dart2js cps: Better side-effect tracking in loops.

pkg/compiler/lib/src/cps_ir/loop_hierarchy.dart

Index: pkg/compiler/lib/src/cps_ir/loop_hierarchy.dart
diff --git a/pkg/compiler/lib/src/cps_ir/loop_hierarchy.dart b/pkg/compiler/lib/src/cps_ir/loop_hierarchy.dart
index fc639442a227812c311a8ddefdb2cca163151edf..3aa5bc9bf64e548bb6373543b869fece700db572 100644
--- a/pkg/compiler/lib/src/cps_ir/loop_hierarchy.dart
+++ b/pkg/compiler/lib/src/cps_ir/loop_hierarchy.dart
@@ -7,21 +7,21 @@ library dart2js.cps_ir.loop_hierarchy;
 import 'cps_ir_nodes.dart';
 
 /// Determines the effective nesting of loops.
-/// 
+///
 /// The effective nesting of loops is different from the lexical nesting, since
-/// recursive continuations can generally contain all the code following 
+/// recursive continuations can generally contain all the code following
 /// after the loop in addition to the looping code itself.
-/// 
+///
 /// For example, the 'else' branch below is not effectively part of the loop:
-/// 
-///   let rec kont x = 
-///     if (<loop condition>) 
+///
+///   let rec kont x =
+///     if (<loop condition>)
 ///       <loop body>
 ///       InvokeContinuation kont x'
-///     else 
+///     else
 ///       <after loop>
 ///       return p.foo()
-/// 
+///
 /// We use the term "loop" to mean recursive continuation.
 /// The `null` value is used to represent a context not part of any loop.
 class LoopHierarchy {
@@ -36,7 +36,7 @@ class LoopHierarchy {
   int currentDepth = 0;
 
   /// Computes the loop hierarchy for the given function.
-  /// 
+  ///
   /// Parent pointers must be computed for [node].
   LoopHierarchy(FunctionDefinition node) {
     _processBlock(node.body, null);
@@ -47,21 +47,21 @@ class LoopHierarchy {
     return cont.isRecursive ? cont : loopTarget[cont];
   }
 
-  /// Returns the innermost loop which the given loop is part of, other
+  /// Returns the innermost loop which the given continuation is part of, other
   /// than itself.
-  Continuation getEnclosingLoop(Continuation loop) {
-    return loopTarget[loop];
+  Continuation getEnclosingLoop(Continuation cont) {
+    return loopTarget[cont];

[asgerf, 2015/11/05 12:13:42]

The only "change" here is that we may now ask for the enclosing loop of any
continuation.

   }
 
   /// Marks the innermost loop as a subloop of the other loop.
-  /// 
+  ///
   /// Returns the innermost loop.
-  /// 
+  ///
   /// Both continuations, [c1] and [c2] may be null (i.e. no loop).
-  /// 
+  ///
   /// A loop is said to be a subloop of an enclosing loop if it can invoke
   /// that loop recursively. This information is stored in [loopTarget].
-  /// 
+  ///
   /// This method is only invoked with two distinct loops if there is a
   /// point that can reach a recursive invocation of both loops.
   /// This implies that one loop is nested in the other, because they must
@@ -83,7 +83,7 @@ class LoopHierarchy {
 
   /// Analyzes the body of [cont] and returns the innermost loop
   /// that can be invoked recursively from [cont] (other than [cont] itself).
-  /// 
+  ///
   /// [catchLoop] is the innermost loop that can be invoked recursively
   /// from the current exception handler.
   Continuation _processContinuation(Continuation cont, Continuation catchLoop) {