mirror of
https://github.com/tinygo-org/tinygo.git
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Ayke van Laethem
da0161d6ab
On WebAssembly it is possible to grow the heap with the memory.grow instruction. This commit implements this feature and with that also removes the -heap-size flag that was reportedly broken (I haven't verified that). This should make it easier to use TinyGo for WebAssembly, where there was no good reason to use a fixed heap size. This commit has no effect on baremetal targets with optimizations enabled.
53 lines
1.1 KiB
Go
53 lines
1.1 KiB
Go
// +build wasm
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package runtime
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import (
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"unsafe"
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)
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const GOARCH = "wasm"
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// The bitness of the CPU (e.g. 8, 32, 64).
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const TargetBits = 32
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//go:extern __heap_base
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var heapStartSymbol [0]byte
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//export llvm.wasm.memory.size.i32
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func wasm_memory_size(index int32) int32
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//export llvm.wasm.memory.grow.i32
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func wasm_memory_grow(index int32, delta int32) int32
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var (
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heapStart = uintptr(unsafe.Pointer(&heapStartSymbol))
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heapEnd = uintptr(wasm_memory_size(0) * wasmPageSize)
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)
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const wasmPageSize = 64 * 1024
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// Align on word boundary.
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func align(ptr uintptr) uintptr {
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return (ptr + 3) &^ 3
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}
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func getCurrentStackPointer() uintptr
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// growHeap tries to grow the heap size. It returns true if it succeeds, false
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// otherwise.
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func growHeap() bool {
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// Grow memory by the available size, which means the heap size is doubled.
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memorySize := wasm_memory_size(0)
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result := wasm_memory_grow(0, memorySize)
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if result == -1 {
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// Grow failed.
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return false
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}
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setHeapEnd(uintptr(wasm_memory_size(0) * wasmPageSize))
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// Heap has grown successfully.
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return true
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}
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