Test fix for TestNewSizeFlags.java to reflect bew max of young gen spaces

Author: jsikstro

test/hotspot/jtreg/gc/arguments/TestNewSizeFlags.java

@@ -286,6 +286,20 @@ private static MemoryUsage getYoungGenUsage() {
             if (YOUNG_GC_TYPE == GCTypes.YoungGCType.G1) {
                 return new MemoryUsage(edenUsageInit + survivorUsageInit, 0,
                         edenUsageCommited + survivorUsageCommited, Long.MAX_VALUE);
+            } else if (YOUNG_GC_TYPE == GCTypes.YoungGCType.DefNew) {
+                // Eden might grow to be almost the entire young generation,
+                // so it is approximated as the size for the entire young
+                // generation.
+                long youngGenUsageMax = edenUsage.getMax();
+
+                long combinedSurvivorUsageMax = 2 * survivorUsage.getMax();
+                if (combinedSurvivorUsageMax > youngGenUsageMax) {
+                  throw new RuntimeException("Unexpectedly large survivorUsage combined maximum value: " + combinedSurvivorUsageMax);
+                }
+
+                return new MemoryUsage(edenUsageInit + survivorUsageInit * 2, 0,
+                        edenUsageCommited + survivorUsageCommited * 2,
+                        youngGenUsageMax);
             } else {
                 return new MemoryUsage(edenUsageInit + survivorUsageInit * 2, 0,
                         edenUsageCommited + survivorUsageCommited * 2,