[wasm] Bump helix V8 image and re-enable exnref CI legs (#129849)

eng/pipelines/common/templates/wasm-runtime-tests.yml

@@ -48,10 +48,5 @@ jobs:
             creator: dotnet-bot
             testRunNamePrefixSuffix: Mono_$(_BuildConfig)
             testBuildArgs: /p:InstallV8ForTests=false
-            # Build the runtime tests for browser, but don't send them to Helix to run on V8: the
-            # V8 baked into the helix-webassembly container doesn't support exnref
-            # yet, so the tests abort at startup. Re-enable the run once the new V8 image is
-            # available. See ActiveIssue https://github.com/dotnet/runtime/issues/129849
-            sendToHelix: false
       extraVariablesTemplates:
         - template: /eng/pipelines/common/templates/runtimes/test-variables.yml

eng/pipelines/coreclr/templates/helix-queues-setup.yml

@@ -70,9 +70,9 @@ jobs:
     # Browser wasm
     - ${{ if eq(parameters.platform, 'browser_wasm') }}:
       - ${{ if eq(variables['System.TeamProject'], 'public') }}:
-        - (Ubuntu.2604.Amd64.Open)AzureLinux.3.Amd64.Open@mcr.microsoft.com/dotnet-buildtools/prereqs:ubuntu-26.04-helix-webassembly-amd64@sha256:3ef1314b50ac039078f6406d649d5ac72715deccd07bcbfe3dd43fa438be3fbd
+        - (Ubuntu.2604.Amd64.Open)AzureLinux.3.Amd64.Open@mcr.microsoft.com/dotnet-buildtools/prereqs:ubuntu-26.04-helix-webassembly-amd64@sha256:73db6e433bb7e9ef8546b35688b727f2f559b9ac5fea21c77d56795b74b197b8
       - ${{ if eq(variables['System.TeamProject'], 'internal') }}:
-        - (Ubuntu.2604.Amd64)AzureLinux.3.Amd64@mcr.microsoft.com/dotnet-buildtools/prereqs:ubuntu-26.04-helix-webassembly-amd64@sha256:3ef1314b50ac039078f6406d649d5ac72715deccd07bcbfe3dd43fa438be3fbd
+        - (Ubuntu.2604.Amd64)AzureLinux.3.Amd64@mcr.microsoft.com/dotnet-buildtools/prereqs:ubuntu-26.04-helix-webassembly-amd64@sha256:73db6e433bb7e9ef8546b35688b727f2f559b9ac5fea21c77d56795b74b197b8
 
     # iOS devices
     - ${{ if in(parameters.platform, 'ios_arm64') }}:

eng/pipelines/libraries/helix-queues-setup.yml

@@ -170,15 +170,15 @@ jobs:
 
     # WASI
     - ${{ if eq(parameters.platform, 'wasi_wasm') }}:
-      - (Ubuntu.2604.Amd64.Open)AzureLinux.3.Amd64.Open@mcr.microsoft.com/dotnet-buildtools/prereqs:ubuntu-26.04-helix-webassembly-amd64@sha256:3ef1314b50ac039078f6406d649d5ac72715deccd07bcbfe3dd43fa438be3fbd
+      - (Ubuntu.2604.Amd64.Open)AzureLinux.3.Amd64.Open@mcr.microsoft.com/dotnet-buildtools/prereqs:ubuntu-26.04-helix-webassembly-amd64@sha256:73db6e433bb7e9ef8546b35688b727f2f559b9ac5fea21c77d56795b74b197b8
 
     # Browser WebAssembly
     - ${{ if eq(parameters.platform, 'browser_wasm') }}:
-      - (Ubuntu.2604.Amd64.Open)AzureLinux.3.Amd64.Open@mcr.microsoft.com/dotnet-buildtools/prereqs:ubuntu-26.04-helix-webassembly-amd64@sha256:3ef1314b50ac039078f6406d649d5ac72715deccd07bcbfe3dd43fa438be3fbd
+      - (Ubuntu.2604.Amd64.Open)AzureLinux.3.Amd64.Open@mcr.microsoft.com/dotnet-buildtools/prereqs:ubuntu-26.04-helix-webassembly-amd64@sha256:73db6e433bb7e9ef8546b35688b727f2f559b9ac5fea21c77d56795b74b197b8
 
     # Browser WebAssembly Firefox
     - ${{ if eq(parameters.platform, 'browser_wasm_firefox') }}:
-      - (Ubuntu.2604.Amd64.Open)AzureLinux.3.Amd64.Open@mcr.microsoft.com/dotnet-buildtools/prereqs:ubuntu-26.04-helix-webassembly-amd64@sha256:3ef1314b50ac039078f6406d649d5ac72715deccd07bcbfe3dd43fa438be3fbd
+      - (Ubuntu.2604.Amd64.Open)AzureLinux.3.Amd64.Open@mcr.microsoft.com/dotnet-buildtools/prereqs:ubuntu-26.04-helix-webassembly-amd64@sha256:73db6e433bb7e9ef8546b35688b727f2f559b9ac5fea21c77d56795b74b197b8
 
     # Browser WebAssembly windows
     - ${{ if in(parameters.platform, 'browser_wasm_win', 'wasi_wasm_win') }}:

eng/pipelines/performance/runtime-wasm-perf.yml

@@ -4,11 +4,15 @@
 
 trigger: none
 
-# Disabled: the perf wasm v8 job installs V8 via jsvu, and the V8 binary it currently
-# installs does not support exnref yet, so the MicroBenchmarks Helix
-# job aborts at startup. Re-enable once an exnref-capable V8 is pinned. See
-# ActiveIssue https://github.com/dotnet/runtime/issues/129849
-pr: none
+pr:
+  branches:
+    include:
+    - main
+  paths:
+    include:
+    - eng/pipelines/performance/*
+    - eng/testing/performance/*
+    - eng/testing/BrowserVersions.props
 
 resources:
   repositories:

eng/pipelines/runtime-linker-tests.yml

@@ -135,11 +135,5 @@ extends:
             postBuildSteps:
               - template: /eng/pipelines/libraries/execute-trimming-tests-steps.yml
                 parameters:
-                    # Publish the trimmed browser apps, but don't run them on V8: the V8 baked into
-                    # the helix-webassembly container doesn't support exnref yet,
-                    # so run-v8.sh aborts at startup. SkipTrimmingTestsRun keeps the build/publish
-                    # coverage and only skips ExecuteApplications. Re-enable the run once the new V8
-                    # image is available. See
-                    # ActiveIssue https://github.com/dotnet/runtime/issues/129849
-                    extraTestArgs: '/p:WasmBuildNative=false /p:RuntimeFlavor=Mono /p:ToolsConfiguration=Debug /p:SkipTrimmingTestsRun=true'
+                    extraTestArgs: '/p:WasmBuildNative=false /p:RuntimeFlavor=Mono /p:ToolsConfiguration=Debug'
                     runAotTests: false

eng/pipelines/runtime.yml

@@ -1009,8 +1009,7 @@ extends:
           extraBuildArgs: /p:AotHostArchitecture=x64 /p:AotHostOS=$(_hostedOS)
           scenarios:
             - WasmTestOnFirefox
-            # ActiveIssue https://github.com/dotnet/runtime/issues/129849
-            # - WasmTestOnV8
+            - WasmTestOnV8
 
       # EAT Library tests - only run on linux
       - template: /eng/pipelines/common/templates/wasm-library-aot-tests.yml

src/tasks/WasmBuildTasks/UpdateChromeVersions.cs

@@ -25,6 +25,11 @@ public partial class UpdateChromeVersions : MBU.Task
     private const string s_v8CanaryBaseUrl = "https://storage.googleapis.com/chromium-v8/official/canary";
     private const int s_versionCheckThresholdDays = 1;
 
+    // The V8 used for testing must support the standardized exnref exception-handling proposal.
+    // Chrome milestones can map to older V8 builds, so never downgrade the pinned V8 below this
+    // floor. See https://github.com/dotnet/runtime/issues/129849
+    private static readonly Version s_minV8Version = new(15, 1, 103);
+
     private static readonly HttpClient s_httpClient = new();
 
     [GeneratedRegex("#define V8_BUILD_NUMBER (\\d+)")]
@@ -215,23 +220,24 @@ private static void UpdateNodeValue(XmlDocument xmlDoc, string nodeName, string
 
         string foundV8Version = await FindV8VersionFromChromeVersion(foundRelease.version).ConfigureAwait(false);
 
+        // Never downgrade V8 below the exnref-capable floor, even if the Chrome milestone maps to an older build.
+        if (Version.TryParse(foundV8Version, out Version? candidateV8Version) && candidateV8Version < s_minV8Version)
+        {
+            string existingV8Version = GetExistingV8Version(osIdentifier);
+            Log.LogWarning($"Computed V8 version {foundV8Version} for {osIdentifier} is below the minimum " +
+                            $"exnref-capable version {s_minV8Version} — keeping the existing V8 version {existingV8Version}.");
+            foundV8Version = existingV8Version;
+            if (string.IsNullOrEmpty(foundV8Version))
+                throw new LogAsErrorException($"Computed V8 version for {osIdentifier} is below {s_minV8Version} and no existing version found in {ChromeVersionsPath}");
+        }
         // Validate that a prebuilt V8 binary exists on the CDN that jsvu uses for downloading.
-        if (!await IsV8BinaryAvailableAsync(osPrefix, foundV8Version).ConfigureAwait(false))
+        else if (!await IsV8BinaryAvailableAsync(osPrefix, foundV8Version).ConfigureAwait(false))
         {
             string v8BinaryUrl = GetV8BinaryUrl(osPrefix, foundV8Version);
             Log.LogWarning($"V8 binary not available at {v8BinaryUrl} — keeping the existing V8 version for {osIdentifier}.");
 
             // Fall back to the existing V8 version from BrowserVersions.props
-            XmlDocument existingDoc = new XmlDocument();
-            existingDoc.Load(ChromeVersionsPath);
-            string existingV8VersionNodeName = string.Equals(osIdentifier, "linux", StringComparison.OrdinalIgnoreCase)
-                ? "linux_V8Version"
-                : string.Equals(osIdentifier, "windows", StringComparison.OrdinalIgnoreCase)
-                    ? "win_V8Version"
-                    : string.Equals(osIdentifier, "Mac", StringComparison.OrdinalIgnoreCase)
-                        ? "macos_V8Version"
-                        : throw new LogAsErrorException($"Unknown OS identifier '{osIdentifier}' for V8 version fallback");
-            foundV8Version = GetNodeValue(existingDoc, existingV8VersionNodeName);
+            foundV8Version = GetExistingV8Version(osIdentifier);
             if (string.IsNullOrEmpty(foundV8Version))
                 throw new LogAsErrorException($"V8 binary for {osIdentifier} not available on CDN and no existing version found in {ChromeVersionsPath}");
         }
@@ -279,6 +285,20 @@ async Task<string> FindV8VersionFromChromeVersion(string chromeVersion)
         }
     }
 
+    private string GetExistingV8Version(string osIdentifier)
+    {
+        XmlDocument existingDoc = new XmlDocument();
+        existingDoc.Load(ChromeVersionsPath);
+        string existingV8VersionNodeName = string.Equals(osIdentifier, "linux", StringComparison.OrdinalIgnoreCase)
+            ? "linux_V8Version"
+            : string.Equals(osIdentifier, "windows", StringComparison.OrdinalIgnoreCase)
+                ? "win_V8Version"
+                : string.Equals(osIdentifier, "Mac", StringComparison.OrdinalIgnoreCase)
+                    ? "macos_V8Version"
+                    : throw new LogAsErrorException($"Unknown OS identifier '{osIdentifier}' for V8 version fallback");
+        return GetNodeValue(existingDoc, existingV8VersionNodeName);
+    }
+
     private static string GetV8BinaryUrl(string osPrefix, string v8Version)
     {
         string jsvuPlatform = osPrefix switch