[GR-67472] Fix options ReservedAddressSpaceSize and MaxReservedAddressSpaceSize.

PullRequest: graal/21445

Author: christianhaeubl

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

@@ -144,13 +144,16 @@ public AddressRangeCommittedMemoryProvider() {
     @Override
     @Uninterruptible(reason = "Still being initialized.")
     public int initialize(WordPointer heapBasePointer, IsolateArguments arguments) {
-        UnsignedWord maxAddressSpaceSize = ReferenceAccess.singleton().getMaxAddressSpaceSize();
         UnsignedWord reserved = Word.unsigned(IsolateArgumentAccess.readLong(arguments, IsolateArgumentParser.getOptionIndex(SubstrateGCOptions.ReservedAddressSpaceSize)));
         if (reserved.equal(0)) {
-            /* Reserve a 32 GB address space, except if a larger heap size was specified. */
+            /*
+             * Reserve a 32 GB address space, except if a larger heap size was specified, or if the
+             * maximum address space size is less than that.
+             */
             UnsignedWord maxHeapSize = Word.unsigned(IsolateArgumentAccess.readLong(arguments, IsolateArgumentParser.getOptionIndex(SubstrateGCOptions.MaxHeapSize)));
-            reserved = UnsignedUtils.clamp(maxHeapSize, Word.unsigned(MIN_RESERVED_ADDRESS_SPACE_SIZE), maxAddressSpaceSize);
+            reserved = UnsignedUtils.max(maxHeapSize, Word.unsigned(MIN_RESERVED_ADDRESS_SPACE_SIZE));
         }
+        reserved = UnsignedUtils.min(reserved, ReferenceAccess.singleton().getMaxAddressSpaceSize());
 
         UnsignedWord alignment = unsigned(Heap.getHeap().getPreferredAddressSpaceAlignment());
         WordPointer beginOut = StackValue.get(WordPointer.class);

substratevm/src/com.oracle.svm.core/src/com/oracle/svm/core/IsolateArgumentParser.java

@@ -389,7 +389,14 @@ protected void initialize(IsolateArguments arguments, CEntryPointCreateIsolatePa
             arguments.setIsCompilationIsolate(false);
         }
 
-        writeLong(arguments, getOptionIndex(SubstrateGCOptions.ReservedAddressSpaceSize), parameters.reservedSpaceSize().rawValue());
+        /*
+         * If a value for ReservedAddressSpaceSize is set in the isolate parameters, then this value
+         * has a higher priority than a default value that was set at build-time.
+         */
+        UnsignedWord reservedAddressSpaceSize = parameters.reservedSpaceSize();
+        if (reservedAddressSpaceSize.notEqual(0)) {
+            writeLong(arguments, getOptionIndex(SubstrateGCOptions.ReservedAddressSpaceSize), reservedAddressSpaceSize.rawValue());
+        }
     }
 
     @Uninterruptible(reason = CALLED_FROM_UNINTERRUPTIBLE_CODE, mayBeInlined = true)