[teamchong]

On wasm and wasip1, -stack-size sizes goroutine stacks when a scheduler is active, but was ignored when -scheduler=none was set (leaving wasm-ld at its 64 KiB default linear stack).

Forward -stack-size as -z stack-size=<bytes> to wasm-ld when -scheduler=none is set.

package main

func recurse(n int) int {
	var buf [1024]byte
	if n == 0 {
		return int(buf[0])
	}
	return int(buf[n&1023]) + recurse(n-1)
}

func main() {
	println(recurse(200))
}

Before (dev):

$ tinygo run -target=wasip1 -scheduler=none -stack-size=1MB repro.go
wasm trap: out of bounds memory access (64 KiB linear stack overflow)

After (this PR):

$ tinygo run -target=wasip1 -scheduler=none -stack-size=1MB repro.go
0

[davecheney]

Do we need to gate this on the scheduler flag or can the linker flag be forwarded unconditionally?

[teamchong]

with asyncify, goroutine stacks (including main) are allocated on the heap using -stack-size, and wasm-ld's linear stack is only used by the scheduler loop — so passing -z stack-size to wasm-ld would reserve -stack-size a second time in static memory

with -scheduler=none, the whole program runs on wasm-ld's stack and -stack-size is otherwise ignored

happy to make it unconditional if you prefer though