speed up --reduce-test

[alexlamsl]

• avoid pathological test case branches via adaptive time-out
• use initial test case elapsed time to adjust maximum time-out
• index output cache using hash instead of raw source

[kzc]

Good stuff.

XOR bug enthusiasts like me will save a lot of time. :-)

$ time bin/uglifyjs -c --reduce-test <<< 'var a=0;do{}while(a||(3^3));console.log(a);'
// reduce test pass 1, iteration 0: 44 bytes
// reduce test pass 1, iteration 25: 39 bytes
// reduce test pass 1: 24 bytes
// reduce test pass 2: 16 bytes
// reduce test pass 3: 16 bytes
do {
    0;
} while (3 ^ 3);
// output: 
// minify: Error: Script execution timed out.
// options: {
//   "compress": true,
//   "mangle": false
// }

real	0m11.011s
user	0m11.004s
sys	0m0.052s

Now that pathological cases have been dealt with, you might consider increasing the number of passes from 3 to 4 or higher so that the larger test cases like the one you pointed out earlier today could be further reduced. Perhaps test case minified size (> 250 bytes) and total run time (under 20 seconds) can be taken into account before running further passes.

[kzc]

Wait, never mind - that won't work... I didn't realize that Node 10 cannot reduce this test case further with more passes:
#3725 (comment)

[kzc]

It would be useful to tack on an extra comment at the end of the reduced test case showing the Node process.version needed to reproduce the problem.

[alexlamsl]

Grrr... need to update all those mocha tests for that extra line of comment 🤣