Test named sha2_byte crashes during compliation

[joss-aztec]

Aim

Test named sha2_byte should compile

Expected Behavior

^

Bug

It appears to hang during the cfg flatten pass.

To Reproduce

Installation Method

None

Nargo Version

No response

Additional Context

No response

Would you like to submit a PR for this Issue?

No

Support Needs

No response

[TomAFrench]

Duplicate of #1259

[joss-aztec]

This issue is specifically tracking a bug in the SSA refactor. The new SSA hangs. The old SSA throws.

[joss-aztec]

Sorry, I tell a lie. It doesn't hang. But the error feedback definitely needs improving:

The application panicked (crashed).
Message:  assertion failed: index < array.len()
Location: crates/noirc_evaluator/src/ssa_refactor/ir/instruction.rs:294

[joss-aztec]

Also affects test named sha2_blocks

[ludamad]

This turns out to be related to #1756. This can be seen by removing the top half of the called sha function:

// SHA-256 hash function
fn digest<N>(msg: [u8; N]) -> [u8; 32] {
    let mut msg_block: [u8; 64] = [0; 64];
    let mut h: [u32; 8] = [1779033703,3144134277,1013904242,2773480762,1359893119,2600822924,528734635,1541459225]; // Intermediate hash, starting with the canonical initial value
    let mut c: [u32; 8] = [0; 8]; // Compression of current message block as sequence of u32
    let mut out_h: [u8; 32] = [0; 32]; // Digest as sequence of bytes
    let mut i = 0; // Message byte pointer

    for k in 0 .. msg.len() {
        // Populate msg_block
        msg_block[i] = msg[k];
        i = i + 1;
        if i == 64 { // Enough to hash block
            c = sha_c(msg_u8_to_u32(msg_block), h);
            for j in 0..8 {
                h[j] = c[j] + h[j];
            }
            
            i = 0;
        }
    }

    // Pad the rest such that we have a [u32; 2] block at the end representing the length
    // of the message, and a block of 1 0 ... 0 following the message (i.e. [1 << 7, 0, ..., 0]).
    msg_block[i] = 1 << 7;
    i = i + 1;


    out_h
}

Which gets the

Message:  internal error: entered unreachable code: Expected all allocate instructions to be removed before acir_gen
Location: crates/noirc_evaluator/src/ssa_refactor/acir_gen/mod.rs:258

error

[jfecher]

The original error is gone now but sha2_byte now crashes with:

The application panicked (crashed).
Message:  Vector::index_mut: index out of bounds
Location: /Users/.../.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/im-15.1.0/./src/vector/mod.rs:838