jpountz commented on a change in pull request #69:
URL: https://github.com/apache/lucene/pull/69#discussion_r608737981
##########
File path: lucene/core/src/java/org/apache/lucene/codecs/lucene90/PForUtil.java
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@@ -121,4 +167,146 @@ void skip(DataInput in) throws IOException {
in.skipBytes(forUtil.numBytes(bitsPerValue) + (numExceptions << 1));
}
}
+
+ /**
+ * Fill {@code longs} with the final values for the case of all deltas being
1. Note this assumes
+ * there are no exceptions to apply.
+ */
+ private static void prefixSumOfOnes(long[] longs, long base) {
+ System.arraycopy(IDENTITY_PLUS_ONE, 0, longs, 0, ForUtil.BLOCK_SIZE);
+ // This loop gets auto-vectorized
+ for (int i = 0; i < ForUtil.BLOCK_SIZE; ++i) {
+ longs[i] += base;
+ }
+ }
+
+ /**
+ * Fill {@code longs} with the final values for the case of all deltas being
{@code val}. Note
+ * this assumes there are no exceptions to apply.
+ */
+ private static void prefixSumOf(long[] longs, long base, long val) {
+ for (int i = 0; i < ForUtil.BLOCK_SIZE; i++) {
+ longs[i] = (i + 1) * val + base;
Review comment:
You need to look at the produced assembly. To do this I usually write a
JMH benchmark which I then run with `-prof perfasm` so that JMH shows me how
the assembly looks like for the hot code paths. Note that it requires libhsdis
to be dropped in the `lib` folder of your JDK.
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