Adjust MaxSurvivorSpaces option depending on policy.

Author: peter-hofer

substratevm/src/com.oracle.svm.core.genscavenge/src/com/oracle/svm/core/genscavenge/AbstractCollectionPolicy.java

@@ -42,6 +42,13 @@
 
 abstract class AbstractCollectionPolicy implements CollectionPolicy {
 
+    protected static final int MAX_TENURING_THRESHOLD = 15;
+
+    static int getMaxSurvivorSpaces(Integer optionValue) {
+        assert optionValue == null || optionValue >= 0;
+        return (optionValue != null) ? optionValue : AbstractCollectionPolicy.MAX_TENURING_THRESHOLD;
+    }
+
     /*
      * Constants that can be made options if desirable. These are -XX options in HotSpot, refer to
      * their descriptions for details. The values are HotSpot defaults unless labeled otherwise.

substratevm/src/com.oracle.svm.core.genscavenge/src/com/oracle/svm/core/genscavenge/BasicCollectionPolicies.java

@@ -50,6 +50,11 @@ public static class Options {
         public static final HostedOptionKey<Long> AllocationBeforePhysicalMemorySize = new HostedOptionKey<>(1L * 1024L * 1024L);
     }
 
+    static int getMaxSurvivorSpaces(@SuppressWarnings("unused") Integer optionValue) {
+        assert optionValue == null || optionValue >= 0;
+        return 0; // override option (if set): 0 not supported
+    }
+
     private BasicCollectionPolicies() {
     }
 

substratevm/src/com.oracle.svm.core.genscavenge/src/com/oracle/svm/core/genscavenge/CollectionPolicy.java

@@ -43,17 +43,23 @@ final class Options {
     }
 
     @Platforms(Platform.HOSTED_ONLY.class)
-    static CollectionPolicy getInitialPolicy() {
+    static String getInitialPolicyName() {
         if (SubstrateOptions.UseEpsilonGC.getValue()) {
-            return new BasicCollectionPolicies.NeverCollect();
+            return "NeverCollect";
         } else if (!SubstrateOptions.useRememberedSet()) {
-            return new BasicCollectionPolicies.OnlyCompletely();
+            return "OnlyCompletely";
         }
         String name = Options.InitialCollectionPolicy.getValue();
         String legacyPrefix = "com.oracle.svm.core.genscavenge.CollectionPolicy$";
         if (name.startsWith(legacyPrefix)) {
-            name = name.substring(legacyPrefix.length());
+            return name.substring(legacyPrefix.length());
         }
+        return name;
+    }
+
+    @Platforms(Platform.HOSTED_ONLY.class)
+    static CollectionPolicy getInitialPolicy() {
+        String name = getInitialPolicyName();
         switch (name) {
             case "Adaptive":
                 return new AdaptiveCollectionPolicy();
@@ -71,6 +77,15 @@ static CollectionPolicy getInitialPolicy() {
         throw UserError.abort("Policy %s does not exist.", name);
     }
 
+    @Platforms(Platform.HOSTED_ONLY.class)
+    static int getMaxSurvivorSpaces(Integer optionValue) {
+        String name = getInitialPolicyName();
+        if ("Adaptive".equals(name) || "Proportionate".equals(name)) {
+            return AbstractCollectionPolicy.getMaxSurvivorSpaces(optionValue);
+        }
+        return BasicCollectionPolicies.getMaxSurvivorSpaces(optionValue);
+    }
+
     String getName();
 
     /**

substratevm/src/com.oracle.svm.core.genscavenge/src/com/oracle/svm/core/genscavenge/HeapParameters.java

@@ -25,9 +25,11 @@
 package com.oracle.svm.core.genscavenge;
 
 import org.graalvm.collections.EconomicMap;
+import org.graalvm.collections.UnmodifiableEconomicMap;
 import org.graalvm.compiler.api.replacements.Fold;
 import org.graalvm.compiler.options.Option;
 import org.graalvm.compiler.options.OptionKey;
+import org.graalvm.compiler.options.OptionValues;
 import org.graalvm.compiler.word.Word;
 import org.graalvm.nativeimage.Platform;
 import org.graalvm.nativeimage.Platforms;
@@ -81,7 +83,20 @@ protected void onValueUpdate(EconomicMap<OptionKey<?>, Object> values, Long oldV
         public static final RuntimeOptionKey<Boolean> TraceHeapChunks = new RuntimeOptionKey<>(false);
 
         @Option(help = "Maximum number of survivor spaces.") //
-        public static final HostedOptionKey<Integer> MaxSurvivorSpaces = new HostedOptionKey<>(15);
+        public static final HostedOptionKey<Integer> MaxSurvivorSpaces = new HostedOptionKey<Integer>(15) {
+            @Override
+            public Integer getValueOrDefault(UnmodifiableEconomicMap<OptionKey<?>, Object> values) {
+                Integer value = (Integer) values.get(this);
+                UserError.guarantee(value == null || value >= 0, "%s value must be greater than or equal to 0", getName());
+                return CollectionPolicy.getMaxSurvivorSpaces(value);
+            }
+
+            @Override
+            public Integer getValue(OptionValues values) {
+                assert checkDescriptorExists();
+                return getValueOrDefault(values.getMap());
+            }
+        };
 
         @Option(help = "Determines if a full GC collects the young generation separately or together with the old generation.") //
         public static final RuntimeOptionKey<Boolean> CollectYoungGenerationSeparately = new RuntimeOptionKey<>(false);