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-rw-r--r--test/files/jvm/bytecode-test-example/Foo_1.scala9
-rw-r--r--test/files/jvm/bytecode-test-example/Test.scala32
2 files changed, 41 insertions, 0 deletions
diff --git a/test/files/jvm/bytecode-test-example/Foo_1.scala b/test/files/jvm/bytecode-test-example/Foo_1.scala
new file mode 100644
index 0000000000..4f679d156f
--- /dev/null
+++ b/test/files/jvm/bytecode-test-example/Foo_1.scala
@@ -0,0 +1,9 @@
+class Foo_1 {
+ def foo(x: AnyRef): Int = {
+ val bool = x == null
+ if (x != null)
+ 1
+ else
+ 0
+ }
+}
diff --git a/test/files/jvm/bytecode-test-example/Test.scala b/test/files/jvm/bytecode-test-example/Test.scala
new file mode 100644
index 0000000000..d668059cb7
--- /dev/null
+++ b/test/files/jvm/bytecode-test-example/Test.scala
@@ -0,0 +1,32 @@
+import scala.tools.partest.BytecodeTest
+
+import scala.tools.nsc.util.JavaClassPath
+import java.io.InputStream
+import scala.tools.asm
+import asm.ClassReader
+import asm.tree.{ClassNode, InsnList}
+import scala.collection.JavaConverters._
+
+object Test extends BytecodeTest {
+ def show: Unit = {
+ val classNode = loadClassNode("Foo_1")
+ val methodNode = getMethod(classNode, "foo")
+ println(countNullChecks(methodNode.instructions))
+ }
+
+ def countNullChecks(insnList: InsnList): Int = {
+ /** Is given instruction a null check?
+ * NOTE
+ * This will detect direct null compparsion as in
+ * if (x == null) ...
+ * and not indirect as in
+ * val foo = null
+ * if (x == foo) ...
+ */
+ def isNullCheck(node: asm.tree.AbstractInsnNode): Boolean = {
+ val opcode = node.getOpcode
+ (opcode == asm.Opcodes.IFNULL) || (opcode == asm.Opcodes.IFNONNULL)
+ }
+ insnList.iterator.asScala.count(isNullCheck)
+ }
+}