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8220496: Race in java_lang_String::length() when deduplicating

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Reviewed-by: rkennke, pliden
This commit is contained in:
Claes Redestad 2019-03-13 17:32:17 +01:00
parent 1057f7e2a7
commit 1bfa5cee8c
5 changed files with 39 additions and 29 deletions
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12
src/hotspot/share/gc/shared/stringdedup/stringDedupTable.cpp
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@ -269,21 +269,13 @@ void StringDedupTable::transfer(StringDedupEntry** pentry, StringDedupTable* des
*list = entry;
}
bool StringDedupTable::equals(typeArrayOop value1, typeArrayOop value2) {
return (oopDesc::equals(value1, value2) ||
(value1->length() == value2->length() &&
(!memcmp(value1->base(T_BYTE),
value2->base(T_BYTE),
value1->length() * sizeof(jbyte)))));
}
typeArrayOop StringDedupTable::lookup(typeArrayOop value, bool latin1, unsigned int hash,
StringDedupEntry** list, uintx &count) {
for (StringDedupEntry* entry = *list; entry != NULL; entry = entry->next()) {
if (entry->hash() == hash && entry->latin1() == latin1) {
oop* obj_addr = (oop*)entry->obj_addr();
oop obj = NativeAccess<ON_PHANTOM_OOP_REF | AS_NO_KEEPALIVE>::oop_load(obj_addr);
if (equals(value, static_cast<typeArrayOop>(obj))) {
if (java_lang_String::value_equals(value, static_cast<typeArrayOop>(obj))) {
obj = NativeAccess<ON_PHANTOM_OOP_REF>::oop_load(obj_addr);
return static_cast<typeArrayOop>(obj);
}
@ -633,7 +625,7 @@ void StringDedupTable::verify() {
while (*entry2 != NULL) {
typeArrayOop value2 = (*entry2)->obj();
bool latin1_2 = (*entry2)->latin1();
guarantee(latin1_1 != latin1_2 || !equals(value1, value2), "Table entries must not have identical arrays");
guarantee(latin1_1 != latin1_2 || !java_lang_String::value_equals(value1, value2), "Table entries must not have identical arrays");
entry2 = (*entry2)->next_addr();
}
entry1 = (*entry1)->next_addr();