src/hotspot/share/runtime/arguments.cpp

rev 47591 : Add Thread Local handshakes and thread local polling
rev 47600 : [mq]: Option-Cleanup-12

@@ -48,10 +48,11 @@
 #include "runtime/commandLineFlagRangeList.hpp"
 #include "runtime/globals.hpp"
 #include "runtime/globals_extension.hpp"
 #include "runtime/java.hpp"
 #include "runtime/os.hpp"
+#include "runtime/safepointMechanism.hpp"
 #include "runtime/vm_version.hpp"
 #include "services/management.hpp"
 #include "services/memTracker.hpp"
 #include "utilities/align.hpp"
 #include "utilities/defaultStream.hpp"

@@ -4611,10 +4612,42 @@
   if (!UseBiasedLocking || EmitSync != 0) {
     UseOptoBiasInlining = false;
   }
 #endif
 
+  bool aot_enabled = UseAOT && ((AOTLibrary != NULL) || !FLAG_IS_DEFAULT(UseAOT));
+  bool jvmci_enabled = NOT_JVMCI(false) JVMCI_ONLY(EnableJVMCI || UseJVMCICompiler);
+  bool handshakes_supported = SafepointMechanism::supports_thread_local_poll() && !aot_enabled && !jvmci_enabled && ThreadLocalHandshakes;
+  // ThreadLocalHandshakesConstraintFunc handles the constraints.
+  // Here we try to figure out if a mutual exclusive option have been set.
+  if (handshakes_supported) {
+    if (FLAG_IS_DEFAULT(UseAOT)) {
+      FLAG_SET_DEFAULT(UseAOT, false); // Clear the AOT flag to make sure it doesn't try to initialize.
+    }
+  } else {
+    if (FLAG_IS_DEFAULT(ThreadLocalHandshakes) && ThreadLocalHandshakes) {
+      if (!SafepointMechanism::supports_thread_local_poll()) {
+        // Unsupported platform should have ThreadLocalHandshakes default set to false.
+        log_debug(ergo)("Disabling ThreadLocalHandshakes unsupported plaform.");
+        FLAG_SET_ERGO(bool, ThreadLocalHandshakes, false);
+      } else if (!FLAG_IS_DEFAULT(UseAOT) && UseAOT) {
+        // If user enabled AOT but ThreadLocalHandshakes is at default set it to false.
+        log_debug(ergo)("Disabling ThreadLocalHandshakes for UseAOT.");
+        FLAG_SET_ERGO(bool, ThreadLocalHandshakes, false);
+      } else if (jvmci_enabled){
+        // If user enabled JVMCI but ThreadLocalHandshakes is at default set it to false.
+        log_debug(ergo)("Disabling ThreadLocalHandshakes for EnableJVMCI/UseJVMCICompiler.");
+        FLAG_SET_ERGO(bool, ThreadLocalHandshakes, false);
+      }
+    }
+  }
+  if (FLAG_IS_DEFAULT(ThreadLocalHandshakes) || !SafepointMechanism::supports_thread_local_poll()) {
+    log_debug(ergo)("ThreadLocalHandshakes %s", ThreadLocalHandshakes ? "enabled." : "disabled.");
+  } else {
+    log_info(ergo)("ThreadLocalHandshakes %s", ThreadLocalHandshakes ? "enabled." : "disabled.");
+  }
+
   return JNI_OK;
 }
 
 jint Arguments::adjust_after_os() {
   if (UseNUMA) {