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

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

// Scenario: some function is being edited; the outer function has to have its
// positions patched. Accoring to a special markup of function text
// corresponding byte-code PCs should coincide before change and after it.

Debug = debug.Debug
Debug.setListener(function() {});

eval(
    "function F1() {  return 5; }\n" +
    "function ChooseAnimal(/*$*/ ) {\n" +
    "/*$*/ var x = F1(/*$*/ );\n" +
    "/*$*/ var res/*$*/  =/*$*/ (function() { return 'Cat'; } )();\n" +
    "/*$*/ var y/*$*/  = F2(/*$*/ F1()/*$*/ , F1(/*$*/ )/*$*/ );\n" +
    "/*$*/ if (/*$*/ x.toString(/*$*/ )) { /*$*/ y = 3;/*$*/  } else {/*$*/  y = 8;/*$*/  }\n" +
    "/*$*/ var z = /*$*/ x * y;\n" +
    "/*$*/ return/*$*/  res/*$*/  + z;/*$*/  }\n" +
    "function F2(x, y) { return x + y; }"
);

// Find all *$* markers in text of the function and read corresponding statement
// PCs.
function ReadMarkerPositions(func) {
  var text = func.toString();
  var positions = new Array();
  var match;
  var pattern = /\/\*\$\*\//g;
  while ((match = pattern.exec(text)) != null) {
    positions.push(match.index);
  }
  return positions;
}

function ReadPCMap(func, positions) {
  var res = new Array();
  for (var i = 0; i < positions.length; i++) {
    var pc = Debug.LiveEdit.GetPcFromSourcePos(func, positions[i]);

    if (typeof pc === 'undefined') {
      // Function was marked for recompilation and it's code was replaced with a
      // stub. This can happen at any time especially if we are running with
      // --stress-opt. There is no way to get PCs now.
      return;
    }

    res.push(pc);
  }

  return res;
}

function ApplyPatch(orig_animal, new_animal) {
  var res = ChooseAnimal();
  assertEquals(orig_animal + "15", res);

  var script = Debug.findScript(ChooseAnimal);

  var orig_string = "'" + orig_animal + "'";
  var patch_string = "'" + new_animal + "'";
  var patch_pos = script.source.indexOf(orig_string);

  var change_log = new Array();

  Debug.LiveEdit.TestApi.ApplySingleChunkPatch(script,
                                               patch_pos,
                                               orig_string.length,
                                               patch_string,
                                               change_log);

  print("Change log: " + JSON.stringify(change_log) + "\n");

  var markerPositions = ReadMarkerPositions(ChooseAnimal);
  var pcArray = ReadPCMap(ChooseAnimal, markerPositions);

  var res = ChooseAnimal();
  assertEquals(new_animal + "15", res);

  return pcArray;
}

var pcArray1 = ApplyPatch('Cat', 'Dog');

// When we patched function for the first time it was deoptimized.
// Check that after the second patch maping between sources position and
// pcs will not change.

var pcArray2 = ApplyPatch('Dog', 'Capybara');

print(pcArray1);
print(pcArray2);

// Function can be marked for recompilation at any point (especially if we are
// running with --stress-opt). When we mark function for recompilation we
// replace it's code with stub. So there is no reliable way to get PCs for
// function.
if (pcArray1 && pcArray2) {
  assertArrayEquals(pcArray1, pcArray2);
}

Debug.setListener(null);