Instead of SetVariable having 2x2 modes for variable/lexical and
initialize/set, those 4 modes are now separate instructions, which
makes each instruction much less branchy.
Instead, generate bytecode to execute their AST nodes and save the
resulting operands inside the NewClass instruction.
Moving property expression evaluation to happen before NewClass
execution also moves along creation of new private environment and
its population with private members (private members should be visible
during property evaluation).
Before:
- NewClass
After:
- CreatePrivateEnvironment
- AddPrivateName
- ...
- AddPrivateName
- NewClass
- LeavePrivateEnvironment
This patch adds a register freelist to Bytecode::Generator and switches
all operands inside the generator to a new ScopedOperand type that is
ref-counted and automatically frees the register when nothing uses it.
This dramatically reduces the size of bytecode executable register
windows, which were often in the several thousands of registers for
large functions. Most functions now use less than 100 registers.
If all lexical declaration use local variables then there is no need
to allocate declarative environment.
With this change we skip ~3x more environment allocations on Github.
If a function has the following properties:
- uses only local variables and registers
- does not use `this`
- does not use `new.target`
- does not use `super`
- does not use direct eval() calls
then it is possible to entirely skip function environment allocation
because it will never be used
This change adds gathering of information whether a function needs to
access `this` from environment and updates `prepare_for_ordinary_call()`
to skip allocation when possible.
For now, this optimisation is too aggressively blocked; e.g. if `this`
is used in a function scope, then all functions in outer scopes have to
allocate an environment. It could be improved in the future, although
this implementation already allows skipping >80% of environment
allocations on Discord, GitHub and Twitter.
This is pure prep work for refactoring the bytecode to use more operands
instead of only registers.
generate_bytecode() virtuals now return an Optional<Operand>, and the
idea is to return an Operand referring to the value produced by this
AST node.
They also take an Optional<Operand> "preferred_dst" input. This is
intended to communicate the caller's preference for an output operand,
if any. This will be used to elide temporaries when we can store the
result directly in a local, for example.
This commit un-deprecates DeprecatedString, and repurposes it as a byte
string.
As the null state has already been removed, there are no other
particularly hairy blockers in repurposing this type as a byte string
(what it _really_ is).
This commit is auto-generated:
$ xs=$(ack -l \bDeprecatedString\b\|deprecated_string AK Userland \
Meta Ports Ladybird Tests Kernel)
$ perl -pie 's/\bDeprecatedString\b/ByteString/g;
s/deprecated_string/byte_string/g' $xs
$ clang-format --style=file -i \
$(git diff --name-only | grep \.cpp\|\.h)
$ gn format $(git ls-files '*.gn' '*.gni')
This greatly reduces the number of compilations necessary when functions
declaring local functions are re-executed.
For example Octane/typescript.js goes from 58080 bytecode executables
to 960.
This will not meaningfully affect short array literals, but it does
give us a bit of extra perf when evaluating huge array expressions like
in Kraken/imaging-darkroom.js
These cases were found with GCC's `-Wsuggest-final-{types,methods}`
warnings, which catch calls that could have been devirtualized had we
declared the functions `final` in the source.
To reproduce, Link Time Optimization needs to be enabled. The easiest
way to achieve this is to set the `CMAKE_INTERPROCEDURAL_OPTIMIZATION`
cache variable to `ON`. The `.incbin` directive in LibCompress' Brotli
decompressor might needs to be changed to an absolute path for this to
work.
This commit also removes a pair of unused virtual functions.
This loosens the connection to the AST interpreter and will allow us to
generate SourceRanges for the Bytecode interpreter in the future as well
Moves UnrealizedSourceRanges from TracebackFrame to the JS namespace for
this
We can delete for_each_bound_name() because there is more generic
version of this function called for_each_bound_identifier() that gives
you identifier using which you can get both name and check if it is
local/global.
Previously, the usage of local variables was limited for all function
declarations. This change relaxes the restriction and only prohibits
locals for hoistable annexB declarations.
This modification enables the parser to determine whether an identifier
used within a function refers to a local variable or not. In this
context, a local identifier means that it is not captured by any nested
function declaration which means it modified only from inside a
function.
The information about whether identifier is local is stored inside
Identifier AST node and also contains information about the index of
local variable inside a function and information about total number
of local variables used by a function is stored in function nodes.
By using Identifier class to represent the name of a class expression,
it becomes possible to consistently store information within the
identifier object, indicating whether the name refers to a local
variable or not.
This makes them trivially copyable, which is an assumption multiple
optimizations use when rebuilding the instruction stream.
This fixes most optimized crashes in the test262 suite.
Instead of assuming that there's an active AST interpreter, this code
now takes VM& everywhere and invokes the appropriate interpreter.
92 new passes on test262. :^)
