v8/test/mjsunit/assert-opt-and-deopt.js

// Copyright 2011 the V8 project authors. All rights reserved.
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// modification, are permitted provided that the following conditions are
// met:
//
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// Flags: --allow-natives-syntax
// Flags: --noconcurrent-recompilation

if (%IsConcurrentRecompilationSupported()) {
  print("Concurrent recompilation is turned on after all. Skipping this test.");
  quit();
}

/**
 * This class shows how to use %GetOptimizationCount() and
 * %GetOptimizationStatus() to infer information about opts and deopts.
 * Might be nice to put this into mjsunit.js, but that doesn't depend on
 * the --allow-natives-syntax flag so far.
 */
function OptTracker() {
  this.opt_counts_ = {};
}

/**
 * Always call this at the beginning of your test, once for each function
 * that you later want to track de/optimizations for. It is necessary because
 * tests are sometimes executed several times in a row, and you want to
 * disregard counts from previous runs.
 */
OptTracker.prototype.CheckpointOptCount = function(func) {
  this.opt_counts_[func] = %GetOptimizationCount(func);
};

OptTracker.prototype.AssertOptCount = function(func, optcount) {
  if (this.DisableAsserts_(func)) {
    return;
  }
  assertEquals(optcount, this.GetOptCount_(func));
};

OptTracker.prototype.AssertDeoptCount = function(func, deopt_count) {
  if (this.DisableAsserts_(func)) {
    return;
  }
  assertEquals(deopt_count, this.GetDeoptCount_(func));
};

OptTracker.prototype.AssertDeoptHappened = function(func, expect_deopt) {
  if (this.DisableAsserts_(func)) {
    return;
  }
  if (expect_deopt) {
    assertTrue(this.GetDeoptCount_(func) > 0);
  } else {
    assertEquals(0, this.GetDeoptCount_(func));
  }
}

OptTracker.prototype.AssertIsOptimized = function(func, expect_optimized) {
  if (this.DisableAsserts_(func)) {
    return;
  }
  var opt_status = %GetOptimizationStatus(func);
  assertTrue((opt_status & V8OptimizationStatus.kIsFunction) !== 0);
  assertEquals(expect_optimized,
               (opt_status & V8OptimizationStatus.kOptimized) !== 0);
}

/**
 * @private
 */
OptTracker.prototype.GetOptCount_ = function(func) {
  var raw_count = %GetOptimizationCount(func);
  if (func in this.opt_counts_) {
    var checkpointed_count = this.opt_counts_[func];
    return raw_count - checkpointed_count;
  }
  return raw_count;
}

/**
 * @private
 */
OptTracker.prototype.GetDeoptCount_ = function(func) {
  var count = this.GetOptCount_(func);
  var opt_status = %GetOptimizationStatus(func);
  if ((opt_status & V8OptimizationStatus.kOptimized) !== 0) {
    count -= 1;
  }
  return count;
}

/**
 * @private
 */
OptTracker.prototype.DisableAsserts_ = function(func) {
  var opt_status = %GetOptimizationStatus(func);
  return (opt_status & V8OptimizationStatus.kAlwaysOptimize) !== 0 ||
         (opt_status & V8OptimizationStatus.kNeverOptimize) !== 0;
}
// (End of class OptTracker.)

// Example function used by the test below.
function f(a) {
  return a+1;
}

var tracker = new OptTracker();
tracker.CheckpointOptCount(f);

tracker.AssertOptCount(f, 0);
tracker.AssertIsOptimized(f, false);
tracker.AssertDeoptHappened(f, false);
tracker.AssertDeoptCount(f, 0);

f(1);

%OptimizeFunctionOnNextCall(f);
f(1);

tracker.AssertOptCount(f, 1);
tracker.AssertIsOptimized(f, true);
tracker.AssertDeoptHappened(f, false);
tracker.AssertDeoptCount(f, 0);

%DeoptimizeFunction(f);

tracker.AssertOptCount(f, 1);
tracker.AssertIsOptimized(f, false);
tracker.AssertDeoptHappened(f, true);
tracker.AssertDeoptCount(f, 1);

// Let's trigger optimization for another type.
for (var i = 0; i < 5; i++) f("a");

%OptimizeFunctionOnNextCall(f);
f("b");

tracker.AssertOptCount(f, 2);
tracker.AssertIsOptimized(f, true);
tracker.AssertDeoptHappened(f, true);
tracker.AssertDeoptCount(f, 1);