1 files changed, 35 insertions, 0 deletions
diff --git a/lib/modti3.c b/lib/modti3.c
new file mode 100644
index 000000000..91ff8aa5d
--- /dev/null
+++ b/lib/modti3.c
@@ -0,0 +1,35 @@
+//===-- modti3.c - Implement __modti3 -------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements __modti3 for the compiler_rt library.
+//
+//===----------------------------------------------------------------------===//
+
+#if __x86_64
+
+#include "int_lib.h"
+
+tu_int __udivmodti4(tu_int a, tu_int b, tu_int* rem);
+
+// Returns: a % b
+
+ti_int
+__modti3(ti_int a, ti_int b)
+{
+    const int bits_in_tword_m1 = (int)(sizeof(ti_int) * CHAR_BIT) - 1;
+    ti_int s = b >> bits_in_tword_m1;  // s = b < 0 ? -1 : 0
+    b = (b ^ s) - s;                   // negate if s == -1
+    s = a >> bits_in_tword_m1;         // s = a < 0 ? -1 : 0
+    a = (a ^ s) - s;                   // negate if s == -1
+    ti_int r;
+    __udivmodti4(a, b, (tu_int*)&r);
+    return (r ^ s) - s;                // negate if s == -1
+}
+
+#endif