Whenever interp hits an unreachable instruction, it bails out at that
point. However, it used to insert new instructions at the bottom with
the old init calls still at the top. So when a panic() happened in a
non-main package, the last packages to init would actually be called
first.
This commit fixes this by setting the insert point at the top of
runtime.initAll before starting interpretation, so the initialization
order is still correct when a panic() happens during init.
The interp package interprets calls in runtime.initAll and replaces
these calls with non-interpretable instructions if needed.
When hitting an unreachable instruction, this call should be removed,
but it wasn't. This commit makes sure the call is removed even before
trying to interpret the package init function.
Before this commit, goroutine support was spread through the compiler.
This commit changes this support, so that the compiler itself only
generates simple intrinsics and leaves the real support to a compiler
pass that runs as one of the TinyGo-specific optimization passes.
The biggest change, that was done together with the rewrite, was support
for goroutines in WebAssembly for JavaScript. The challenge in
JavaScript is that in general no blocking operations are allowed, which
means that programs that call time.Sleep() but do not start goroutines
also have to be scheduled by the scheduler.
This reduces complexity in the compiler without affecting binary sizes
too much.
Cortex-M0: no changes
Linux x64: no changes
WebAssembly: some testcases (calls, coroutines, map) are slightly bigger
This interpreter currently complements the Go SSA level interpreter. It
may stay complementary or may be the only interpreter in the future.
This interpreter is experimental and not yet finished (there are known
bugs!) so it is disabled by default. It can be enabled by passing the
-initinterp flag.
The goal is to be able to run all initializations at compile time except
for the ones having side effects. This mostly works except perhaps for a
few edge cases.
In the future, this interpeter may be used to actually run regular Go
code, perhaps in a shell.
