8270991: G1 Full GC always performs heap verification after JDK-8269295

Reviewed-by: iwalulya, kbarrett

src/hotspot/share/gc/g1/g1CollectedHeap.cpp

@@ -1028,6 +1028,9 @@ void G1CollectedHeap::prepare_heap_for_full_collection() {
 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
   assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
   assert_used_and_recalculate_used_equal(this);
+  if (!VerifyBeforeGC) {
+    return;
+  }
   _verifier->verify_region_sets_optional();
   _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
   _verifier->check_bitmaps("Full GC Start");
@@ -1073,6 +1076,9 @@ void G1CollectedHeap::abort_refinement() {
 }
 
 void G1CollectedHeap::verify_after_full_collection() {
+  if (!VerifyAfterGC) {
+    return;
+  }
   _hrm.verify_optional();
   _verifier->verify_region_sets_optional();
   _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);

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

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2015, 2021, 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
@@ -34,6 +34,8 @@
  * @modules java.management
  * @library /test/lib
  * @library /
+ * @build sun.hotspot.WhiteBox
+ * @run driver jdk.test.lib.helpers.ClassFileInstaller sun.hotspot.WhiteBox
  * @run driver gc.arguments.TestVerifyBeforeAndAfterGCFlags
  */
 
@@ -44,6 +46,8 @@
 import jdk.test.lib.process.OutputAnalyzer;
 import jdk.test.lib.process.ProcessTools;
 
+import sun.hotspot.WhiteBox;
+
 public class TestVerifyBeforeAndAfterGCFlags {
 
     // VerifyBeforeGC:[Verifying threads heap tenured eden syms strs zone dict metaspace chunks hand code cache ]
@@ -63,30 +67,40 @@ public static void main(String args[]) throws Exception {
                                                    "-XX:-DisplayVMOutput",
                                                    "VerifyBeforeGC",
                                                    "VerifyAfterGC" });
-        testVerifyFlags(false, false, filteredOpts);
-        testVerifyFlags(true,  true,  filteredOpts);
-        testVerifyFlags(true,  false, filteredOpts);
-        testVerifyFlags(false, true,  filteredOpts);
+        // Young GC
+        testVerifyFlags(false, false, false, filteredOpts);
+        testVerifyFlags(true,  true,  false, filteredOpts);
+        testVerifyFlags(true,  false, false, filteredOpts);
+        testVerifyFlags(false, true,  false, filteredOpts);
+        // Full GC
+        testVerifyFlags(false, false, true, filteredOpts);
+        testVerifyFlags(true,  true,  true, filteredOpts);
+        testVerifyFlags(true,  false, true, filteredOpts);
+        testVerifyFlags(false, true,  true, filteredOpts);
     }
 
     public static void testVerifyFlags(boolean verifyBeforeGC,
                                        boolean verifyAfterGC,
+                                       boolean doFullGC,
                                        String[] opts) throws Exception {
         ArrayList<String> vmOpts = new ArrayList<>();
         if (opts != null && (opts.length > 0)) {
             Collections.addAll(vmOpts, opts);
         }
         Collections.addAll(vmOpts, new String[] {
+                                       "-Xbootclasspath/a:.",
+                                       "-XX:+UnlockDiagnosticVMOptions",
+                                       "-XX:+WhiteBoxAPI",
                                        "-Xlog:gc+verify=debug",
                                        "-Xmx5m",
                                        "-Xms5m",
                                        "-Xmn3m",
-                                       "-XX:+UnlockDiagnosticVMOptions",
                                        (verifyBeforeGC ? "-XX:+VerifyBeforeGC"
                                                        : "-XX:-VerifyBeforeGC"),
                                        (verifyAfterGC ? "-XX:+VerifyAfterGC"
                                                       : "-XX:-VerifyAfterGC"),
-                                       GarbageProducer.class.getName() });
+                                       GarbageProducer.class.getName(),
+                                       doFullGC ? "t" : "f" });
         ProcessBuilder pb = GCArguments.createJavaProcessBuilder(vmOpts);
         OutputAnalyzer analyzer = new OutputAnalyzer(pb.start());
 
@@ -111,10 +125,12 @@ public static class GarbageProducer {
         static long[][] garbage = new long[10][];
 
         public static void main(String args[]) {
-            int j = 0;
-            for(int i = 0; i<1000; i++) {
-                garbage[j] = new long[10000];
-                j = (j+1)%garbage.length;
+            WhiteBox wb = WhiteBox.getWhiteBox();
+
+            if (args[0].equals("t")) {
+                wb.fullGC();
+            } else {
+                wb.youngGC();
             }
         }
     }