v8/test/mjsunit/debug-liveedit-patch-positions-replace.js

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// Flags: --expose-debug-as debug
// Get the Debug object exposed from the debug context global object.

// Scenario: a function is being changed, which causes enclosing function to
// have its positions patched; position changing requires new instance of Code
// object to be introduced; the function happens to be on stack at this moment;
// later it will resume over new instance of Code.
// Before the change 2 rinfo are 22 characters away from each other. After the
// change they are 114 characters away from each other. New instance of Code is
// required when those numbers cross the border value of 64 (in any direction).

Debug = debug.Debug

eval(
    "function BeingReplaced(changer, opt_x, opt_y) {\n" +
    "  changer();\n" +
    "  var res = new Object();\n" +
    "  if (opt_x) { res.y = opt_y; }\n" +
    "  res.a = (function() {})();\n" +
    "  return res.a;\n" +
    "}"
);

var script = Debug.findScript(BeingReplaced);

var orig_body = "{}";
var patch_pos = script.source.indexOf(orig_body);
// Line long enough to change rinfo encoding.
var new_body_patch = "{return 'Capybara';" +
    "                                                                          " +
    "}";

var change_log = new Array();
function Changer() {
  Debug.LiveEdit.ApplyPatch(script, patch_pos, orig_body.length, new_body_patch, change_log);
  print("Change log: " + JSON.stringify(change_log) + "\n");
}

function NoOp() {
}

function CallM(changer) {
  // We expect call IC here after several function runs.
  return BeingReplaced(changer);
}

// This several iterations should cause call IC for BeingReplaced call. This IC
// will keep reference to code object of BeingRepalced function. This reference
// should also be patched. Unfortunately, this is a manually checked fact (from
// debugger or debug print) and doesn't work as an automatic test.
CallM(NoOp);
CallM(NoOp);
CallM(NoOp);

var res = CallM(Changer);
assertEquals("Capybara", res);