From b25b721a6a85559971ef466703121d633a00ff41 Mon Sep 17 00:00:00 2001
From: SachinVin <sachinvinayak2000@gmail.com>
Date: Fri, 24 Apr 2020 21:23:38 +0530
Subject: [PATCH] a64_emiter: CountLeadingZeros intrinsic shortcuts

---
 src/backend/A64/emitter/a64_emitter.cpp | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/src/backend/A64/emitter/a64_emitter.cpp b/src/backend/A64/emitter/a64_emitter.cpp
index efdd5ffc..0718afb6 100644
--- a/src/backend/A64/emitter/a64_emitter.cpp
+++ b/src/backend/A64/emitter/a64_emitter.cpp
@@ -22,7 +22,16 @@ const int kWRegSizeInBits = 32;
 const int kXRegSizeInBits = 64;
 
 // The below few functions are taken from V8.
-int CountLeadingZeros(uint64_t value, int width) {
+int CountLeadingZeros(u64 value, int width) {
+#ifdef _MSC_VER
+    if (width == 64) {
+        return _CountLeadingZeros64(value);
+    }
+#else
+    if (width == 64) {
+        return __builtin_clzll(value);
+    }
+#endif
     // TODO(jbramley): Optimize this for ARM64 hosts.
     int count = 0;
     uint64_t bit_test = 1ULL << (width - 1);