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8345465: Fix performance regression on x64 after JDK-8345120

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Reviewed-by: mcimadamore
This commit is contained in:
Per Minborg 2024-12-10 10:01:27 +00:00
parent 2979806c72
commit 06c44dd568
2 changed files with 29 additions and 24 deletions
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29
src/java.base/share/classes/jdk/internal/foreign/StringSupport.java
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@ -130,8 +130,8 @@ public final class StringSupport {
final long toOffset) {
final long length = toOffset - fromOffset;
segment.checkBounds(fromOffset, length);
if (length == 0) {
// The state has to be checked explicitly for zero-length segments
if (length < Byte.BYTES) {
// There can be no null terminator present
segment.scope.checkValidState();
throw nullNotFound(segment, fromOffset, toOffset);
}
@ -164,7 +164,8 @@ public final class StringSupport {
final long toOffset) {
final long length = toOffset - fromOffset;
segment.checkBounds(fromOffset, length);
if (length == 0) {
if (length < Short.BYTES) {
// There can be no null terminator present
segment.scope.checkValidState();
throw nullNotFound(segment, fromOffset, toOffset);
}
@ -199,19 +200,23 @@ public final class StringSupport {
final long toOffset) {
final long length = toOffset - fromOffset;
segment.checkBounds(fromOffset, length);
if (length == 0) {
if (length < Integer.BYTES) {
// There can be no null terminator present
segment.scope.checkValidState();
throw nullNotFound(segment, fromOffset, toOffset);
}
final long longBytes = length & LONG_MASK;
final long longLimit = fromOffset + longBytes;
long offset = fromOffset;
for (; offset < longLimit; offset += Long.BYTES) {
long val = SCOPED_MEMORY_ACCESS.getLongUnaligned(segment.sessionImpl(), segment.unsafeGetBase(), segment.unsafeGetOffset() + offset, !Architecture.isLittleEndian());
if (mightContainZeroInt(val)) {
for (int j = 0; j < Long.BYTES; j += Integer.BYTES) {
if (SCOPED_MEMORY_ACCESS.getIntUnaligned(segment.sessionImpl(), segment.unsafeGetBase(), segment.unsafeGetOffset() + offset + j, !Architecture.isLittleEndian()) == 0) {
return requireWithinStringSize(offset + j - fromOffset, segment, fromOffset, toOffset);
// For quad byte strings, it does not pay off to use long scanning on x64
if (!Architecture.isX64()) {
final long longBytes = length & LONG_MASK;
final long longLimit = fromOffset + longBytes;
for (; offset < longLimit; offset += Long.BYTES) {
long val = SCOPED_MEMORY_ACCESS.getLongUnaligned(segment.sessionImpl(), segment.unsafeGetBase(), segment.unsafeGetOffset() + offset, !Architecture.isLittleEndian());
if (mightContainZeroInt(val)) {
for (int j = 0; j < Long.BYTES; j += Integer.BYTES) {
if (SCOPED_MEMORY_ACCESS.getIntUnaligned(segment.sessionImpl(), segment.unsafeGetBase(), segment.unsafeGetOffset() + offset + j, !Architecture.isLittleEndian()) == 0) {
return requireWithinStringSize(offset + j - fromOffset, segment, fromOffset, toOffset);
}
}
}
}