Fixed a bug in the optimizer which was preventi...

Fixed a bug in the optimizer which was preventing private methods from
being inlined. Also relaxes a condition related to the "liftedTry"
problem: the inliner has to exclude certain methods from consideration
if there is a value on the stack and the method being inlined has
exception handlers. The new condition is as before, except that it does
not exclude methods of the "try/finally" variety (i.e. finalizers, but
no other exception handlers.) This is necessary to optimize this common
pattern:

  @inline private def foo(body: => Unit) {
    val saved = something
    try body
    finally something = saved
  }

The closure for "body" can be fully eliminated, but only if the contents
of foo can be inlined into the caller.

Closes #4764, review by rompf.

1 files changed, 52 insertions, 0 deletions

diff --git a/test/files/run/private-inline.scala b/test/files/run/private-inline.scala
new file mode 100644
index 0000000000..5181ac8ba3
--- /dev/null
+++ b/test/files/run/private-inline.scala
@@ -0,0 +1,52 @@
+
+final class A {
+  private var x1 = false
+  var x2 = false
+
+  // manipulates private var
+  @inline private def wrapper1[T](body: => T): T = {
+    val saved = x1
+    x1 = true
+    try body
+    finally x1 = saved
+  }
+  // manipulates public var
+  @inline private def wrapper2[T](body: => T): T = {
+    val saved = x2
+    x2 = true
+    try body
+    finally x2 = saved
+  }
+
+  // not inlined
+  def f1a() = wrapper1(5)
+  // inlined!
+  def f1b() = identity(wrapper1(5))
+
+  // not inlined
+  def f2a() = wrapper2(5)
+  // inlined!
+  def f2b() = identity(wrapper2(5))
+}
+
+object Test {
+  def methodClasses = List("f1a", "f1b", "f2a", "f2b") map ("A$$anonfun$" + _ + "$1")
+
+  def main(args: Array[String]): Unit = {
+    val a = new A
+    import a._
+    println(f1a() + f1b() + f2a() + f2b())
+
+    // Don't know how else to test this: all these should have been
+    // inlined, so all should fail.
+    methodClasses foreach { clazz =>
+
+      val foundClass = (
+        try   Class.forName(clazz)
+        catch { case _ => null }
+      )
+
+      assert(foundClass == null, foundClass)
+    }
+  }
+}