8329749: Obsolete the unused UseNeon flag

Reviewed-by: chagedorn, kvn, aph

Author: TobiHartmann

src/hotspot/cpu/aarch64/globals_aarch64.hpp

@@ -85,8 +85,6 @@ define_pd_global(intx, InlineSmallCode,          1000);
                                                                         \
   product(bool, NearCpool, true,                                        \
          "constant pool is close to instructions")                      \
-  product(bool, UseNeon, false,                                         \
-          "Use Neon for CRC32 computation")                             \
   product(bool, UseCRC32, false,                                        \
           "Use CRC32 instructions for CRC32 computation")               \
   product(bool, UseCryptoPmullForCRC32, false,                          \

src/hotspot/share/runtime/arguments.cpp

@@ -537,6 +537,7 @@ static SpecialFlag const special_jvm_flags[] = {
 
   { "ParallelOldDeadWoodLimiterMean",   JDK_Version::undefined(), JDK_Version::jdk(23), JDK_Version::jdk(24) },
   { "ParallelOldDeadWoodLimiterStdDev", JDK_Version::undefined(), JDK_Version::jdk(23), JDK_Version::jdk(24) },
+  { "UseNeon",                      JDK_Version::undefined(), JDK_Version::jdk(23), JDK_Version::jdk(24) },
 #ifdef ASSERT
   { "DummyObsoleteTestFlag",        JDK_Version::undefined(), JDK_Version::jdk(18), JDK_Version::undefined() },
 #endif

src/jdk.internal.vm.ci/share/classes/jdk/vm/ci/aarch64/AArch64.java

@@ -190,7 +190,6 @@ public enum CPUFeature implements CPUFeatureName {
      */
     public enum Flag {
         UseCRC32,
-        UseNeon,
         UseSIMDForMemoryOps,
         AvoidUnalignedAccesses,
         UseLSE,

src/jdk.internal.vm.ci/share/classes/jdk/vm/ci/hotspot/aarch64/AArch64HotSpotJVMCIBackendFactory.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2015, 2024, 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
@@ -58,9 +58,6 @@ private static EnumSet<AArch64.Flag> computeFlags(AArch64HotSpotVMConfig config)
         if (config.useCRC32) {
             flags.add(AArch64.Flag.UseCRC32);
         }
-        if (config.useNeon) {
-            flags.add(AArch64.Flag.UseNeon);
-        }
         if (config.useSIMDForMemoryOps) {
             flags.add(AArch64.Flag.UseSIMDForMemoryOps);
         }

src/jdk.internal.vm.ci/share/classes/jdk/vm/ci/hotspot/aarch64/AArch64HotSpotVMConfig.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2016, 2024, 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
@@ -44,7 +44,6 @@ class AArch64HotSpotVMConfig extends HotSpotVMConfigAccess {
      * These flags are set based on the corresponding command line flags.
      */
     final boolean useCRC32 = getFlag("UseCRC32", Boolean.class);
-    final boolean useNeon = getFlag("UseNeon", Boolean.class);
     final boolean useSIMDForMemoryOps = getFlag("UseSIMDForMemoryOps", Boolean.class);
     final boolean avoidUnalignedAccesses = getFlag("AvoidUnalignedAccesses", Boolean.class);
     final boolean useLSE = getFlag("UseLSE", Boolean.class);