- Implemented [Require by String with Relative
Paths](https://github.com/luau-lang/rfcs/blob/master/docs/new-require-by-string-semantics.md)
RFC
- Implemented [Require by String with
Aliases](https://github.com/luau-lang/rfcs/blob/master/docs/require-by-string-aliases.md)
RFC with support for `paths` and `alias` arrays in .luarc
- Added SUBRK and DIVRK bytecode instructions to speed up
constant-number and constant/number operations
- Added `--vector-lib`, `--vector-ctor` and `--vector-type` options to
luau-compile to support code with vectors
New Solver
- Correctness fixes to subtyping
- Improvements to dataflow analysis
Native Code Generation
- Added bytecode analysis pass to predict type tags used in operations
- Fixed rare cases of numerical loops being generated without an
interrupt instruction
- Restored optimization data propagation into the linear block
- Duplicate buffer length checks are optimized away
Miscellaneous
- Small performance improvements to new non-strict mode
- Introduced more scripts for fuzzing Luau and processing the results,
including fuzzer build support for CMake
Co-authored-by: Alexander McCord <amccord@roblox.com>
Co-authored-by: Andy Friesen <afriesen@roblox.com>
Co-authored-by: Aviral Goel <agoel@roblox.com>
Co-authored-by: David Cope <dcope@roblox.com>
Co-authored-by: Lily Brown <lbrown@roblox.com>
Co-authored-by: Vighnesh Vijay <vvijay@roblox.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>
---------
Co-authored-by: Aaron Weiss <aaronweiss@roblox.com>
Co-authored-by: Alexander McCord <amccord@roblox.com>
Co-authored-by: Andy Friesen <afriesen@roblox.com>
Co-authored-by: Aviral Goel <agoel@roblox.com>
Co-authored-by: David Cope <dcope@roblox.com>
Co-authored-by: Lily Brown <lbrown@roblox.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>
# What's changed?
* Fixed a bug in type cloning by maintaining persistent types.
* We now parse imprecise integer literals to report the imprecision as a
warning to developers.
* Add a compiler flag to specify the name of the statistics output file.
### New type solver
* Renamed `ConstraintGraphBuilder` to `ConstraintGenerator`
* LValues now take into account the type being assigned during
constraint generation.
* Normalization performance has been improved by 33% by replacing the an
internal usage of `std::unordered_set` with `DenseHashMap`.
* Normalization now has a helper to identify types that are equivalent
to `unknown`, which is being used to fix some bugs in subtyping.
* Uses of the old unifier in the new type solver have been eliminated.
* Improved error explanations for subtyping errors in `TypeChecker2`.
### Native code generation
* Expanded some of the statistics recorded during compilation to include
the number of instructions and blocks.
* Introduce instruction and block count limiters for controlling what
bytecode is translated into native code.
* Implement code generation for byteswap instruction.
### Internal Contributors
Co-authored-by: Aaron Weiss <aaronweiss@roblox.com>
Co-authored-by: Alexander McCord <amccord@roblox.com>
Co-authored-by: Andy Friesen <afriesen@roblox.com>
Co-authored-by: Aviral Goel <agoel@roblox.com>
Co-authored-by: Lily Brown <lbrown@roblox.com>
# New Type Solver
- Implement bidirectional type inference for higher order functions so
that we can provide a more precise type improving the autocomplete's
human factors.
- We seal all tables, so we changed the stringification to make it a
little lighter on users.
- Fixed a case of array-out-of-bound access.
- Type families no longer depends on `TxnLog` and `Unifier`.
- Type refinements now waits until the free types are sufficiently
solved.
# Native Code Generation
- Remove cached slot lookup for `executeSETTABLEKS` function because it
is a fallback in the event of a cache miss, making the cached slot
lookup redundant.
- Optimized repeated array lookups, e.g. `a[3]` in `a[3] = a[3] / 2` is
done once.
# Misc
- On some platforms, it is necessary to use `gmtime_s` with the
arguments reversed to get the current time. You can now define
`DOCTEST_CONFIG_USE_GMTIME_S` to build and run unit tests on those
platforms.
---------
Co-authored-by: Arseny Kapoulkine <arseny.kapoulkine@gmail.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>
Co-authored-by: Andy Friesen <afriesen@roblox.com>
Co-authored-by: Lily Brown <lbrown@roblox.com>
Co-authored-by: Aaron Weiss <aaronweiss@roblox.com>
- Updated Roblox copyright to 2023
- Floor division operator `//` (implements #832)
- Autocomplete now shows `end` within `do` blocks
- Restore BraceType when using `Lexer::lookahead` (fixes#1019)
# New typechecker
- Subtyping tests between metatables and tables
- Subtyping tests between string singletons and tables
- Subtyping tests for class types
# Native codegen
- Fixed macOS test failure (wrong spill restore offset)
- Fixed clobbering of non-volatile xmm registers on Windows
- Fixed wrong storage location of SSA reg spills
- Implemented A64 support for add/sub extended
- Eliminated zextReg from A64 lowering
- Remove identical table slot lookups
- Propagate values from predecessor into the linear block
- Disabled reuse slot optimization
- Keep `LuaNode::val` check for nil when optimizing `CHECK_SLOT_MATCH`
- Implemented IR translation of `table.insert` builtin
- Fixed mmap error handling on macOS/Linux
# Tooling
- Used `|` as a column separator instead of `+` in `bench.py`
- Added a `table.sort` micro-benchmark
- Switched `libprotobuf-mutator` to a less problematic version
* Better indentation in multi-line type mismatch error messages
* Error message clone can no longer cause a stack overflow (when
typechecking with retainFullTypeGraphs set to false); fixes
https://github.com/Roblox/luau/issues/975
* `string.format` with %s is now ~2x faster on strings smaller than 100
characters
Native code generation:
* All VM side exits will block return to the native execution of the
current function to preserve correctness
* Fixed executable page allocation on Apple platforms when using
hardened runtime
* Added statistics for code generation (no. of functions compiler,
memory used for different areas)
* Fixed issue with function entry type checks performed more that once
in some functions
Type checker/autocomplete:
* `Luau::autocomplete` no longer performs typechecking internally, make
sure to run `Frontend::check` before performing autocomplete requests
* Autocomplete string suggestions without "" are now only suggested
inside the ""
* Autocomplete suggestions now include `function (anonymous autofilled)`
key with a full suggestion for the function expression (with arguments
included) stored in `AutocompleteEntry::insertText`
* `AutocompleteEntry::indexedWithSelf` is provided for function call
suggestions made with `:`
* Cyclic modules now see each other type exports as `any` to prevent
memory use-after-free (similar to module return type)
Runtime:
* Updated inline/loop unroll cost model to better handle assignments
(Fixes https://github.com/Roblox/luau/issues/978)
* `math.noise` speed was improved by ~30%
* `table.concat` speed was improved by ~5-7%
* `tonumber` and `tostring` now have fastcall paths that execute ~1.5x
and ~2.5x faster respectively (fixes#777)
* Fixed crash in `luaL_typename` when index refers to a non-existing
value
* Fixed potential out of memory scenario when using `string.sub` or
`string.char` in a loop
* Fixed behavior of some fastcall builtins when called without arguments
under -O2 to match original functions
* Support for native code execution in VM is now enabled by default
(note: native code still has to be generated explicitly)
* `Codegen::compile` now accepts `CodeGen_OnlyNativeModules` flag. When
set, only modules that have a `--!native` hot-comment at the top will be
compiled to native code
In our new typechecker:
* Generic type packs are no longer considered to be variadic during
unification
* Timeout and cancellation now works in new solver
* Fixed false positive errors around 'table' and 'function' type
refinements
* Table literals now use covariant unification rules. This is sound
since literal has no type specified and has no aliases
* Fixed issues with blocked types escaping the constraint solver
* Fixed more places where error messages that should've been suppressed
were still reported
* Fixed errors when iterating over a top table type
In our native code generation (jit):
* 'DebugLuauAbortingChecks' flag is now supported on A64
* LOP_NEWCLOSURE has been translated to IR
* Optimized operations like instantiation and module export for very
large types
In our new typechecker:
* Typechecking of function calls was rewritten to handle more cases
correctly
* Fixed a crash that can happen after self-referential type is exported
from a module
* Fixed a false positive error in string comparison
* Added handling of `for...in` variable type annotations and fixed
issues with the iterator call inside
* Self-referential 'hasProp' and 'setProp' constraints are now handled
correctly
In our native code generation (jit):
* Added '--target' argument to luau-compile to test multiple
architectures different from host architecture
* GC barrier tag check is skipped if type is already known to be
GC-collectable
* Added GET_TYPE/GET_TYPEOF instructions for type/typeof fast-calls
* Improved code size of interrupt handlers on X64
A pretty small changelist this week:
* When type inference fails to find any matching overload for a
function, we were declining to commit any changes to the type graph at
all. This was resulting in confusing type errors in certain cases. Now,
when a matching overload cannot be found, we always commit to the first
overload we tried.
JIT
* Fix missing variadic register invalidation in FALLBACK_GETVARARGS
* Add a missing null pointer check for the result of luaT_gettm
---------
Co-authored-by: Arseny Kapoulkine <arseny.kapoulkine@gmail.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>
* Fixed gcc warning about uninitialized `std::optional`
* Fixed inlining of functions when they are used to compute their own
arguments
In the new type solver:
* Type families that are not part of a function signature cannot be
resolved at instantiation time and will now produce an error. This will
be relaxed in the future when we get constraint clauses on function
signatures (internally)
* `never` type is now comparable
* Improved typechecking of `for..in` statements
* Fixed checks for number type in `Add` type family
* Performance was improved, with particularly large gains on large
projects
And in native code generation (jit):
* We eliminated the call instruction overhead when native code support
is enabled in the VM
* Small optimizations to arm64 lowering
* Reworked LOP_GETIMPORT handling to reduce assembly code size
* Fixed non-deterministic binary output
* Fixed bad code generation caused by incorrect SSA to VM register links
invalidation
---------
Co-authored-by: Arseny Kapoulkine <arseny.kapoulkine@gmail.com>
Co-authored-by: Andy Friesen <afriesen@roblox.com>
* `ClassType` can now have an indexer defined on it. This allows custom
types to be used in `t[x]` expressions.
* Fixed search for closest executable breakpoint line. Previously,
breakpoints might have been skipped in `else` blocks at the end of a
function
* Fixed how unification is performed for two optional types `a? <: b?`,
previously it might have unified either 'a' or 'b' with 'nil'. Note that
this fix is not enabled by default yet (see the list in
`ExperimentalFlags.h`)
In the new type solver, a concept of 'Type Families' has been
introduced.
Type families can be thought of as type aliases with custom type
inference/reduction logic included with them.
For example, we can have an `Add<T, U>` type family that will resolve
the type that is the result of adding two values together.
This will help type inference to figure out what 'T' and 'U' might be
when explicit type annotations are not provided.
In this update we don't define any type families, but they will be added
in the near future.
It is also possible for Luau embedders to define their own type families
in the global/environment scope.
Other changes include:
* Fixed scope used to find out which generic types should be included in
the function generic type list
* Fixed a crash after cyclic bound types were created during unification
And in native code generation (jit):
* Use of arm64 target on M1 now requires macOS 13
* Entry into native code has been optimized. This is especially
important for coroutine call/pcall performance as they involve going
through a C call frame
* LOP_LOADK(X) translation into IR has been improved to enable type
tag/constant propagation
* arm64 can use integer immediate values to synthesize floating-point
values
* x64 assembler removes duplicate 64bit numbers from the data section to
save space
* Linux `perf` can now be used to profile native Luau code (when running
with --codegen-perf CLI argument)
* Added a limit on how many instructions the Compiler can safely produce
(reported by @TheGreatSageEqualToHeaven)
C++ API Changes:
* With work started on read-only and write-only properties,
`Property::type` member variable has been replaced with `TypeId type()`
and `setType(TypeId)` functions.
* New `LazyType` unwrap callback now has a `void` return type, all
that's required from the callback is to write into `unwrapped` field.
In our work on the new type solver, the following issues were fixed:
* Work has started to support https://github.com/Roblox/luau/pull/77 and
https://github.com/Roblox/luau/pull/79
* Refinements are no longer applied on l-values, removing some
false-positive errors
* Improved overload resolution against expected result type
* `Frontend::prepareModuleScope` now works in the new solver
* Cofinite strings are now comparable
And these are the changes in native code generation (JIT):
* Fixed MIN_NUM and MAX_NUM constant fold when one of the arguments is
NaN
* Added constant folding for number conversions and bit operations
* Value spilling and rematerialization is now supported on arm64
* Improved FASTCALL2K IR generation to support second argument constant
* Added value numbering and load/store propagation optimizations
* Added STORE_VECTOR on arm64, completing the IR lowering on this target
* A small subset of control-flow refinements have been added to
recognize type options that are unreachable after a
conditional/unconditional code block. (Fixes
https://github.com/Roblox/luau/issues/356).
Some examples:
```lua
local function f(x: string?)
if not x then return end
-- x is 'string' here
end
```
Throwing calls like `error` or `assert(false)` instead of 'return' are
also recognized.
Existing complex refinements like type/typeof and tagged union checks
are expected to work, among others.
To enable this feature, `LuauTinyControlFlowAnalysis` exclusion has to
be removed from `ExperimentalFlags.h`.
If will become enabled unconditionally in the near future.
* Linter has been integrated into the typechecker analysis so that
type-aware lint warnings can work in any mode
`Frontend::lint` methods were deprecated, `Frontend::check` has to be
used instead with `runLintChecks` option set.
Resulting lint warning are located inside `CheckResult`.
* Fixed large performance drop and increased memory consumption when
array is filled at an offset (Fixes
https://github.com/Roblox/luau/issues/590)
* Part of [Type error suppression
RFC](https://github.com/Roblox/luau/blob/master/rfcs/type-error-suppression.md)
was implemented making subtyping checks with `any` type transitive.
---
In our work on the new type-solver:
* `--!nocheck` mode no longer reports type errors
* New solver will not be used for `--!nonstrict` modules until all
issues with strict mode typechecking are fixed
* Added control-flow aware type refinements mentioned earlier
In native code generation:
* `LOP_NAMECALL` has been translated to IR
* `type` and `typeof` builtin fastcalls have been translated to
IR/assembly
* Additional steps were taken towards arm64 support
* Fix#817
* Fix#850
* Optimize math.floor/ceil/round with SSE4.1
* Results in a ~7-9% speedup on the math-cordic benchmark.
* Optimized table.sort.
* table.sort is now ~4.1x faster (when not using a predicate) and ~2.1x
faster when using a simple predicate. Performance may improve further in
the future.
* Reorganize the memory ownership of builtin type definitions.
* This is a small initial step toward affording parallel typechecking.
The new type solver is coming along nicely. We are working on fixing
crashes and bugs.
A few major changes to native codegen landed this week:
* Fixed lowering of Luau IR mod instruction when first argument is a
constant
* Added VM register data-flow/capture analysis
* Fixed issues with optimizations in unreachable blocks
---------
Co-authored-by: Arseny Kapoulkine <arseny.kapoulkine@gmail.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>
We've made a few small changes to reduce the amount of stack we use when
typechecking nested method calls (eg `foo:bar():baz():quux()`).
We've also fixed a small bytecode compiler issue that caused us to emit
redundant jump instructions in code that conditionally uses `break` or
`continue`.
On the new solver, we've switched to a new, better way to handle
augmentations to unsealed tables. We've also made some substantial
improvements to type inference and error reporting on function calls.
These things should both be on par with the old solver now.
The main improvements to the native code generator have been elimination
of some redundant type tag checks. Also, we are starting to inline
particular fastcalls directly to IR.
---------
Co-authored-by: Arseny Kapoulkine <arseny.kapoulkine@gmail.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>
This week we only have updates to new type solver and JIT. Both projects
are still in the process of being built out. Neither are ready for
general use yet.
In the new solver, we fixed issues with recursive type aliases.
Duplicated type parameters are once again reported, exported types are
being recorder and function argument names are placed inside function
types.
We also made improvements to restore parts of bidirectional type
tracking.
On native code generation side, namecall instruction lowering was fixed,
we fixed inconsistencies in IR command definitions and added utility
function to help with constant folding.
* For autocomplete, additional information is included in Scope for type
alias name locations and names of imported modules
* Improved autocomplete suggestions in 'for' and 'while' loop headers
* String match functions return types are now optional strings and
numbers because match is not guaranteed at runtime
* Fixed build issue on gcc 11 and up (Fixes
https://github.com/Roblox/luau/issues/806)
* Fixed unions of `nil` types displaying as `?`
* Internal normalization now handles class types which can make
previously failing (incorrectly) sub-typing checks to succeed
* The AST JSON encoder will now stringify infinity and NaN according to the JSON5 spec using the tokens `Infinity`, `-Infinity`, and `NaN`.
* Improve autocompletion of table keys if the type of that key is a union of string singletons.
* Type mismatch errors now mention if unification failed in covariant or
invariant context, to explain why sometimes derived class can't be
converted to base class or why `T` can't be converted into `T?` and so
on
* Class type indexing is no longer an error in non-strict mode (still an
error in strict mode)
* Fixed cyclic type packs not being displayed in the type
* Added an error when unrelated types are compared with `==`/`~=`
* Fixed false positive errors involving sub-type tests an `never` type
* Fixed miscompilation of multiple assignment statements (Fixes
https://github.com/Roblox/luau/issues/754)
* Type inference stability improvements
* Reduce the stack utilization of type checking.
* Improve the error message that's reported when a delimiting comma is
missing from a table literal. eg
```lua
local t = {
first = 1
second = 2
}```
* Reoptimized math.min/max/bit32 builtins assuming at least 2 arguments are used (1-2% lift on some benchmarks)
* Type errors that mention function types no longer have redundant parenthesis around return type
* Luau REPL now supports --compile=remarks which displays the source code with optimization remarks embedded as comments
* Builtin calls are slightly faster when called with 1-2 arguments (~1% improvement in some benchmarks)
- Fix rare type checking bugs with invalid generic types escaping the
module scope
- Fix type checking of variadic type packs in certain cases
- Implement type normalization, which resolves a large set of various
issues with unions/intersections in type checker
- Improve parse errors for trailing commas in function calls and type
lists
- Reduce profiling skew when using --profile with very high frequencies
- Improve performance of `lua_getinfo` (`debug.info`, `debug.traceback`
and profiling overhead are now 20% faster/smaller)
- Improve performance of polymorphic comparisons (1-2% lift on some
benchmarks)
- Improve performance of closure creation (1-2% lift on some benchmarks)
- Improve string comparison performance (4% lift on string sorting)
- Type aliases can no longer override primitive types; attempts to do
that will result in a type error
- Fix misleading type error messages for mismatches in expression list
length during assignment
- Fix incorrect type name display in certain cases
- setmetatable/getmetatable are now ~2x faster
- tools/perfstat.py can be used to display statistics about profiles
captured via --profile switch
- Remove type definitions of
`utf8.nfcnormalize`/`nfdnormalize`/`graphemes` that aren't supported by
standalone Luau library
- Add `lua_costatus` to retrieve extended thread status (similar to
`coroutine.status`)
- Improve GC sweeping performance (2-10% improvement on allocation-heavy
benchmarks)
- Fix autocomplete not suggesting globals defined after the cursor (fixes#622)
- Improve type checker stability
- Reduce parser C stack consumption which fixes some stack overflow crashes on deeply nested sources
- Improve performance of bit32.extract/replace when width is implied (~3% faster chess)
- Improve performance of bit32.extract when field/width are constants (~10% faster base64)
- Heap dump now annotates thread stacks with local variable/function names
- Rework transaction log used for type checking which should result in more robust type checking internals with fewer bugs
- Reduce the amount of memory consumed by type checker on large module graphs
- Type checker now errors on attempts to change the type of imported module fields
- The return type of newproxy is now any (fixes#296)
- Implement new number printing algorithm (Schubfach) which makes tostring() produce precise (round-trippable) and short decimal output up to 10x faster
- Fix lua_Debug::linedefined to point to the line with the function definition instead of the first statement (fixes#265)
- Fix minor bugs in Tab completion in Repl
- Repl now saves/restores command history in ~/.luau_history
This doesn't contain all changes for 507 yet but we might want to do the
Luau 0.507 release a bit earlier to end the year sooner.
Changes:
- Type ascription (::) now permits casts between related types in both directions, allowing to refine or loosen the type (RFC #56)
- Fix type definition for tonumber to return number? since the input string isn't guaranteed to contain a valid number
- Fix type refinements for field access via []
- Many stability fixes for type checker
- Provide extra information in error messages for type mismatches in more cases
- Improve performance of type checking for large unions when union members are string literals
- Add coverage reporting support to Repl (--coverage command line argument) and lua_getcoverage C API
- Work around code signing issues during Makefile builds on macOS
- Improve performance of truthiness checks in some cases, particularly on Apple M1, resulting in 10-25% perf gains on qsort benchmark depending on the CPU/compiler
- Fix support for little-endian systems; IBM s390x here we go!
- Improve error recovery during type checking
- Initial (not fully complete) implementation for singleton types (RFC RFC: Singleton types #37)
- Implement a C-friendly interface for compiler (luacode.h)
- Remove C++ features from lua.h (removed default arguments from luau_load and lua_pushcfunction)
- Fix lua_breakpoint behavior when enabled=false
- Implement coroutine.close (RFC RFC: coroutine.close #88)
Note, this introduces small breaking changes in lua.h:
- luau_load env argument is now required, pass an extra 0
- lua_pushcfunction now must be called with 3 arguments; if you were calling it with 2 arguments, pass an extra NULL; if you were calling it with 4, use lua_pushcclosure.
These changes are necessary to make sure lua.h can be used from pure C - the future release will make it possible by adding an option to luaconf.h to change function name mangling to be C-compatible. We don't anticipate breaking the FFI interface in the future, but this change was necessary to restore C compatibility.
Closes#121Fixes#213
- Type mismatch errors now show detailed information for compound types, highlighting the mismatching component
- Fix string.pack bug on ARM when packing negative numbers using unsigned formats
- Implement bit32.countlz/countrz (RFC RFC: bit32.countlz/countrz #89)
- Minor compiler throughput optimization (~2% faster compilation)
- Improve transpiler behavior for edge cases and better test coverage (not exposed through CLI at the moment)
- Improve error recovery when parsing invalid assignments
- Build fixes for fuzzing targets
- A series of major optimizations to type checking performance on complex
programs/types (up to two orders of magnitude speedup for programs
involving huge tagged unions)
- Fix a few issues encountered by UBSAN (and maybe fix s390x builds)
- Fix gcc-11 test builds
- Fix a rare corner case where luau_load wouldn't wake inactive threads
which could result in a use-after-free due to GC
- Fix CLI crash when error object that's not a string escapes to top level
- Fix Makefile suffixes on macOS
Co-authored-by: Rodactor <rodactor@roblox.com>
Changes:
- Support for time tracing for analysis/compiler (not currently exposed
through CLI)
- Support for type pack arguments in type aliases (#83)
- Basic support for require(path) in luau-analyze
- Add a lint warning for table.move with 0 index as part of
TableOperation lint
- Remove last STL dependency from Luau.VM
- Minor VS2022 performance tuning
Co-authored-by: Rodactor <rodactor@roblox.com>
