From 5b7bf2e9d4ee02cbec1105ad6e890c34a4da1beb Mon Sep 17 00:00:00 2001
From: Hennadii Stepanov <32963518+hebasto@users.noreply.github.com>
Date: Sun, 4 Jun 2023 15:51:44 +0100
Subject: [PATCH] Use `__shiftright128` intrinsic in `secp256k1_u128_rshift` on
 MSVC

---
 src/int128_struct_impl.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/int128_struct_impl.h b/src/int128_struct_impl.h
index 990982da8..962a71d13 100644
--- a/src/int128_struct_impl.h
+++ b/src/int128_struct_impl.h
@@ -80,7 +80,12 @@ static SECP256K1_INLINE void secp256k1_u128_rshift(secp256k1_uint128 *r, unsigne
      r->lo = r->hi >> (n-64);
      r->hi = 0;
    } else if (n > 0) {
+#if defined(_MSC_VER) && defined(_M_X64)
+     VERIFY_CHECK(n < 64);
+     r->lo = __shiftright128(r->lo, r->hi, n);
+#else
      r->lo = ((1U * r->hi) << (64-n)) | r->lo >> n;
+#endif
      r->hi >>= n;
    }
 }