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8221724: Enable archiving of Strings with hash 0

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Reviewed-by: jiangli, iklam
This commit is contained in:
Claes Redestad 2019-04-02 11:37:11 +02:00
parent 1908897b93
commit 3880f3db74
4 changed files with 39 additions and 15 deletions
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4
src/hotspot/share/classfile/stringTable.cpp
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@ -761,10 +761,6 @@ struct CopyToArchive : StackObj {
return true;
}
unsigned int hash = java_lang_String::hash_code(s);
if (hash == 0) {
// We do not archive Strings with a 0 hashcode because ......
return true;
}
java_lang_String::set_hash(s, hash);
oop new_s = StringTable::create_archived_string(s, Thread::current());

4
src/hotspot/share/oops/constantPool.cpp
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@ -280,9 +280,7 @@ void ConstantPool::archive_resolved_references(Thread* THREAD) {
rr->obj_at_put(i, NULL);
if (p != NULL && i < ref_map_len) {
int index = object_to_cp_index(i);
// Skip the entry if the string hash code is 0 since the string
// is not included in the shared string_table, see StringTable::copy_shared_string.
if (tag_at(index).is_string() && java_lang_String::hash_code(p) != 0) {
if (tag_at(index).is_string()) {
oop op = StringTable::create_archived_string(p, THREAD);
// If the String object is not archived (possibly too large),
// NULL is returned. Also set it in the array, so we won't

6
test/hotspot/jtreg/runtime/appcds/sharedStrings/HelloStringPlus.java
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@ -1,5 +1,5 @@
/*
* Copyright (c) 2015, 2017, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2015, 2019, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -66,8 +66,8 @@ public class HelloStringPlus {
// Check intern() method for "" string
String empty = "";
String empty_interned = empty.intern();
if (wb.isShared(empty)) {
throw new RuntimeException("Empty string should not be shared");
if (!wb.isShared(empty)) {
throw new RuntimeException("Empty string should be shared");
}
if (empty_interned != empty) {
throw new RuntimeException("Different string is returned from intern() for empty string");

40
test/hotspot/jtreg/runtime/appcds/sharedStrings/LockStringTest.java
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@ -1,5 +1,5 @@
/*
* Copyright (c) 2015, 2017, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2015, 2019, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -25,19 +25,49 @@
import sun.hotspot.WhiteBox;
public class LockStringTest extends Thread {
static String lock = "StringLock";
static boolean done = false;
static String lock;
static boolean done;
static WhiteBox wb = WhiteBox.getWhiteBox();
public static void main(String[] args) throws Exception {
WhiteBox wb = WhiteBox.getWhiteBox();
if (wb.areSharedStringsIgnored()) {
System.out.println("The shared strings are ignored");
System.out.println("LockStringTest: PASS");
return;
}
if (!wb.isShared(LockStringTest.class)) {
throw new RuntimeException("Failed: LockStringTest class is not shared.");
}
// Note: This class is archived. All string literals (including the ones used in this class)
// in all archived classes are interned into the CDS shared string table.
doTest("StringLock", false);
doTest("", true);
// The following string has a 0 hashCode. Calling String.hashCode() could cause
// the String.hash field to be written into, if so make sure we don't functionally
// break.
doTest("\u0121\u0151\u00a2\u0001\u0001\udbb2", true);
}
private static void doTest(String s, boolean hasZeroHashCode) throws Exception {
lock = s;
done = false;
if (!wb.isShared(lock)) {
throw new RuntimeException("Failed: String is not shared.");
throw new RuntimeException("Failed: String \"" + lock + "\" is not shared.");
}
if (hasZeroHashCode && lock.hashCode() != 0) {
throw new RuntimeException("Shared string \"" + lock + "\" should have 0 hashCode, but is instead " + lock.hashCode());
}
String copy = new String(lock);
if (lock.hashCode() != copy.hashCode()) {
throw new RuntimeException("Shared string \"" + lock + "\" does not have the same hashCode as its non-shared copy");
}
new LockStringTest().start();