector3_to_vector
 RefinementTest.typeguard_in_assert_position
 RefinementTest.typeguard_narrows_for_table
 RefinementTest.x_as_any_if_x_is_instance_elseif_x_is_table
@@ -457,6 +461,10 @@ TypePackTests.type_pack_type_parameters
 TypePackTests.unify_variadic_tails_in_arguments
 TypePackTests.unify_variadic_tails_in_arguments_free
 TypePackTests.variadic_packs
+TypeReductionTests.discriminable_unions
+TypeReductionTests.intersections_with_negations
+TypeReductionTests.negations
+TypeReductionTests.unions_with_negations
 TypeSingletons.error_detailed_tagged_union_mismatch_bool
 TypeSingletons.error_detailed_tagged_union_mismatch_string
 TypeSingletons.function_call_with_singletons

tools/heapgraph.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/python3
 # This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
 
 # Given two heap snapshots (A & B), this tool performs reachability analysis on new objects allocated in B

tools/heapstat.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/python3
 # This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
 
 # Given a heap snapshot, this tool gathers basic statistics about the allocated objects

tools/lvmexecute_split.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/python3
 # This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
 
 # This code can be used to split lvmexecute.cpp VM switch into separate functions for use as native code generation fallbacks
@@ -34,7 +34,7 @@ source = """// This file is part of the Luau programming language and is license
 function = ""
 signature = ""
 
-includeInsts = ["LOP_NEWCLOSURE", "LOP_NAMECALL", "LOP_FORGPREP", "LOP_GETVARARGS", "LOP_DUPCLOSURE", "LOP_PREPVARARGS", "LOP_COVERAGE", "LOP_BREAK", "LOP_GETGLOBAL", "LOP_SETGLOBAL", "LOP_GETTABLEKS", "LOP_SETTABLEKS"]
+includeInsts = ["LOP_NEWCLOSURE", "LOP_NAMECALL", "LOP_FORGPREP", "LOP_GETVARARGS", "LOP_DUPCLOSURE", "LOP_PREPVARARGS", "LOP_BREAK", "LOP_GETGLOBAL", "LOP_SETGLOBAL", "LOP_GETTABLEKS", "LOP_SETTABLEKS"]
 
 state = 0
 

tools/numprint.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/python3
 # This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
 
 # This code can be used to generate power tables for Schubfach algorithm (see lnumprint.cpp)

tools/patchtests.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/python3
 # This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
 
 # This code can be used to patch Compiler.test.cpp following bytecode changes, based on error output

tools/perfgraph.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/python3
 # This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
 
 # Given a profile dump, this tool generates a flame graph based on the stacks listed in the profile

tools/perfstat.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/python3
 # This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
 
 # Given a profile dump, this tool displays top functions based on the stacks listed in the profile

tools/stack-usage-reporter.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/python3
 # This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
 
 # The purpose of this script is to analyze disassembly generated by objdump or

tools/test_dcr.py

@@ -1,3 +1,4 @@
+#!/usr/bin/python3
 # This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
 
 import argparse

tools/tracegraph.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/python3
 # This file is part of the Luau programming language and is licensed under MIT License; see LICENSE.txt for details
 
 # Given a trace event file, this tool generates a flame graph based on the event scopes present in the file