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8141132: JEP 254: Compact Strings

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Adopt a more space-efficient internal representation for strings.

Co-authored-by: Brent Christian <brent.christian@oracle.com>
Co-authored-by: Vivek Deshpande <vivek.r.deshpande@intel.com>
Co-authored-by: Charlie Hunt <charlie.hunt@oracle.com>
Co-authored-by: Vladimir Kozlov <vladimir.kozlov@oracle.com>
Co-authored-by: Roger Riggs <roger.riggs@oracle.com>
Co-authored-by: Xueming Shen <xueming.shen@oracle.com>
Co-authored-by: Aleksey Shipilev <aleksey.shipilev@oracle.com>
Co-authored-by: Sandhya Viswanathan <sandhya.viswanathan@intel.com>
Reviewed-by: alanb, bdelsart, coleenp, iklam, jiangli, jrose, kevinw, naoto, pliden, roland, smarks, twisti
This commit is contained in:
Tobias Hartmann 2015-11-03 09:41:03 +01:00
parent 4e24e2cc6c
commit 7af927f9c1
74 changed files with 4838 additions and 1683 deletions
Download patch file Download diff file Expand all files Collapse all files

95
hotspot/src/share/vm/classfile/javaClasses.hpp
View file

@ -53,28 +53,28 @@
class java_lang_String : AllStatic {
private:
static int value_offset;
static int offset_offset;
static int count_offset;
static int hash_offset;
static int coder_offset;
static bool initialized;
static Handle basic_create(int length, TRAPS);
static Handle basic_create(int length, bool byte_arr, TRAPS);
static void set_offset(oop string, int offset) {
static void set_coder(oop string, jbyte coder) {
assert(initialized, "Must be initialized");
if (offset_offset > 0) {
string->int_field_put(offset_offset, offset);
}
}
static void set_count( oop string, int count) {
assert(initialized, "Must be initialized");
if (count_offset > 0) {
string->int_field_put(count_offset, count);
if (coder_offset > 0) {
string->byte_field_put(coder_offset, coder);
}
}
public:
// Coders
enum Coder {
CODER_LATIN1 = 0,
CODER_UTF16 = 1
};
static void compute_offsets();
// Instance creation
@ -86,37 +86,29 @@ class java_lang_String : AllStatic {
static Handle create_from_platform_dependent_str(const char* str, TRAPS);
static Handle char_converter(Handle java_string, jchar from_char, jchar to_char, TRAPS);
static bool has_offset_field() {
assert(initialized, "Must be initialized");
return (offset_offset > 0);
}
static bool has_count_field() {
assert(initialized, "Must be initialized");
return (count_offset > 0);
}
static bool has_hash_field() {
assert(initialized, "Must be initialized");
return (hash_offset > 0);
}
static bool has_coder_field() {
assert(initialized, "Must be initialized");
return (coder_offset > 0);
}
static void set_compact_strings(bool value);
static int value_offset_in_bytes() {
assert(initialized && (value_offset > 0), "Must be initialized");
return value_offset;
}
static int count_offset_in_bytes() {
assert(initialized && (count_offset > 0), "Must be initialized");
return count_offset;
}
static int offset_offset_in_bytes() {
assert(initialized && (offset_offset > 0), "Must be initialized");
return offset_offset;
}
static int hash_offset_in_bytes() {
assert(initialized && (hash_offset > 0), "Must be initialized");
return hash_offset;
}
static int coder_offset_in_bytes() {
assert(initialized && (coder_offset > 0), "Must be initialized");
return coder_offset;
}
static void set_value_raw(oop string, typeArrayOop buffer) {
assert(initialized, "Must be initialized");
@ -142,28 +134,30 @@ class java_lang_String : AllStatic {
assert(is_instance(java_string), "must be java_string");
return java_string->int_field(hash_offset);
}
static int offset(oop java_string) {
static bool is_latin1(oop java_string) {
assert(initialized, "Must be initialized");
assert(is_instance(java_string), "must be java_string");
if (offset_offset > 0) {
return java_string->int_field(offset_offset);
if (coder_offset > 0) {
jbyte coder = java_string->byte_field(coder_offset);
assert(CompactStrings || coder == CODER_UTF16, "Must be UTF16 without CompactStrings");
return coder == CODER_LATIN1;
} else {
return 0;
return false;
}
}
static int length(oop java_string) {
assert(initialized, "Must be initialized");
assert(is_instance(java_string), "must be java_string");
if (count_offset > 0) {
return java_string->int_field(count_offset);
} else {
typeArrayOop value_array = ((typeArrayOop)java_string->obj_field(value_offset));
if (value_array == NULL) {
return 0;
} else {
return value_array->length();
}
typeArrayOop value_array = ((typeArrayOop)java_string->obj_field(value_offset));
if (value_array == NULL) {
return 0;
}
int arr_length = value_array->length();
if (!is_latin1(java_string)) {
assert((arr_length & 1) == 0, "should be even for UTF16 string");
arr_length >>= 1; // convert number of bytes to number of elements
}
return arr_length;
}
static int utf8_length(oop java_string);
@ -187,7 +181,7 @@ class java_lang_String : AllStatic {
// hash P(31) from Kernighan & Ritchie
//
// For this reason, THIS ALGORITHM MUST MATCH String.hashCode().
template <typename T> static unsigned int hash_code(T* s, int len) {
static unsigned int hash_code(const jchar* s, int len) {
unsigned int h = 0;
while (len-- > 0) {
h = 31*h + (unsigned int) *s;
@ -195,7 +189,18 @@ class java_lang_String : AllStatic {
}
return h;
}
static unsigned int hash_code(const jbyte* s, int len) {
unsigned int h = 0;
while (len-- > 0) {
h = 31*h + (((unsigned int) *s) & 0xFF);
s++;
}
return h;
}
static unsigned int hash_code(oop java_string);
static unsigned int latin1_hash_code(typeArrayOop value, int len);
// This is the string hash code used by the StringTable, which may be
// the same as String.hashCode or an alternate hash code.
@ -451,7 +456,7 @@ class java_lang_ThreadGroup : AllStatic {
// parent ThreadGroup
static oop parent(oop java_thread_group);
// name
static typeArrayOop name(oop java_thread_group);
static const char* name(oop java_thread_group);
// ("name as oop" accessor is not necessary)
// Number of threads in group
static int nthreads(oop java_thread_group);