From 904fed2d2e7125aef40bb43c4f25af9b9c00df65 Mon Sep 17 00:00:00 2001
From: Martin Odersky <odersky@gmail.com>
Date: Fri, 26 Jan 2018 16:56:41 +0100
Subject: [PATCH 1/2] Fix #746: Generate efficient try cases for parameterized
 exceptions

We were missing a case for AppliedType
---
 .../dotty/tools/dotc/transform/TryCatchPatterns.scala  |  2 ++
 tests/pos/i746.scala                                   | 10 ++++++++++
 2 files changed, 12 insertions(+)
 create mode 100644 tests/pos/i746.scala

diff --git a/compiler/src/dotty/tools/dotc/transform/TryCatchPatterns.scala b/compiler/src/dotty/tools/dotc/transform/TryCatchPatterns.scala
index a669dcb79843..eb4183167097 100644
--- a/compiler/src/dotty/tools/dotc/transform/TryCatchPatterns.scala
+++ b/compiler/src/dotty/tools/dotc/transform/TryCatchPatterns.scala
@@ -76,6 +76,8 @@ class TryCatchPatterns extends MiniPhase {
       (pre == NoPrefix || pre.widen.typeSymbol.isStatic) && // Does not require outer class check
       !tp.symbol.is(Flags.Trait) && // Traits not supported by JVM
       tp.derivesFrom(defn.ThrowableClass)
+    case tp: AppliedType =>
+      isSimpleThrowable(tp.tycon)
     case _ =>
       false
   }
diff --git a/tests/pos/i746.scala b/tests/pos/i746.scala
new file mode 100644
index 000000000000..c221cfc00e28
--- /dev/null
+++ b/tests/pos/i746.scala
@@ -0,0 +1,10 @@
+class Test[T] {
+
+  def f(x: Int) = try {
+    ???
+  }
+  catch {
+    case ex: scala.runtime.NonLocalReturnControl[T @scala.unchecked] =>
+      ???
+  }
+}

From 578b3341876b391f273840fa7af2dcdfdc5c3195 Mon Sep 17 00:00:00 2001
From: Allan Renucci <allan.renucci@gmail.com>
Date: Fri, 26 Jan 2018 19:30:08 +0100
Subject: [PATCH 2/2] Add bytecode test

---
 .../backend/jvm/DottyBytecodeTests.scala      | 28 +++++++++++++++++++
 tests/pos/i746.scala                          | 10 -------
 2 files changed, 28 insertions(+), 10 deletions(-)
 delete mode 100644 tests/pos/i746.scala

diff --git a/compiler/test/dotty/tools/backend/jvm/DottyBytecodeTests.scala b/compiler/test/dotty/tools/backend/jvm/DottyBytecodeTests.scala
index d288e26f1950..9f90bedf2598 100644
--- a/compiler/test/dotty/tools/backend/jvm/DottyBytecodeTests.scala
+++ b/compiler/test/dotty/tools/backend/jvm/DottyBytecodeTests.scala
@@ -3,6 +3,8 @@ package dotty.tools.backend.jvm
 import org.junit.Assert._
 import org.junit.Test
 
+import scala.tools.asm.Opcodes
+
 class TestBCode extends DottyBytecodeTest {
   import ASMConverters._
   @Test def nullChecks = {
@@ -213,4 +215,30 @@ class TestBCode extends DottyBytecodeTest {
       assert(!arrayWrapped, "Arrays should not be wrapped when passed to a Java varargs method\n")
     }
   }
+
+  @Test def efficientTryCases = {
+    val source =
+      """
+        |class Test {
+        |  def test =
+        |    try print("foo")
+        |    catch {
+        |      case _: scala.runtime.NonLocalReturnControl[_] => ()
+        |    }
+        |}
+      """.stripMargin
+
+    checkBCode(source) { dir =>
+      val moduleIn = dir.lookupName("Test.class", directory = false)
+      val moduleNode = loadClassNode(moduleIn.input)
+      val method = getMethod(moduleNode, "test")
+
+      val hasInstanceof = instructionsFromMethod(method).exists {
+        case TypeOp(Opcodes.INSTANCEOF, _) => true
+        case _ => false
+      }
+
+      assert(!hasInstanceof, "Try case should not issue INSTANCEOF opcode\n")
+    }
+  }
 }
diff --git a/tests/pos/i746.scala b/tests/pos/i746.scala
deleted file mode 100644
index c221cfc00e28..000000000000
--- a/tests/pos/i746.scala
+++ /dev/null
@@ -1,10 +0,0 @@
-class Test[T] {
-
-  def f(x: Int) = try {
-    ???
-  }
-  catch {
-    case ex: scala.runtime.NonLocalReturnControl[T @scala.unchecked] =>
-      ???
-  }
-}