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The State of
AssemblyScript
2018
Emscripten & WebAssembly Night #6
2018.12.14
@kazupon
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Who am I ?
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CTO
Vue.js Core Team
Vue.js japan users group organizer
vue-i18n author
WebAssembly Love ❤
@kazu_pon kazupon
kazupon
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Introduction
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Last a year …
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https://qiita.com/chikoski/items/d98ed0a98acfa896869f
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https://qiita.com/kazupon/items/37e1ee9db0ca5419c517
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One year has passed.
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During this time,
AssemblyScript evolves
little by little.
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Today Contents
About recently updates of
AssemblyScript
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ATTENTION !!
• AssemblyScript v5 is WIP
(Not published in NPM)
• It might be changed in future
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What is
AssemblyScript?
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Compile a strictly-typed subset
of TypeScript to WebAssembly
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Recently updates
from last year
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Hot topics
•Memory management
•AssemblyScript loader
•GC Implementation
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Memory Management
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Kind of allocators
• allocator/arena
• allocator/tlsf
• allocator/buddy
• allocator/system
HEAP_BASE
(the first 8 byte aligned
offset after static)
Static
Heap
Memory
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• Accumulates memory with no mechanism to free specific
segments
allocator/arena
Static
Allocated
memory.allocate(1024)
startOffset
offset
64KB (page x)
Allocatable Heap region
Memory
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• Simply increase the memory size, when memory size will
be about to fill.
allocator/arena
Static
Allocated
memory.allocate(1024)
startOffset
offset
64KB
Memory
memory.grow(2)
128KB
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• when memory.reset, resets the counting memory offset to
its initial value and starts all over again.
allocator/arena
Static
Heap
memory.reset()
startOffset
offset
128KB
Memory
64KB
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allocate / free of memory
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• You can use your custom memory allocator !
allocator/system
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Memory Layout
• String
e.g. const str: string = ‘Hello’
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Memory Layout
• Arrays: All arrays store their contents in an ArrayBuffer
behind the scenes.
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Memory Layout
• ArrayBuffer layout
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AssemblyScript loader
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What is it?
• Provide some APIs of convenient AssemblyScript modules
loading
• Demangles module
• Exports to a friendly object structure compatible
WebIDL and TypeScript definitions for JS env
• Some useful utilities as helper API, to read/write data
from/to memory
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Demangles module structure
add
Point
thisPtr
x (getter/setter)
y (getter/setter)
add (method)
I8 U8 I16 U16
I32 U32 I64 U64
F32
F64
Static
Heap
WASM module
Demangles module
Wrap
Wrap
Return the
pointer
Memory
Ref
newString getString
… Utilities
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How to use demangles module
Static
Heap
Memory 32
64
0x00010000
p1
0x00010008
thisPtr 0x00010000
x
y
pass the pointer
pass the pointer
0x00000000
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Working with strings and arrays
• ex: object path parser
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Reading/writing basic
values to/from memory
https://github.com/AssemblyScript/assemblyscript/tree/master/lib/loader#readingwriting-basic-values-tofrom-memory
Static
Heap
Memory
FF
FF
0x00010000
ptr: 0x00010000
0x00010001
U8
0x00000000
U16
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GC implementation
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Experimental !!
https://github.com/AssemblyScript/assemblyscript/pull/196
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Manually GC release
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GC related issues
• GC experimentation
• GitHub Issue Number: #89
• Implement reference counting and/or garbage collection
• GitHub Issue Number: #16
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In future …
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Status / Roadmap
• Standard library comatibility
• TypeScript comatiplity
• WASM features
• Managed object runtime
https://next.assemblyscript.org/#/development/roadmap
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Closing
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Closing
•AssemblyScript is steadily evolving
•Memory management
•AssemblyScript loader
•GC Implementation
•It has a potential as WASM app
implementation language!
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Thanks!