Function reduce

cranelift/src/bugpoint.rs:807–907

(isa: &dyn TargetIsa, mut func: Function, verbose: bool)

}

fn reduce(isa: &dyn TargetIsa, mut func: Function, verbose: bool) -> Result<(Function, String)> {
    let mut context = CrashCheckContext::new(isa);

    if let CheckResult::Succeed = context.check_for_crash(&func) {
        anyhow::bail!("Given function compiled successfully or gave a verifier error.");
    }

    try_resolve_aliases(&mut context, &mut func);
    try_remove_srclocs(&mut context, &mut func);

    for pass_idx in 0..100 {
        let mut should_keep_reducing = false;
        let mut phase = 0;

        loop {
            let mut mutator: Box<dyn Mutator> = match phase {
                0 => Box::new(RemoveInst::new(&func)),
                1 => Box::new(ReplaceInstWithConst::new(&func)),
                2 => Box::new(ReplaceInstWithTrap::new(&func)),
                3 => Box::new(MoveInstToEntryBlock::new(&func)),
                4 => Box::new(RemoveBlock::new(&func)),
                5 => Box::new(ReplaceBlockParamWithConst::new(&func)),
                6 => Box::new(RemoveUnusedEntities::new()),
                7 => Box::new(MergeBlocks::new(&func)),
                _ => break,
            };

            println!("pass {} phase {}", pass_idx, mutator.name());

            for _ in 0..10000 {
                let (mutated_func, msg, mutation_kind) = match mutator.mutate(func.clone()) {
                    Some(res) => res,
                    None => {
                        break;
                    }
                };

                if let ProgressStatus::Skip = mutation_kind {
                    // The mutator didn't change anything, but we want to try more mutator
                    // iterations.
                    continue;
                }

                match context.check_for_crash(&mutated_func) {
                    CheckResult::Succeed => {
                        // Mutating didn't hit the problem anymore, discard changes.
                        continue;
                    }
                    CheckResult::Crash(_) => {
                        // Panic remained while mutating, make changes definitive.
                        func = mutated_func;

                        // Notify the mutator that the mutation was successful.
                        mutator.did_crash();

                        let verb = match mutation_kind {
                            ProgressStatus::ExpandedOrShrinked => {
                                should_keep_reducing = true;