Fixed Issue 5321

2 files changed, 177 insertions, 0 deletions

diff --git a/test/files/run/test-cpp.check b/test/files/run/test-cpp.check
new file mode 100644
index 0000000000..40a976119f
--- /dev/null
+++ b/test/files/run/test-cpp.check
@@ -0,0 +1,73 @@
+37c37
+<   locals: value args, value x, value y
+---
+>   locals: value args
+42,43d41
+<     52	CONSTANT(2)
+<     52	STORE_LOCAL(value x)
+45,46d42
+<     53	LOAD_LOCAL(value x)
+<     53	STORE_LOCAL(value y)
+49c45
+<     54	LOAD_LOCAL(value y)
+---
+>     54	CONSTANT(2)
+92c88
+<   locals: value args, value x, value y
+---
+>   locals: value args, value x
+101,102d96
+<     82	LOAD_LOCAL(value x)
+<     82	STORE_LOCAL(value y)
+105c99
+<     83	LOAD_LOCAL(value y)
+---
+>     83	LOAD_LOCAL(value x)
+135c129
+<   locals: value args, value x, value y
+---
+>   locals: value args
+140,141d133
+<     66	THIS(TestAliasChainDerefThis)
+<     66	STORE_LOCAL(value x)
+143,144d134
+<     67	LOAD_LOCAL(value x)
+<     67	STORE_LOCAL(value y)
+147c137
+<     68	LOAD_LOCAL(value y)
+---
+>     68	THIS(Object)
+176c166
+<   locals: value x, value y
+---
+>   locals: value x
+181,182d170
+<     29	LOAD_LOCAL(value x)
+<     29	STORE_LOCAL(value y)
+185c173
+<     30	LOAD_LOCAL(value y)
+---
+>     30	LOAD_LOCAL(value x)
+223,224d210
+<     97	LOAD_LOCAL(variable x)
+<     97	STORE_LOCAL(variable y)
+227c213
+<     98	LOAD_LOCAL(variable y)
+---
+>     98	LOAD_LOCAL(variable x)
+233,234d218
+<     101	LOAD_LOCAL(variable y)
+<     101	STORE_LOCAL(variable x)
+236c220
+<     102	LOAD_LOCAL(variable x)
+---
+>     102	LOAD_LOCAL(variable y)
+345c329
+<     41	THIS(TestSetterInline)
+---
+>     41	THIS(Object)
+347c331
+<     41	CALL_METHOD TestSetterInline._postSetHook_$eq (static-instance)
+---
+>     41	STORE_FIELD variable _postSetHook (dynamic)
+
diff --git a/test/files/run/test-cpp.scala b/test/files/run/test-cpp.scala
new file mode 100644
index 0000000000..5b3bc7b746
--- /dev/null
+++ b/test/files/run/test-cpp.scala
@@ -0,0 +1,104 @@
+/**
+ * The only change is in the decision to replace a LOAD_LOCAL(l)
+ * in the copy-propagation performed before ClosureElimination.
+ *
+ * In the general case, the local variable 'l' is connected through
+ * a alias chain with other local variables and at the end of the 
+ * alias chain there may be a Value, call it 'v'.
+ *
+ * If 'v' is cheaper to access (it is a Deref(This) or Const(_)), then
+ * replace the instruction to load it from the cheaper place. 
+ * Otherwise, we use the local variable at the end of the alias chain
+ * instead of 'l'.
+ */
+
+import scala.tools.partest.IcodeTest
+
+object Test extends IcodeTest {
+  override def printIcodeAfterPhase = "dce"
+}
+
+import scala.util.Random._
+
+/** 
+ * The example in the bug report (Issue-5321): an alias chain which store 
+ * an Unknown. Should remove local variable 'y'.
+ */
+object TestBugReport {
+  def test(x: Int) = {
+    val y = x
+    println(y)
+  }
+}
+
+/**
+ * The code taken from scala.tools.nsc.settings.Settings:
+ * After inlining of the setter is performed, there is an opportunity for
+ * copy-propagation to eliminate some local variables.
+ */
+object TestSetterInline {
+  private var _postSetHook: this.type => Unit = (x: this.type) => ()
+  def withPostSetHook(f: this.type => Unit): this.type = { _postSetHook = f ; this }
+}
+
+
+/** 
+ * The access of the local variable 'y' should be replaced by the
+ * constant.
+ */ 
+object TestAliasChainConstat {
+
+  def main(args: Array[String]): Unit = {
+    val x = 2
+    val y = x
+    println(y) 
+  }
+}
+
+/** 
+ * At the end of the alias chain we have a reference to 'this'.
+ * The local variables should be all discarded and replace by a
+ * direct reference to this
+ */
+class TestAliasChainDerefThis {
+
+  def main(args: Array[String]): Unit = {
+    val x = this
+    val y = x
+    println(y)
+  }
+}
+
+/**
+ * At the end of the alias chain, there is the value of a field.
+ * The use of variable 'y' should be replaced by 'x', not by an access
+ * to the field 'f' since it is more costly. 
+ */
+object TestAliasChainDerefField {
+  def f = nextInt
+
+  def main(args: Array[String]): Unit = {
+    val x = f
+    val y = x
+    println(y)
+  }
+}
+
+
+/**
+ * The first time 'println' is called, 'x' is replaced by 'y' 
+ * and the second time, 'y' is replaced by 'x'. But none of them
+ * can be removed.
+ */
+object TestDifferentBindings {
+
+  def main(args: Array[String]): Unit = {
+    var x = nextInt
+    var y = x
+    println(y)
+
+    y = nextInt
+    x = y
+    println(x)
+  }
+}