ufuzz failure

[alexlamsl]

// original code
// (beautified)
var _calls_ = 10, a = 100, b = 10, c = 0;

function f0() {
    (c = c + 1) + (--b + (0 === 1 ? a : b) || 7).toString()[a++];
    switch (b /= a) {
      case ((await, await_2, b_2) => (b_1 => {
            var b_2 = {
                foo: --b + !(({} + false) * (undefined === "c") / (22 & 23..toString() | /[a2][^e]+$/ ^ undefined)),
                1.5: /[abc4]/.test((+function b_2() {
                }() || b || 5).toString()),
                "": await && await.get
            }, await = (c = c + 1) + (b + 1 - .1 - .1 - .1);
            var bar_2 = {
                [-0 in {
                    then: (c = 1 + c, (-3 >> ([ , 0 ].length === 2)) - (-0 << {}) && 3 % undefined < (-1 & -2)),
                    next: (c = 1 + c, await && (await[b_1] = ((b_2 && (b_2[c = 1 + c, 
                    {} % 5 % ("" <= "object") >> ("a" + 3) * (-4 >= 23..toString())] = [ , 0 ].length === 2 ^ 3)) & !{}) >> (NaN && (NaN[c = 1 + c, 
                    0 % 22 > (-0 & 25) | (false - 3) % ("undefined" <= this)] = "number" - 23..toString())) - (true != "foo"))),
                    0: (c = 1 + c, (([] | this) >>> "number" + true) * +(b_2 = "b" && -1)),
                    NaN: (c = 1 + c, ((b_1 && (b_1[c = 1 + c, ((this | 25) <= ([ , 0 ].length === 2 == "object")) % ((this === -4) % (/[a2][^e]+$/ >= 5))] = undefined - -5)) >>> (22 << 38..toString())) - ((38..toString(), 
                    [ , 0 ].length === 2) >= ("" !== null)))
                }]: ~((0 || -4) & false != 0 || "b" >= /[a2][^e]+$/ ^ (await && (await.done += "" & [ , 0 ][1]))),
                "": --b + (typeof undefined_2 == "symbol"),
                3: {
                    "-2": (c = 1 + c, await_2 && (await_2.a += "" << ([ , 0 ].length === 2) >>> (null ^ "foo") && (Infinity ^ 5) & -0 == [ , 0 ][1])),
                    [(c = 1 + c, (true * [] > (c = c + 1, -1)) - ((b_1 && (b_1[c = 1 + c, 
                    ("undefined" == "b") >>> (NaN = [ , 0 ][1] == 2) >> (b_2 && (b_2[{
                        async: (c = 1 + c, ("" % "bar" & 1 - 2) / (("" === 22) / (-0 !== this))),
                        "\t": (c = 1 + c, ("" == "a") * ({} <= -1) % ((1 | "bar") % (-2 | {}))),
                        3: (c = 1 + c, c = c + 1, ("" >> -2) - (true >> "foo")),
                        get: (c = 1 + c, await && (await.NaN += 3 * 0 / ("c" == true) === (-3 || -1) > (-2 < "number"))),
                        length: (c = 1 + c, (38..toString() - /[a2][^e]+$/ ^ ([ , 0 ][1] ^ 22)) % ("" / 24..toString() << ("c" ^ 4)))
                    }.set] = -4 + 5 <= void true))] = this & null)) >= void "function"))]: (c = 1 + c, 
                    (5 > "b") - "bar" % "a" & "b" !== 25 !== (NaN && (NaN[c = 1 + c, 
                    this === 2 & (this, "bar"), 23..toString() > this === 2 - 4] /= 25 % 24..toString()))),
                    a: (c = 1 + c, (-1 ^ "bar" && true === -3) < (5 === "function") >> "" * [ , 0 ][1]),
                    set: (c = 1 + c, (await = (0 ^ 38..toString()) & (2 ^ "c")) >= (/[a2][^e]+$/ === -5) >> [] - -2)
                }
            }[a++], NaN = (c = c + 1) + function b_2_1() {};
        })())(a++ + [ --b + [ /[abc4]/g.exec((5 % "foo" + (24..toString() ^ 23..toString()) << (undefined % false || null <= "object") || b || 5).toString()) ] ][a++ + (typeof NaN_2 === "crap")], "b"):
        break;

      case (c = c + 1) + (a && a[a++ + (a && typeof a.a == "function" && --_calls_ >= 0 && a.a())]):
        return a++ + [ +function() {
            switch (a++ + (c = 1 + c, (-4 !== true) + "a" % /[a2][^e]+$/ | "number" + undefined + (true < -4))) {
              case --b + (a && typeof a.null == "function" && --_calls_ >= 0 && a.null(-1)):
                break;

              case a:
                c = 1 + c, 5 << this < ("number" !== "bar") | 3 >>> "function" << ("undefined" ^ [ , 0 ].length === 2);
                c = 1 + c, (a <<= null / undefined) - (c = c + 1, "function") > NaN + "foo" - (-5 - 24..toString());
                break;

              case delete ((5 <= {} != "function" >> 24..toString()) >= (-1 >= -0 >= 0 >>> 1)):
                c = 1 + c, a && (a[b = a] += (a += "" / 4 + ("a" + 25)) >>> (-0 / "a" <= NaN << -5));
                break;

              case {}.value:
                break;
            }
            try {
                {
                    var brake11 = 5;
                    do {
                        c = 1 + c, "number" === "bar" != (a += "" !== ([ , 0 ].length === 2)) && 24..toString() << [] ^ (/[a2][^e]+$/ | "");
                    } while ((c = 1 + c, (a && ({
                        1.5: a.next
                    } = {
                        1.5: (-3 ^ -4) <= (3 ^ -1)
                    })) ^ (a && (a[(c = 1 + c, ("" ^ "a", -4 < "undefined") << (([ , 0 ].length === 2 && -0) == 4 / [])) ? (c = 1 + c, 
                    (c = c + 1, 0 % 38..toString()) + ((3 | -3) << /[a2][^e]+$/ - -4)) : (c = 1 + c, 
                    delete (/[a2][^e]+$/ !== [ , 0 ][1]) !== [] >= "undefined" >= /[a2][^e]+$/ / "")] = ("number" <= "c") >>> [] / -3))) && --brake11 > 0);
                }
            } catch (bar) {
                c = 1 + c, "a" >> "c" >>> (NaN >= true) & false == 25 != (-2, 22);
                c = 1 + c, bar && (bar[b <<= a] %= ("function" - 38..toString() != 2 >> undefined) >= "b" * "c" + (NaN >> -3));
            }
        }(), (c = c + 1) + (--b + {
            length: --b + !((-1 & 38..toString()) != (NaN & -0) ^ (25 | -3 && "foo" | true)),
            value: typeof f2 == "function" && --_calls_ >= 0 && f2(),
            next: (c = c + 1) + 24..toString(),
            1.5: {
                ...a,
                value: (c = 1 + c, (NaN - -1 ^ 25 != 25) > (25 <= -1 > ("function" == /[a2][^e]+$/))),
                length: (c = 1 + c, ("" > 0) << (Infinity ^ 22) || null / -0 ^ "foo" > Infinity),
                done: (c = 1 + c, ("b" ^ "") == (null && -1) | (/[a2][^e]+$/ == true) % ("" | /[a2][^e]+$/)),
                in: (c = 1 + c, a = (null ^ Infinity) - ("function" == "number") | (false & "c") === 5 >> "a")
            }[c = 1 + c, (a && (a.var >>>= -0 + 2 > ("object" === 38..toString()))) >= ([] === -0 && (false || /[a2][^e]+$/))]
        } ? a++ + NaN : (c = c + 1) + {}), -0, --b + (a && typeof a.static == "function" && --_calls_ >= 0 && (--b + (typeof f2 == "function" && --_calls_ >= 0 && f2() || a || 3).toString(), 
        a.static)`tmpl${void setImmediate(() => a && typeof a.null == "function" && --_calls_ >= 0 && a.null(0, (c = 1 + c, 
        ("number" >= 4 && null >> false) == (22 << 0 ^ (3 | [])))))}${typeof a == "function" && --_calls_ >= 0 && a`${c = 1 + c, 
        +((false || 23..toString()) >> +24..toString())}${c = 1 + c, (a && (a.__proto__ += (25 && 24..toString()) < (25, 
        []))) - (c = c + 1, a && (a.value = -4 >= 1))}${c = 1 + c, (true != -4) / (a && (a[c = 1 + c, 
        (4 | NaN | (-5 && -3)) >> (a %= (c = c + 1, 4) >= ({} | null))] += "" !== Infinity)) * ((a && (a.foo += ("bar", 
        "c"))) < (-0 | Infinity))}`}${typeof a == "function" && --_calls_ >= 0 && a((c = 1 + c, 
        (a += "function" || {}) >>> (true && "c") | ("undefined" == "") << (/[a2][^e]+$/ != 23..toString())))}`), b-- ][--b + (typeof f1 == "function" && --_calls_ >= 0 && f1(typeof a == "function" && --_calls_ >= 0 && a(--b + (b += a)), a++ + (a && a.a), 3))];
        {
            var brake15 = 5;
            while ((--b + --b || a || 3).toString() && --brake15 > 0) {
                var expr16 = +b;
                for (var key16 in expr16) {
                    c = 1 + c;
                    var let_1 = expr16[key16];
                    var b_2;
                }
            }
        }
        break;

      default:
      case (c = c + 1) + a++:
        {
            {
                var brake19 = 5;
                while (--b + (typeof f2 == "function" && --_calls_ >= 0 && f2`\\${c = 1 + c, 
                ("a" > -3) / (NaN + true) != (a && (a.undefined = 23..toString() != "c" || false == "object"))}${a++ + this}`) && --brake19 > 0) {
                    {
                        var foo = function f1(c_1, let_1) {
                        }(0, [ , 0 ][1]);
                    }
                    {
                        return foo && typeof foo.in == "function" && --_calls_ >= 0 && foo.in("object");
                    }
                    {
                        var brake23 = 5;
                        while (/[abc4]/.test(((c = 1 + c, +23..toString() + (NaN > "undefined") >> (-3 / -2 < "function" * "object")) || b || 5).toString()) && --brake23 > 0) {
                            switch (c = 1 + c, ((NaN, {}) == ("number" ^ -2)) - (NaN >>> "" != ("a" === ""))) {
                              case c = 1 + c, +("" && -5) ^ (c = c + 1, undefined) >>> (24..toString() != 22):
                                ;
                                break;

                              case c = 1 + c, ((foo = -5 + []) & false >= 3) < (0 << 3 ^ [ , 0 ][1] != 23..toString()):
                                ;
                                break;

                              case c = 1 + c, 24..toString() >= 22 >= void true | + -1 >= (NaN == "number"):
                                ;
                                break;

                              case c = 1 + c, (foo && (foo.then -= 1 !== "b")) % ("undefined" + "number") | {} + "b" >>> (Infinity << 38..toString()):
                                ;
                                break;
                            }
                        }
                    }
                }
            }
            {
                return a++ + ++a;
            }
            try {
            } catch (arguments_1) {
                var b_2 = (c = c + 1) + (a++ || 5).toString()[arguments_1], bar_1 = --b + (b >>>= a);
                a++ + (arguments_1 = --b + !function() {
                }());
            }
        }
    }
}

var a_2 = f0(--b + /[abc4]/g.exec((--b + (typeof a == "function" && --_calls_ >= 0 && a([])) || b || 5).toString()), "function");

console.log(null, a, b, c, Infinity, NaN, undefined);

// uglified code
// (beautified)
var _calls_ = 10, a = 100, b = 10, c = 0;

function f0() {
    switch (c += 1, --b, b /= ++a) {
      case a++, --b, a++, t = {
            foo: --b + !0,
            1.5: /[abc4]/.test((b || 5).toString()),
            "": n && n.get
        }, n = (c += 1) + (b + 1 - .3), c = 1 + (c = 1 + c), n && (n[void 0] = (!1 & (t && (t[c = 1 + c, 
        0] = 2 === [ , 0 ].length ^ 3))) >> (e && (e[c = 1 + c, !1 | -3 % ("undefined" <= this)] = NaN)) - !0), 
        t = -1, c = 1 + (c = 1 + c), n && (n.done += 0), --b, c = 1 + (c = 1 + c), 
        c = 1 + (c += 1), e && (e[c = 1 + c, this < "23" === -2] /= 1), c = 1 + (c = 1 + c), 
        n = 2, a++, void (e = (c += 1) + function() {}):
        break;

      case (c += 1) + (a && a[a++ + (a && "function" == typeof a.a && 0 <= --_calls_ && a.a())]):
        return a++ + [ +function() {
            switch (a++ + (c = 1 + c, 0)) {
              case --b + (a && "function" == typeof a.null && 0 <= --_calls_ && a.null(-1)):
                break;

              case a:
                c = 1 + (c = 1 + c), a <<= NaN, c += 1;
                break;

              case !0:
                c = 1 + c, a && (a[b = a] += (a += "0a25") >>> !1);
            }
            try {
                for (var t = 5; c = 1 + (c = 1 + c), ((a += "" !== (2 === [ , 0 ].length)) && ({
                    1.5: a.next
                } = {
                    1.5: !1
                })) ^ (a && (a[c = 1 + c, !1 << ((2 === [ , 0 ].length && -0) == 1 / 0) ? (c = 1 + c, 
                c += 1, -1) : (c = 1 + c, !0)] = 0)) && 0 < --t; ) {}
            } catch (t) {
                c = 1 + (c = 1 + c), t && (t[b <<= a] %= !1);
            }
        }(), (c += 1) + (--b + {
            length: --b + !0,
            value: "function" == typeof f2 && 0 <= --_calls_ && f2(),
            next: (c += 1) + "24",
            1.5: {
                ...a,
                value: !1,
                length: 0,
                done: 0,
                in: (c = 1 + (c = 1 + (c = 1 + (c = 1 + c))), a = 0)
            }[c = 1 + c, !1 <= (a && (a.var >>>= !0))]
        } ? a++ + NaN : (c += 1) + {}), -0, --b + (a && "function" == typeof a.static && 0 <= --_calls_ && (--b, 
        ("function" == typeof f2 && 0 <= --_calls_ && f2() || a || 3).toString(), 
        a.static)`tmpl${void setImmediate(() => a && "function" == typeof a.null && 0 <= --_calls_ && a.null(0, (c = 1 + c, 
        !1)))}${"function" == typeof a && 0 <= --_calls_ && a`${c = 1 + c, 0}${c = 1 + c, 
        (a && (a.__proto__ += !1)) - (c += 1, a && (a.value = !1))}${c = 1 + c, 
        !0 / (a && (a[c = 1 + c, -3 >> (a %= (c += 1, !0))] += !0)) * ((a && (a.foo += "c")) < 0)}`}${"function" == typeof a && 0 <= --_calls_ && a((c = 1 + c, 
        (a += "function") >>> "c" | 0))}`), b-- ][--b + ("function" == typeof f1 && 0 <= --_calls_ && f1("function" == typeof a && 0 <= --_calls_ && a(--b + (b += a)), a++ + (a && a.a), 3))];

      default:
      case (c += 1) + a++:
        return --b, "function" == typeof f2 && 0 <= --_calls_ && f2`\\${c = 1 + c, 
        NaN != (a && (a.undefined = !0))}${a++ + this}`, a++ + ++a;
    }
    var t, n, e;
}

var a_2 = f0(--b + /[abc4]/g.exec((--b + ("function" == typeof a && 0 <= --_calls_ && a([])) || b || 5).toString()), "function");

console.log(null, a, b, c, 1 / 0, NaN, void 0);

original result:
null 106 -3.9306930693069306 16 Infinity NaN undefined

uglified result:
null 108 -3.9306930693069306 16 Infinity NaN undefined

// reduced test case (output will differ)

// (beautified)
var a = 0, c;

function f0() {
    switch (0) {
      case c:
      case a:
        var brake19 = 0;
        while (--brake19) {
            var foo;
            return foo;
        }
        return ++a;
    }
}

f0();

console.log(a);
// output: 0
// 
// minify: 1
// 
// options: {
//   "compress": {
//     "passes": 1000000,
//     "sequences": 1000000,
//     "unsafe": true,
//     "unsafe_Function": true,
//     "unsafe_math": true,
//     "unsafe_proto": true,
//     "unsafe_regexp": true
//   },
//   "mangle": {
//     "v8": true
//   },
//   "output": {
//     "v8": true
//   },
//   "validate": true
// }

minify(options):
{
  "compress": {
    "passes": 1000000,
    "sequences": 1000000,
    "unsafe": true,
    "unsafe_Function": true,
    "unsafe_math": true,
    "unsafe_proto": true,
    "unsafe_regexp": true
  },
  "mangle": {
    "v8": true
  },
  "output": {
    "v8": true
  }
}

Suspicious compress options:
  dead_code
  evaluate
  if_return
  loops
  passes
  reduce_vars