8152953: ForceSafepoint operations should be more specific

Reviewed-by: dholmes, sspitsyn, rkennke, coleenp

hotspot/src/share/vm/classfile/classLoader.cpp

@@ -1945,7 +1945,7 @@ void ClassLoader::compile_the_world_in(char* name, Handle loader, TRAPS) {
             if (can_be_compiled(m, comp_level)) {
               if (++_codecache_sweep_counter == CompileTheWorldSafepointInterval) {
                 // Give sweeper a chance to keep up with CTW
-                VM_ForceSafepoint op;
+                VM_CTWThreshold op;
                 VMThread::execute(&op);
                 _codecache_sweep_counter = 0;
               }

hotspot/src/share/vm/code/icBuffer.cpp

@@ -126,8 +126,8 @@ ICStub* InlineCacheBuffer::new_ic_stub() {
     // We do this by forcing a safepoint
     EXCEPTION_MARK;
 
-    VM_ForceSafepoint vfs;
-    VMThread::execute(&vfs);
+    VM_ICBufferFull ibf;
+    VMThread::execute(&ibf);
     // We could potential get an async. exception at this point.
     // In that case we will rethrow it to ourselvs.
     if (HAS_PENDING_EXCEPTION) {

hotspot/src/share/vm/prims/jvmtiEnv.cpp

@@ -985,8 +985,8 @@ JvmtiEnv::SuspendThreadList(jint request_count, const jthread* request_list, jvm
     results[i] = JVMTI_ERROR_NONE;  // indicate successful suspend
   }
   if (needSafepoint > 0) {
-    VM_ForceSafepoint vfs;
-    VMThread::execute(&vfs);
+    VM_ThreadsSuspendJVMTI tsj;
+    VMThread::execute(&tsj);
   }
   // per-thread suspend results returned via results parameter
   return JVMTI_ERROR_NONE;

hotspot/src/share/vm/runtime/synchronizer.cpp

@@ -1063,7 +1063,7 @@ static void InduceScavenge(Thread * Self, const char * Whence) {
     // Must VM_Operation instance be heap allocated as the op will be enqueue and posted
     // to the VMthread and have a lifespan longer than that of this activation record.
     // The VMThread will delete the op when completed.
-    VMThread::execute(new VM_ForceAsyncSafepoint());
+    VMThread::execute(new VM_ScavengeMonitors());
 
     if (ObjectMonitor::Knob_Verbose) {
       tty->print_cr("INFO: Monitor scavenge - STW posted @%s (%d)",

hotspot/src/share/vm/runtime/thread.cpp

@@ -2275,7 +2275,7 @@ void JavaThread::java_suspend() {
     }
   }
 
-  VM_ForceSafepoint vm_suspend;
+  VM_ThreadSuspend vm_suspend;
   VMThread::execute(&vm_suspend);
 }
 

hotspot/src/share/vm/runtime/vm_operations.hpp

@@ -106,6 +106,11 @@
   template(MarkActiveNMethods)                    \
   template(PrintCompileQueue)                     \
   template(PrintClassHierarchy)                   \
+  template(ThreadSuspend)                         \
+  template(CTWThreshold)                          \
+  template(ThreadsSuspendJVMTI)                   \
+  template(ICBufferFull)                          \
+  template(ScavengeMonitors)                      \
 
 class VM_Operation: public CHeapObj<mtInternal> {
  public:
@@ -238,20 +243,41 @@ class VM_ClearICs: public VM_Operation {
   VMOp_Type type() const { return VMOp_ClearICs; }
 };
 
-// dummy vm op, evaluated just to force a safepoint
+// empty vm op, evaluated just to force a safepoint
 class VM_ForceSafepoint: public VM_Operation {
  public:
-  VM_ForceSafepoint() {}
   void doit()         {}
   VMOp_Type type() const { return VMOp_ForceSafepoint; }
 };
 
-// dummy vm op, evaluated just to force a safepoint
-class VM_ForceAsyncSafepoint: public VM_Operation {
+// empty vm op, when forcing a safepoint to suspend a thread
+class VM_ThreadSuspend: public VM_ForceSafepoint {
  public:
-  VM_ForceAsyncSafepoint() {}
-  void doit()              {}
-  VMOp_Type type() const                         { return VMOp_ForceAsyncSafepoint; }
+  VMOp_Type type() const { return VMOp_ThreadSuspend; }
+};
+
+// empty vm op, when forcing a safepoint due to ctw threshold is reached for the sweeper
+class VM_CTWThreshold: public VM_ForceSafepoint {
+ public:
+  VMOp_Type type() const { return VMOp_CTWThreshold; }
+};
+
+// empty vm op, when forcing a safepoint to suspend threads from jvmti
+class VM_ThreadsSuspendJVMTI: public VM_ForceSafepoint {
+ public:
+  VMOp_Type type() const { return VMOp_ThreadsSuspendJVMTI; }
+};
+
+// empty vm op, when forcing a safepoint due to inline cache buffers being full
+class VM_ICBufferFull: public VM_ForceSafepoint {
+ public:
+  VMOp_Type type() const { return VMOp_ICBufferFull; }
+};
+
+// empty asynchronous vm op, when forcing a safepoint to scavenge monitors
+class VM_ScavengeMonitors: public VM_ForceSafepoint {
+ public:
+  VMOp_Type type() const                         { return VMOp_ScavengeMonitors; }
   Mode evaluation_mode() const                   { return _async_safepoint; }
   bool is_cheap_allocated() const                { return true; }
 };