Bug 1729563 - Add shell flag for change-array-by-copy methods r=mgaudet,arai

Add a build flag and shell flag for enabling change-array-by-copy methods.
    The flags currently have no effect.

Differential Revision: https://phabricator.services.mozilla.com/D127201

js/moz.configure

@@ -1126,3 +1126,25 @@ set_define(
     True,
     when=depends(target)(lambda t: t.os == "WASI"),
 )
+
+# Enable change-array-by-copy
+# ===================================================
+def use_change_array_by_copy():
+    return False
+
+
+option(
+    "--enable-change-array-by-copy",
+    default=use_change_array_by_copy(),
+    help="{Enable|Disable} change-array-by-copy method pref/command-line option (disabled by default)",
+)
+
+
+@depends("--enable-change-array-by-copy")
+def enable_change_array_by_copy(value):
+    if value:
+        return True
+
+
+set_config("ENABLE_CHANGE_ARRAY_BY_COPY", enable_change_array_by_copy)
+set_define("ENABLE_CHANGE_ARRAY_BY_COPY", enable_change_array_by_copy)

js/public/ContextOptions.h

@@ -51,6 +51,9 @@ class JS_PUBLIC_API ContextOptions {
         fuzzing_(false),
         privateClassFields_(false),
         privateClassMethods_(false),
+ #ifdef ENABLE_CHANGE_ARRAY_BY_COPY
+        changeArrayByCopy_(false),
+ #endif
         ergonomicBrandChecks_(false) {
   }
   // clang-format on
@@ -161,6 +164,14 @@ class JS_PUBLIC_API ContextOptions {
     return *this;
   }
 
+#ifdef ENABLE_CHANGE_ARRAY_BY_COPY
+  bool changeArrayByCopy() const { return changeArrayByCopy_; }
+  ContextOptions& setChangeArrayByCopy(bool enabled) {
+    changeArrayByCopy_ = enabled;
+    return *this;
+  }
+#endif
+
   bool classStaticBlocks() const { return classStaticBlocks_; }
   ContextOptions& setClassStaticBlocks(bool enabled) {
     classStaticBlocks_ = enabled;
@@ -276,6 +287,9 @@ class JS_PUBLIC_API ContextOptions {
   bool fuzzing_ : 1;
   bool privateClassFields_ : 1;
   bool privateClassMethods_ : 1;
+#ifdef ENABLE_CHANGE_ARRAY_BY_COPY
+  bool changeArrayByCopy_ : 1;
+#endif
   bool ergonomicBrandChecks_ : 1;
   bool classStaticBlocks_ : 1;
 };

js/src/builtin/TestingFunctions.cpp

@@ -212,6 +212,14 @@ static bool GetRealmConfiguration(JSContext* cx, unsigned argc, Value* vp) {
     return false;
   }
 
+#ifdef ENABLE_CHANGE_ARRAY_BY_COPY
+  bool changeArrayByCopy = cx->options().changeArrayByCopy();
+  if (!JS_SetProperty(cx, info, "enableChangeArrayByCopy",
+                      changeArrayByCopy ? TrueHandleValue : FalseHandleValue)) {
+    return false;
+  }
+#endif
+
   args.rval().setObject(*info);
   return true;
 }
@@ -523,6 +531,15 @@ static bool GetBuildConfiguration(JSContext* cx, unsigned argc, Value* vp) {
     return false;
   }
 
+#ifdef ENABLE_CHANGE_ARRAY_BY_COPY
+  value = BooleanValue(true);
+#else
+  value = BooleanValue(false);
+#endif
+  if (!JS_SetProperty(cx, info, "change-array-by-copy", value)) {
+    return false;
+  }
+
   args.rval().setObject(*info);
   return true;
 }

js/src/shell/js.cpp

@@ -630,6 +630,9 @@ bool shell::enableIteratorHelpers = false;
 bool shell::enablePrivateClassFields = false;
 bool shell::enablePrivateClassMethods = false;
 bool shell::enableErgonomicBrandChecks = true;
+#ifdef ENABLE_CHANGE_ARRAY_BY_COPY
+bool shell::enableChangeArrayByCopy = false;
+#endif
 bool shell::useOffThreadParseGlobal = true;
 bool shell::enableClassStaticBlocks = true;
 #ifdef JS_GC_ZEAL
@@ -11303,6 +11306,9 @@ static bool SetContextOptions(JSContext* cx, const OptionParser& op) {
   enablePrivateClassMethods = !op.getBoolOption("disable-private-methods");
   enableErgonomicBrandChecks =
       !op.getBoolOption("disable-ergonomic-brand-checks");
+#ifdef ENABLE_CHANGE_ARRAY_BY_COPY
+  enableChangeArrayByCopy = op.getBoolOption("enable-change-array-by-copy");
+#endif
   enableClassStaticBlocks = !op.getBoolOption("disable-class-static-blocks");
   useOffThreadParseGlobal = op.getBoolOption("off-thread-parse-global");
   useFdlibmForSinCosTan = op.getBoolOption("use-fdlibm-for-sin-cos-tan");
@@ -11335,6 +11341,9 @@ static bool SetContextOptions(JSContext* cx, const OptionParser& op) {
       .setPrivateClassFields(enablePrivateClassFields)
       .setPrivateClassMethods(enablePrivateClassMethods)
       .setErgnomicBrandChecks(enableErgonomicBrandChecks)
+#ifdef ENABLE_CHANGE_ARRAY_BY_COPY
+      .setChangeArrayByCopy(enableChangeArrayByCopy)
+#endif
       .setClassStaticBlocks(enableClassStaticBlocks);
 
   JS::SetUseOffThreadParseGlobal(useOffThreadParseGlobal);
@@ -12285,6 +12294,15 @@ int main(int argc, char** argv) {
       !op.addBoolOption(
           '\0', "disable-ergonomic-brand-checks",
           "Disable ergonomic brand checks for private class fields") ||
+#ifdef ENABLE_CHANGE_ARRAY_BY_COPY
+      !op.addBoolOption('\0', "enable-change-array-by-copy",
+                        "Enable change-array-by-copy methods") ||
+      !op.addBoolOption('\0', "disable-change-array-by-copy",
+                        "Disable change-array-by-copy methods") ||
+#else
+      !op.addBoolOption('\0', "enable-change-array-by-copy", "no-op") ||
+      !op.addBoolOption('\0', "disable-change-array-by-copy", "no-op") ||
+#endif
       !op.addBoolOption('\0', "enable-top-level-await",
                         "Enable top-level await") ||
       !op.addBoolOption('\0', "disable-class-static-blocks",

js/src/shell/jsshell.h

@@ -136,6 +136,9 @@ extern bool enableIteratorHelpers;
 extern bool enablePrivateClassFields;
 extern bool enablePrivateClassMethods;
 extern bool enableErgonomicBrandChecks;
+#ifdef ENABLE_CHANGE_ARRAY_BY_COPY
+extern bool enableChangeArrayByCopy;
+#endif
 extern bool enableClassStaticBlocks;
 #ifdef JS_GC_ZEAL
 extern uint32_t gZealBits;

js/src/tests/user.js

@@ -34,3 +34,4 @@ user_pref("javascript.options.experimental.weakrefs.expose_cleanupSome", true);
 user_pref("javascript.options.experimental.iterator_helpers", true);
 user_pref("javascript.options.experimental.top_level_await", true);
 user_pref("javascript.options.experimental.ergonomic_brand_checks", true);
+user_pref("javascript.options.experimental.enable_change_array_by_copy", false);

js/xpconnect/src/XPCJSContext.cpp

@@ -989,6 +989,10 @@ static void ReloadPrefsCallback(const char* pref, void* aXpccx) {
 
   bool ergnomicBrandChecksEnabled = Preferences::GetBool(
       JS_OPTIONS_DOT_STR "experimental.ergonomic_brand_checks");
+#ifdef ENABLE_CHANGE_ARRAY_BY_COPY
+  bool enableChangeArrayByCopy = Preferences::GetBool(
+      JS_OPTIONS_DOT_STR "experimental.enable_change_array_by_copy");
+#endif
 
   bool classStaticBlocksEnabled = Preferences::GetBool(
       JS_OPTIONS_DOT_STR "experimental.class_static_blocks");
@@ -1042,6 +1046,9 @@ static void ReloadPrefsCallback(const char* pref, void* aXpccx) {
       .setPrivateClassFields(privateFieldsEnabled)
       .setPrivateClassMethods(privateMethodsEnabled)
       .setClassStaticBlocks(classStaticBlocksEnabled)
+#ifdef ENABLE_CHANGE_ARRAY_BY_COPY
+      .setChangeArrayByCopy(enableChangeArrayByCopy)
+#endif
       .setErgnomicBrandChecks(ergnomicBrandChecksEnabled);
 
   JS::SetUseFdlibmForSinCosTan(

js/xpconnect/tests/chrome/chrome.ini

@@ -34,6 +34,7 @@ support-files =
 prefs =
   javascript.options.large_arraybuffers=true
   javascript.options.experimental.ergonomic_brand_checks=true
+  javascript.options.experimental.enable_change_array_by_copy=false
   
 [test_APIExposer.xhtml]
 [test_bug361111.xhtml]

js/xpconnect/tests/mochitest/mochitest.ini

@@ -44,6 +44,7 @@ prefs =
   javascript.options.weakrefs=true
   javascript.options.experimental.ergonomic_brand_checks=true
   javascript.options.experimental.top_level_await=true
+  javascript.options.experimental.enable_change_array_by_copy=false
 
 [test_bug384632.html]
 [test_bug390488.html]

modules/libpref/init/StaticPrefList.yaml

@@ -6088,6 +6088,12 @@
   value: true
   mirror: always
 
+  # Experimental support for change-array-by-copy methods
+- name: javascript.options.experimental.enable_change_array_by_copy
+  type: bool
+  value: false
+  mirror: always
+
   # Experimental support for Top-level Await in JavaScript.
 -   name: javascript.options.experimental.top_level_await
     type: bool