This method was introduced in c204e8fc67 "just in case" and was never
used. Therefore we're free to change its semantics and use it in all new
generated code (with API version >= 1.4), without even worrying that the
newly used API will leak from inline functions in stdlib when used with
an older API version. Since we agreed to change the type of thrown
exceptions to java.lang.NPE in KT-22275, invoke a new method
throwJavaNpe now which throws that exception instead of KNPE.
Note that the additional method that takes an exception message is still
unused and exists just in case we need to use it in the future. The new
method throwJavaNpe is public also "just in case" we need to invoke it
in the future; currently it's not invoked from the bytecode.
#KT-22275 In Progress
Simplify ifs when branches have condition true/false.
Simplify blocks containing only a variable declaration
and a variable get of the same variable. Simplify to
just the condition.
Do not introduce temporary variables for constants for
null checks. Constants have no side-effects and can be
reloaded freely instead of going through a local.
This simplifies code such as "42.toLong()!!" so that the
resulting code has no branches and uses no locals. The
simplifications happen as follows:
```
block
temp = 42.toLong()
when
(temp == null) throw NPE
(true) load temp
---> null test simplification
block
temp = 42.toLong()
when
(false) throw NPE
(true) load temp
---> when simplification
block
temp = 42.toLong()
load temp
---> block simplification
42.toLong()
```
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.
