[wasm] Add Chrome flag for WebAssembly Memory64

Bug: 41480344
Change-Id: I1f2da9409c8762aa0cf3a95f5339c07d95c15efd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5530099
Commit-Queue: Avi Drissman <avi@chromium.org>
Reviewed-by: Avi Drissman <avi@chromium.org>
Auto-Submit: Deepti Gandluri <gdeepti@chromium.org>
Reviewed-by: Adam Klein <adamk@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1301632}

chrome/browser/about_flags.cc

@@ -4037,6 +4037,9 @@ const FeatureEntry kFeatureEntries[] = {
     {"enable-webassembly-tiering", flag_descriptions::kEnableWasmTieringName,
      flag_descriptions::kEnableWasmTieringDescription, kOsAll,
      FEATURE_VALUE_TYPE(features::kWebAssemblyTiering)},
+    {"enable-webassembly-memory64", flag_descriptions::kEnableWasmMemory64Name,
+     flag_descriptions::kEnableWasmMemory64Description, kOsAll,
+     FEATURE_VALUE_TYPE(features::kWebAssemblyMemory64)},
     {"enable-future-v8-vm-features", flag_descriptions::kV8VmFutureName,
      flag_descriptions::kV8VmFutureDescription, kOsAll,
      FEATURE_VALUE_TYPE(features::kV8VmFuture)},

chrome/browser/flag-metadata.json

@@ -4094,6 +4094,14 @@
     // disabled and thus all code is compiled ahead of time.
     "expiry_milestone": -1
   },
+  {
+    "name": "enable-webassembly-memory64",
+    "owners": [ "clemensb@chromium.org", "sbc@chromium.org", "wasm-team@google.com" ],
+    // This flag is used by developers and partners to experiment with
+    // the WebAssembly Memory64 proposal which enables 64-bit indices
+    // on Wasm memory.
+    "expiry_milestone": 135
+  },
   {
     "name": "enable-webassembly-tiering",
     "owners": [ "clemensb@chromium.org", "wasm-team@google.com" ],

chrome/browser/flag_descriptions.cc

@@ -1636,6 +1636,10 @@ const char kEnableWasmGarbageCollectionDescription[] =
     "Enables the experimental Garbage Collection (GC) extensions to "
     "WebAssembly.";
 
+const char kEnableWasmMemory64Name[] = "WebAssembly Memory64";
+const char kEnableWasmMemory64Description[] =
+    "Enables 64-bit memory indices on WebAssembly operations";
+
 const char kEnableWasmRelaxedSimdName[] = "WebAssembly Relaxed SIMD";
 const char kEnableWasmRelaxedSimdDescription[] =
     "Enables the use of WebAssembly vector operations with relaxed semantics";

chrome/browser/flag_descriptions.h

@@ -935,6 +935,9 @@ extern const char kEnableWasmGarbageCollectionDescription[];
 extern const char kEnableWasmLazyCompilationName[];
 extern const char kEnableWasmLazyCompilationDescription[];
 
+extern const char kEnableWasmMemory64Name[];
+extern const char kEnableWasmMemory64Description[];
+
 extern const char kEnableWasmRelaxedSimdName[];
 extern const char kEnableWasmRelaxedSimdDescription[];
 

content/public/common/content_features.cc

@@ -1074,6 +1074,11 @@ BASE_FEATURE(kWebAssemblyLazyCompilation,
              "WebAssemblyLazyCompilation",
              base::FEATURE_ENABLED_BY_DEFAULT);
 
+// Enable WebAssembly Memory64.
+BASE_FEATURE(kWebAssemblyMemory64,
+             "WebAssemblyMemory64",
+             base::FEATURE_DISABLED_BY_DEFAULT);
+
 // Enable WebAssembly tiering (Liftoff -> TurboFan).
 BASE_FEATURE(kWebAssemblyTiering,
              "WebAssemblyTiering",

content/public/common/content_features.h

@@ -227,6 +227,7 @@ CONTENT_EXPORT BASE_DECLARE_FEATURE(kWebAppSystemMediaControlsWin);
 CONTENT_EXPORT BASE_DECLARE_FEATURE(kWebAssemblyBaseline);
 CONTENT_EXPORT BASE_DECLARE_FEATURE(kEnableExperimentalWebAssemblyJSPI);
 CONTENT_EXPORT BASE_DECLARE_FEATURE(kWebAssemblyLazyCompilation);
+CONTENT_EXPORT BASE_DECLARE_FEATURE(kWebAssemblyMemory64);
 CONTENT_EXPORT BASE_DECLARE_FEATURE(kWebAssemblyTiering);
 CONTENT_EXPORT BASE_DECLARE_FEATURE(kWebAssemblyTrapHandler);
 CONTENT_EXPORT BASE_DECLARE_FEATURE(kWebBluetooth);

content/renderer/render_process_impl.cc

@@ -169,6 +169,10 @@ RenderProcessImpl::RenderProcessImpl()
                         "--wasm-lazy-compilation",
                         "--no-wasm-lazy-compilation");
 
+  SetV8FlagIfOverridden(features::kWebAssemblyMemory64,
+                        "--experimental-wasm-memory64",
+                        "--no-experimental-wasm-memory64");
+
   SetV8FlagIfOverridden(features::kWebAssemblyTiering, "--wasm-tier-up",
                         "--no-wasm-tier-up");
 

tools/metrics/histograms/enums.xml

@@ -20798,6 +20798,7 @@ from previous Chrome versions.
   <int value="-205975637" label="WebUIDarkMode:enabled"/>
   <int value="-205401012" label="webrtc-hw-encoding:disabled"/>
   <int value="-204978485" label="WallpaperFullScreenPreview:enabled"/>
+  <int value="-204371461" label="WebAssemblyMemory64:enabled"/>
   <int value="-204355195" label="secondary-ui-md"/>
   <int value="-203968600" label="SyncSupportSecondaryAccount:disabled"/>
   <int value="-203058505" label="QueryTilesSegmentation:disabled"/>
@@ -24811,6 +24812,7 @@ from previous Chrome versions.
   <int value="1558757619"
       label="AccessibilitySelectToSpeakPageMigration:enabled"/>
   <int value="1559034872" label="AutofillPrefilledFields:enabled"/>
+  <int value="1559515245" label="WebAssemblyMemory64:disabled"/>
   <int value="1560188739" label="reader-mode-heuristics"/>
   <int value="1561281771" label="PriceTrackingIconColors:enabled"/>
   <int value="1561833662" label="AndroidBrowserControlsInViz:disabled"/>