Unfold pattern alternatives in genicode.

Implemented unfolding of pattern alternatives
that can be translated into switch table in
genicode. This way pattern matcher can keep
simple patterns as-is and let backend handle
translation of them instead of generating
bunch of LabelDefs and jumps.

Review by @dragos or @magarciaEPFL as both
seem to know genicode very well.

1 files changed, 9 insertions, 0 deletions

diff --git a/src/compiler/scala/tools/nsc/backend/icode/GenICode.scala b/src/compiler/scala/tools/nsc/backend/icode/GenICode.scala
index 3d650ef753..3baff7da9e 100644
--- a/src/compiler/scala/tools/nsc/backend/icode/GenICode.scala
+++ b/src/compiler/scala/tools/nsc/backend/icode/GenICode.scala
@@ -1072,6 +1072,15 @@ abstract class GenICode extends SubComponent  {
                 targets = tmpCtx.bb :: targets
               case Ident(nme.WILDCARD) =>
                 default = tmpCtx.bb
+              case Alternative(alts) =>
+                alts foreach {
+                  case Literal(value) =>
+                    tags = value.intValue :: tags
+                    targets = tmpCtx.bb :: targets
+                  case _ =>
+                    abort("Invalid case in alternative in switch-like pattern match: " +
+                          tree + " at: " + tree.pos)
+                }
               case _ =>
                 abort("Invalid case statement in switch-like pattern match: " +
                       tree + " at: " + (tree.pos))