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[Wasm] Stop using unsigned numbers in ScopedMemoryAllocator

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It turned out that using unsigned numbers is heavy both in terms of size and performance.
We can consider switching back (KT-58041) as soon as we implement unsigned numbers and operations using wasm built-in capabilities (KT-58039).
This commit is contained in:
Zalim Bashorov
2023-04-17 15:33:32 +02:00
committed by Space Team
parent c114afb55d
commit 6bfd1e7e9f
5 changed files with 19 additions and 16 deletions
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libraries/stdlib/wasm/src/kotlin/wasm/unsafe/MemoryAllocation.kt
+15 -12
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@@ -77,6 +77,7 @@ internal fun createAllocatorInTheNewScope(): ScopedMemoryAllocator {
@UnsafeWasmMemoryApi
internal var currentAllocator: ScopedMemoryAllocator? = null
// TODO(KT-58041): Consider switching back to using ULong
@PublishedApi
@UnsafeWasmMemoryApi
internal class ScopedMemoryAllocator(
@@ -87,10 +88,12 @@ internal class ScopedMemoryAllocator(
) : MemoryAllocator() {
// true if allocator is out of scope
private var destroyed = false
// true if child allocator is active
private var suspended = false
// all memory is available starting from this address
private var availableAddress: ULong = startAddress.toULong()
private var availableAddress = startAddress
override fun allocate(size: Int): Pointer {
check(!destroyed) { "ScopedMemoryAllocator is destroyed when out of scope" }
@@ -98,28 +101,28 @@ internal class ScopedMemoryAllocator(
// Pad available address to align it to 8
// 8 is a max alignment number currently needed for Wasm component model canonical ABI
val align = 8uL
val result = (availableAddress + align - 1uL) and (align - 1uL).inv()
check(result % 8uL == 0uL)
val align = 8
val result = (availableAddress + align - 1) and (align - 1).inv()
check(result > 0 && result % align == 0) { "result must be > 0 and 8-byte aligned" }
availableAddress = result + size.toULong()
if (availableAddress > UInt.MAX_VALUE.toULong()) {
error("Out of linear memory. All available address space (4gb) is used.")
if (Int.MAX_VALUE - availableAddress < size) {
error("Out of linear memory. All available address space (2gb) is used.")
}
val currentMaxSize = wasmMemorySize().toULong() * WASM_PAGE_SIZE_IN_BYTES.toULong()
availableAddress = result + size
val currentMaxSize = wasmMemorySize() * WASM_PAGE_SIZE_IN_BYTES
if (availableAddress >= currentMaxSize) {
val numPagesToGrow =
(availableAddress - currentMaxSize) / WASM_PAGE_SIZE_IN_BYTES.toULong() + 2uL
(availableAddress - currentMaxSize) / WASM_PAGE_SIZE_IN_BYTES + 2
if (wasmMemoryGrow(numPagesToGrow.toInt()) == -1) {
if (wasmMemoryGrow(numPagesToGrow) == -1) {
error("Out of linear memory. memory.grow returned -1")
}
}
check(availableAddress < wasmMemorySize().toULong() * WASM_PAGE_SIZE_IN_BYTES.toULong())
check(availableAddress < wasmMemorySize() * WASM_PAGE_SIZE_IN_BYTES)
return Pointer(result.toUInt())
}