1 files changed, 51 insertions, 0 deletions
diff --git a/contrib/llvm-project/compiler-rt/lib/builtins/multi3.c b/contrib/llvm-project/compiler-rt/lib/builtins/multi3.c
new file mode 100644
index 000000000000..d9d8b59cd3ef
--- /dev/null
+++ b/contrib/llvm-project/compiler-rt/lib/builtins/multi3.c
@@ -0,0 +1,51 @@
+//===-- multi3.c - Implement __multi3 -------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements __multi3 for the compiler_rt library.
+//
+//===----------------------------------------------------------------------===//
+
+#include "int_lib.h"
+
+#ifdef CRT_HAS_128BIT
+
+// Returns: a * b
+
+static ti_int __mulddi3(du_int a, du_int b) {
+  twords r;
+  const int bits_in_dword_2 = (int)(sizeof(di_int) * CHAR_BIT) / 2;
+  const du_int lower_mask = (du_int)~0 >> bits_in_dword_2;
+  r.s.low = (a & lower_mask) * (b & lower_mask);
+  du_int t = r.s.low >> bits_in_dword_2;
+  r.s.low &= lower_mask;
+  t += (a >> bits_in_dword_2) * (b & lower_mask);
+  r.s.low += (t & lower_mask) << bits_in_dword_2;
+  r.s.high = t >> bits_in_dword_2;
+  t = r.s.low >> bits_in_dword_2;
+  r.s.low &= lower_mask;
+  t += (b >> bits_in_dword_2) * (a & lower_mask);
+  r.s.low += (t & lower_mask) << bits_in_dword_2;
+  r.s.high += t >> bits_in_dword_2;
+  r.s.high += (a >> bits_in_dword_2) * (b >> bits_in_dword_2);
+  return r.all;
+}
+
+// Returns: a * b
+
+COMPILER_RT_ABI ti_int __multi3(ti_int a, ti_int b) {
+  twords x;
+  x.all = a;
+  twords y;
+  y.all = b;
+  twords r;
+  r.all = __mulddi3(x.s.low, y.s.low);
+  r.s.high += x.s.high * y.s.low + x.s.low * y.s.high;
+  return r.all;
+}
+
+#endif // CRT_HAS_128BIT