Initial import of compiler-rt.
-
git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@74292 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/multi3.c b/lib/multi3.c
new file mode 100644
index 0000000..8ba6550
--- /dev/null
+++ b/lib/multi3.c
@@ -0,0 +1,57 @@
+//===-- multi3.c - Implement __multi3 -------------------------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements __multi3 for the compiler_rt library.
+//
+//===----------------------------------------------------------------------===//
+
+#if __x86_64
+
+#include "int_lib.h"
+
+// 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.low = (a & lower_mask) * (b & lower_mask);
+ du_int t = r.low >> bits_in_dword_2;
+ r.low &= lower_mask;
+ t += (a >> bits_in_dword_2) * (b & lower_mask);
+ r.low += (t & lower_mask) << bits_in_dword_2;
+ r.high = t >> bits_in_dword_2;
+ t = r.low >> bits_in_dword_2;
+ r.low &= lower_mask;
+ t += (b >> bits_in_dword_2) * (a & lower_mask);
+ r.low += (t & lower_mask) << bits_in_dword_2;
+ r.high += t >> bits_in_dword_2;
+ r.high += (a >> bits_in_dword_2) * (b >> bits_in_dword_2);
+ return r.all;
+}
+
+// Returns: a * b
+
+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.low, y.low);
+ r.high += x.high * y.low + x.low * y.high;
+ return r.all;
+}
+
+#endif