Modify minimize exit points to only visit changed functions.

------------- Created by MOE: https://github.com/google/moe MOE_MIGRATED_REVID=125255755
google · Jun 20, 2016 · 3d64f6a · 3d64f6a
1 parent 329111b
commit 3d64f6a
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Showing 3 changed files with 28 additions and 27 deletions.
diff --git a/src/com/google/javascript/jscomp/MinimizeExitPoints.java b/src/com/google/javascript/jscomp/MinimizeExitPoints.java
@@ -17,7 +17,8 @@
 package com.google.javascript.jscomp;
 
 import com.google.common.base.Preconditions;
-import com.google.javascript.jscomp.NodeTraversal.AbstractPostOrderCallback;
+import com.google.javascript.jscomp.NodeTraversal.AbstractShallowCallback;
+import com.google.javascript.jscomp.NodeTraversal.FunctionCallback;
 import com.google.javascript.rhino.IR;
 import com.google.javascript.rhino.Node;
 import com.google.javascript.rhino.Token;
@@ -31,10 +32,7 @@
  *
  * @author johnlenz@google.com (John Lenz)
  */
-class MinimizeExitPoints
+class MinimizeExitPoints extends AbstractShallowCallback implements CompilerPass {
-    extends AbstractPostOrderCallback
-    implements CompilerPass {
-
   AbstractCompiler compiler;
 
   MinimizeExitPoints(AbstractCompiler compiler) {
@@ -43,8 +41,15 @@ class MinimizeExitPoints
 
   @Override
   public void process(Node externs, Node root) {
-    // TODO(johnlenz): only inspect changed functions
+    NodeTraversal.traverseChangedFunctions(compiler, new FunctionCallback() {
-    NodeTraversal.traverseEs6(compiler, root, this);
+        @Override
+        public void enterFunction(AbstractCompiler compiler, Node root) {
+          if (root.isFunction()) {
+            root = root.getLastChild();
+          }
+          NodeTraversal.traverseEs6(compiler, root, MinimizeExitPoints.this);
+        }
+    });
   }
 
   @Override
@@ -72,11 +77,12 @@ public void visit(NodeTraversal t, Node n, Node parent) {
         }
         break;
 
-      case FUNCTION:
+      case BLOCK:
-        // FYI: the function will be analyzed w/out a call to
+        // The traversal starts at the function block so `parent` will be null, so we use
-        // NodeTraversal/pushScope. Bypassing pushScope could cause a bug if
+        // getParent here.
-        // there is code that relies on NodeTraversal knowing the correct scope.
+        if (n.getParent() != null && n.getParent().isFunction()) {
-        tryMinimizeExits(n.getLastChild(), Token.RETURN, null);
+          tryMinimizeExits(n, Token.RETURN, null);
+        }
         break;
 
       case SWITCH:
@@ -165,16 +171,15 @@ void tryMinimizeExits(Node n, Token exitType, @Nullable String labelName) {
     }
 
     // The rest assumes a block with at least one child, bail on anything else.
-    if (!n.isBlock() || n.getLastChild() == null) {
+    if (!n.isBlock() || !n.hasChildren()) {
       return;
     }
 
     // Multiple if-exits can be converted in a single pass.
     // Convert "if (blah) break;  if (blah2) break; other_stmt;" to
     // become "if (blah); else { if (blah2); else { other_stmt; } }"
     // which will get converted to "if (!blah && !blah2) { other_stmt; }".
-    for (Node c : n.children()) {
+    for (Node c = n.getFirstChild(); c != null; c = c.getNext()) {
-
       // An 'if' block to process below.
       if (c.isIf()) {
         Node ifTree = c;

diff --git a/test/com/google/javascript/jscomp/CreateSyntheticBlocksTest.java b/test/com/google/javascript/jscomp/CreateSyntheticBlocksTest.java
@@ -43,15 +43,13 @@ protected CompilerPass getProcessor(final Compiler compiler) {
       public void process(Node externs, Node js) {
         new CreateSyntheticBlocks(compiler, START_MARKER, END_MARKER).process(
             externs, js);
-        NodeTraversal.traverseEs6(compiler, js, new MinimizeExitPoints(compiler));
+        new MinimizeExitPoints(compiler).process(externs, js);
-
         new PeepholeOptimizationsPass(compiler,
             new PeepholeRemoveDeadCode(),
             new PeepholeMinimizeConditions(true /* late */, false /* useTypes */),
             new PeepholeFoldConstants(true, false))
             .process(externs, js);
         new MinimizeExitPoints(compiler).process(externs, js);
-
         new Denormalize(compiler).process(externs, js);
       }
     };

diff --git a/test/com/google/javascript/jscomp/MinimizeExitPointsTest.java b/test/com/google/javascript/jscomp/MinimizeExitPointsTest.java
@@ -16,20 +16,13 @@
 
 package com.google.javascript.jscomp;
 
-import com.google.javascript.rhino.Node;
-
 /**
  * @author johnlenz@google.com (John Lenz)
  */
 public final class MinimizeExitPointsTest extends CompilerTestCase {
   @Override
   protected CompilerPass getProcessor(final Compiler compiler) {
-    return new CompilerPass() {
+    return new MinimizeExitPoints(compiler);
-      @Override
-      public void process(Node externs, Node js) {
-        NodeTraversal.traverseEs6(compiler, js, new MinimizeExitPoints(compiler));
-      }
-    };
   }
 
   @Override
@@ -78,7 +71,12 @@ public void testBreakOptimization() throws Exception {
          "f:g:{if(a()){}else{}}");
   }
 
-  public void testFunctionReturnOptimization() throws Exception {
+  public void testFunctionReturnOptimization1() throws Exception {
+    fold("function f(){return}",
+         "function f(){}");
+  }
+
+  public void testFunctionReturnOptimization2() throws Exception {
     fold("function f(){if(a()){b();if(c())return;}}",
          "function f(){if(a()){b();if(c());}}");
     fold("function f(){if(x)return; x=3; return; }",