- Extract all backend codegen tests that specifically target behaviour
in to-be-deprecated functionality from language versions < 1.3"
- Remove those tests from the JVM IR test suite.
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.
See `ExpressionCodegen.genEqualsForExpressionsPreferIeee754Arithmetic`:
the behavior here actually depends on the API version, not any language
feature
NB we use 'Intrinsics.areEqual(Double, Double)' and
'Intrinsics.areEqual(Float, Float)', because right now we take
nullability from the inferred type of the expression (which is 'Any?' in
the test cases).
We should probably reconsider this in case of more exact information
available from the data flow analysis, e.g., in case of
fun test(x: Any?) =
x is Serializable && x is Double? && x == 0.0
We statically know that 'x' is not null in 'x == 0.0' (although it's
neither nullability of it's numeric type 'Double?' nor the nullability
of the inferred type 'Any?').
There might be some edge effects in the performance related to byte code
size and preventive unboxing and so on.
