swift234

SILGen: Peephole lvalue-to-lvalue initializations as copy_addrs.

If we're using emitExprInto to emit a LoadExpr, we can handle that by emitting a copy_addr from the underlying lvalue to the initialization instead of building and storing the rvalue, which plays better with the direction we're taking for value semantics optimizations.

This is currently guarded behind a flag -enable-silgen-lvalue-peepholes because it introduces a miscompile in the stdlib that crashes some tests; requires further investigation before making live.

Swift SVN r9027