Similarly to previous commit, this method was unused since its
introduction before 1.0, so we're changing its semantics to throw NPE
and starting to use it with API version >= 1.4.
#KT-22275 In Progress
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
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.
KT-16194 Code with unnecessary safe call contains redundant boxing/unboxing for primitive values
KT-12839 Two null checks are generated when manually null checking platform type
Recognize some additional cases of trivial null checks and trivial instance-of checks.
A variable is "checked for null", if it is:
- a function parameter checked with 'INVOKESTATIC kotlin/jvm/internal/Intrinsics.checkParameterIsNotNull'
- checked for nullability with 'IFNULL/IFNONNULL'
- checked for nullability with 'INSTANCEOF'
(if objectref is instance-of T, then objectref is non-null)
Before analyzing nullability, introduce synthetic assumptions for execution branches
where a variable is guaranteed to be null or not null. For example, the following bytecode:
ALOAD 1 // Ljava/lang/String;
IFNULL L
<non-null branch>
L:
<null branch>
is transformed to
ALOAD 1
IFNULL L1
NEW java/lang/String
ASTORE 1 // tells analyzer that variable 1 is non-null
<non-null branch>
L:
<null branch>
L1:
ACONST_NULL
ASTORE 1 // tells analyzer that variable 1 is null
GOTO L
After the analysis is performed on a preprocessed method,
remember the results for "interesting" instructions
and revert the preprocessing transformations.
After that, perform bytecode transformations as usual.
Do not transform INSTANCEOF to-be-reified, because reification at call site
can introduce null checks. E.g.,
inline fun <reified T> isNullable() = null is T
...
assert(isNullable<String?>())
