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7102776: Pack instanceKlass boolean fields into single u1 field

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Reduce class runtime memory usage by packing 4 instanceKlass boolean fields into single u1 field. Save 4-byte for each loaded class.

Reviewed-by: dholmes, bobv, phh, twisti, never, coleenp
This commit is contained in:
Jiangli Zhou 2011-11-17 12:53:59 -05:00 • committed by Coleen Phillimore
parent 9d6d4e292b
commit ee88278d34
5 changed files with 50 additions and 20 deletions
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48
hotspot/src/share/vm/oops/instanceKlass.hpp
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@ -230,10 +230,7 @@ class instanceKlass: public Klass {
int _static_oop_field_count;// number of static oop fields in this klass
int _nonstatic_oop_map_size;// size in words of nonstatic oop map blocks
int _java_fields_count; // The number of declared Java fields
bool _is_marked_dependent; // used for marking during flushing and deoptimization
bool _rewritten; // methods rewritten.
bool _has_nonstatic_fields; // for sizing with UseCompressedOops
bool _should_verify_class; // allow caching of preverification
u2 _minor_version; // minor version number of class file
u2 _major_version; // major version number of class file
ClassState _init_state; // state of class
@ -260,6 +257,19 @@ class instanceKlass: public Klass {
JvmtiCachedClassFieldMap* _jvmti_cached_class_field_map; // JVMTI: used during heap iteration
volatile u2 _idnum_allocated_count; // JNI/JVMTI: increments with the addition of methods, old ids don't change
// Compact the following four boolean flags into 1-bit each. These four flags
// were defined as separate boolean fields and each was 1-byte before. Since
// there are 2 bytes unused after the _idnum_allocated_count field, place the
// _misc_flags field after _idnum_allocated_count to utilize the unused bits
// and save total 4-bytes.
enum {
IS_MARKED_DEPENDENT = 0x1, // used for marking during flushing and deoptimization
REWRITTEN = 0x2, // methods rewritten.
HAS_NONSTATIC_FIELDS = 0x4, // for sizing with UseCompressedOops
SHOULD_VERIFY_CLASS = 0x8 // allow caching of preverification
};
u1 _misc_flags;
// embedded Java vtable follows here
// embedded Java itables follows here
// embedded static fields follows here
@ -269,8 +279,14 @@ class instanceKlass: public Klass {
friend class SystemDictionary;
public:
bool has_nonstatic_fields() const { return _has_nonstatic_fields; }
void set_has_nonstatic_fields(bool b) { _has_nonstatic_fields = b; }
bool has_nonstatic_fields() const { return (_misc_flags & HAS_NONSTATIC_FIELDS) != 0; }
void set_has_nonstatic_fields(bool b) {
if (b) {
_misc_flags |= HAS_NONSTATIC_FIELDS;
} else {
_misc_flags &= ~HAS_NONSTATIC_FIELDS;
}
}
// field sizes
int nonstatic_field_size() const { return _nonstatic_field_size; }
@ -378,15 +394,23 @@ class instanceKlass: public Klass {
bool is_in_error_state() const { return _init_state == initialization_error; }
bool is_reentrant_initialization(Thread *thread) { return thread == _init_thread; }
int get_init_state() { return _init_state; } // Useful for debugging
bool is_rewritten() const { return _rewritten; }
bool is_rewritten() const { return (_misc_flags & REWRITTEN) != 0; }
// defineClass specified verification
bool should_verify_class() const { return _should_verify_class; }
void set_should_verify_class(bool value) { _should_verify_class = value; }
bool should_verify_class() const { return (_misc_flags & SHOULD_VERIFY_CLASS) != 0; }
void set_should_verify_class(bool value) {
if (value) {
_misc_flags |= SHOULD_VERIFY_CLASS;
} else {
_misc_flags &= ~SHOULD_VERIFY_CLASS;
}
}
// marking
bool is_marked_dependent() const { return _is_marked_dependent; }
void set_is_marked_dependent(bool value) { _is_marked_dependent = value; }
bool is_marked_dependent() const { return (_misc_flags & IS_MARKED_DEPENDENT) != 0; }
void set_is_marked_dependent() { _misc_flags |= IS_MARKED_DEPENDENT; }
void clear_is_marked_dependent() { _misc_flags &= ~IS_MARKED_DEPENDENT; }
// initialization (virtuals from Klass)
bool should_be_initialized() const; // means that initialize should be called
@ -756,7 +780,7 @@ private:
#else
void set_init_state(ClassState state) { _init_state = state; }
#endif
void set_rewritten() { _rewritten = true; }
void set_rewritten() { _misc_flags |= REWRITTEN; }
void set_init_thread(Thread *thread) { _init_thread = thread; }
u2 idnum_allocated_count() const { return _idnum_allocated_count; }