Constant folding doesn't update result value references

[joss-aztec]

Aim

To compile the test named sha256

use dep::std;

fn main(x: Field, result: [u8; 32]) {
    let digest = std::hash::sha256([x as u8]);
    assert(digest == result);
}

Expected Behavior

It compiles

Bug

Compile crashes with output (I've modified the printer to include instruction ids):

After Mem2Reg:
fn main f1 {
  b0(v0: Field, v1: [u8; 32]):
    v2 = (Id(0))cast v0 as u8
    v5 = (Id(1))call sha256([v2])
    v6 = (Id(2))eq v5, v1
    constrain v6
    return unit 0
}

After Constant Folding:
fn main f1 {
  b0(v0: Field, v1: [u8; 32]):
    v8 = (Id(4))cast v0 as u8
    v9 = (Id(5))call sha256([v2])
    v10 = (Id(6))eq v9, v1
    constrain v10
    return unit 0
}

The application panicked (crashed).
Message:  internal error: entered unreachable code: ICE: Should have been in cache Instruction { instruction: Id(0), position: 0, typ: Numeric(Unsigned { bit_size: 8 }) }
Location: crates/noirc_evaluator/src/ssa_refactor/acir_gen/mod.rs:345

Notice that during constant folding instruction Id(0) doesn't exist, but it did in mem2reg.

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

[joss-aztec]

Tests that are likely failing because of this:

• simple_shield
• sha256

[joss-aztec]

Test named keccak256 also affected