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//! Tuning Wasmtime for fast Wasm execution.
use wasmtime::{Config, Engine, Result, Strategy};
fn main() -> Result<()> {
let mut config = Config::new();
// Enable the Cranelift optimizing compiler.
config.strategy(Strategy::Cranelift);
// Enable signals-based traps. This is required to elide explicit
// bounds-checking.
config.signals_based_traps(true);
// Configure linear memories such that explicit bounds-checking can be
// elided.
config.memory_reservation(1 << 32);
config.memory_guard_size(1 << 32);
if CROSS_COMPILING {
// When cross-compiling, force-enable various ISA extensions.
//
// Warning: it is wildly unsafe to run a pre-compiled Wasm program that
// enabled a particular ISA extension on a machine that does not
// actually support that ISA extension!!!
unsafe {
if let Err(error) = config.target("x86_64") {
eprintln!(
"Wasmtime was not compiled with the x86_64 backend for \
Cranelift enabled: {error:?}",
);
return Ok(());
}
config.cranelift_flag_enable("has_sse41");
config.cranelift_flag_enable("has_avx");
config.cranelift_flag_enable("has_avx2");
config.cranelift_flag_enable("has_lzcnt");
}
}
// Build an `Engine` with our `Config` that is tuned for fast Wasm
// execution.
let engine = match Engine::new(&config) {
Ok(engine) => engine,
Err(error) => {
eprintln!("Configuration is incompatible with this host platform: {error:?}");
return Ok(());
}
};
// Now we can use `engine` to compile and/or run some Wasm programs...
let _ = engine;
Ok(())
}
const CROSS_COMPILING: bool = false;