mirror of
https://github.com/tinygo-org/tinygo.git
synced 2026-08-07 04:23:41 +00:00
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.
64 lines
1.4 KiB
Go
64 lines
1.4 KiB
Go
// +build gc.leaking
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package runtime
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// This GC implementation is the simplest useful memory allocator possible: it
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// only allocates memory and never frees it. For some constrained systems, it
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// may be the only memory allocator possible.
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import (
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"unsafe"
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)
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// Ever-incrementing pointer: no memory is freed.
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var heapptr = heapStart
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func alloc(size uintptr) unsafe.Pointer {
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// TODO: this can be optimized by not casting between pointers and ints so
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// much. And by using platform-native data types (e.g. *uint8 for 8-bit
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// systems).
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size = align(size)
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addr := heapptr
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heapptr += size
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for heapptr >= heapEnd {
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// Try to increase the heap and check again.
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if growHeap() {
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continue
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}
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// Failed to make the heap bigger, so we must really be out of memory.
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runtimePanic("out of memory")
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}
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for i := uintptr(0); i < uintptr(size); i += 4 {
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ptr := (*uint32)(unsafe.Pointer(addr + i))
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*ptr = 0
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}
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return unsafe.Pointer(addr)
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}
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func free(ptr unsafe.Pointer) {
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// Memory is never freed.
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}
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func GC() {
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// No-op.
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}
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func KeepAlive(x interface{}) {
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// Unimplemented. Only required with SetFinalizer().
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}
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func SetFinalizer(obj interface{}, finalizer interface{}) {
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// Unimplemented.
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}
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func initHeap() {
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// Nothing to initialize.
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}
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// setHeapEnd sets a new (larger) heapEnd pointer.
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func setHeapEnd(newHeapEnd uintptr) {
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// This "heap" is so simple that simply assigning a new value is good
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// enough.
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heapEnd = newHeapEnd
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}
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