G1: Refactor remembered sets

Summary

Obsolete the product options -XX:G1RSetRegionEntries and -XX:G1RSetSparseRegionEntries for removal. The algorithms and data structures they configure have been removed.

Using these options will generate a warning. These options will be removed in a future release.

Problem

In JDK-8017163 the existing remembered set storing cards in the Java heap has been replaced by a completely new implementation. So these configuration options are not in use any more.

Solution

Obsolete the affected options -XX:G1RSetSparseRegionEntries and -XX:G1RSetRegionEntries for later removal.

Specification

diff --git a/src/hotspot/share/runtime/arguments.cpp b/src/hotspot/share/runtime/arguments.cpp
index d1116467de1..c6b9307d8fb 100644
--- a/src/hotspot/share/runtime/arguments.cpp
+++ b/src/hotspot/share/runtime/arguments.cpp
@@ -525,6 +525,8 @@ static SpecialFlag const special_jvm_flags[] = {
   { "SuspendRetryCount",            JDK_Version::undefined(), JDK_Version::jdk(17), JDK_Version::jdk(18) },
   { "SuspendRetryDelay",            JDK_Version::undefined(), JDK_Version::jdk(17), JDK_Version::jdk(18) },
   { "CriticalJNINatives",           JDK_Version::jdk(16), JDK_Version::jdk(17), JDK_Version::jdk(18) },
+  { "G1RSetRegionEntries",          JDK_Version::undefined(), JDK_Version::jdk(18), JDK_Version::jdk(19) },
+  { "G1RSetSparseRegionEntries",    JDK_Version::undefined(), JDK_Version::jdk(18), JDK_Version::jdk(19) },
   { "AlwaysLockClassLoader",        JDK_Version::jdk(17), JDK_Version::jdk(18), JDK_Version::jdk(19) },
   { "UseBiasedLocking",             JDK_Version::jdk(15), JDK_Version::jdk(18), JDK_Version::jdk(19) },
   { "BiasedLockingStartupDelay",    JDK_Version::jdk(15), JDK_Version::jdk(18), JDK_Version::jdk(19) },