Optimisation difference between `!x` and `x == false`

[karwa]

Description

No response

Reproduction

for a in 0...Int8.max {
    for b in 0...Int8.max {
        let x = a.subtractingReportingOverflow(b).overflow
        precondition(!x)
    }
}

When written this way, the compiler knows that x is always false, and optimises away the entire loop. However, if I change the precondition to:

precondition(x == false)

Suddenly it seems unable to optimise this code. Both are compiled with -O.

Check it out on this Godbolt

Expected behavior

When x is a Bool, !x and x == false are equivalent, so I expect the optimiser to handle them equally well.

Environment

Swift version 5.9 (swift-5.9-RELEASE)
Target: x86_64-unknown-linux-gnu

Godbolt link provided above for trying this version of the compiler on this target.

Additional information

No response