From 37f375ddebbd0f2918c0036f7f9468bfd73cb86e Mon Sep 17 00:00:00 2001
From: Ilya Tokar <tokarip@google.com>
Date: Fri, 18 Nov 2022 21:51:44 +0000
Subject: [PATCH] Add prefetch to zippy decompess,

PiperOrigin-RevId: 489554313
---
 snappy.cc | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/snappy.cc b/snappy.cc
index c830fb9..903a7f7 100644
--- a/snappy.cc
+++ b/snappy.cc
@@ -69,6 +69,12 @@
 #include <arm_acle.h>
 #endif
 
+#if defined(__GNUC__)
+#define SNAPPY_PREFETCH(ptr) __builtin_prefetch(ptr, 0, 3)
+#else
+#define SNAPPY_PREFETCH(ptr) (void)(ptr)
+#endif
+
 #include <algorithm>
 #include <array>
 #include <cstddef>
@@ -1192,6 +1198,8 @@ std::pair<const uint8_t*, ptrdiff_t> DecompressBranchless(
       // The throughput is limited by instructions, unrolling the inner loop
       // twice reduces the amount of instructions checking limits and also
       // leads to reduced mov's.
+
+      SNAPPY_PREFETCH(ip+128);
       for (int i = 0; i < 2; i++) {
         const uint8_t* old_ip = ip;
         assert(tag == ip[-1]);