Merge pull request #2169 from JamesIry/master_SI-7181

SI-7181 Eliminate unnecessary duplicates of finally blocks

2 files changed, 50 insertions, 0 deletions

diff --git a/test/files/jvm/t7181/Foo_1.scala b/test/files/jvm/t7181/Foo_1.scala
new file mode 100644
index 0000000000..f9dfdd4442
--- /dev/null
+++ b/test/files/jvm/t7181/Foo_1.scala
@@ -0,0 +1,26 @@
+class Exception1 extends RuntimeException
+class Exception2 extends RuntimeException
+
+class Foo_1 {
+  def foo(baz: Baz) {
+    try {
+      baz.bar
+    } catch {
+      case _: Exception1 => println("exception 1")
+      case _: Exception2 => println("exception 2")
+    } finally {
+      // this should be the only copy of the magic constant 3
+      // making it easy to detect copies of this finally block
+      println(s"finally ${3}")
+    }
+    println(s"normal flow")
+  }
+}
+
+trait Baz {
+  // does it throw? who knows? This way
+  // I can ensure that no optimization that honors
+  // separate compilation could ever
+  // change the exception handling structure
+  def bar: Unit
+}
diff --git a/test/files/jvm/t7181/Test.scala b/test/files/jvm/t7181/Test.scala
new file mode 100644
index 0000000000..35dba436c1
--- /dev/null
+++ b/test/files/jvm/t7181/Test.scala
@@ -0,0 +1,24 @@
+import scala.tools.partest.BytecodeTest
+import scala.tools.asm
+import asm.tree.InsnList
+import scala.collection.JavaConverters._
+
+object Test extends BytecodeTest {
+  def show: Unit = {
+    val classNode = loadClassNode("Foo_1")
+    val methodNode = getMethod(classNode, "foo")
+    // there should be 2 copies of the finally block, each with the magic constant 3
+    // one for the "normal" exit
+    // one for the uncaught exception exit
+    // prior to this PR there would have been 4 since each exception handler would also get a copy
+    val expected = 2
+    val got = countMagicThrees(methodNode.instructions)
+    assert(got == expected, s"expected $expected but got $got magic threes")
+  }
+
+  def countMagicThrees(insnList: InsnList): Int = {
+    def isMagicThree(node: asm.tree.AbstractInsnNode): Boolean =
+      (node.getOpcode == asm.Opcodes.ICONST_3)
+    insnList.iterator.asScala.count(isMagicThree)
+  }
+}