Code Analysis and optimization

[Zomis]

First of all, remember that the only thing that can change a Brainfuck program behavior is user-input, with the , Brainfuck command.

• [x] Scan for how many times loops are executed. Find out if some loops are only executed specific number of times, possibly expand them.

• [x] Avoid taking unnecessary turns, for example:

  right 2 minus 1 left 1 inc 1 right 1

  which equals to >>-<+> can become simply >+>-

• [x] Track which memory positions are used or not

Optimize some things for speed (number of instructions being performed when running), optimize some things for code compactness.

[Zomis]

See https://github.com/Zomis/BrainDuck/commit/b5ee5ecaee01a41697b408821e8ba89aa1cc151c and a couple of parent commits for optimizations and the reasoning behind them

[Zomis]

Also see https://github.com/Zomis/BrainDuck/commit/3e84dcb1da27b8380e6ba343f4a9cbdd9fc7b429 and http://codegolf.stackexchange.com/questions/16732/minify-brainfuck

[Zomis]

About >>-<+> which can become simply >+>-:

Reset the check after each [ ] . ,, when one of those characters come up, analyse the recent > < + - characters and see if the effect caused by those characters can be achieved in a better way.

For example, >>-<+> results in the integer array [ 0, 1, -1 ] and the offset 2 (meaning that we have moved 2 steps to the right after the sequence has been performed). The shortest way to accomplish the same integer array is clearly to do >+>-.

The reason to not include [ ] in the check is because that is a conditional check, and needs a loop-analyse before any conclusions can be drawn about whether or not it will always be performed a specific number of times or not. Possibly include those in the analyse at a later time.