JVM_IR: Do not add redundant field initializers.

Initializers are "set field" expressions and are considered redundant when they are: 1. In the primary constructor; and 2. Set the field to `0`, `false`, or `null`; and 3. Have a `null` origin. I.e., not in an initializer block or constructor body, and therefore the field could not have been set by a prior expression.
2019-01-30 16:18:59 -08:00
parent 9e8972f1f9
commit e91a16556c
4 changed files with 149 additions and 1 deletions
@@ -0,0 +1,94 @@
+// No initializers for this class because the fields/properties are initialized to defaults.
+class RedundantInitializersToDefault {
+    companion object {
+        // Constants
+        const val constInt: Int = 0
+        const val constByte: Byte = 0
+        const val constLong: Long = 0L
+        const val constShort: Short = 0
+        const val constDouble: Double = 0.0
+        const val constFloat: Float = 0.0f
+        const val constBoolean: Boolean = false
+        const val constChar: Char = '\u0000'
+    }
+
+    // Properties
+
+    val myIntPropFromConst: Int = constInt
+    val myBytePropFromConst: Byte = constByte
+    val myLongPropFromConst: Long = constLong
+    val myShortPropFromConst: Short = constShort
+    val myDoublePropFromConst: Double = constDouble
+    val myFloatPropFromConst: Float = constFloat
+    val myBooleanPropFromConst: Boolean = constBoolean
+    val myCharPropFromConst: Char = constChar
+
+    val myIntProp: Int = 0
+    val myByteProp: Byte = 0
+    val myLongProp: Long = 0L
+    val myShortProp: Short = 0
+    val myDoubleProp: Double = 0.0
+    val myFloatProp: Float = 0.0f
+    val myBooleanProp: Boolean = false
+    val myCharProp: Char = '\u0000'
+
+    val myStringProp: String? = null
+    val myAnyProp: Any? = null
+    val myObjectProp: java.lang.Object? = null
+    val myIntegerProp: java.lang.Integer? = null
+
+    // Fields
+
+    @JvmField
+    val myIntFieldFromConst: Int = constInt
+    @JvmField
+    val myByteFieldFromConst: Byte = constByte
+    @JvmField
+    val myLongFieldFromConst: Long = constLong
+    @JvmField
+    val myShortFieldFromConst: Short = constShort
+    @JvmField
+    val myDoubleFieldFromConst: Double = constDouble
+    @JvmField
+    val myFloatFieldFromConst: Float = constFloat
+    @JvmField
+    val myBooleanFieldFromConst: Boolean = constBoolean
+    @JvmField
+    val myCharFieldFromConst: Char = constChar
+
+    @JvmField
+    val myIntField: Int = 0
+    @JvmField
+    val myByteField: Byte = 0
+    @JvmField
+    val myLongField: Long = 0L
+    @JvmField
+    val myShortField: Short = 0
+    @JvmField
+    val myDoubleField: Double = 0.0
+    @JvmField
+    val myFloatField: Float = 0.0f
+    @JvmField
+    val myBooleanField: Boolean = false
+    @JvmField
+    val myCharField: Char = '\u0000'
+
+    @JvmField
+    val myStringField: String? = null
+    @JvmField
+    val myAnyField: Any? = null
+    @JvmField
+    val myObjectField: java.lang.Object? = null
+    @JvmField
+    val myIntegerField: java.lang.Integer? = null
+}
+
+class NonRedundantInitializers {
+    // NOT redundant because the JVM's default values for floating-point types are positive 0.0.
+    // See: https://docs.oracle.com/javase/specs/jvms/se8/html/jvms-2.html#jvms-2.3
+    val myDouble: Double = -0.0
+    val myFloat: Float = -0.0f
+}
+
+// 0 PUTFIELD RedundantInitializersToDefault
+// 2 PUTFIELD NonRedundantInitializers