8269126: Rename G1AllowPreventiveGC option to G1UsePreventiveGC

Reviewed-by: iwalulya, kbarrett

Author: Thomas Schatzl

src/hotspot/share/gc/g1/g1Policy.cpp

@@ -1416,7 +1416,7 @@ static size_t get_num_regions_adjust_for_plab_waste(size_t byte_count) {
 }
 
 bool G1Policy::preventive_collection_required(uint alloc_region_count) {
-  if (!G1AllowPreventiveGC || !Universe::is_fully_initialized()) {
+  if (!G1UsePreventiveGC || !Universe::is_fully_initialized()) {
     // Don't attempt any preventive GC's if the feature is disabled,
     // or before initialization is complete.
     return false;

src/hotspot/share/gc/g1/g1_globals.hpp

@@ -340,7 +340,7 @@
           "percentage of the currently used memory.")                       \
           range(0.0, 1.0)                                                   \
                                                                             \
-  product(bool, G1AllowPreventiveGC, true, DIAGNOSTIC,                      \
+  product(bool, G1UsePreventiveGC, true, DIAGNOSTIC,                        \
           "Allows collections to be triggered proactively based on the      \
            number of free regions and the expected survival rates in each   \
            section of the heap.")

test/hotspot/jtreg/gc/g1/TestGCLogMessages.java

@@ -248,7 +248,7 @@ private void testWithEvacuationFailureLogs() throws Exception {
                                                                   "-XX:G1EvacuationFailureALotCount=100",
                                                                   "-XX:G1EvacuationFailureALotInterval=1",
                                                                   "-XX:+UnlockDiagnosticVMOptions",
-                                                                  "-XX:-G1AllowPreventiveGC",
+                                                                  "-XX:-G1UsePreventiveGC",
                                                                   "-Xlog:gc+phases=debug",
                                                                   GCTestWithEvacuationFailure.class.getName());
 
@@ -261,7 +261,7 @@ private void testWithEvacuationFailureLogs() throws Exception {
                                                    "-Xmn16M",
                                                    "-Xms32M",
                                                    "-XX:+UnlockDiagnosticVMOptions",
-                                                   "-XX:-G1AllowPreventiveGC",
+                                                   "-XX:-G1UsePreventiveGC",
                                                    "-Xlog:gc+phases=trace",
                                                    GCTestWithEvacuationFailure.class.getName());
 

test/hotspot/jtreg/gc/g1/TestVerifyGCType.java

@@ -126,7 +126,7 @@ private static void testYoungEvacFail() throws Exception {
                                                         "-XX:G1EvacuationFailureALotCount=100",
                                                         "-XX:G1EvacuationFailureALotInterval=1",
                                                         "-XX:+UnlockDiagnosticVMOptions",
-                                                        "-XX:-G1AllowPreventiveGC"});
+                                                        "-XX:-G1UsePreventiveGC"});
         output.shouldHaveExitValue(0);
 
         verifyCollection("Pause Young (Normal)", false, false, true, output.getStdout());