8003985: Support @Contended Annotation - JEP 142

Summary: HotSpot changes to support @Contended annotation.
Reviewed-by: coleenp, kvn, jrose
Contributed-by: NAleksey Shipilev <aleksey.shipilev@oracle.com>

agent/src/share/classes/sun/jvm/hotspot/oops/InstanceKlass.java

@@ -52,6 +52,8 @@ public class InstanceKlass extends Klass {
   private static int LOW_OFFSET;
   private static int HIGH_OFFSET;
   private static int FIELD_SLOTS;
+  private static short FIELDINFO_TAG_SIZE;
+  private static short FIELDINFO_TAG_OFFSET;
 
   // ClassState constants
   private static int CLASS_STATE_ALLOCATED;
@@ -96,9 +98,12 @@ public class InstanceKlass extends Klass {
     NAME_INDEX_OFFSET              = db.lookupIntConstant("FieldInfo::name_index_offset").intValue();
     SIGNATURE_INDEX_OFFSET         = db.lookupIntConstant("FieldInfo::signature_index_offset").intValue();
     INITVAL_INDEX_OFFSET           = db.lookupIntConstant("FieldInfo::initval_index_offset").intValue();
-    LOW_OFFSET                     = db.lookupIntConstant("FieldInfo::low_offset").intValue();
-    HIGH_OFFSET                    = db.lookupIntConstant("FieldInfo::high_offset").intValue();
+    LOW_OFFSET                     = db.lookupIntConstant("FieldInfo::low_packed_offset").intValue();
+    HIGH_OFFSET                    = db.lookupIntConstant("FieldInfo::high_packed_offset").intValue();
     FIELD_SLOTS                    = db.lookupIntConstant("FieldInfo::field_slots").intValue();
+    FIELDINFO_TAG_SIZE             = db.lookupIntConstant("FIELDINFO_TAG_SIZE").shortValue();
+    FIELDINFO_TAG_OFFSET           = db.lookupIntConstant("FIELDINFO_TAG_OFFSET").shortValue();
+
     // read ClassState constants
     CLASS_STATE_ALLOCATED = db.lookupIntConstant("InstanceKlass::allocated").intValue();
     CLASS_STATE_LOADED = db.lookupIntConstant("InstanceKlass::loaded").intValue();
@@ -314,8 +319,12 @@ public class InstanceKlass extends Klass {
 
   public int getFieldOffset(int index) {
     U2Array fields = getFields();
-    return VM.getVM().buildIntFromShorts(fields.at(index * FIELD_SLOTS + LOW_OFFSET),
-                                         fields.at(index * FIELD_SLOTS + HIGH_OFFSET));
+    short lo = fields.at(index * FIELD_SLOTS + LOW_OFFSET);
+    short hi = fields.at(index * FIELD_SLOTS + HIGH_OFFSET);
+    if ((lo & FIELDINFO_TAG_SIZE) == FIELDINFO_TAG_OFFSET) {
+      return VM.getVM().buildIntFromShorts(lo, hi) >> FIELDINFO_TAG_SIZE;
+    }
+    throw new RuntimeException("should not reach here");
   }
 
   // Accessors for declared fields

src/cpu/sparc/vm/vm_version_sparc.cpp

@@ -259,6 +259,10 @@ void VM_Version::initialize() {
   if (!has_vis1()) // Drop to 0 if no VIS1 support
     UseVIS = 0;
 
+  if (FLAG_IS_DEFAULT(ContendedPaddingWidth) &&
+    (cache_line_size > ContendedPaddingWidth))
+    ContendedPaddingWidth = cache_line_size;
+
 #ifndef PRODUCT
   if (PrintMiscellaneous && Verbose) {
     tty->print("Allocation");
@@ -286,6 +290,9 @@ void VM_Version::initialize() {
     if (PrefetchFieldsAhead > 0) {
       tty->print_cr("PrefetchFieldsAhead %d", PrefetchFieldsAhead);
     }
+    if (ContendedPaddingWidth > 0) {
+      tty->print_cr("ContendedPaddingWidth %d", ContendedPaddingWidth);
+    }
   }
 #endif // PRODUCT
 }

src/cpu/x86/vm/vm_version_x86.cpp

@@ -734,6 +734,10 @@ void VM_Version::get_processor_features() {
   PrefetchFieldsAhead         = prefetch_fields_ahead();
 #endif
 
+  if (FLAG_IS_DEFAULT(ContendedPaddingWidth) &&
+     (cache_line_size > ContendedPaddingWidth))
+     ContendedPaddingWidth = cache_line_size;
+
 #ifndef PRODUCT
   if (PrintMiscellaneous && Verbose) {
     tty->print_cr("Logical CPUs per core: %u",
@@ -780,6 +784,9 @@ void VM_Version::get_processor_features() {
     if (PrefetchFieldsAhead > 0) {
       tty->print_cr("PrefetchFieldsAhead %d", PrefetchFieldsAhead);
     }
+    if (ContendedPaddingWidth > 0) {
+      tty->print_cr("ContendedPaddingWidth %d", ContendedPaddingWidth);
+    }
   }
 #endif // !PRODUCT
 }

src/share/vm/classfile/classFileParser.hpp

@@ -95,17 +95,20 @@ class ClassFileParser VALUE_OBJ_CLASS_SPEC {
       _method_DontInline,
       _method_LambdaForm_Compiled,
       _method_LambdaForm_Hidden,
+      _sun_misc_Contended,
       _annotation_LIMIT
     };
     const Location _location;
     int _annotations_present;
+    u2 _contended_group;
+
     AnnotationCollector(Location location)
     : _location(location), _annotations_present(0)
     {
       assert((int)_annotation_LIMIT <= (int)sizeof(_annotations_present) * BitsPerByte, "");
     }
     // If this annotation name has an ID, report it (or _none).
-    ID annotation_index(Symbol* name);
+    ID annotation_index(ClassLoaderData* loader_data, Symbol* name);
     // Set the annotation name:
     void set_annotation(ID id) {
       assert((int)id >= 0 && (int)id < (int)_annotation_LIMIT, "oob");
@@ -114,6 +117,12 @@ class ClassFileParser VALUE_OBJ_CLASS_SPEC {
     // Report if the annotation is present.
     bool has_any_annotations() { return _annotations_present != 0; }
     bool has_annotation(ID id) { return (nth_bit((int)id) & _annotations_present) != 0; }
+
+    void set_contended_group(u2 group) { _contended_group = group; }
+    u2 contended_group() { return _contended_group; }
+
+    void set_contended(bool contended) { set_annotation(_sun_misc_Contended); }
+    bool is_contended() { return has_annotation(_sun_misc_Contended); }
   };
   class FieldAnnotationCollector: public AnnotationCollector {
   public:
@@ -177,6 +186,14 @@ class ClassFileParser VALUE_OBJ_CLASS_SPEC {
                           Array<AnnotationArray*>** fields_type_annotations,
                           u2* java_fields_count_ptr, TRAPS);
 
+  void print_field_layout(Symbol* name,
+                          Array<u2>* fields,
+                          constantPoolHandle cp,
+                          int instance_size,
+                          int instance_fields_start,
+                          int instance_fields_end,
+                          int static_fields_end);
+
   // Method parsing
   methodHandle parse_method(ClassLoaderData* loader_data,
                             constantPoolHandle cp,
@@ -247,7 +264,8 @@ class ClassFileParser VALUE_OBJ_CLASS_SPEC {
                                         int runtime_invisible_annotations_length, TRAPS);
   int skip_annotation(u1* buffer, int limit, int index);
   int skip_annotation_value(u1* buffer, int limit, int index);
-  void parse_annotations(u1* buffer, int limit, constantPoolHandle cp,
+  void parse_annotations(ClassLoaderData* loader_data,
+                         u1* buffer, int limit, constantPoolHandle cp,
                          /* Results (currently, only one result is supported): */
                          AnnotationCollector* result,
                          TRAPS);

src/share/vm/classfile/vmSymbols.hpp

@@ -194,7 +194,10 @@
   template(java_lang_VirtualMachineError,             "java/lang/VirtualMachineError")            \
   template(java_lang_StackOverflowError,              "java/lang/StackOverflowError")             \
   template(java_lang_StackTraceElement,               "java/lang/StackTraceElement")              \
+                                                                                                  \
+  /* Concurrency support */                                                                       \
   template(java_util_concurrent_locks_AbstractOwnableSynchronizer,   "java/util/concurrent/locks/AbstractOwnableSynchronizer") \
+  template(sun_misc_Contended_signature,              "Lsun/misc/Contended;")                     \
                                                                                                   \
   /* class symbols needed by intrinsics */                                                        \
   VM_INTRINSICS_DO(VM_INTRINSIC_IGNORE, template, VM_SYMBOL_IGNORE, VM_SYMBOL_IGNORE, VM_ALIAS_IGNORE) \
@@ -284,7 +287,7 @@
   NOT_LP64(  do_alias(intptr_signature,               int_signature)  )                           \
   LP64_ONLY( do_alias(intptr_signature,               long_signature) )                           \
   template(selectAlternative_signature, "(ZLjava/lang/invoke/MethodHandle;Ljava/lang/invoke/MethodHandle;)Ljava/lang/invoke/MethodHandle;") \
-                                                                                                  \
+                                                                      \
   /* common method and field names */                                                             \
   template(object_initializer_name,                   "<init>")                                   \
   template(class_initializer_name,                    "<clinit>")                                 \

src/share/vm/oops/fieldInfo.hpp

@@ -43,14 +43,29 @@ class FieldInfo VALUE_OBJ_CLASS_SPEC {
  public:
   // fields
   // Field info extracted from the class file and stored
-  // as an array of 7 shorts
+  // as an array of 6 shorts.
+
+#define FIELDINFO_TAG_SIZE             2
+#define FIELDINFO_TAG_BLANK            0
+#define FIELDINFO_TAG_OFFSET           1
+#define FIELDINFO_TAG_TYPE_PLAIN       2
+#define FIELDINFO_TAG_TYPE_CONTENDED   3
+#define FIELDINFO_TAG_MASK             3
+
+  // Packed field has the tag, and can be either of:
+  //    hi bits <--------------------------- lo bits
+  //   |---------high---------|---------low---------|
+  //    ..........................................00  - blank
+  //    [------------------offset----------------]01  - real field offset
+  //    ......................[-------type-------]10  - plain field with type
+  //    [--contention_group--][-------type-------]11  - contended field with type and contention group
   enum FieldOffset {
     access_flags_offset      = 0,
     name_index_offset        = 1,
     signature_index_offset   = 2,
     initval_index_offset     = 3,
-    low_offset               = 4,
-    high_offset              = 5,
+    low_packed_offset        = 4,
+    high_packed_offset       = 5,
     field_slots              = 6
   };
 
@@ -76,17 +91,90 @@ class FieldInfo VALUE_OBJ_CLASS_SPEC {
   void initialize(u2 access_flags,
                   u2 name_index,
                   u2 signature_index,
-                  u2 initval_index,
-                  u4 offset) {
+                  u2 initval_index) {
     _shorts[access_flags_offset] = access_flags;
     _shorts[name_index_offset] = name_index;
     _shorts[signature_index_offset] = signature_index;
     _shorts[initval_index_offset] = initval_index;
-    set_offset(offset);
+    _shorts[low_packed_offset] = 0;
+    _shorts[high_packed_offset] = 0;
   }
 
   u2 access_flags() const                        { return _shorts[access_flags_offset];            }
-  u4 offset() const                              { return build_int_from_shorts(_shorts[low_offset], _shorts[high_offset]); }
+  u4 offset() const {
+    u2 lo = _shorts[low_packed_offset];
+    switch(lo & FIELDINFO_TAG_MASK) {
+      case FIELDINFO_TAG_OFFSET:
+        return build_int_from_shorts(_shorts[low_packed_offset], _shorts[high_packed_offset]) >> FIELDINFO_TAG_SIZE;
+#ifndef PRODUCT
+      case FIELDINFO_TAG_TYPE_PLAIN:
+        ShouldNotReachHere2("Asking offset for the plain type field");
+      case FIELDINFO_TAG_TYPE_CONTENDED:
+        ShouldNotReachHere2("Asking offset for the contended type field");
+      case FIELDINFO_TAG_BLANK:
+        ShouldNotReachHere2("Asking offset for the blank field");
+#endif
+    }
+    ShouldNotReachHere();
+    return 0;
+  }
+
+  bool is_contended() const {
+    u2 lo = _shorts[low_packed_offset];
+    switch(lo & FIELDINFO_TAG_MASK) {
+      case FIELDINFO_TAG_TYPE_PLAIN:
+        return false;
+      case FIELDINFO_TAG_TYPE_CONTENDED:
+        return true;
+#ifndef PRODUCT
+      case FIELDINFO_TAG_OFFSET:
+        ShouldNotReachHere2("Asking contended flag for the field with offset");
+      case FIELDINFO_TAG_BLANK:
+        ShouldNotReachHere2("Asking contended flag for the blank field");
+#endif
+    }
+    ShouldNotReachHere();
+    return false;
+  }
+
+  u2 contended_group() const {
+    u2 lo = _shorts[low_packed_offset];
+    switch(lo & FIELDINFO_TAG_MASK) {
+      case FIELDINFO_TAG_TYPE_PLAIN:
+        return 0;
+      case FIELDINFO_TAG_TYPE_CONTENDED:
+        return _shorts[high_packed_offset];
+#ifndef PRODUCT
+      case FIELDINFO_TAG_OFFSET:
+        ShouldNotReachHere2("Asking the contended group for the field with offset");
+      case FIELDINFO_TAG_BLANK:
+        ShouldNotReachHere2("Asking the contended group for the blank field");
+#endif
+    }
+    ShouldNotReachHere();
+    return 0;
+ }
+
+  u2 allocation_type() const {
+    u2 lo = _shorts[low_packed_offset];
+    switch(lo & FIELDINFO_TAG_MASK) {
+      case FIELDINFO_TAG_TYPE_PLAIN:
+      case FIELDINFO_TAG_TYPE_CONTENDED:
+        return (lo >> FIELDINFO_TAG_SIZE);
+#ifndef PRODUCT
+      case FIELDINFO_TAG_OFFSET:
+        ShouldNotReachHere2("Asking the field type for field with offset");
+      case FIELDINFO_TAG_BLANK:
+        ShouldNotReachHere2("Asking the field type for the blank field");
+#endif
+    }
+    ShouldNotReachHere();
+    return 0;
+  }
+
+  bool is_offset_set() const {
+    return (_shorts[low_packed_offset] & FIELDINFO_TAG_MASK) == FIELDINFO_TAG_OFFSET;
+  }
 
   Symbol* name(constantPoolHandle cp) const {
     int index = name_index();
@@ -106,8 +194,46 @@ class FieldInfo VALUE_OBJ_CLASS_SPEC {
 
   void set_access_flags(u2 val)                  { _shorts[access_flags_offset] = val;             }
   void set_offset(u4 val)                        {
-    _shorts[low_offset] = extract_low_short_from_int(val);
-    _shorts[high_offset] = extract_high_short_from_int(val);
+    val = val << FIELDINFO_TAG_SIZE; // make room for tag
+    _shorts[low_packed_offset] = extract_low_short_from_int(val) | FIELDINFO_TAG_OFFSET;
+    _shorts[high_packed_offset] = extract_high_short_from_int(val);
+  }
+
+  void set_allocation_type(int type) {
+    u2 lo = _shorts[low_packed_offset];
+    switch(lo & FIELDINFO_TAG_MASK) {
+      case FIELDINFO_TAG_BLANK:
+        _shorts[low_packed_offset] = ((type << FIELDINFO_TAG_SIZE)) & 0xFFFF;
+        _shorts[low_packed_offset] &= ~FIELDINFO_TAG_MASK;
+        _shorts[low_packed_offset] |= FIELDINFO_TAG_TYPE_PLAIN;
+        return;
+#ifndef PRODUCT
+      case FIELDINFO_TAG_TYPE_PLAIN:
+      case FIELDINFO_TAG_TYPE_CONTENDED:
+      case FIELDINFO_TAG_OFFSET:
+        ShouldNotReachHere2("Setting the field type with overwriting");
+#endif
+    }
+    ShouldNotReachHere();
+  }
+
+  void set_contended_group(u2 val) {
+    u2 lo = _shorts[low_packed_offset];
+    switch(lo & FIELDINFO_TAG_MASK) {
+      case FIELDINFO_TAG_TYPE_PLAIN:
+        _shorts[low_packed_offset] |= FIELDINFO_TAG_TYPE_CONTENDED;
+        _shorts[high_packed_offset] = val;
+        return;
+#ifndef PRODUCT
+      case FIELDINFO_TAG_TYPE_CONTENDED:
+        ShouldNotReachHere2("Overwriting contended group");
+      case FIELDINFO_TAG_BLANK:
+        ShouldNotReachHere2("Setting contended group for the blank field");
+      case FIELDINFO_TAG_OFFSET:
+        ShouldNotReachHere2("Setting contended group for field with offset");
+#endif
+    }
+    ShouldNotReachHere();
   }
 
   bool is_internal() const {

src/share/vm/oops/fieldStreams.hpp

@@ -160,9 +160,26 @@ class FieldStreamBase : public StackObj {
     return field()->offset();
   }
 
+  int allocation_type() const {
+    return field()->allocation_type();
+  }
+
   void set_offset(int offset) {
     field()->set_offset(offset);
   }
+
+  bool is_offset_set() const {
+    return field()->is_offset_set();
+  }
+
+  bool is_contended() const {
+    return field()->is_contended();
+  }
+
+  int contended_group() const {
+    return field()->contended_group();
+  }
+
 };
 
 // Iterate over only the internal fields

src/share/vm/oops/instanceKlass.hpp

@@ -230,7 +230,8 @@ class InstanceKlass: public Klass {
     _misc_rewritten            = 1 << 0, // methods rewritten.
     _misc_has_nonstatic_fields = 1 << 1, // for sizing with UseCompressedOops
     _misc_should_verify_class  = 1 << 2, // allow caching of preverification
-    _misc_is_anonymous         = 1 << 3  // has embedded _inner_classes field
+    _misc_is_anonymous         = 1 << 3, // has embedded _inner_classes field
+    _misc_is_contended         = 1 << 4  // marked with contended annotation
   };
   u2              _misc_flags;
   u2              _minor_version;        // minor version number of class file
@@ -550,6 +551,17 @@ class InstanceKlass: public Klass {
     return is_anonymous() ? java_mirror() : class_loader();
   }
 
+  bool is_contended() const                {
+    return (_misc_flags & _misc_is_contended) != 0;
+  }
+  void set_is_contended(bool value)        {
+    if (value) {
+      _misc_flags |= _misc_is_contended;
+    } else {
+      _misc_flags &= ~_misc_is_contended;
+    }
+  }
+
   // signers
   objArrayOop signers() const              { return _signers; }
   void set_signers(objArrayOop s)          { klass_oop_store((oop*)&_signers, s); }

src/share/vm/runtime/globals.hpp

@@ -1075,7 +1075,7 @@ class CommandLineFlags {
                                                                             \
   product(intx, ClearFPUAtPark, 0, "(Unsafe,Unstable)" )                    \
                                                                             \
-  product(intx, hashCode, 0,                                                \
+  product(intx, hashCode, 5,                                                \
          "(Unstable) select hashCode generation algorithm" )                \
                                                                             \
   product(intx, WorkAroundNPTLTimedWaitHang, 1,                             \
@@ -1173,6 +1173,18 @@ class CommandLineFlags {
   notproduct(bool, PrintCompactFieldsSavings, false,                        \
           "Print how many words were saved with CompactFields")             \
                                                                             \
+  notproduct(bool, PrintFieldLayout, false,                                 \
+          "Print field layout for each class")                              \
+                                                                            \
+  product(intx, ContendedPaddingWidth, 128,                                 \
+          "How many bytes to pad the fields/classes marked @Contended with")\
+                                                                            \
+  product(bool, EnableContended, true,                                      \
+          "Enable @Contended annotation support")                           \
+                                                                            \
+  product(bool, RestrictContended, true,                                    \
+          "Restrict @Contended to trusted classes")                         \
+                                                                            \
   product(bool, UseBiasedLocking, true,                                     \
           "Enable biased locking in JVM")                                   \
                                                                             \

src/share/vm/runtime/vmStructs.cpp

@@ -2284,10 +2284,17 @@ typedef BinaryTreeDictionary<Metablock, FreeList> MetablockTreeDictionary;
   declare_constant(FieldInfo::name_index_offset)                          \
   declare_constant(FieldInfo::signature_index_offset)                     \
   declare_constant(FieldInfo::initval_index_offset)                       \
-  declare_constant(FieldInfo::low_offset)                                 \
-  declare_constant(FieldInfo::high_offset)                                \
+  declare_constant(FieldInfo::low_packed_offset)                          \
+  declare_constant(FieldInfo::high_packed_offset)                         \
   declare_constant(FieldInfo::field_slots)                                \
                                                                           \
+  /*************************************/                                 \
+  /* FieldInfo tag constants           */                                 \
+  /*************************************/                                 \
+                                                                          \
+  declare_preprocessor_constant("FIELDINFO_TAG_SIZE", FIELDINFO_TAG_SIZE) \
+  declare_preprocessor_constant("FIELDINFO_TAG_OFFSET", FIELDINFO_TAG_OFFSET) \
+                                                                          \
   /************************************************/                      \
   /* InstanceKlass InnerClassAttributeOffset enum */                      \
   /************************************************/                      \