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8222484: Specialize generation of simple String concatenation expressions

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Reviewed-by: jrose, jlaskey
This commit is contained in:
Claes Redestad 2019-04-17 00:06:38 +02:00
parent 7d9e7e1e0b
commit 781fb29580
5 changed files with 177 additions and 96 deletions
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27
make/jdk/src/classes/build/tools/classlist/HelloClasslist.java
View file

@ -1,5 +1,5 @@
/*
* Copyright (c) 2016, 2018, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2016, 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
@ -67,13 +67,24 @@ public class HelloClasslist {
.forEach(System.out::println);
// Common concatenation patterns
String const_I = "string" + args.length;
String const_S = "string" + String.valueOf(args.length);
String S_const = String.valueOf(args.length) + "string";
String S_S = String.valueOf(args.length) + String.valueOf(args.length);
String const_J = "string" + System.currentTimeMillis();
String I_const = args.length + "string";
String J_const = System.currentTimeMillis() + "string";
String SS = String.valueOf(args.length) + String.valueOf(args.length);
String CS = "string" + String.valueOf(args.length);
String SC = String.valueOf(args.length) + "string";
String SCS = String.valueOf(args.length) + "string" + String.valueOf(args.length);
String CSS = "string" + String.valueOf(args.length) + String.valueOf(args.length);
String CSCS = "string" + String.valueOf(args.length) + "string" + String.valueOf(args.length);
String SCSC = String.valueOf(args.length) + "string" + String.valueOf(args.length) + "string";
String CSCSC = "string" + String.valueOf(args.length) + "string" + String.valueOf(args.length) + "string";
String SCSCS = String.valueOf(args.length) + "string" + String.valueOf(args.length) + "string" + String.valueOf(args.length);
String CI = "string" + args.length;
String IC = args.length + "string";
String CIC = "string" + args.length + "string";
String CICI = "string" + args.length + "string" + args.length;
String CJ = "string" + System.currentTimeMillis();
String JC = System.currentTimeMillis() + "string";
String CJC = "string" + System.currentTimeMillis() + "string";
String CJCJ = "string" + System.currentTimeMillis() + "string" + System.currentTimeMillis();
String CJCJC = "string" + System.currentTimeMillis() + "string" + System.currentTimeMillis() + "string";
String newDate = DateTimeFormatter.ISO_LOCAL_DATE_TIME.format(
LocalDateTime.now(ZoneId.of("GMT")));

15
src/java.base/share/classes/java/lang/String.java
View file

@ -1965,20 +1965,7 @@ public final class String
if (str.isEmpty()) {
return this;
}
if (coder() == str.coder()) {
byte[] val = this.value;
byte[] oval = str.value;
int len = val.length + oval.length;
byte[] buf = Arrays.copyOf(val, len);
System.arraycopy(oval, 0, buf, val.length, oval.length);
return new String(buf, coder);
}
int len = length();
int olen = str.length();
byte[] buf = StringUTF16.newBytesFor(len + olen);
getBytes(buf, 0, UTF16);
str.getBytes(buf, len, UTF16);
return new String(buf, UTF16);
return StringConcatHelper.simpleConcat(this, str);
}
/**

144
src/java.base/share/classes/java/lang/StringConcatHelper.java
View file

@ -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
@ -25,6 +25,9 @@
package java.lang;
import jdk.internal.misc.Unsafe;
import jdk.internal.vm.annotation.ForceInline;
/**
* Helper for string concatenation. These methods are mostly looked up with private lookups
* from {@link java.lang.invoke.StringConcatFactory}, and used in {@link java.lang.invoke.MethodHandle}
@ -38,8 +41,10 @@ final class StringConcatHelper {
/**
* Check for overflow, throw exception on overflow.
* @param lengthCoder String length and coder
* @return lengthCoder
*
* @param lengthCoder String length with coder packed into higher bits
* the upper word.
* @return the given parameter value, if valid
*/
private static long checkOverflow(long lengthCoder) {
if ((int)lengthCoder >= 0) {
@ -50,76 +55,83 @@ final class StringConcatHelper {
/**
* Mix value length and coder into current length and coder.
* @param current current length
* @param value value to mix in
* @return new length and coder
* @param lengthCoder String length with coder packed into higher bits
* the upper word.
* @param value value to mix in
* @return new length and coder
*/
static long mix(long current, boolean value) {
return checkOverflow(current + (value ? 4 : 5));
static long mix(long lengthCoder, boolean value) {
return checkOverflow(lengthCoder + (value ? 4 : 5));
}
/**
* Mix value length and coder into current length and coder.
* @param current current length
* @param value value to mix in
* @return new length and coder
* @param lengthCoder String length with coder packed into higher bits
* the upper word.
* @param value value to mix in
* @return new length and coder
*/
static long mix(long current, byte value) {
return mix(current, (int)value);
static long mix(long lengthCoder, byte value) {
return mix(lengthCoder, (int)value);
}
/**
* Mix value length and coder into current length and coder.
* @param current current length
* @param value value to mix in
* @return new length and coder
* @param lengthCoder String length with coder packed into higher bits
* the upper word.
* @param value value to mix in
* @return new length and coder
*/
static long mix(long current, char value) {
return checkOverflow(current + 1) | (StringLatin1.canEncode(value) ? 0 : UTF16);
static long mix(long lengthCoder, char value) {
return checkOverflow(lengthCoder + 1) | (StringLatin1.canEncode(value) ? 0 : UTF16);
}
/**
* Mix value length and coder into current length and coder.
* @param current current length
* @param value value to mix in
* @return new length and coder
* @param lengthCoder String length with coder packed into higher bits
* the upper word.
* @param value value to mix in
* @return new length and coder
*/
static long mix(long current, short value) {
return mix(current, (int)value);
static long mix(long lengthCoder, short value) {
return mix(lengthCoder, (int)value);
}
/**
* Mix value length and coder into current length and coder.
* @param current current length
* @param value value to mix in
* @return new length and coder
* @param lengthCoder String length with coder packed into higher bits
* the upper word.
* @param value value to mix in
* @return new length and coder
*/
static long mix(long current, int value) {
return checkOverflow(current + Integer.stringSize(value));
static long mix(long lengthCoder, int value) {
return checkOverflow(lengthCoder + Integer.stringSize(value));
}
/**
* Mix value length and coder into current length and coder.
* @param current current length
* @param value value to mix in
* @return new length and coder
* @param lengthCoder String length with coder packed into higher bits
* the upper word.
* @param value value to mix in
* @return new length and coder
*/
static long mix(long current, long value) {
return checkOverflow(current + Long.stringSize(value));
static long mix(long lengthCoder, long value) {
return checkOverflow(lengthCoder + Long.stringSize(value));
}
/**
* Mix value length and coder into current length and coder.
* @param current current length
* @param value value to mix in
* @return new length and coder
* @param lengthCoder String length with coder packed into higher bits
* the upper word.
* @param value value to mix in
* @return new length and coder
*/
static long mix(long current, String value) {
current += value.length();
static long mix(long lengthCoder, String value) {
lengthCoder += value.length();
if (value.coder() == String.UTF16) {
current |= UTF16;
lengthCoder |= UTF16;
}
return checkOverflow(current);
return checkOverflow(lengthCoder);
}
/**
@ -285,10 +297,62 @@ final class StringConcatHelper {
}
}
/**
* Perform a simple concatenation between two objects. Added for startup
* performance, but also demonstrates the code that would be emitted by
* {@code java.lang.invoke.StringConcatFactory$MethodHandleInlineCopyStrategy}
* for two Object arguments.
*
* @param first first argument
* @param second second argument
* @return String resulting string
*/
@ForceInline
static String simpleConcat(Object first, Object second) {
String s1 = stringOf(first);
String s2 = stringOf(second);
// start "mixing" in length and coder or arguments, order is not
// important
long indexCoder = mix(initialCoder(), s2);
indexCoder = mix(indexCoder, s1);
byte[] buf = newArray(indexCoder);
// prepend each argument in reverse order, since we prepending
// from the end of the byte array
indexCoder = prepend(indexCoder, buf, s2);
indexCoder = prepend(indexCoder, buf, s1);
return newString(buf, indexCoder);
}
/**
* We need some additional conversion for Objects in general, because
* {@code String.valueOf(Object)} may return null. String conversion rules
* in Java state we need to produce "null" String in this case, so we
* provide a customized version that deals with this problematic corner case.
*/
static String stringOf(Object value) {
String s;
return (value == null || (s = value.toString()) == null) ? "null" : s;
}
private static final long LATIN1 = (long)String.LATIN1 << 32;
private static final long UTF16 = (long)String.UTF16 << 32;
private static final Unsafe UNSAFE = Unsafe.getUnsafe();
/**
* Allocates an uninitialized byte array based on the length and coder information
* in indexCoder
* @param indexCoder
* @return the newly allocated byte array
*/
@ForceInline
static byte[] newArray(long indexCoder) {
byte coder = (byte)(indexCoder >> 32);
int index = (int)indexCoder;
return (byte[]) UNSAFE.allocateUninitializedArray(byte.class, index << coder);
}
/**
* Provides the initial coder for the String.
* @return initial coder, adjusted into the upper half

80
src/java.base/share/classes/java/lang/invoke/StringConcatFactory.java
View file

@ -1,5 +1,5 @@
/*
* Copyright (c) 2015, 2018, 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
@ -26,6 +26,7 @@
package java.lang.invoke;
import jdk.internal.misc.Unsafe;
import jdk.internal.misc.VM;
import jdk.internal.org.objectweb.asm.ClassWriter;
import jdk.internal.org.objectweb.asm.Label;
import jdk.internal.org.objectweb.asm.MethodVisitor;
@ -191,6 +192,8 @@ public final class StringConcatFactory {
*/
private static final ProxyClassesDumper DUMPER;
private static final Class<?> STRING_HELPER;
static {
// In case we need to double-back onto the StringConcatFactory during this
// static initialization, make sure we have the reasonable defaults to complete
@ -202,15 +205,20 @@ public final class StringConcatFactory {
// DEBUG = false; // implied
// DUMPER = null; // implied
Properties props = GetPropertyAction.privilegedGetProperties();
try {
STRING_HELPER = Class.forName("java.lang.StringConcatHelper");
} catch (Throwable e) {
throw new AssertionError(e);
}
final String strategy =
props.getProperty("java.lang.invoke.stringConcat");
VM.getSavedProperty("java.lang.invoke.stringConcat");
CACHE_ENABLE = Boolean.parseBoolean(
props.getProperty("java.lang.invoke.stringConcat.cache"));
VM.getSavedProperty("java.lang.invoke.stringConcat.cache"));
DEBUG = Boolean.parseBoolean(
props.getProperty("java.lang.invoke.stringConcat.debug"));
VM.getSavedProperty("java.lang.invoke.stringConcat.debug"));
final String dumpPath =
props.getProperty("java.lang.invoke.stringConcat.dumpClasses");
VM.getSavedProperty("java.lang.invoke.stringConcat.dumpClasses");
STRATEGY = (strategy == null) ? DEFAULT_STRATEGY : Strategy.valueOf(strategy);
CACHE = CACHE_ENABLE ? new ConcurrentHashMap<>() : null;
@ -1519,6 +1527,33 @@ public final class StringConcatFactory {
static MethodHandle generate(MethodType mt, Recipe recipe) throws Throwable {
// Fast-path two-argument Object + Object concatenations
if (recipe.getElements().size() == 2) {
// Two object arguments
if (mt.parameterCount() == 2 &&
!mt.parameterType(0).isPrimitive() &&
!mt.parameterType(1).isPrimitive()) {
return SIMPLE;
}
// One element is a constant
if (mt.parameterCount() == 1 && !mt.parameterType(0).isPrimitive()) {
MethodHandle mh = SIMPLE;
// Insert constant element
// First recipe element is a constant
if (recipe.getElements().get(0).getTag() == TAG_CONST &&
recipe.getElements().get(1).getTag() != TAG_CONST) {
return MethodHandles.insertArguments(mh, 0,
recipe.getElements().get(0).getValue());
} else if (recipe.getElements().get(1).getTag() == TAG_CONST &&
recipe.getElements().get(0).getTag() != TAG_CONST) {
return MethodHandles.insertArguments(mh, 1,
recipe.getElements().get(1).getValue());
}
// else... fall-through to slow-path
}
}
// Create filters and obtain filtered parameter types. Filters would be used in the beginning
// to convert the incoming arguments into the arguments we can process (e.g. Objects -> Strings).
// The filtered argument type list is used all over in the combinators below.
@ -1626,13 +1661,6 @@ public final class StringConcatFactory {
return mh;
}
@ForceInline
private static byte[] newArray(long indexCoder) {
byte coder = (byte)(indexCoder >> 32);
int index = (int)indexCoder;
return (byte[]) UNSAFE.allocateUninitializedArray(byte.class, index << coder);
}
private static MethodHandle prepender(Class<?> cl) {
return PREPENDERS.computeIfAbsent(cl, PREPEND);
}
@ -1659,16 +1687,15 @@ public final class StringConcatFactory {
}
};
private static final MethodHandle SIMPLE;
private static final MethodHandle NEW_STRING;
private static final MethodHandle NEW_ARRAY;
private static final ConcurrentMap<Class<?>, MethodHandle> PREPENDERS;
private static final ConcurrentMap<Class<?>, MethodHandle> MIXERS;
private static final long INITIAL_CODER;
static final Class<?> STRING_HELPER;
static {
try {
STRING_HELPER = Class.forName("java.lang.StringConcatHelper");
MethodHandle initCoder = lookupStatic(Lookup.IMPL_LOOKUP, STRING_HELPER, "initialCoder", long.class);
INITIAL_CODER = (long) initCoder.invoke();
} catch (Throwable e) {
@ -1678,8 +1705,9 @@ public final class StringConcatFactory {
PREPENDERS = new ConcurrentHashMap<>();
MIXERS = new ConcurrentHashMap<>();
SIMPLE = lookupStatic(Lookup.IMPL_LOOKUP, STRING_HELPER, "simpleConcat", String.class, Object.class, Object.class);
NEW_STRING = lookupStatic(Lookup.IMPL_LOOKUP, STRING_HELPER, "newString", String.class, byte[].class, long.class);
NEW_ARRAY = lookupStatic(Lookup.IMPL_LOOKUP, MethodHandleInlineCopyStrategy.class, "newArray", byte[].class, long.class);
NEW_ARRAY = lookupStatic(Lookup.IMPL_LOOKUP, STRING_HELPER, "newArray", byte[].class, long.class);
}
}
@ -1692,22 +1720,8 @@ public final class StringConcatFactory {
// no instantiation
}
private static class ObjectStringifier {
// We need some additional conversion for Objects in general, because String.valueOf(Object)
// may return null. String conversion rules in Java state we need to produce "null" String
// in this case, so we provide a customized version that deals with this problematic corner case.
private static String valueOf(Object value) {
String s;
return (value == null || (s = value.toString()) == null) ? "null" : s;
}
// Could have used MethodHandles.lookup() instead of Lookup.IMPL_LOOKUP, if not for the fact
// java.lang.invoke Lookups are explicitly forbidden to be retrieved using that API.
private static final MethodHandle INSTANCE =
lookupStatic(Lookup.IMPL_LOOKUP, ObjectStringifier.class, "valueOf", String.class, Object.class);
}
private static final MethodHandle OBJECT_INSTANCE =
lookupStatic(Lookup.IMPL_LOOKUP, STRING_HELPER, "stringOf", String.class, Object.class);
private static class FloatStringifiers {
private static final MethodHandle FLOAT_INSTANCE =
@ -1751,7 +1765,7 @@ public final class StringConcatFactory {
*/
static MethodHandle forMost(Class<?> t) {
if (!t.isPrimitive()) {
return ObjectStringifier.INSTANCE;
return OBJECT_INSTANCE;
} else if (t == float.class) {
return FloatStringifiers.FLOAT_INSTANCE;
} else if (t == double.class) {

7
test/micro/org/openjdk/bench/java/lang/StringConcat.java
View file

@ -1,5 +1,5 @@
/*
* Copyright (c) 2018 Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2018, 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
@ -62,6 +62,11 @@ public class StringConcat {
return "string" + stringValue;
}
@Benchmark
public String concatMethodConstString() {
return "string".concat(stringValue);
}
@Benchmark
public String concatConstIntConstInt() {
return "string" + intValue + "string" + intValue;