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pjfanning pushed a commit to branch main
in repository https://gitbox.apache.org/repos/asf/pekko.git
The following commit(s) were added to refs/heads/main by this push:
new cbd431bd6d ByteStrings: cross-boundary swar (#3430)
cbd431bd6d is described below
commit cbd431bd6d5e7ba1e32c9e91ff5402732aec2696
Author: PJ Fanning <[email protected]>
AuthorDate: Sat Aug 15 13:34:01 2026 +0100
ByteStrings: cross-boundary swar (#3430)
---
.../scala/org/apache/pekko/util/ByteString.scala | 65 ++++++++++++++++------
1 file changed, 47 insertions(+), 18 deletions(-)
diff --git a/actor/src/main/scala/org/apache/pekko/util/ByteString.scala
b/actor/src/main/scala/org/apache/pekko/util/ByteString.scala
index bf551fe380..af10c991a9 100644
--- a/actor/src/main/scala/org/apache/pekko/util/ByteString.scala
+++ b/actor/src/main/scala/org/apache/pekko/util/ByteString.scala
@@ -1393,15 +1393,29 @@ object ByteString {
if (offset + java.lang.Long.BYTES <= firstLen)
first.readLongBEUnchecked(offset)
else if (offset >= firstLen) second.readLongBEUnchecked(offset -
firstLen)
else {
- SWARUtil.getLongBE(
- byteAt(offset, firstLen),
- byteAt(offset + 1, firstLen),
- byteAt(offset + 2, firstLen),
- byteAt(offset + 3, firstLen),
- byteAt(offset + 4, firstLen),
- byteAt(offset + 5, firstLen),
- byteAt(offset + 6, firstLen),
- byteAt(offset + 7, firstLen))
+ // Cross-boundary: build two sub-longs from byteAtUnchecked and
combine.
+ // byteAtUnchecked is a single virtual call per byte (no extra branch
per byte),
+ // and the Long assembly is pure arithmetic with no per-byte branching.
+ val split = firstLen - offset // bytes in first fragment (1-7)
+ val firstPart = {
+ var i = offset
+ var v = 0L
+ while (i < firstLen) {
+ v = (v << 8) | (first.byteAtUnchecked(i).toLong & 0xFF)
+ i += 1
+ }
+ v << ((8 - split) << 3)
+ }
+ val secondPart = {
+ var j = 0
+ var v = 0L
+ while (j < 8 - split) {
+ v = (v << 8) | (second.byteAtUnchecked(j).toLong & 0xFF)
+ j += 1
+ }
+ v
+ }
+ firstPart | secondPart
}
}
@@ -1410,15 +1424,30 @@ object ByteString {
if (offset + java.lang.Long.BYTES <= firstLen)
first.readLongLEUnchecked(offset)
else if (offset >= firstLen) second.readLongLEUnchecked(offset -
firstLen)
else {
- SWARUtil.getLongLE(
- byteAt(offset, firstLen),
- byteAt(offset + 1, firstLen),
- byteAt(offset + 2, firstLen),
- byteAt(offset + 3, firstLen),
- byteAt(offset + 4, firstLen),
- byteAt(offset + 5, firstLen),
- byteAt(offset + 6, firstLen),
- byteAt(offset + 7, firstLen))
+ val split = firstLen - offset
+ val firstPart = {
+ var i = offset
+ var v = 0L
+ var shift = 0
+ while (i < firstLen) {
+ v |= (first.byteAtUnchecked(i).toLong & 0xFF) << shift
+ shift += 8
+ i += 1
+ }
+ v
+ }
+ val secondPart = {
+ var j = 0
+ var v = 0L
+ var shift = split << 3
+ while (j < 8 - split) {
+ v |= (second.byteAtUnchecked(j).toLong & 0xFF) << shift
+ shift += 8
+ j += 1
+ }
+ v
+ }
+ firstPart | secondPart
}
}
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