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Diffstat (limited to 'test/files/jvm/bytecode-test-example/Test.scala')
-rw-r--r-- | test/files/jvm/bytecode-test-example/Test.scala | 32 |
1 files changed, 32 insertions, 0 deletions
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) + } +} |