Introduce lowering to remove null checks for primitive type
expressions and replace them with true/false. Side-effects
are preserved.
Generate ifnull/ifnonnull instructions for null checks instead
of materializing a null literal for an equality check.
This proved to be a fragile technique, which probably doesn't even improve
performance in most cases but has lots of unexpected problems: unconditional
initialization of reflection classes, increasing the size of the bytecode, bugs
with <clinit> in annotations on JVM 6, inability to support conversion of a
class from Kotlin to Java without recompiling clients which use it
reflectively, etc.
Mads Ager