Skip to content

8318457: Use prefix-less prepend methods directly to reduce branches in String concat expressions #16244

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Closed
wants to merge 8 commits into from
Closed

8318457: Use prefix-less prepend methods directly to reduce branches in String concat expressions #16244

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
8 commits
Select commit Hold shift + click to select a range
ae7daf0
Only generate prepend with prefix on non-null constants to avoid bran…
cl4es Oct 18, 2023
fc74a96
Rename NULL to NO_PREFIX to better describe what these are for
cl4es Oct 18, 2023
780d0de
Merge branch 'master' into scf_less_branches
cl4es Oct 18, 2023
eb1883a
FormatItem should call prepend(long, byte[], String)
cl4es Oct 18, 2023
4e7dfc0
Naming consistency: noPrefixPrepender
cl4es Oct 18, 2023
2ad5c76
Make all prepend methods package-private
cl4es Oct 19, 2023
faa823d
dropLookupMode PRIVATE to ensure we don't accidentally use private me…
cl4es Oct 19, 2023
ca0ac91
drop dropLookupMode
cl4es Oct 19, 2023
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
29 changes: 14 additions & 15 deletions src/java.base/share/classes/java/lang/StringConcatHelper.java
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -138,7 +138,6 @@ static long mix(long lengthCoder, String value) {
@PreviewFeature(feature=PreviewFeature.Feature.STRING_TEMPLATES)
static long mix(long lengthCoder, FormatConcatItem value) {
lengthCoder = value.mix(lengthCoder);

return checkOverflow(lengthCoder);
}

Expand All @@ -152,7 +151,7 @@ static long mix(long lengthCoder, FormatConcatItem value) {
* @param value boolean value to encode
* @return updated index (coder value retained)
*/
private static long prepend(long indexCoder, byte[] buf, boolean value) {
static long prepend(long indexCoder, byte[] buf, boolean value) {
int index = (int)indexCoder;
if (indexCoder < UTF16) {
if (value) {
Expand Down Expand Up @@ -198,7 +197,7 @@ private static long prepend(long indexCoder, byte[] buf, boolean value) {
*/
static long prepend(long indexCoder, byte[] buf, boolean value, String prefix) {
indexCoder = prepend(indexCoder, buf, value);
if (prefix != null) indexCoder = prepend(indexCoder, buf, prefix);
indexCoder = prepend(indexCoder, buf, prefix);
return indexCoder;
}

Expand All @@ -212,7 +211,7 @@ static long prepend(long indexCoder, byte[] buf, boolean value, String prefix) {
* @param value char value to encode
* @return updated index (coder value retained)
*/
private static long prepend(long indexCoder, byte[] buf, char value) {
static long prepend(long indexCoder, byte[] buf, char value) {
if (indexCoder < UTF16) {
buf[(int)(--indexCoder)] = (byte) (value & 0xFF);
} else {
Expand All @@ -234,7 +233,7 @@ private static long prepend(long indexCoder, byte[] buf, char value) {
*/
static long prepend(long indexCoder, byte[] buf, char value, String prefix) {
indexCoder = prepend(indexCoder, buf, value);
if (prefix != null) indexCoder = prepend(indexCoder, buf, prefix);
indexCoder = prepend(indexCoder, buf, prefix);
return indexCoder;
}

Expand All @@ -248,7 +247,7 @@ static long prepend(long indexCoder, byte[] buf, char value, String prefix) {
* @param value integer value to encode
* @return updated index (coder value retained)
*/
private static long prepend(long indexCoder, byte[] buf, int value) {
static long prepend(long indexCoder, byte[] buf, int value) {
if (indexCoder < UTF16) {
return StringLatin1.getChars(value, (int)indexCoder, buf);
} else {
Expand All @@ -269,7 +268,7 @@ private static long prepend(long indexCoder, byte[] buf, int value) {
*/
static long prepend(long indexCoder, byte[] buf, int value, String prefix) {
indexCoder = prepend(indexCoder, buf, value);
if (prefix != null) indexCoder = prepend(indexCoder, buf, prefix);
indexCoder = prepend(indexCoder, buf, prefix);
return indexCoder;
}

Expand All @@ -283,7 +282,7 @@ static long prepend(long indexCoder, byte[] buf, int value, String prefix) {
* @param value long value to encode
* @return updated index (coder value retained)
*/
private static long prepend(long indexCoder, byte[] buf, long value) {
static long prepend(long indexCoder, byte[] buf, long value) {
if (indexCoder < UTF16) {
return StringLatin1.getChars(value, (int)indexCoder, buf);
} else {
Expand All @@ -304,7 +303,7 @@ private static long prepend(long indexCoder, byte[] buf, long value) {
*/
static long prepend(long indexCoder, byte[] buf, long value, String prefix) {
indexCoder = prepend(indexCoder, buf, value);
if (prefix != null) indexCoder = prepend(indexCoder, buf, prefix);
indexCoder = prepend(indexCoder, buf, prefix);
return indexCoder;
}

Expand All @@ -318,7 +317,7 @@ static long prepend(long indexCoder, byte[] buf, long value, String prefix) {
* @param value String value to encode
* @return updated index (coder value retained)
*/
private static long prepend(long indexCoder, byte[] buf, String value) {
static long prepend(long indexCoder, byte[] buf, String value) {
indexCoder -= value.length();
if (indexCoder < UTF16) {
value.getBytes(buf, (int)indexCoder, String.LATIN1);
Expand All @@ -341,7 +340,7 @@ private static long prepend(long indexCoder, byte[] buf, String value) {
*/
static long prepend(long indexCoder, byte[] buf, String value, String prefix) {
indexCoder = prepend(indexCoder, buf, value);
if (prefix != null) indexCoder = prepend(indexCoder, buf, prefix);
indexCoder = prepend(indexCoder, buf, prefix);
return indexCoder;
}

Expand All @@ -357,8 +356,7 @@ static long prepend(long indexCoder, byte[] buf, String value, String prefix) {
* @since 21
*/
@PreviewFeature(feature=PreviewFeature.Feature.STRING_TEMPLATES)
private static long prepend(long indexCoder, byte[] buf,
FormatConcatItem value) {
static long prepend(long indexCoder, byte[] buf, FormatConcatItem value) {
try {
return value.prepend(indexCoder, buf);
} catch (Error ex) {
Expand All @@ -384,7 +382,7 @@ private static long prepend(long indexCoder, byte[] buf,
static long prepend(long indexCoder, byte[] buf,
FormatConcatItem value, String prefix) {
indexCoder = prepend(indexCoder, buf, value);
if (prefix != null) indexCoder = prepend(indexCoder, buf, prefix);
indexCoder = prepend(indexCoder, buf, prefix);
return indexCoder;
}

Expand Down Expand Up @@ -586,7 +584,8 @@ static MethodHandle selectPutChar(long indexCoder) {

static MethodHandle lookupStatic(String name, MethodType methodType) {
try {
return MethodHandles.lookup().findStatic(StringConcatHelper.class, name, methodType);
return MethodHandles.lookup()
.findStatic(StringConcatHelper.class, name, methodType);
} catch (NoSuchMethodException|IllegalAccessException e) {
throw new AssertionError(e);
}
Expand Down
31 changes: 19 additions & 12 deletions src/java.base/share/classes/java/lang/invoke/StringConcatFactory.java
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -700,19 +700,12 @@ private static MethodHandle foldInLastMixers(MethodHandle mh, long initialLength
// Simple prependers, single argument. May be used directly or as a
// building block for complex prepender combinators.
private static MethodHandle prepender(String prefix, Class<?> cl) {
MethodHandle prepend;
int idx = classIndex(cl);
if (prefix == null) {
prepend = NULL_PREPENDERS[idx];
if (prepend == null) {
NULL_PREPENDERS[idx] = prepend = MethodHandles.insertArguments(
prepender(cl), 3, (String)null);
}
if (prefix == null || prefix.isEmpty()) {
return noPrefixPrepender(cl);
} else {
prepend = MethodHandles.insertArguments(
return MethodHandles.insertArguments(
prepender(cl), 3, prefix);
}
return prepend;
}

private static MethodHandle prepender(Class<?> cl) {
Expand All @@ -729,6 +722,20 @@ private static MethodHandle prepender(Class<?> cl) {
return prepend;
}

private static MethodHandle noPrefixPrepender(Class<?> cl) {
int idx = classIndex(cl);
MethodHandle prepend = NO_PREFIX_PREPENDERS[idx];
if (prepend == null) {
if (idx == STRING_CONCAT_ITEM) {
cl = FormatConcatItem.class;
}
NO_PREFIX_PREPENDERS[idx] = prepend = JLA.stringConcatHelper("prepend",
methodType(long.class, long.class, byte[].class,
Wrapper.asPrimitiveType(cl))).rebind();
}
return prepend;
}

private static final int INT_IDX = 0,
CHAR_IDX = 1,
LONG_IDX = 2,
Expand Down Expand Up @@ -995,7 +1002,7 @@ private static MethodHandle unaryConcat(Class<?> cl) {
}
}

private static final @Stable MethodHandle[] NULL_PREPENDERS = new MethodHandle[TYPE_COUNT];
private static final @Stable MethodHandle[] NO_PREFIX_PREPENDERS = new MethodHandle[TYPE_COUNT];
private static final @Stable MethodHandle[] PREPENDERS = new MethodHandle[TYPE_COUNT];
private static final @Stable MethodHandle[] MIXERS = new MethodHandle[TYPE_COUNT];
private static final long INITIAL_CODER = JLA.stringConcatInitialCoder();
Expand Down Expand Up @@ -1117,7 +1124,7 @@ public static MethodHandle makeConcatWithTemplate(

Class<?> ttype = ttypes[pos];
// (long,byte[],ttype) -> long
MethodHandle prepender = prepender(fragment.isEmpty() ? null : fragment, ttype);
MethodHandle prepender = prepender(fragment, ttype);
// (byte[],long,ttypes...) -> String (unchanged)
mh = MethodHandles.filterArgumentsWithCombiner(mh, 1, prepender,1, 0, 2 + pos);

Expand Down
5 changes: 2 additions & 3 deletions src/java.base/share/classes/java/util/FormatItem.java
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -61,7 +61,7 @@ class FormatItem {
private static final MethodHandle STRING_PREPEND =
JLA.stringConcatHelper("prepend",
MethodType.methodType(long.class, long.class, byte[].class,
String.class, String.class));
String.class));

private static final MethodHandle SELECT_GETCHAR_MH =
JLA.stringConcatHelper("selectGetChar",
Expand All @@ -87,8 +87,7 @@ private static long stringMix(long lengthCoder, String value) {

private static long stringPrepend(long lengthCoder, byte[] buffer,
String value) throws Throwable {
return (long)STRING_PREPEND.invokeExact(lengthCoder, buffer, value,
(String)null);
return (long)STRING_PREPEND.invokeExact(lengthCoder, buffer, value);
}

private static MethodHandle selectGetChar(long indexCoder) throws Throwable {
Expand Down