Liveness analysis for environment slots in Hydrogen

test/mjsunit/debug-evaluate-locals-optimized-double.js

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 166 matching lines @@
 f(input.length - 1, 11.11, 12.12);
 
 // Add the debug event listener.
 Debug.setListener(listener);
 
 function h(i, x0, y0) {
   var a0 = input[i].a;
   var b0 = input[i].b;
   a0 = a0 + a0 / 100;
   b0 = b0 + b0 / 100;
   debugger;  // Breakpoint.

[titzer, 2013/05/29 16:58:05]

Not sure why we are changing these tests. Does something break with debugging?

[Jakob Kummerow, 2013/06/03 17:50:38]

We need to extend the live ranges of the values that are being inspected beyond
the point where they are inspected. The "debugger;" statement triggers the big
"listener()" function above (lines 65ff.), which has expectations for the local
variables in every stack frame.

This does mean that users inspecting stack frames where local values have been
zapped at the end of their live range will see "undefined" unexpectedly.
Unfortunately, there's nothing we can do to prevent that, because there's no way
to predict if/when a stack frame will be inspected.

+  return a0 + b0;
 };
 
 function g3(i, x1, y1) {
   var a1 = input[i].a;
   var b1 = input[i].b;
   a1 = a1 + a1 / 100;
   b1 = b1 + b1 / 100;
   h(i - 1, a1, b1);
-  return a1+b1;
+  return a1 + b1;
 };
 
 function g2(i) {
   var a2 = input[i].a;
   var b2 = input[i].b;
   a2 = a2 + a2 / 100;
   b2 = b2 + b2 / 100;
   g3(i - 1, a2, b2);
+  return a2 + b2;
 };
 
 function g1(i, x3, y3, z3) {
   var a3 = input[i].a;
   var b3 = input[i].b;
   a3 = a3 + a3 / 100;
   b3 = b3 + b3 / 100;
   new g2(i - 1, a3, b3);
+  return a3 + b3;
 };
 
 function f(i, x4, y4) {
   var a4 = input[i].a;
   var b4 = input[i].b;
   a4 = a4 + a4 / 100;
   b4 = b4 + b4 / 100;
   g1(i - 1, a4, b4);
+  return a4 + b4;
 };
 
 // Test calling f normally and as a constructor.
 f(input.length - 1, 11.11, 12.12);
 f(input.length - 1, 11.11, 12.12, "");
 testingConstructCall = true;
 new f(input.length - 1, 11.11, 12.12);
 new f(input.length - 1, 11.11, 12.12, "");
 
 // Make sure that the debug event listener was invoked.
 assertFalse(exception, "exception in listener " + exception)
 assertTrue(listenerComplete);
 
 //Throw away type information for next run.
 gc();
 
 Debug.setListener(null);