diff -r b786280276dc -r 2f1b308b4469 src/hotspot/share/prims/whitebox.cpp
--- a/src/hotspot/share/prims/whitebox.cpp	Wed Mar 28 11:38:47 2018 +0200
+++ b/src/hotspot/share/prims/whitebox.cpp	Wed Mar 28 11:38:47 2018 +0200
@@ -32,6 +32,7 @@
 #include "code/codeCache.hpp"
 #include "compiler/methodMatcher.hpp"
 #include "compiler/directivesParser.hpp"
+#include "gc/shared/gcConfig.hpp"
 #include "gc/shared/genCollectedHeap.hpp"
 #include "jvmtifiles/jvmtiEnv.hpp"
 #include "memory/metadataFactory.hpp"
@@ -312,47 +313,16 @@
                                         (size_t) magnitude, (size_t) iterations);
 WB_END
 
-static const jint serial_code   = 1;
-static const jint parallel_code = 2;
-static const jint cms_code      = 4;
-static const jint g1_code       = 8;
-
-WB_ENTRY(jint, WB_CurrentGC(JNIEnv* env, jobject o, jobject obj))
-  if (UseSerialGC) {
-    return serial_code;
-  } else if (UseParallelGC || UseParallelOldGC) {
-    return parallel_code;
-  } if (UseConcMarkSweepGC) {
-    return cms_code;
-  } else if (UseG1GC) {
-    return g1_code;
-  }
-  ShouldNotReachHere();
-  return 0;
+WB_ENTRY(jboolean, WB_IsGCSupported(JNIEnv* env, jobject o, jint name))
+  return GCConfig::is_gc_supported((CollectedHeap::Name)name);
 WB_END
 
-WB_ENTRY(jint, WB_AllSupportedGC(JNIEnv* env, jobject o, jobject obj))
-#if INCLUDE_ALL_GCS
-  return serial_code | parallel_code | cms_code | g1_code;
-#else
-  return serial_code;
-#endif // INCLUDE_ALL_GCS
+WB_ENTRY(jboolean, WB_IsGCSelected(JNIEnv* env, jobject o, jint name))
+  return GCConfig::is_gc_selected((CollectedHeap::Name)name);
 WB_END
 
-WB_ENTRY(jboolean, WB_GCSelectedByErgo(JNIEnv* env, jobject o, jobject obj))
-  if (UseSerialGC) {
-    return FLAG_IS_ERGO(UseSerialGC);
-  } else if (UseParallelGC) {
-    return FLAG_IS_ERGO(UseParallelGC);
-  } else if (UseParallelOldGC) {
-    return FLAG_IS_ERGO(UseParallelOldGC);
-  } else if (UseConcMarkSweepGC) {
-    return FLAG_IS_ERGO(UseConcMarkSweepGC);
-  } else if (UseG1GC) {
-    return FLAG_IS_ERGO(UseG1GC);
-  }
-  ShouldNotReachHere();
-  return false;
+WB_ENTRY(jboolean, WB_IsGCSelectedErgonomically(JNIEnv* env, jobject o))
+  return GCConfig::is_gc_selected_ergonomically();
 WB_END
 
 WB_ENTRY(jboolean, WB_isObjectInOldGen(JNIEnv* env, jobject o, jobject obj))
@@ -2162,10 +2132,10 @@
   {CC"handshakeWalkStack", CC"(Ljava/lang/Thread;Z)I", (void*)&WB_HandshakeWalkStack },
   {CC"addCompilerDirective",    CC"(Ljava/lang/String;)I",
                                                       (void*)&WB_AddCompilerDirective },
-  {CC"removeCompilerDirective",   CC"(I)V",             (void*)&WB_RemoveCompilerDirective },
-  {CC"currentGC",                 CC"()I",            (void*)&WB_CurrentGC},
-  {CC"allSupportedGC",            CC"()I",            (void*)&WB_AllSupportedGC},
-  {CC"gcSelectedByErgo",          CC"()Z",            (void*)&WB_GCSelectedByErgo},
+  {CC"removeCompilerDirective",   CC"(I)V",           (void*)&WB_RemoveCompilerDirective },
+  {CC"isGCSupported",             CC"(I)Z",           (void*)&WB_IsGCSupported},
+  {CC"isGCSelected",              CC"(I)Z",           (void*)&WB_IsGCSelected},
+  {CC"isGCSelectedErgonomically", CC"()Z",            (void*)&WB_IsGCSelectedErgonomically},
   {CC"supportsConcurrentGCPhaseControl", CC"()Z",     (void*)&WB_SupportsConcurrentGCPhaseControl},
   {CC"getConcurrentGCPhases",     CC"()[Ljava/lang/String;",
                                                       (void*)&WB_GetConcurrentGCPhases},