swift234

SILGen: Copy blocks received as function arguments.

We want to generally treat blocks as heap objects until proven stack-able by escape analysis, like we do generally with other heap entities. The only place we should be exposed to stack blocks is when they're passed as arguments, so handle this by copy_block'ing any block arguments we get in the function prolog. Optimization can eliminate them when analysis shows the block doesn't escape or is already on the heap.

Swift SVN r16096