These wrappers will make it much easier to do various operations on the
different ArrayBuffer-related classes in LibWeb compared to the current
solution, which is to just accept a Handle<Object> everywhere (and use
"any" in the *.idl files).
Co-Authored-By: Matthew Olsson <mattco@serenityos.org>
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 patch adds two macros to declare per-type allocators:
- JS_DECLARE_ALLOCATOR(TypeName)
- JS_DEFINE_ALLOCATOR(TypeName)
When used, they add a type-specific CellAllocator that the Heap will
delegate allocation requests to.
The result of this is that GC objects of the same type always end up
within the same HeapBlock, drastically reducing the ability to perform
type confusion attacks.
It also improves HeapBlock utilization, since each block now has cells
sized exactly to the type used within that block. (Previously we only
had a handful of block sizes available, and most GC allocations ended
up with a large amount of slack in their tails.)
There is a small performance hit from this, but I'm sure we can make
up for it elsewhere.
Note that the old size-based allocators still exist, and we fall back
to them for any type that doesn't have its own CellAllocator.
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
When deciding whether we need to create a full-blown `arguments` object,
we look at various things, starting as early as in the parser.
Until now, if the parser saw the identifier `arguments`, we'd decide
that it's enough of a clue that we should create the `arguments` object
since somebody is obviously accessing it.
However, that missed the case where someone is just accessing a property
named `arguments` on some object. In such cases (`o.arguments`), we now
hold off on creating an `arguments` object.
~11% speed-up on Octane/typescript.js :^)
Previously, certain crafted input could cause the JS parser to hang, as
it repeatedly tried to parse an EOF token after hitting an "invalid
destructuring assignment target" error. This change ensures that we
stop parsing after hitting this error condition.
Array.length is magical (since it has to reflect the number of elements
in the object's property storage).
We now handle it specially in jitted code, giving us a massive speed-up
on Kraken/ai-astar.js (and probably many other things as well) :^)
Until now, the unwind context stack has not been maintained by jitted
code, which meant we were unable to support the `with` statement.
This is a first step towards supporting that by making jitted code
call out to C++ to update the unwind context stack when entering/leaving
unwind contexts.
We also introduce a new "Catch" bytecode instruction that moves the
current exception into the accumulator. It's always emitted at the start
of a "catch" block.
