Array copy optimization

[charles-cooper]

What I did

Optimize compiler-generated array copies. Depends on #1479 because of a conflict

How I did it

Remove bounds checks for when a loop is compiler-generated.

How to verify it

Check before/after IR for this contract

BIG_VALUE: constant(uint256) = 100

@public
def do_work(a: uint256[BIG_VALUE]):
    assert self != msg.sender

@public
def do_something(a: uint256[BIG_VALUE]):
    self.do_work(a)

Description for the changelog

Optimize compiler-generated array copies

Cute Animal Picture

[jacqueswww]

@charles-cooper I am not sure the description matches the code?
ie. where is the array copy optimisation?

[charles-cooper]

@jacqueswww I force pushed so the diff is cleaner now. The array bounds check is elided in the make_setter loop now, so instead of

for (i = 0; i < len; i++) {
  dst[uclamplt(i, len)] = src[uclamplt(i, len)]
}

it is now effectively

for (i = 0; i < len; i++) {
  dst[i] = src[i]
}