From 7a3444bf1f17f909188ed0dccf210a7301a2717d Mon Sep 17 00:00:00 2001
From: David CARLIER <devnexen@gmail.com>
Date: Wed, 10 Mar 2021 09:04:01 -0800
Subject: [PATCH] Mac M1 crc32 intrinsics ARM64 check support proposal (#7893)

Summary: Pull Request resolved: https://github.com/facebook/rocksdb/pull/7893

Reviewed By: ajkr

Differential Revision: D26050966

Pulled By: jay-zhuang

fbshipit-source-id: 9df2bb65d82defd7fad49d5369979b03e22d39c2
---
 util/crc32c_arm64.cc | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/util/crc32c_arm64.cc b/util/crc32c_arm64.cc
index e04e38c0c..a799fb605 100644
--- a/util/crc32c_arm64.cc
+++ b/util/crc32c_arm64.cc
@@ -19,6 +19,9 @@
 #ifndef HWCAP_PMULL
 #define HWCAP_PMULL (1 << 4)
 #endif
+#if defined(__APPLE__)
+#include <sys/sysctl.h>
+#endif
 
 #ifdef HAVE_ARM64_CRYPTO
 /* unfolding to compute 8 * 3 = 24 bytes parallelly */
@@ -43,6 +46,7 @@
 extern bool pmull_runtime_flag;
 
 uint32_t crc32c_runtime_check(void) {
+#if !defined(__APPLE__)
   uint64_t auxv = 0;
 #if defined(ROCKSDB_AUXV_GETAUXVAL_PRESENT)
   auxv = getauxval(AT_HWCAP);
@@ -50,9 +54,16 @@ uint32_t crc32c_runtime_check(void) {
   elf_aux_info(AT_HWCAP, &auxv, sizeof(auxv));
 #endif
   return (auxv & HWCAP_CRC32) != 0;
+#else
+  int r;
+  size_t l = sizeof(r);
+  if (sysctlbyname("hw.optional.armv8_crc32", &r, &l, NULL, 0) == -1) return 0;
+  return r == 1;
+#endif
 }
 
 bool crc32c_pmull_runtime_check(void) {
+#if !defined(__APPLE__)
   uint64_t auxv = 0;
 #if defined(ROCKSDB_AUXV_GETAUXVAL_PRESENT)
   auxv = getauxval(AT_HWCAP);
@@ -60,6 +71,9 @@ bool crc32c_pmull_runtime_check(void) {
   elf_aux_info(AT_HWCAP, &auxv, sizeof(auxv));
 #endif
   return (auxv & HWCAP_PMULL) != 0;
+#else
+  return true;
+#endif
 }
 
 #ifdef ROCKSDB_UBSAN_RUN