This feature had bitrotted somewhat and would trigger errors because
PrimitiveStrings were "destroyed" but because of this mode they were not
removed from the string cache. Even fixing that case running test-js
with the options still failed in more places.
This abstracts a vector of Cell* with a strongly typed span() accessor
that gives you Span<T*> instead of Span<Cell*>.
It is intended to replace MarkedValueList in situations where you only
need to store pointers to Cell (or an even more specific type of Cell).
The API can definitely be improved, it's just the bare basics for now.
The way that transition avoidance (foo_without_transition) was
implemented led to shapes being unshareable and caused shape explosion
instead, precisely what we were trying to avoid.
This patch removes all the attempts to avoid transitioning shapes, and
instead *adds* transitions when changing an object's prototype.
This makes transitions flow naturally, and as a result we end up with
way fewer shape objects in real-world situations.
When we run out of big problems, we can get back to avoiding transitions
as an optimization, but for now, let's avoid ballooning our processes
with a unique shape for every object.
This patch ups the max number of heap allocations between each GC
from 10'000 to 100'000. This is still relatively aggressive but already
does a good job of cutting down on time spent in GC.
This patch adds a `-z` option to js and test-js. When run in this mode,
garbage cells are never actually destroyed. We instead keep them around
in a special zombie state.
This allows us to validate that zombies don't get marked in future GC
scans (since there were not supposed to be any more references!) :^)
Cells get notified when they become a zombie (via did_become_zombie())
and this is used by WeakContainer cells to deregister themselves from
the heap.
This should fix the flaky tests of test-js.
It also fixes the tests when running with the -g flag since the values
will not be garbage collected too soon.
- Replace the misleading abuse of the m_transitions_enabled flag for the
fast path without lookup with a new m_initialized boolean that's set
either by Heap::allocate() after calling the Object's initialize(), or
by the GlobalObject in its special initialize_global_object(). This
makes it work regardless of the shape's uniqueness.
- When we're adding a new property past the initialization phase,
there's no need to do a second metadata lookup to retrieve the storage
value offset - it's known to always be the shape's property count
minus one. Also, instead of doing manual storage resizing and
assignment via indexing, just use Vector::append().
- When we didn't add a new property but are overwriting an existing one,
the property count and therefore storage value offset doesn't change,
so we don't have to retrieve it either.
As a result, Object::set_shape() is now solely responsible for updating
the m_shape pointer and is not resizing storage anymore, so I moved it
into the header.
This patch adds a BlockAllocator to the GC heap where we now cache up to
64 HeapBlock-sized mmap's that get recycled when allocating HeapBlocks.
This improves test-js runtime performance by ~35%, pretty cool! :^)
SPDX License Identifiers are a more compact / standardized
way of representing file license information.
See: https://spdx.dev/resources/use/#identifiers
This was done with the `ambr` search and replace tool.
ambr --no-parent-ignore --key-from-file --rep-from-file key.txt rep.txt *
This commit makes the user-facing StdLibExtras templates and utilities
arguably more nice-looking by removing the need to reach into the
wrapper structs generated by them to get the value/type needed.
The C++ standard library had to invent `_v` and `_t` variants (likely
because of backwards compat), but we don't need to cater to any codebase
except our own, so might as well have good things for free. :^)
