improve cps handling of if-then-else. no review.

git-svn-id: http://lampsvn.epfl.ch/svn-repos/scala/scala/trunk@26092 5e8d7ff9-d8ef-0310-90f0-a4852d11357a

src/continuations/plugin/scala/tools/selectivecps/SelectiveANFTransform.scala

@@ -173,40 +173,44 @@ abstract class SelectiveANFTransform extends PluginComponent with Transform with
 
           (Nil, tree1, cpsA)
 
-        case If(cond, thenp, elsep) =>
-          
-          val (condStats, condVal, spc) = transInlineValue(cond, cpsA)
+          case If(cond, thenp, elsep) =>
+            /* possible situations:
+            cps before (cpsA)
+            cps in condition (spc)  <-- synth flag set if *only* here!
+            cps in (one or both) branches */
+            val (condStats, condVal, spc) = transInlineValue(cond, cpsA)
+            val (cpsA2, cpsR2) = if (hasSynthMarker(tree.tpe)) 
+              (spc, linearize(spc, getAnswerTypeAnn(tree.tpe))) else
+              (None, getAnswerTypeAnn(tree.tpe)) // if no cps in condition, branches must conform to tree.tpe directly
+            val thenVal = transExpr(thenp, cpsA2, cpsR2)
+            val elseVal = transExpr(elsep, cpsA2, cpsR2)
 
-          val (cpsA2, cpsR2) = (spc, linearize(spc, getAnswerTypeAnn(tree.tpe)))
-//          val (cpsA2, cpsR2) = (None, getAnswerTypeAnn(tree.tpe))
-          val thenVal = transExpr(thenp, cpsA2, cpsR2)
-          val elseVal = transExpr(elsep, cpsA2, cpsR2)
-          
-          // check that then and else parts agree (not necessary any more, but left as sanity check)
-          if (cpsR.isDefined) {
-            if (elsep == EmptyTree)
-              unit.error(tree.pos, "always need else part in cps code")
-          }
-          if (hasAnswerTypeAnn(thenVal.tpe) != hasAnswerTypeAnn(elseVal.tpe)) {
-            unit.error(tree.pos, "then and else parts must both be cps code or neither of them")
-          }
+            // check that then and else parts agree (not necessary any more, but left as sanity check)
+            if (cpsR.isDefined) {
+              if (elsep == EmptyTree)
+                unit.error(tree.pos, "always need else part in cps code")
+            }
+            if (hasAnswerTypeAnn(thenVal.tpe) != hasAnswerTypeAnn(elseVal.tpe)) {
+              unit.error(tree.pos, "then and else parts must both be cps code or neither of them")
+            }
 
-          (condStats, updateSynthFlag(treeCopy.If(tree, condVal, thenVal, elseVal)), spc)
+            (condStats, updateSynthFlag(treeCopy.If(tree, condVal, thenVal, elseVal)), spc)
 
-        case Match(selector, cases) =>
-        
-          val (selStats, selVal, spc) = transInlineValue(selector, cpsA)
-          val (cpsA2, cpsR2) = (spc, linearize(spc, getAnswerTypeAnn(tree.tpe)))
-//          val (cpsA2, cpsR2) = (None, getAnswerTypeAnn(tree.tpe))
+          case Match(selector, cases) =>
 
-          val caseVals = for {
-            cd @ CaseDef(pat, guard, body) <- cases
-            bodyVal = transExpr(body, cpsA2, cpsR2)
-          } yield {
-            treeCopy.CaseDef(cd, transform(pat), transform(guard), bodyVal)
-          }
-          
-          (selStats, updateSynthFlag(treeCopy.Match(tree, selVal, caseVals)), spc)
+            val (selStats, selVal, spc) = transInlineValue(selector, cpsA)
+            val (cpsA2, cpsR2) = if (hasSynthMarker(tree.tpe)) 
+              (spc, linearize(spc, getAnswerTypeAnn(tree.tpe))) else
+              (None, getAnswerTypeAnn(tree.tpe))
+
+            val caseVals = for {
+              cd @ CaseDef(pat, guard, body) <- cases
+              bodyVal = transExpr(body, cpsA2, cpsR2)
+            } yield {
+              treeCopy.CaseDef(cd, transform(pat), transform(guard), bodyVal)
+            }
+
+            (selStats, updateSynthFlag(treeCopy.Match(tree, selVal, caseVals)), spc)
 
 
         case ldef @ LabelDef(name, params, rhs) =>

test/files/continuations-run/ifelse4.check

@@ -0,0 +1,4 @@
+10
+10
+10
+10

test/files/continuations-run/ifelse4.scala

@@ -0,0 +1,31 @@
+import scala.util.continuations._
+
+object Test {
+  def sh(x1:Int) = shift( (k: Int => Int) => k(k(k(x1))))
+  
+  def testA(x1: Int): Int @cps[Int] = {
+      sh(x1)
+      if (x1==42) x1 else sh(x1)
+  }
+
+  def testB(x1: Int): Int @cps[Int] = {
+      if (sh(x1)==43) x1 else x1
+  }
+  
+  def testC(x1: Int): Int @cps[Int] = {
+      sh(x1)
+      if (sh(x1)==44) x1 else x1
+  }
+
+  def testD(x1: Int): Int @cps[Int] = {
+      sh(x1)
+      if (sh(x1)==45) x1 else sh(x1)
+  }
+
+  def main(args: Array[String]): Any = {
+    println(reset(1 + testA(7)))
+    println(reset(1 + testB(9)))
+    println(reset(1 + testC(9)))
+    println(reset(1 + testD(7)))
+  }
+}

test/files/continuations-run/patvirt.check

@@ -0,0 +1,2 @@
+10
+11

test/files/continuations-run/patvirt.scala

@@ -0,0 +1,32 @@
+import scala.util.continuations._
+
+object Test {
+  def sh(x1:Int) = shift( (k: Int => Int) => k(k(k(x1))))
+  
+  def test(x1: Int) = {
+    val o7 = {
+      val o6 = {
+        val o3 = 
+          if (7 == x1) Some(x1)
+          else None
+
+        if (o3.isEmpty) None
+        else Some(sh(x1))
+      }
+      if (o6.isEmpty) {
+        val o5 =
+          if (8 == x1) Some(x1)
+          else None
+
+        if (o5.isEmpty) None
+        else Some(sh(x1))
+      } else o6
+    }
+    o7.get
+  }
+
+  def main(args: Array[String]): Any = {
+    println(reset(1 + test(7)))
+    println(reset(1 + test(8)))
+  }
+}