improve long-range decoder speed

on enwik9 at level 22 (which is almost a worst case scenario), speed improves by +7% on my laptop (415 -> 445 MB/s)
2018-11-08 12:47:46 -08:00
parent 8bed4012bd
commit 9126da5b5c
3 changed files with 14 additions and 12 deletions
@@ -1054,7 +1054,7 @@ ZSTD_decompressSequencesLong_body(
            seq_t const sequence = ZSTD_decodeSequenceLong(&seqState, isLongOffset);
            size_t const oneSeqSize = ZSTD_execSequenceLong(op, oend, sequences[(seqNb-ADVANCED_SEQS) & STORED_SEQS_MASK], &litPtr, litEnd, prefixStart, dictStart, dictEnd);
            if (ZSTD_isError(oneSeqSize)) return oneSeqSize;
-            PREFETCH(sequence.match);  /* note : it's safe to invoke PREFETCH() on any memory address, including invalid ones */
+            PREFETCH_L1(sequence.match); PREFETCH_L1(sequence.match + sequence.matchLength - 1); /* note : it's safe to invoke PREFETCH() on any memory address, including invalid ones */
            sequences[seqNb & STORED_SEQS_MASK] = sequence;
            op += oneSeqSize;
        }