swift234

SILGenPattern: Destroy destructured subject rvalue before entering cases.

Before, we left the switch subject rvalue to be cleaned up at the close of the switch's scope. This is a bit wasteful because it keeps the rvalue live long after it's actually needed, and destroying the subject potentially requires replicating a bunch of destructuring we already do in the course of the pattern match. This patch changes things so that, just prior to entering a case, we clean up the destructured occurrence vector we have at the point of entering the case, which should be equivalent to but potentially more efficient than destroying the original subject rvalue.

Swift SVN r7814