Loops are followed by read(Unit) in order to prevent the CFA from thinking that the condition is returned

idea/src/org/jetbrains/jet/lang/cfg/JetControlFlowProcessor.java

@@ -332,6 +332,7 @@ public class JetControlFlowProcessor {
             }
             builder.jump(loopEntryPoint);
             builder.exitLoop(expression);
+            builder.readUnit(expression);
         }
 
         @Override
@@ -348,6 +349,7 @@ public class JetControlFlowProcessor {
             }
             builder.jumpOnTrue(loopEntryPoint);
             builder.exitLoop(expression);
+            builder.readUnit(expression);
         }
 
         @Override
@@ -363,6 +365,7 @@ public class JetControlFlowProcessor {
             }
             builder.nondeterministicJump(loopEntryPoint);
             builder.exitLoop(expression);
+            builder.readUnit(expression);
         }
 
         @Override

idea/src/org/jetbrains/jet/lang/resolve/TopDownAnalyzer.java

@@ -366,7 +366,10 @@ public class TopDownAnalyzer {
                 collectReachable(enterInstruction, visited);
 
                 for (Instruction instruction : pseudocode.getInstructions()) {
-                    if (!visited.contains(instruction) && instruction instanceof JetElementInstruction) {
+                    if (!visited.contains(instruction) &&
+                        instruction instanceof JetElementInstruction &&
+                        // TODO : do {return} while (1 > a)
+                        !(instruction instanceof ReadUnitValueInstruction)) {
                         unreachableElements.add(((JetElementInstruction) instruction).getElement());
                     }
                 }
@@ -376,13 +379,6 @@ public class TopDownAnalyzer {
             public void collectDominatedExpressions(@NotNull JetExpression dominator, @NotNull Collection<JetElement> dominated) {
                 Instruction dominatorInstruction = representativeInstructions.get(dominator);
                 if (dominatorInstruction == null) {
-//                    assert
-//                            dominator instanceof JetContinueExpression ||
-//                            dominator instanceof JetBreakExpression ||
-//                            dominator instanceof JetReturnExpression ||
-//                            dominator instanceof JetBlockExpression ||
-//                            dominator instanceof JetFunctionLiteralExpression
-//                        : "No representative instruction for a Nothing-typed expression: " + dominator.getText();
                     return;
                 }
                 SubroutineEnterInstruction enterInstruction = dominatorInstruction.getOwner().getEnterInstruction();

idea/testData/cfg/Finally.instructions

@@ -227,8 +227,9 @@ l4:
 l6:
     r(2)
     jmp(l3)
-l1:
 l2:
+    read (Unit)
+l1:
     <END>
 =====================
 == t3 ==
@@ -265,6 +266,7 @@ l5:
 l6:
     jmp(l4)
 l3:
+    read (Unit)
     r(5)
 l2:
     r(2)
@@ -303,8 +305,9 @@ l5:
     read (Unit)
 l6:
     jmp(l4)
-l2:
 l3:
+    read (Unit)
+l2:
     r(2)
 l1:
     <END>
@@ -347,8 +350,9 @@ l4:
 l6:
     r(2)
     jmp?(l3)
-l1:
 l2:
+    read (Unit)
+l1:
     <END>
 =====================
 == t3 ==
@@ -388,6 +392,7 @@ l5:
 l6:
     jmp?(l4)
 l3:
+    read (Unit)
     r(5)
 l2:
     r(2)
@@ -429,8 +434,9 @@ l5:
     read (Unit)
 l6:
     jmp?(l4)
-l2:
 l3:
+    read (Unit)
+l2:
     r(2)
 l1:
     <END>

idea/testData/cfg/OnlyWhileInFunctionBody.instructions

@@ -0,0 +1,42 @@
+== main ==
+fun main() {
+    while(1 > 0) {
+      2
+    }
+}
+---------------------
+l0:
+    <START>
+l3:
+    r(1)
+    r(0)
+    r(>)
+    r(1 > 0)
+    jf(l2)
+    r(2)
+    jmp(l3)
+l2:
+    read (Unit)
+l1:
+    <END>
+=====================
+== dowhile ==
+fun dowhile() {
+    do {return}
+    while(1 > 0)
+}
+---------------------
+l0:
+    <START>
+l3:
+    ret l1
+    r(1)
+    r(0)
+    r(>)
+    r(1 > 0)
+    jt(l3)
+l2:
+    read (Unit)
+l1:
+    <END>
+=====================

idea/testData/cfg/OnlyWhileInFunctionBody.jet

@@ -0,0 +1,10 @@
+fun main() {
+    while(1 > 0) {
+      2
+    }
+}
+
+fun dowhile() {
+    do {return}
+    while(1 > 0)
+}