Ziele Untersuchung
mit Columbo Integrität von
Datenbanken Interaktion und
Portierbarkeit Ergonomie der
Schnittstellen

Angebot Produkte Projekt Beratung

Mittel Analytik Modellierung Sprachen Algebra Logik Hardware Denken Kreativität

Zusammenhänge Gesellschaft Wirtschaft Branche Firma


products/sources/formale Sprachen/C/Firefox/js/src/jsapi-tests/ (Browser von der Mozilla Stiftung Version 136.0.1^©) Datei vom 10.2.2025 mit Größe 4 kB

Quelle testDeduplication.cpp Sprache: C

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* vim: set ts=8 sts=2 et sw=2 tw=80:
*/
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include <string.h>

#include "gc/GC.h"

#include "js/RootingAPI.h"
#include "js/StableStringChars.h"
#include "js/String.h"  // JS::StringToLinearString

#include "jsapi-tests/tests.h"

#include "vm/JSContext.h"
#include "vm/StringType.h"

#include "vm/JSContext-inl.h"

static bool SameChars(JSContext* cx, JSString* str1, JSString* str2,
                      size_t offset) {
  JS::AutoCheckCannotGC nogc(cx);

  const JS::Latin1Char* chars1 =
      JS::StringToLinearString(cx, str1)->latin1Chars(nogc);
  const JS::Latin1Char* chars2 =
      JS::StringToLinearString(cx, str2)->latin1Chars(nogc);

  return chars1 == chars2 + offset;
}

BEGIN_TEST(testDeduplication_ASSC) {
  AutoGCParameter disableSemispace(cx, JSGC_SEMISPACE_NURSERY_ENABLED, 0);

  // Test with a long enough string to avoid inline chars allocation.
  const char text[] =
      "Andthebeastshallcomeforthsurroundedbyaroilingcloudofvengeance."
      "Thehouseoftheunbelieversshallberazedandtheyshallbescorchedtoth"
      "eearth.Theirtagsshallblinkuntiltheendofdays.";

  // Create a string to deduplicate later strings to.
  JS::RootedString original(cx);
  JS::RootedString str(cx);
  JS::RootedString dep(cx);
  JS::RootedString depdep(cx);
  JS::RootedString str2(cx);
  JS::RootedString dep2(cx);
  JS::RootedString depdep2(cx);

  if (!cx->zone()->allocNurseryStrings()) {
    // This test requires nursery-allocated strings, so that they will go
    // through the deduplication pass during minor GC.
    return true;
  }

  {
    // This test checks the behavior when GC is performed after allocating
    // all the following strings.
    // GC shouldn't happen in between them, even in compacting jobs.
    js::gc::AutoSuppressGC suppress(cx);

    original = JS_NewStringCopyZ(cx, text);
    CHECK(original);

    // Create a chain of dependent strings, with a base string whose contents
    // match `original`'s.
    str = JS_NewStringCopyZ(cx, text);
    CHECK(str && !str->isTenured());

    dep = JS_NewDependentString(cx, str, 10, 100);
    CHECK(dep && !dep->isTenured());

    depdep = JS_NewDependentString(cx, dep, 10, 80);
    CHECK(depdep && !depdep->isTenured());

    // Repeat. This one will not be prevented from deduplication.
    str2 = JS_NewStringCopyZ(cx, text);
    CHECK(str2 && !str2->isTenured());

    dep2 = JS_NewDependentString(cx, str2, 10, 100);
    CHECK(dep2 && !dep2->isTenured());

    depdep2 = JS_NewDependentString(cx, dep2, 10, 80);
    CHECK(depdep2 && !depdep2->isTenured());
  }

  // Initializing an AutoStableStringChars with `depdep` will prevent the
  // owner of its chars (`str`) from being deduplicated, but only if the
  // chars are stored in the malloc heap. Force `str` to be nondeduplicatable
  // unconditionally to avoid depending on the exact set of things that are
  // enabled.
  str->setNonDeduplicatable();
  JS::AutoStableStringChars stable(cx);
  CHECK(stable.init(cx, depdep));

  CHECK(stable.latin1Range().length() == 80);

  const JS::Latin1Char* chars = stable.latin1Chars();
  CHECK(memcmp(chars, text + 20, 80 * sizeof(JS::Latin1Char)) == 0);

  // `depdep` should share chars with `str` but not with `original`.
  CHECK(SameChars(cx, depdep, str, 20));
  CHECK(!SameChars(cx, depdep, original, 20));

  // Same for `depdep2`.
  CHECK(SameChars(cx, depdep2, str2, 20));
  CHECK(!SameChars(cx, depdep2, original, 20));

  // Do a minor GC that will deduplicate `str2` to `original`, and would have
  // deduplicated `str` as well if it weren't prevented by the
  // AutoStableStringChars.
  cx->minorGC(JS::GCReason::API);

  // `depdep` should still share chars with `str` but not with `original`.
  CHECK(SameChars(cx, depdep, str, 20));
  CHECK(!SameChars(cx, depdep, original, 20));

  // `depdep2` should now share chars with both `str2` and `original`. Or with
  // `str`, since it could legitimately have been detected to be identical to
  // the tenured `depdep` and deduplicated to that.
  CHECK(SameChars(cx, depdep2, str2, 20) || SameChars(cx, depdep2, str, 20));

  // TODO: this currently breaks because we are more conservative than we need
  // to be with handling the DEPENDED_ON_BIT and deduplication. This will be
  // fixed in bug 1900142
  // CHECK(SameChars(cx, depdep2, original, 20) ||
  //       SameChars(cx, depdep2, str, 20));

  // Make sure AutoStableStringChars uses the correct length when strings are
  // tenured.
  JS::AutoStableStringChars stable2(cx);
  CHECK(stable2.init(cx, depdep));
  // This should get the length from the dependent string, not the string that
  // owns its data.
  CHECK(stable2.latin1Range().length() == 80);

  return true;
}
END_TEST(testDeduplication_ASSC)

quality100%

¤ Dauer der Verarbeitung: 0.15 Sekunden (vorverarbeitet) ¤

Wurzel

Suchen

Beweissystem der NASA

Beweissystem Isabelle

NIST Cobol Testsuite

Cephes Mathematical Library

Wiener Entwicklungsmethode

Haftungshinweis

Die Informationen auf dieser Webseite wurden nach bestem Wissen sorgfältig zusammengestellt. Es wird jedoch weder Vollständigkeit, noch Richtigkeit, noch Qualität der bereit gestellten Informationen zugesichert.