[PATCH v2 3/7] include: Add a _umul128 intrinsic definition.

[Rémi Bernon]

From: Rémi Bernon

---
 include/msvcrt/intrin.h |  4 ++++
 include/winnt.h         | 14 ++++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/include/msvcrt/intrin.h b/include/msvcrt/intrin.h
index ba825b7b09e..03d856c5933 100644
--- a/include/msvcrt/intrin.h
+++ b/include/msvcrt/intrin.h
@@ -90,6 +90,10 @@ unsigned __int64 __getReg(int);

#endif

+#if defined(_MSC_VER) && defined(__x86_64__)
+unsigned __int64 _umul128(unsigned __int64,unsigned __int64,unsigned __int64*);
+#endif
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/include/winnt.h b/include/winnt.h
index c810830b2b3..794970a35f5 100644
--- a/include/winnt.h
+++ b/include/winnt.h
@@ -7397,6 +7397,20 @@ static FORCEINLINE void YieldProcessor(void)
 #endif
 }

+#if defined(_MSC_VER) && !defined(__arm64ec__) && (!defined(__clang__) || __has_builtin(_umul128))
+#define UnsignedMultiply128 _umul128
+DWORD64 _umul128(DWORD64,DWORD64,DWORD64*);
+#pragma intrinsic(_umul128)
+#elif !defined(__i386__)
+static FORCEINLINE DWORD64 UnsignedMultiply128( DWORD64 a, DWORD64 b, DWORD64 *hi )
+{
+    unsigned __int128 v = (unsigned __int128)a * b;
+    *hi = v >> 64;
+    return (DWORD64)v;
+}
+#define _umul128 UnsignedMultiply128
+#endif
+
 #ifdef __cplusplus
 }
 #endif