Mem2reg block parameter aliases handled incorrectly

[jfecher]

Aim

unconstrained fn main(mut x: i32) {
    mutate_alias(&mut x, &mut x);
    assert_eq(x, 1);
}

unconstrained fn mutate_alias(x: &mut i32, y: &mut i32) {
    *x = 0;
    *y = 1;
    assert_eq(*x, 1);
}

Expected Behavior

The test to pass

Bug

Test fails because we wrongly optimize the assert_eq(*x, 1) to assert_eq(0, 1), wrongly assuming that x can't be aliased to y.

To fix this, parameters should be pessimistically assumed to be aliases to all other parameters.

To Reproduce

Workaround

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Workaround Description

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Additional Context

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Project Impact

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Blocker Context

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Proving Backend Tooling & Version

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