Function compute_cache_key

cranelift/codegen/src/incremental_cache.rs:165–187

Compute a cache key, and hash it on your behalf. Since computing the `CacheKey` is a bit expensive, it should be done as least as possible.

(isa: &dyn TargetIsa, func: &Function)

///
/// Since computing the `CacheKey` is a bit expensive, it should be done as least as possible.
pub fn compute_cache_key(isa: &dyn TargetIsa, func: &Function) -> CacheKeyHash {
    use core::hash::{Hash as _, Hasher};
    use sha2::Digest as _;

    struct Sha256Hasher(sha2::Sha256);

    impl Hasher for Sha256Hasher {
        fn finish(&self) -> u64 {
            panic!("Sha256Hasher doesn't support finish!");
        }
        fn write(&mut self, bytes: &[u8]) {
            self.0.update(bytes);
        }
    }

    let cache_key = CacheKey::new(isa, func);

    let mut hasher = Sha256Hasher(sha2::Sha256::new());
    cache_key.hash(&mut hasher);
    let hash: [u8; 32] = hasher.0.finalize().into();

    CacheKeyHash(hash)
}

/// Given a function that's been successfully compiled, serialize it to a blob that the caller may
/// store somewhere for future use by `try_finish_recompile`.