[GR-51349] Let getMaxLaneCount() report zero for now.

PullRequest: graal/16584

Author: fniephaus

substratevm/src/com.oracle.svm.core/src/com/oracle/svm/core/jdk/Target_jdk_internal_vm_vector_VectorSupport.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2023, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2023, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -27,7 +27,6 @@
 import com.oracle.svm.core.annotate.Delete;
 import com.oracle.svm.core.annotate.Substitute;
 import com.oracle.svm.core.annotate.TargetClass;
-import com.oracle.svm.core.util.VMError;
 
 @TargetClass(className = "jdk.internal.vm.vector.VectorSupport")
 public final class Target_jdk_internal_vm_vector_VectorSupport {
@@ -37,6 +36,10 @@ public final class Target_jdk_internal_vm_vector_VectorSupport {
     @SuppressWarnings("unused")
     @Substitute
     public static int getMaxLaneCount(Class<?> etype) {
-        throw VMError.unsupportedFeature("VectorSupport.getMaxLaneCount not supported.");
+        /*
+         * GR-51303: The Vector API is not yet optimized by the Graal compiler. But instead of
+         * letting applications fail, always return a max lane count of zero for now.
+         */
+        return 0;
     }
 }

substratevm/src/com.oracle.svm.hosted/src/com/oracle/svm/hosted/ProgressReporterFeature.java

@@ -45,6 +45,7 @@
 import com.oracle.svm.hosted.util.CPUTypeAMD64;
 import com.oracle.svm.hosted.util.CPUTypeRISCV64;
 import com.oracle.svm.util.LogUtils;
+import com.oracle.svm.util.ReflectionUtil;
 
 @AutomaticallyRegisteredFeature
 public class ProgressReporterFeature implements InternalFeature {
@@ -62,6 +63,15 @@ public void duringAnalysis(DuringAnalysisAccess access) {
         reporter.reportStageProgress();
     }
 
+    @Override
+    public void afterAnalysis(AfterAnalysisAccess access) {
+        var vectorSpeciesClass = ReflectionUtil.lookupClass(true, "jdk.incubator.vector.VectorSpecies");
+        if (vectorSpeciesClass != null && access.isReachable(vectorSpeciesClass)) {
+            LogUtils.warning(
+                            "This application uses a preview of the Vector API, which is functional but slow on Native Image because it is not yet optimized by the Graal compiler. Please keep this in mind when evaluating performance.");
+        }
+    }
+
     @Override
     public void afterCompilation(AfterCompilationAccess access) {
         if (SubstrateOptions.BuildOutputBreakdowns.getValue()) {