Add option to disable optimization

By default we run par test under -optimise. But occasionally we need
to test optimizations in isolation. This commit adds a Ynooptimise
flag that turns the optimize flags off back off after they've been
turned on.

A test is included to ensure that -Ynooptimise turns off optimizations
and an existing test is modified to show that optimizations coming
after -Ynooptimise in command line are enabled.

1 files changed, 23 insertions, 0 deletions

diff --git a/test/files/jvm/nooptimise/Test.scala b/test/files/jvm/nooptimise/Test.scala
new file mode 100644
index 0000000000..ec8daa6e16
--- /dev/null
+++ b/test/files/jvm/nooptimise/Test.scala
@@ -0,0 +1,23 @@
+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")
+    // if optimization didn't run then
+    // there should be some useless instructions 
+    // with the magic constant 3
+    val expected = 1
+    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)
+  }
+}