wasmtime main.rs with explicit panic! signals 4

From: Jesper Schmitz Mouridsen <jsm_at_FreeBSD.org>
Date: Sun, 03 Dec 2023 22:07:16 UTC
Hi

Just a note *perhaps* related to Firefox crashing with signal 4 [1]
This is really a **perhaps** because I have no clue, but an explicit 
panic from rust in wasm32-wasi causes a signal 4 crash only on arm64 as 
opposed to amd64.. FWIW:
main.rs

fn main()  {
panic!();
}

rustc --target wasm32-wasi main.rs (on linux)

wasmtime [2] main.wasm gives on arm64

explicit panic
note: run with `RUST_BACKTRACE=1` environment variable to display a 
backtrace
Illegal instruction (core dumped)

and on amd64
thread 'main' panicked at main.rs:2:1:
explicit panic
note: run with `RUST_BACKTRACE=1` environment variable to display a 
backtrace
Error: failed to run main module `main.wasm`

Caused by:
     0: failed to invoke command default
     1: error while executing at wasm backtrace:
            0: 0x4a16 - <unknown>!__rust_start_panic
            1: 0x485a - <unknown>!rust_panic
            2: 0x478d - 
<unknown>!std::panicking::rust_panic_with_hook::h639672e96e0f2421
            3:  0x41c - 
<unknown>!std::panicking::begin_panic::{{closure}}::heb5f2434a371507e
            4:  0x37a - 
<unknown>!std::sys_common::backtrace::__rust_end_short_backtrace::hd6c4b8ac380c74ed
            5:  0x5b8 - 
<unknown>!std::panicking::begin_panic::h00c5404b50e70c31
            6:  0xb48 - <unknown>!main::main::hd80a274883898d96
            7:  0x451 - 
<unknown>!core::ops::function::FnOnce::call_once::hc7ab48c327164eaa
            8:  0x428 - 
<unknown>!std::sys_common::backtrace::__rust_begin_short_backtrace::h00cde78d9b3ae99b
            9:  0x509 - 
<unknown>!std::rt::lang_start::{{closure}}::hecd871948b8b4e5c
           10: 0x22ce - 
<unknown>!std::rt::lang_start_internal::h409072ad2c29d9a2
           11:  0x4b4 - <unknown>!std::rt::lang_start::hf51f2ca32a721dea
           12:  0xb6c - <unknown>!__main_void
           13:  0x2ba - <unknown>!_start
        note: using the `WASMTIME_BACKTRACE_DETAILS=1` environment 
variable may show more debugging information
     2: wasm trap: wasm `unreachable` instruction executed


1
https://lists.freebsd.org/archives/freebsd-arm/2023-December/003323.html
2
https://github.com/bytecodealliance/wasmtime.git