This simplifies the calling convention and consolidates the call frame stack
and value stack into a single stack.
As a result, the cost of function calls decreases because we now don't need
to check the boundary twice (value and call frame stacks) at each function call.
The following is the result of the benchmark for recursive Fibonacci
function in integration_test/bench/testdata/case.go, and it shows that
this actually improves the performance of function calls.
[amd64]
name old time/op new time/op delta
Invocation/compiler/fib_for_5-32 109ns ± 3% 81ns ± 1% -25.86% (p=0.008 n=5+5)
Invocation/compiler/fib_for_10-32 556ns ± 3% 473ns ± 3% -14.99% (p=0.008 n=5+5)
Invocation/compiler/fib_for_20-32 61.4µs ± 2% 55.9µs ± 5% -8.98% (p=0.008 n=5+5)
Invocation/compiler/fib_for_30-32 7.41ms ± 3% 6.83ms ± 3% -7.90% (p=0.008 n=5+5)
[arm64]
name old time/op new time/op delta
Invocation/compiler/fib_for_5-10 67.7ns ± 1% 60.2ns ± 1% -11.12% (p=0.000 n=9+9)
Invocation/compiler/fib_for_10-10 487ns ± 1% 460ns ± 0% -5.56% (p=0.000 n=10+9)
Invocation/compiler/fib_for_20-10 58.0µs ± 1% 54.3µs ± 1% -6.38% (p=0.000 n=10+10)
Invocation/compiler/fib_for_30-10 7.12ms ± 1% 6.67ms ± 1% -6.31% (p=0.000 n=10+9)
Signed-off-by: Takeshi Yoneda <takeshi@tetrate.io>
This introduces wasm.CallEngine internal type, and assign it to the api.Function
implementations. api.Function.Call now uses that CallEngine assigned to it
to make function calls.
Internally, when creating CallEngine implementation, the compiler engine allocates
call frames and values stack. Previously, we allocate these stacks for each function calls,
which was a severe overhead as we can recognize in the benchmarks. As a result,
this reduces the memory usage (== reduces the GC jobs) as long as we reuse
the same api.Function multiple times.
As a side effect, now api.Function.Call is not goroutine-safe. So this adds the comment
about it on that method.
Signed-off-by: Takeshi Yoneda <takeshi@tetrate.io>
