# What's changed?
* Compiler now targets bytecode version 5 by default, this includes
support for vector type literals and sub/div opcodes with a constant on
lhs
### New Type Solver
* Normalizer type inhabitance check has been optimized
* Added ability to reduce cyclic `and`/`or` type families
### Native Code Generation
* `CodeGen::compile` now returns more specific causes of a code
generation failure
* Fixed linking issues on platforms that don't support unwind frame data
registration
---
### Internal Contributors
Co-authored-by: Andy Friesen <afriesen@roblox.com>
Co-authored-by: Aviral Goel <agoel@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: Vighnesh <vvijay@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>
- 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>
Right now, we can compile R\*K for all arithmetic instructions, but K\*R
gets compiled into two instructions (LOADN/LOADK + arithmetic opcode).
This is problematic since it leads to reduced performance for some code.
However, we'd like to avoid adding reverse variants of ADDK et al for
all opcodes to avoid the increase in I$ footprint for interpreter.
Looking at the arithmetic instructions, % and // don't have interesting
use cases for K\*V; ^ is sometimes used with constant on the left hand
side but this would need to call pow() by necessity in all cases so it
would be slow regardless of the dispatch overhead. This leaves the four
basic arithmetic operations.
For + and \*, we can implement a compiler-side optimization in the
future that transforms K\*R to R\*K automatically. This could either be
done unconditionally at -O2, or conditionally based on the type of the
value (driven by type annotations / inference) -- this technically
changes behavior in presence of metamethods, although it might be
sensible to just always do this because non-commutative +/* are evil.
However, for - and / it is impossible for the compiler to optimize this
in the future, so we need dedicated opcodes. This only increases the
interpreter size by ~300 bytes (~1.5%) on X64.
This makes spectral-norm and math-partial-sums 6% faster; maybe more
importantly, voxelgen gets 1.5% faster (so this change does have
real-world impact).
To avoid the proliferation of bytecode versions this change piggybacks
on the bytecode version bump that was just made in 604 for vector
constants; we would still be able to enable these independently but
we'll consider v5 complete when both are enabled.
Related: #626
---------
Co-authored-by: vegorov-rbx <75688451+vegorov-rbx@users.noreply.github.com>
With this optimization, built-in vector constructor calls with 3/4 arguments are detected by the compiler and turned into vector constants when the arguments are constant numbers.
Requires optimization level 2 because built-ins are not folded otherwise by the compiler.
Bytecode version is bumped because of the new constant type, but old bytecode versions can still be loaded.
The following synthetic benchmark shows ~6.6x improvement.
```
local v
for i = 1, 10000000 do
v = vector(1, 2, 3)
v = vector(1, 2, 3)
v = vector(1, 2, 3)
v = vector(1, 2, 3)
v = vector(1, 2, 3)
v = vector(1, 2, 3)
v = vector(1, 2, 3)
v = vector(1, 2, 3)
v = vector(1, 2, 3)
v = vector(1, 2, 3)
end
```
Also tried a more real world scenario and could see a few percent improvement.
Added a new fast flag LuauVectorLiterals for enabling the feature.
---------
Co-authored-by: Petri Häkkinen <petrih@rmd.remedy.fi>
Co-authored-by: vegorov-rbx <75688451+vegorov-rbx@users.noreply.github.com>
Co-authored-by: Arseny Kapoulkine <arseny.kapoulkine@gmail.com>
# What's changed?
- Record the location of properties for table types (closes#802)
- Implement stricter UTF-8 validations as per the RFC
(https://github.com/luau-lang/rfcs/pull/1)
- Implement `buffer` as a new type in both the old and new solvers.
- Changed errors produced by some `buffer` builtins to be a bit more
generic to avoid platform-dependent error messages.
- Fixed a bug where `Unifier` would copy some persistent types, tripping
some internal assertions.
- Type checking rules on relational operators is now a little bit more
lax.
- Improve dead code elimination for some `if` statements with complex
always-false conditions
## New type solver
- Dataflow analysis now generates phi nodes on exit of branches.
- Dataflow analysis avoids producing a new definition for locals or
properties that are not owned by that loop.
- If a function parameter has been constrained to `never`, report errors
at all uses of that parameter within that function.
- Switch to using the new `Luau::Set` to replace `std::unordered_set` to
alleviate some poor allocation characteristics which was negatively
affecting overall performance.
- Subtyping can now report many failing reasons instead of just the
first one that we happened to find during the test.
- Subtyping now also report reasons for type pack mismatches.
- When visiting `if` statements or expressions, the resulting context
are the common terms in both branches.
## Native codegen
- Implement support for `buffer` builtins to its IR for x64 and A64.
- Optimized `table.insert` by not inserting a table barrier if it is
fastcalled with a constant.
## 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: Arseny Kapoulkine <arseny@roblox.com>
Co-authored-by: Aviral Goel <agoel@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>
## What's changed
- `bit32.byteswap` added
([RFC](4f543ec23b/docs/function-bit32-byteswap.md))
- Buffer library implementation
([RFC](4f543ec23b/docs/type-byte-buffer.md))
- Fixed a missing `stdint.h` include
- Fixed parser limiter for recursive type annotations being kind of
weird (fixes#645)
### Native Codegen
- Fixed a pair of issues when lowering `bit32.extract`
- Fixed a narrow edge case that could result in an infinite loop without
an interruption
- Fixed a negative array out-of-bounds access issue
- Temporarily reverted linear block predecessor value propagation
### New type solver
- We now type check assignments to annotated variables
- Fixed some test cases under local type inference
- Moved `isPending` checks for type families to improve performance
- Optimized our process for testing if a free type is sufficiently
solved
- Removed "none ptr" from lea instruction disassembly logging
### Build system & tooling
- CMake configuration now validates dependencies to maintain separation
between components
- Improvements to the fuzzer coverage
- Deduplicator for fuzzed callstacks
---------
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: Aaron Weiss <aaronweiss@roblox.com>
Co-authored-by: Vighnesh Vijay <vvijay@roblox.com>
### What's Changed
- Improve readability of unions and intersections by limiting the number
of elements of those types that can be presented on a single line (gated
under `FFlag::LuauToStringSimpleCompositeTypesSingleLine`)
- Adds a new option to the compiler `--record-stats` to record and
output compilation statistics
- `if...then...else` expressions are now optimized into `AND/OR` form
when possible.
### VM
- Add a new `buffer` type to Luau based on the [buffer
RFC](https://github.com/Roblox/luau/pull/739) and additional C API
functions to work with it; this release does not include the library.
- Internal C API to work with string buffers has been updated to align
with Lua version more closely
### Native Codegen
- Added support for new X64 instruction (rev) and new A64 instruction
(bswap) in the assembler
- Simplified the way numerical loop condition is translated to IR
### New Type Solver
- Operator inference now handled by type families
- Created a new system called `Type Paths` to explain why subtyping
tests fail in order to improve the quality of error messages.
- Systematic changes to implement Data Flow analysis in the new solver
(`Breadcrumb` removed and replaced with `RefinementKey`)
---
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>
Co-authored-by: Vighnesh Vijay <vvijay@roblox.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>
---------
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>
Co-authored-by: Alexander McCord <amccord@roblox.com>
Co-authored-by: Aviral Goel <agoel@roblox.com>
## What's Changed
- Improve POSIX compliance in `CLI/FileUtils.cpp` by @SamuraiCrow #1064
- `AstStat*::hasEnd` is deprecated; use `AstStatBlock::hasEnd` instead
- Added a lint for common misuses of the `#` operator
- Luau now issues deprecated diagnostics for some uses of `getfenv` and
`setfenv`
- Fixed a case where we included a trailing space in some error
stringifications
### Compiler
- Do not do further analysis in O2 on self functions
- Improve detection of invalid repeat..until expressions vs continue
### New Type Solver
- We now cache subtype test results to improve performance
- Improved operator inference mechanics (aka type families)
- Further work towards type states
- Work towards [new non-strict
mode](https://github.com/Roblox/luau/blob/master/rfcs/new-nonstrict.md)
continues
### Native Codegen
- Instruction last use locations should follow the order in which blocks
are lowered
- Add a bonus assertion to IrLoweringA64::tempAddr
---
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: Aaron Weiss <aaronweiss@roblox.com>
Co-authored-by: Alexander McCord <amccord@roblox.com>
Co-authored-by: Vighnesh Vijay <vvijay@roblox.com>
* Include `windows.h` rather than `Windows.h` to make things compile on
MinGW.
* Custom implementation of timegm/os.time for all platforms
* Disable builtin constant folding when getfenv/setfenv are used
* Fixes https://github.com/Roblox/luau/issues/1042
* Fixes https://github.com/Roblox/luau/issues/1043
New Type Checker
* Initial work toward type states.
* Rework most overloadable operators to use type families.
* Initial work toward our new nonstrict mode.
Native Codegen
* Fix native code generation for dead loops
* Annotate top-level functions as cold
* Slightly smaller/faster x64 Luau calls
* emitInstCall used to not set savedpc itself, but now it does for
consistency with all other implementations
* Implement cmov support for X64
* Fix assertion in luau-compile when module is empty
* Optimize A64 calls at some code size cost
* Inline constant array index offset into the load/store instruction
* Increase x64 spill slots from 5 to 13
---------
Co-authored-by: Arseny Kapoulkine <arseny.kapoulkine@gmail.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>
Co-authored-by: Lily Brown <lbrown@roblox.com>
Co-authored-by: Aaron Weiss <aaronweiss@roblox.com>
Co-authored-by: Alexander McCord <amccord@roblox.com>
* Rerun clang-format on the code
* Fix the variance on indexer result subtyping. This fixes some issues
with inconsistent error reporting.
* Fix a bug in the normalization logic for intersections of strings
New Type Solver
* New overload selection logic
* Subtype tests now correctly treat a generic as its upper bound within
that generic's scope
* Semantic subtyping for negation types
* Semantic subtyping between strings and compatible table types like
`{lower: (string) -> string}`
* Further work toward finalizing our new subtype test
* Correctly generalize module-scope symbols
Native Codegen
* Lowering statistics for assembly
* Make executable allocation size/limit configurable without a rebuild.
Use `FInt::LuauCodeGenBlockSize` and `FInt::LuauCodeGenMaxTotalSize`.
---------
Co-authored-by: Arseny Kapoulkine <arseny.kapoulkine@gmail.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>
Co-authored-by: Lily Brown <lbrown@roblox.com>
* AST queries at position where function name is will now return
AstExprLocal
* Lexer performance has been slightly improved
* Fixed incorrect string singleton autocomplete suggestions (fixes#858)
* Improved parsing error messages
* Fixed crash on null pointer access in unification (fixes#1017)
* Native code support is enabled by default and `native=1`
(make)/`LUAU_NATIVE` (CMake)/`-DLUA_CUSTOM_EXECUTION` configuration is
no longer required
New typechecker:
* New subtyping check can now handle generic functions and tables
(including those that contain cycles)
Native code generation:
* Loops with non-numeric parameters are now handled by VM to streamline
native code
* Array size check can be optimized away in SETLIST
* On failure, CodeGen::compile returns a reason
* Fixed clobbering of non-volatile xmm registers on Windows
* Fix a use-after-free bug in the new type cloning algorithm
* Tighten up the type of `coroutine.wrap`. It is now `<A..., R...>(f:
(A...) -> R...) -> ((A...) -> R...)`
* Break `.luaurc` out into a separate library target `Luau.Config`. This
makes it easier for applications to reason about config files without
also depending on the type inference engine.
* Move typechecking limits into `FrontendOptions`. This allows embedders
more finely-grained control over autocomplete's internal time limits.
* Fix stability issue with debugger onprotectederror callback allowing
break in non-yieldable contexts
New solver:
* Initial work toward [Local Type
Inference](0e1082108f/rfcs/local-type-inference.md)
* Introduce a new subtyping test. This will be much nicer than the old
test because it is completely separate both from actual type inference
and from error reporting.
Native code generation:
* Added function to compute iterated dominance frontier
* Optimize barriers in SET_UPVALUE when tag is known
* Cache lua_State::global in a register on A64
* Optimize constant stores in A64 lowering
* Track table array size state to optimize array size checks
* Add split tag/value store into a VM register
* Check that spills can outlive the block only in specific conditions
---------
Co-authored-by: Arseny Kapoulkine <arseny.kapoulkine@gmail.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>
* 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
* Progress toward a diffing algorithm for types. We hope that this will
be useful for writing clearer error messages.
* Add a missing recursion limiter in `Unifier::tryUnifyTables`. This was
causing a crash in certain situations.
* Luau heap graph enumeration improvements:
* Weak references are not reported
* Added tag as a fallback name of non-string table links
* Included top Luau function information in thread name to understand
where thread might be suspended
* Constant folding for `math.pi` and `math.huge` at -O2
* Optimize `string.format` and `%*`
* This change makes string interpolation 1.5x-2x faster depending on the
number and type of formatted components, assuming a few are using
primitive types, and reduces associated GC pressure.
New type checker:
* Initial work toward tracking the upper and lower bounds of types
accurately.
Native code generation (JIT):
* Add IrCmd::CHECK_TRUTHY for improved assert fast-calls
* Do not compute type map for modules without types
* Capture metatable+readonly state for NEW_TABLE IR instructions
* Replace JUMP_CMP_ANY with CMP_ANY and existing JUMP_EQ_INT
* Add support for exits to VM with reentry lock in VmExit
---------
Co-authored-by: Arseny Kapoulkine <arseny.kapoulkine@gmail.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>
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
* Added support for async typechecking cancellation using a token passed
through frontend options
* Added luaC_enumheap for building debug tools that need a graph of Luau
heap
In our new typechecker:
* Errors or now suppressed when checking property lookup of
error-suppressing unions
In our native code generation (jit):
* Fixed unhandled value type in NOT_ANY lowering
* Fast-call tag checks will exit to VM on failure, instead of relying on
a native fallback
* Added vector type to the type information
* Eliminated redundant direct jumps across dead blocks
* Debugger APIs are now disabled for call frames executing natively
* Implemented support for unwind registration on macOS 14
* Fixed indexing table intersections using `x["prop"]` syntax:
https://github.com/Roblox/luau/pull/971
* Add console output codepage for Windows:
https://github.com/Roblox/luau/pull/967
* Added `Frontend::parse` for a fast source graph preparation
* luau_load should check GC
* Work toward a type-diff system for nicer error messages
New Solver
* Correctly suppress errors in more cases
* Further improvements to typechecking of function calls and return
statements
* Crash fixes
* Propagate refinements drawn from the condition of a while loop into
the loop body
JIT
* Fix accidental bailout for math.frexp/modf/sign in A64
* Work toward bringing type annotation info in
* Do not propagate Luau IR constants of wrong type into load
instructions
* CHECK_SAFEENV exits to VM on failure
* Implement error handling in A64 reg allocator
* Inline the string.len builtin
* Do not enter native code of a function if arguments don’t match
---------
Co-authored-by: Arseny Kapoulkine <arseny.kapoulkine@gmail.com>
Co-authored-by: Vyacheslav Egorov <vegorov@roblox.com>
* Definition files can now ascribe indexers to class types.
(https://github.com/Roblox/luau/pull/949)
* Remove --compile support from the REPL. You can just use luau-compile
instead.
* When an exception is thrown during parallel typechecking (usually an
ICE), we now gracefully stop typechecking and drain active workers
before rethrowing the exception.
New solver
* Include more source location information when we hit an internal
compiler error
* Improve the logic that simplifies intersections of tables
JIT
* Save testable type annotations to bytecode
* Improve block placement for linearized blocks
* Add support for lea reg, [rip+offset] for labels
* Unify X64 and A64 codegen for RETURN
* Outline interrupt handlers for X64
* Remove global rArgN in favor of build.abi
* Change A64 INTERRUPT lowering to match X64
---------
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>
Once again, all of our changes this week are for new type solver and the
JIT.
In the new type solver, we fixed cyclic type alias handling and multiple
stability issues.
In the JIT, our main progress was for arm64, where, after lowering 36%
of instructions, we start seeing first Luau functions executing
natively.
For x64, we performed code cleanup and refactoring to allow for future
optimizations.
* 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
* Fixed incorrect lexeme generated for string parts in the middle of an
interpolated string (Fixes https://github.com/Roblox/luau/issues/744)
* DeprecatedApi lint can report some issues without type inference
information
* Fixed performance of autocomplete requests when suggestions have large
intersection types (Solves
https://github.com/Roblox/luau/discussions/847)
* Marked `table.getn`/`foreach`/`foreachi` as deprecated ([RFC:
Deprecate
table.getn/foreach/foreachi](https://github.com/Roblox/luau/blob/master/rfcs/deprecate-table-getn-foreach.md))
* With -O2 optimization level, we now optimize builtin calls based on
known argument/return count.
Note that this change can be observable if `getfenv/setfenv` is used to
substitute a builtin, especially if arity is different.
Fastcall heavy tests show a 1-2% improvement.
* Luau can now be built with clang-cl (Fixes
https://github.com/Roblox/luau/issues/736)
We also made many improvements to our experimental components.
For our new type solver:
* Overhauled data flow analysis system, fixed issues with 'repeat'
loops, global variables and type annotations
* Type refinements now work on generic table indexing with a string
literal
* Type refinements will properly track potentially 'nil' values (like
t[x] for a missing key) and their further refinements
* Internal top table type is now isomorphic to `{}` which fixes issues
when `typeof(v) == 'table'` type refinement is handled
* References to non-existent types in type annotations no longer resolve
to 'error' type like in old solver
* Improved handling of class unions in property access expressions
* Fixed default type packs
* Unsealed tables can now have metatables
* Restored expected types for function arguments
And for native code generation:
* Added min and max IR instructions mapping to vminsd/vmaxsd on x64
* We now speculatively extract direct execution fast-paths based on
expected types of expressions which provides better optimization
opportunities inside a single basic block
* Translated existing math fastcalls to IR form to improve tag guard
removal and constant propagation
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>
* Fixed rare use-after-free in analysis during table unification
A lot of work these past months went into two new Luau components:
* A near full rewrite of the typechecker using a new deferred constraint
resolution system
* Native code generation for AoT/JiT compilation of VM bytecode into x64
(avx)/arm64 instructions
Both of these components are far from finished and we don't provide
documentation on building and using them at this point.
However, curious community members expressed interest in learning about
changes that go into these components each week, so we are now listing
them here in the 'sync' pull request descriptions.
---
New typechecker can be enabled by setting
DebugLuauDeferredConstraintResolution flag to 'true'.
It is considered unstable right now, so try it at your own risk.
Even though it already provides better type inference than the current
one in some cases, our main goal right now is to reach feature parity
with current typechecker.
Features which improve over the capabilities of the current typechecker
are marked as '(NEW)'.
Changes to new typechecker:
* Regular for loop index and parameters are now typechecked
* Invalid type annotations on local variables are ignored to improve
autocomplete
* Fixed missing autocomplete type suggestions for function arguments
* Type reduction is now performed to produce simpler types to be
presented to the user (error messages, custom LSPs)
* Internally, complex types like '((number | string) & ~(false?)) |
string' can be produced, which is just 'string | number' when simplified
* Fixed spots where support for unknown and never types was missing
* (NEW) Length operator '#' is now valid to use on top table type, this
type comes up when doing typeof(x) == "table" guards and isn't available
in current typechecker
---
Changes to native code generation:
* Additional math library fast calls are now lowered to x64: math.ldexp,
math.round, math.frexp, math.modf, math.sign and math.clamp
* 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>
* Fixed garbage data in module scopes when type graph is not retained
* LOP_MOVE with the same source and target registers is no longer
generated (Fixes https://github.com/Roblox/luau/issues/793)
* 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
* Support `["prop"]` syntax on class definitions in definition files.
(#704)
* Improve type checking performance for complex overloaded functions
* Fix rare cases of incorrect stack traces for out of memory errors at
runtime
* 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)
- 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)
- Improve ComparisonPrecedence lint suggestions for three-way comparisons (X < Y < Z)
- Improve type checking stability
- Improve location information for errors when parsing invalid type annotations
- Compiler now generates bytecode version 3 in all configurations
- Improve performance of comparisons against numeric constants on AArch64
- Fix DeprecatedGlobal warning text in cases when the global is deprecated without a suggested alternative
- Fix an off-by-one error in type error text for incorrect use of string.format
- Reduce stack consumption further during parsing, hopefully eliminating stack overflows during parsing/compilation for good
- Mark interpolated string support as experimental (requires --fflags=LuauInterpolatedStringBaseSupport to enable)
- Simplify garbage collection treatment of upvalues, reducing cache misses during sweeping stage and reducing the cost of upvalue assignment (SETUPVAL); supersedes #643
- Simplify garbage collection treatment of sleeping threads
- Simplify sweeping of alive threads, reducing cache misses during sweeping stage
- Simplify management of string buffers, removing redundant linked list operations
Implements the string interpolation RFC (#165).
Adds the string interpolation as per the RFC.
```lua
local name = "world"
print(`Hello {name}!`) -- Hello world!
```
Co-authored-by: Arseny Kapoulkine <arseny.kapoulkine@gmail.com>
Co-authored-by: Alexander McCord <11488393+alexmccord@users.noreply.github.com>
- 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
* Fix free Luau type being fully overwritten by 'any' and causing UAF
* Fix lua_clonefunction implementation replacing top instead of pushing
* Falsey values other than false can now narrow refinements
* Fix lua_getmetatable, lua_getfenv not waking thread up
* FIx a case where lua_objlen could push a new string without thread wakeup or GC
* Moved Luau math and bit32 definitions to definition file
* Improve Luau parse recovery of incorrect return type token
* Run clang-format
* Contains a preliminary implementation of deferred constraint resolution
* Reduce stack usage by some recursive functions
* Fix a bug when smartCloning a BoundTypeVar
* Remove some GC related flags from VM
* Adds a currently unused x86-64 assembler as a prerequisite for possible future JIT compilation
* Fix a bug in table iteration (closes Possible table iteration bug #504)
* Improved warning method when function is used as a type
* Fix a bug with unsandboxed iteration with pairs()
* Type of coroutine.status() is now a union of value types
* Bytecode output for tests/debugging now has labels
* Improvements to loop unrolling cost estimation
* Report errors when the key obviously doesn't exist in the table
