Consider while (true) {...} loops as infinite loops.

------------- Created by MOE: https://github.com/google/moe MOE_MIGRATED_REVID=126325051
google · Jun 30, 2016 · 12bcd8b · 12bcd8b
1 parent c874409
commit 12bcd8b
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Showing 2 changed files with 15 additions and 12 deletions.
diff --git a/src/com/google/javascript/jscomp/ControlFlowAnalysis.java b/src/com/google/javascript/jscomp/ControlFlowAnalysis.java
@@ -373,24 +373,27 @@ private void handleIf(Node node) {
   }
 
   private void handleWhile(Node node) {
+    Node cond = node.getFirstChild();
     // Control goes to the first statement if the condition evaluates to true.
-    createEdge(node, Branch.ON_TRUE,
-        computeFallThrough(node.getSecondChild()));
+    createEdge(node, Branch.ON_TRUE, computeFallThrough(cond.getNext()));
 
-    // Control goes to the follow() if the condition evaluates to false.
-    createEdge(node, Branch.ON_FALSE,
-        computeFollowNode(node, this));
+    if (!cond.isTrue()) {
+      // Control goes to the follow() if the condition evaluates to false.
+      createEdge(node, Branch.ON_FALSE, computeFollowNode(node, this));
+    }
     connectToPossibleExceptionHandler(
         node, NodeUtil.getConditionExpression(node));
   }
 
   private void handleDo(Node node) {
+    Node cond = node.getFirstChild();
     // The first edge can be the initial iteration as well as the iterations
     // after.
-    createEdge(node, Branch.ON_TRUE, computeFallThrough(node.getFirstChild()));
-    // The edge that leaves the do loop if the condition fails.
-    createEdge(node, Branch.ON_FALSE,
-        computeFollowNode(node, this));
+    createEdge(node, Branch.ON_TRUE, computeFallThrough(cond));
+    if (!cond.isTrue()) {
+      // The edge that leaves the do loop if the condition fails.
+      createEdge(node, Branch.ON_FALSE, computeFollowNode(node, this));
+    }
     connectToPossibleExceptionHandler(
         node, NodeUtil.getConditionExpression(node));
   }

diff --git a/test/com/google/javascript/jscomp/NewTypeInferenceES5OrLowerTest.java b/test/com/google/javascript/jscomp/NewTypeInferenceES5OrLowerTest.java
@@ -356,7 +356,7 @@ public void testEmptyBlockPropagation() {
   public void testForLoopInference() {
     typeCheck(LINE_JOINER.join(
         "var x = 5;",
-        "for (;true;) {",
+        "for (;x < 10;) {",
         "  x = 'str';",
         "}",
         "var /** (string|number) */ y = x;",
@@ -365,15 +365,15 @@ public void testForLoopInference() {
 
     typeCheck(LINE_JOINER.join(
         "var x = 5;",
-        "while (true) {",
+        "while (x < 10) {",
         "  x = 'str';",
         "}",
         "(function(/** string */ s){})(x);",
         "var /** (string|number) */ y = x;"),
         NewTypeInference.INVALID_ARGUMENT_TYPE);
 
     typeCheck(LINE_JOINER.join(
-        "while (true) {",
+        "while (true || false) {",
         "  var x = 'str';",
         "}",
         "var /** (string|undefined) */ y = x;",