120 lines
4.5 KiB
Diff
120 lines
4.5 KiB
Diff
Subject: Backport JDK-8325730 StringBuilder.toString allocation for the empty String
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---
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.../share/classes/java/lang/StringBuffer.java | 5 ++++-
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.../share/classes/java/lang/StringBuilder.java | 7 +++++--
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.../org/openjdk/bench/java/lang/StringBuffers.java | 8 +++++++-
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.../org/openjdk/bench/java/lang/StringBuilders.java | 10 +++++++++-
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4 files changed, 25 insertions(+), 5 deletions(-)
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diff --git a/src/java.base/share/classes/java/lang/StringBuffer.java b/src/java.base/share/classes/java/lang/StringBuffer.java
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index d77462f0c..1aeceb959 100644
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--- a/src/java.base/share/classes/java/lang/StringBuffer.java
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+++ b/src/java.base/share/classes/java/lang/StringBuffer.java
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@@ -1,5 +1,5 @@
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/*
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- * Copyright (c) 1994, 2023, Oracle and/or its affiliates. All rights reserved.
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+ * Copyright (c) 1994, 2024, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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@@ -735,6 +735,9 @@ import jdk.internal.vm.annotation.IntrinsicCandidate;
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@Override
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@IntrinsicCandidate
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public synchronized String toString() {
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+ if (length() == 0) {
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+ return "";
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+ }
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if (toStringCache == null) {
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return toStringCache = new String(this, null);
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}
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diff --git a/src/java.base/share/classes/java/lang/StringBuilder.java b/src/java.base/share/classes/java/lang/StringBuilder.java
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index c42422e62..d7ff5ee35 100644
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--- a/src/java.base/share/classes/java/lang/StringBuilder.java
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+++ b/src/java.base/share/classes/java/lang/StringBuilder.java
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@@ -1,5 +1,5 @@
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/*
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- * Copyright (c) 2003, 2023, Oracle and/or its affiliates. All rights reserved.
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+ * Copyright (c) 2003, 2024, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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@@ -471,8 +471,11 @@ public final class StringBuilder
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@Override
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@IntrinsicCandidate
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public String toString() {
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+ if (length() == 0) {
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+ return "";
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+ }
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// Create a copy, don't share the array
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- return new String(this);
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+ return new String(this, null);
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}
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/**
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diff --git a/test/micro/org/openjdk/bench/java/lang/StringBuffers.java b/test/micro/org/openjdk/bench/java/lang/StringBuffers.java
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index b3d4d85c7..fea64c0d2 100644
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--- a/test/micro/org/openjdk/bench/java/lang/StringBuffers.java
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+++ b/test/micro/org/openjdk/bench/java/lang/StringBuffers.java
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@@ -1,5 +1,5 @@
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/*
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- * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
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+ * Copyright (c) 2014, 2024, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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@@ -80,4 +80,10 @@ public class StringBuffers {
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return blaha.substring(30, 35);
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}
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+ StringBuffer sb = new StringBuffer();
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+
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+ @Benchmark
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+ public String emptyToString() {
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+ return sb.toString();
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+ }
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}
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diff --git a/test/micro/org/openjdk/bench/java/lang/StringBuilders.java b/test/micro/org/openjdk/bench/java/lang/StringBuilders.java
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index 40f41659e..29827b7f0 100644
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--- a/test/micro/org/openjdk/bench/java/lang/StringBuilders.java
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+++ b/test/micro/org/openjdk/bench/java/lang/StringBuilders.java
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@@ -1,5 +1,5 @@
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/*
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- * Copyright (c) 2014, 2019, Oracle and/or its affiliates. All rights reserved.
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+ * Copyright (c) 2014, 2024, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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@@ -364,6 +364,11 @@ public class StringBuilders {
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return sbUtf16.charAt(charAt_index);
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}
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+ @Benchmark
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+ public String emptyToString(Data data) {
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+ return data.sbEmpty.toString();
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+ }
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+
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@State(Scope.Thread)
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public static class Data {
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int i = 0;
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@@ -380,6 +385,7 @@ public class StringBuilders {
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}
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}
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+ StringBuilder sbEmpty;
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String str;
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String utf16Str;
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CharSequence cs;
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@@ -398,6 +404,8 @@ public class StringBuilders {
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}
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private void generateData() {
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+ sbEmpty = new StringBuilder(length);
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+
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char[] chars = "abcdefghijklmnopqrstuvwxyz0123456789".toCharArray();
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StringBuilder sb = new StringBuilder(length);
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--
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2.33.0
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